Slashdot Mirror
Neil deGrasse Tyson On How To Stop a Meteor Hitting the Earth
An anonymous reader writes "Astrophysicist Neil deGrasse Tyson talks stopping extinction-level meteor hits: '...Here in America, we're really good at blowing stuff up and less good at knowing where the pieces land, you know...So, people who have studied the problem generally – and I'm in this camp – see a deflection scenario is more sound and more controllable. So if this is the asteroid and it's sort of headed toward us, one way is you send up a space ship and they'll both feel each other. And the space ship hovers. And they'll both feel each other's gravity. And they want to sort of drift toward one another. But you don't let that happen. You set off little retro rockets that prevent it. And the act of doing so slowly tugs the asteroid into a new orbit.'"
that feel when you're feeling another's feel in space
Reads more like an article on his talking about How other people talk about stopping one from hitting the earth.
The blast from the little retro rockets hitting the much larger asteroid, will cancel the whole thing out - every action having an equal and opposite reaction and all that pesky old Newtonian conservation of momentum stuff...
Excuse me, but please get off my Pennisetum Clandestinum, eh!
The "pull" between a spaceship and an asteroid would be equal to the apparent weight of the spaceship on its surface, decreased by the square of the distance between the two objects. This would reduce the traction to a very limited amount.
You'd get better results with a cable from the ship attached to the surface, but the problem would be the rotation of both objects.
To do a decent job, the spaceship would need to collect a large quantity of mass before attempting to drag the asteroid.
Speaking as an non American can I say that you are really REALLY good at blowing stuff up and shooting stuff too.
I agree, he's great for explaining stupid shit to proles, but as far as a professional scientist goes he has very little credibility in my book.
Great. You'd be comfortable with this future:
Scientists: By the way, there is a huge hunk of rock that is going to hit the earth tomorrow and wipe us all out.
Public: Wait - what? Why didn't you warn us?
Scientists: We discussed it at length at our obscure meetings. Why should we have to take time out of our important work to explain complicated shit in your terms? Stupid proles.
If Slashdot were chemistry it would look like this:Cadaverine
We blow shit up so well is because we understand that accuracy by volume is the best way to hit your target. What makes this guy think anyone's going to meet up with an asteroid traveling at who knows what speed.
I agree, he's great for explaining stupid shit to proles, but as far as a professional scientist goes he has very little credibility in my book.
It's scientists like him that are personable and able to "explain stupid shit to proles" that help keep people interested in science and help make sure the scientists in your "credibility book" get enough funding from the proles to do their work.
Maybe I'm having a hard time understanding what he's talking about, but this sounds like a violation of Newtons III at a glance. Suppose you have an asteroid in space, and a rocket beside it. The asteroid attracts the rocket, and likewise the rocket the asteroid. For the rocket to "tug" the asteroid away, it will have to use some sort of propulsion, and all we really have are momentum-exchange drives - rockets, ion-thrusters, ect. To move, it must thrust with a larger force than the force of gravity, in exactly the opposite direction of the gravitiational force vector. The problem is, those particles used for thrusting the rocket, will impact the asteroid as well, assuming the asteroid is large enough to worry about moving. Even worse, some of them may even recoil! Wouldn't this absorbtion of momentum of the ions, gas, ect, undo the "tug" of the rocket in the first place?
That's what stopped that meteor in Russia.
Pretty sure this solution was given... decades ago.
Why do you say that? He's an established scientist and has a Bachelors in Physics and a Graduate/PH-D in Astrophysics. He's held positions at several universities and is the director of the Hayden Planetarium. Sure he goes on television more than your average physicist, but so did Carl Sagan. He's charismatic, and it works well for him. Nothing wrong with that.
Dr. Phil is a pool of waste that puts people on television and exposes their issues to millions of viewers, for the ratings and a fat pay check. He doesn't add anything to his profession, and his discussions on television don't enlighten anyone.
There's a huge difference.
Come on people, we need to mix up our delusions! It's more fun that way!
Or alternately, how big will the spaceship need to be? How quick would the space ship need to be for gravity to have any impact? Would it work on an asteroid couple of miles across, moving at say 25km a sec, which I am told is the average orbital speed?
More questions than answers I say.
If you are going to use this method, then the more mass in your ship the better. Unfortunately, that means a more expensive launch. If you plan ahead, you figure out a way to accumulate debris and smaller rocks at some stable orbital point so when you need mass you can launch a light ship, go to the rockyard, and gather up more mass at reduced cost.
If Slashdot were chemistry it would look like this:Cadaverine
The whole idea is conceptually idiotic. You spend a strong force of reaction mass ejection to maintain a weak force of gravity at a constant distance from the target mass producing a microscopic tug on the object. This guy must have received his degree in a box of crackerjack. .5 times 1.0 x -9. .5 x 1.0-9 x t x t
Place the reaction mass generator (be it ion jet, or rocket) directly on the mass and divert it. If this is done at a large distance, the force needed is quite small, and calculable.. Large explosions will also fragment the mass, if they are placed so explosive force is trapped and bursts the object from within. A mountain of gravel will fragment as it hits the atmosphere, but it is preferable to scatter it in advance so the impact is spread both in time and in space. A solid iron mass is the worst case for explosive disruption - needing many drilled holes and many explosives and it will resist fragmentation. It will also be most amenable to the reaction mass approach since it will provide a solid mounting surface and torque as well as thrust be be applied. If you emplace a one pound force thrust mechanism on a million ton mass, how much time is needed to move it one earth diameter.? One million tons = 2 billion pounds. Acceleration of
s =5 a tt = 42 million feet =
t x t = 42,000,000/.5 x 10--9 = 84,000,000 x 1.0 +9 = 84,000,000,000,000,000 ~300,000,000 seconds One year = ~32 million seconds, so you need 10 years of one pound and one year of 10 pounds thrust to move it one earth diameter. This is just rough math, so an error of 10 might be in there?
I usually welcome hearing Tyson's latest addition to lay science understanding.
I sort of like character-celebrity-scientists. Mister Wizard, Bill Nye, and local college instructor / news-show scientist "Chemical Kim" are just a few of the scientists I applaud for their work in bringing science to the masses as a fun and interesting subject.
I don't like the stand-in experts like Michiu Kaku or Tyson, who take a different tack of bringing science to just a large audience, not really packaged for the masses at all, often with their own opinions added, and typically very pompously presented.
Tyson manages to keep my respect by being relatively sane and mainstream, basing his conclusions and projections on "establishment" science.
I can't say the same for Kaku, who I haven't heard from in awhile because I purposefully stop visiting web sites and stop listening to radio shows that give him a podium (no, this is not a viable way to get me to stop visiting /.)
But Tyson also manages to capture my interest by doing the same thing Bill Nye does: making comments about human affairs and human nature. They both humanize science.
But Tyson's pomposity sort of makes it hard for me to "like" him. And I just read something about him recently, so now it's like a second serving of buttered scallops when I clearly had trouble finishing the first serving.
"Stratigraphically the origin of agriculture and thermonuclear destruction will appear essentially simultaneous" -- Lee
he's gone downhill since he was the star on Doogie Howser.
rewriting history since 2109
Sure. Use rockets to get away from a close objet in vacum. Gravity is square root of distance and you use reaction engines is space. You see the pbm ? You push on the asteriod as much as you pull him. Too bad. bootstraping not a great concept in space me dynamics.
- Captain ! It works ! The aster moves towards us ! We saved mankind !
- Good. Now fire the rockets to bring him away.
- Captain when we fire the rockets it seems to push him away and send it back to earth
- Damn. You mean just like when we use rockets on earth to lift off ? That's a big surprise. Nobody ever though about that back there ? Are they really that stupid ? WTF saving them ? Lets leave them to their fate.
- Captain. What if we land on the other side and fire keep pushing from there ?
- Really ? Allo Houston ?
If you change its orbit, the meteor may be set on a collision course in a later go-around. What you want to do is change its orbit so all future approaches are farther from impacting earth, not just this time. Another-words, pay attention to what you are doing. Do not just do something short term.
wake up and hold your nose
the EM drive has no emissions:
http://en.wikipedia.org/wiki/EmDrive
Some drink at the fountain of knowledge. Others just gargle.
That comment is so incredibly stupid that I wonder if it may have been typed by Dr Phil himself.
But, he just stomped on the idea for the Open Crowd Source Asteroids Initiative.
A giant bank of lasers spread over the Earth activated by an online MMG of people playing a "free" version of " Asteroids" fed by satellite for positioning and trajectory.
Some people just have no imagination...
*Repent!Quit Your Job!Slack Off!The World Ends Tomorrow and You May Die!
Not Mike Tyson, it's Neil De Grasse Tyson, Miss Latella.
*Repent!Quit Your Job!Slack Off!The World Ends Tomorrow and You May Die!
Using gravity to slowly nudge an asteroid from its trajectory is impractical and a foolish suggestion. Why?
All asteroids large enough to make this work are known and known not to collide with earth. All asteroids that are a threat to earth are small, unknown and liable to be discovered only a relatively short time - certainly not decades - before impacting earth. There is also good reason to expect those to be more common than the claim that they only hit earth "once a century". A typical dangerous asteroid to be discovered will measure between 15m and 100m. That's a simple matter of the chance to detect such asteroids being very small, while the numbers in which they occur are much larger than anything in the several 100m or km class.
We also happen to have just right stuff to do something about the typical asteroids - rockets capable to carry a few tons of stuff beyond earth orbit, anywhere within the solar system. Crash a compact impactor (lead, steel, depleted uranium ... whatever) into the asteroid at your typical speed of 10km/s or more (depending on the exact trajectory and propulsion used) and the kinetic energy released will be sufficient to break it up into small enough pieces. Each ton of material impacting at this speed has the energy of four Tallboy bombs. Those had enough energy to make craters 24m deep and 30m wide on earth.
This works because the large energy is carried by a small mass with little momentum of itself, which means that the energy will be released in all directions, just like a conventional bomb would. Such a collision creates debris small enough to burn up harmlessly in the atmosphere (albeit in spectacular fashion).
"Knowing where the pieces land" seems like a red herring.
If we detect an asteroid a long way out on a collision course with Earth, then altering its velocity by just a bit will push it off of course and it'll miss us. If you set off an explosion near an asteroid, it will indeed likely fragment, but the only way we're still getting hit is if a large chunk somehow gets *no* delta-v from the explosion, and if that chunk is big enough to survive reentry.
OTOH, if we detect a big asteroid close to us, there may not be time for these things, and we need a large impulse quickly.
Either way, "nuke it" seems like the most sensible thing. Yes, this is a drastic thing, but if it's a true doomsday asteroid then it's called for.
Wouldn't it just be better to smack into one side of the asteroid at full speed rather than use a bunch of energy to get to the asteroid, a bunch more to slow down and rendezvous, then use little puffs of energy to try and modify its orbit?
Seems to me that all that reaction mass would be much better served by hitting the rock traveling at 4X,000 MPH.
I am very small, utmostly microscopic.
Yep. Surely it's far better to fire a cable at it and give it a good pull at 100% engine thrust than wait for a microscopic amount of gravity to have an effect.
No sig today...
Actually according to Doug Adams definitive history:
On a planet called Golgafrincham there was an an nouncement that the planet would soon be destroyed in a great catastrophe They planned an evacuation using a group of arcs:.
The passengers of the “A” ark were to be all the brilliant leaders, scientists, great musicians, data analysts, engineers and architects. The passengers of the “B” ark were to be all the “middle men” , marketing executives, telephone sanitizers , sales assistants and telemarketers etc. The passengers of the “C” ark were to be the real workers, construction, manufacturing and other craftsman.
As I remember it, everyone fought for a place on the B Arc which blasted off into space programmed to land on the third planet of an obscure star at the edge of the galaxy. Shortly after its departure, they discovered it was all a mistake and the planet was not going to be destroyed.
Golgafrincham entered into a period of exceptional peace and prosperity.
The planet that was the destination of the B Arc had a different kind of history.
When you are dancing with wolves, never limp
Im glad he stopped tweeting retarded shit that didnt even make sense in an attempt to look smart, and is doing actual science. Its hard to have respect for someone who claims a cars performance is based only on horsepower, cant understand why we use horsepower to measure engine output, yet uses AUs in his field of work every day, which are also relativistic non metric units of measurement.
Worst...
Writing...
Ever
In the course of about seven paragraphs, he manages to take a shot at America twice (good at blowing things up and not dealing with the fallout, if American politicians find out about an extinction level asteroid hitting in 100 years time they'll just kick the can down the road).
I'm not saying that those two observations are false in more general terms, but what evidence does he have that we act that way when dealing with real civilization threats or difficult engineering challenges? He's talking about the one country that has actually landed people on the moon and brought them back - we may have (sadly in my view) changed priorities since then, but we've shown we can do it if we want/need to. And we've generally picked the right side on civilization threats (against fascism, totalitarianism, etc.) - not a perfect record, of course, but compared to the other great powers of the past few centuries, certainly on the better side of the curve (which of the following have we been significantly worse than in the past two hundred years - British Empire, Soviet Union, Germany, Imperial Japan, China?).
The more likely scenario is having to deal with 15 different but legitimate theories and methods to perform the deflection (the gravity solution he prefers, changing the albedo, giving it a nudge, etc.) and either some analysis paralysis based off that or panicked politicians picking the wrong one. Even we Ammurkins have seen enough killer asteroid movies to know something should be done. Heck, if SpaceX marketed it right, it could be a self-financing private venture posing as a movie...
Diffrent kind of future. US.
We don't have to follow the "fight fire with fire" methodology. If the weakest force in the universe is pulling an asteroid towards the earth, we needn't use the weakest force in the universe to steer it away. The electromagnetic force is 10^36 times more powerful. Superconducting magnets require only the energy to get them started and keep them cool. Most asteroids are more than one part in a undecillion feromagnetic. So make use of it. And if threat happens to be composed of a diamagnetic material (e.g. comet water), use that to repel it away. Using gravity is just daft unless you have no alternative.
There is already a plan to test deflecting an asteroid by impact.
Actually, they died by a mysterious virus spread through their filthy phones unless I'm mistaken.
All asteroids large enough to make this work are known and known not to collide with earth.
All presently known asteroids large enough...
Fixed that for you. We find things in space all the time that we weren't aware of before. You are claiming we know of every body that could possibly threaten us when we cannot possibly be certain of that.
Golgafrincham entered into a period of exceptional peace and prosperity.
Um, no. They all died from a virulent disease contracted from a dirty telephone.
No sig today...
Oh, I get it - whitey made science but can't spell worth a damn. Makes perfect sense.
How come Slashdot never gets Slashdotted?
Why can't we go the dinosaur way? What's wrong with that? When it's time it's time. It's extinction! Why bother extending our pathetic time slice on earth? I'd sort of feel good knowing that everyone is going to die the same day as me.
He doesn't add anything to his profession
I disagree. I think he's a great example for other circus performers.
The idea of using gravity (the proper name is Gravity Tractor) to deflect incoming rocks has been around for some years now - and it wasn't Neil's idea.
This might work too if you remember to have them closely orbiting together...
Everything I write is lies, read between the lines.
Others have pointed out the folly of getting rid of the Telephone Sanitization Engineers, but I'd like to point out that it wasn't a mistake. The B Ark people thought it was a mistake, yes, but it was clearly an organized effort to get rid of all the useless jackasses on their planet. It's too bad they misclassified theTelephone Sanitization Engineers,
There have been a lot of discussions about these asteroid scenarios. The real trick, is to identify the threat early. The doctor is right, we're good at blowing things up, then wondering where shit's going to land. That's why it's so important to identify the threat early. If you can send out an impactor rocket months before the projected impact, then you can use a small amount of power to move the asteroid into a new orbit. We like making things go "boom", with or without the audible "boom". So, give the rocket a big explosive warhead. Hell, give it a nuke. Land or hit the asteroid on the side, not head on. Blow your rocket up, watch how the orbit changes, and if necessary hit it with a second blast. No big problem. If you actually fracture the asteroid, and you now have two or three large pieces, watch them long enough to decide if any of them are still a hazard. Send another rocket as necessary.
I'm not averse to blowing things up, but it probably isn't necessary. Early intervention will probably mean that the rocket can just land on one side or another, and fire it's rockets long enough to alter the course of the asteroid.
That space tugboat idea just doesn't seem like it's going to be very effective. Firing your rockets in various directions, while hoping the asteroid follows you around? Some of that reaction mass is going to hit the asteroid, negating your feeble gravity tugging efforts.
"Windows is like the faint smell of piss in a subway: it's there, and there's nothing you can do about it." - Charlie Br
Let the meteor come!
The proposal I heard before was to use a smaller asteroid which could be moved more easily. Shift the smaller asteroid into a moon like orbit of the large mass to shift it's trajectory by less than a degree years before impact. An explosion would take care of a smaller object like the one that exploded over Russia but a KT sized one would need a larger nuke than we can make or numerous smaller explosions just to fragment it. If we were unlucky enough to have an iron asteroid that size headed for us a nuke would be like hitting a cannon ball with a hammer. You'd be lucky to scratch the surface. The point is if you can detect them decades ahead of impact then a smaller asteroid could be used to deflect it. Others have proposed the tugboat approach so there must be something in the math to make it practical. One problem with your math is it's all dependent on the mass of the tug boat rocket so without that number how can you do any calculations? It's why most proposals have talked about using an asteroid for mass. An elliptical orbit would cause pressure on the main asteroid with each orbit. By adjusting the orbit and applying thrust at the right point you should be able to increase the affect.
Remember, best block, no be there.
If Sam Kinison were alive today, he'd apply his philosophy on world hunger and say:
You want to help end extinction-level meteors? Stop sending up shit to blow them up. Don't send them another one, send up huge orbit-altering rockets. Send the UN a guy that says, "You know, we've been coming up with a plan to blow up meteors for about 35 years now and we were blowing stuff up, and we realized there wouldn't BE extinction-level meteors if you people would live where the METEORS AREN'T! YOU LIVE INSIDE AN ASTEROID BELT!! UNDERSTAND THAT? YOU LIVE IN A FUCKING ASTEROID BELT!! Stop wasting rockets by launching them at each other. You too, North Korea... don't give me that look. We're going to do this together in one shot.
The most-effective solution is don't be where the meteor is going to be. This worked well for me the other week. Giant meteor fell in Siberia and I wasn't there.
The whole idea is conceptually idiotic. You spend a strong force of reaction mass ejection to maintain a weak force of gravity at a constant distance from the target mass producing a microscopic tug on the object. This guy must have received his degree in a box of crackerjack.
Place the reaction mass generator (be it ion jet, or rocket) directly on the mass and divert it.
Amazing that they didn't think of that!!! You must be a genius...
Or... maybe they did consider that, then realised that many, many small asteroids are apparently heaps of weakly bound rubble, just as bad as a solid object when hitting the surface of earth, but impossible to attach a rocket to.
The "gravity tug" concept works the same regardless of the structural integrity of the asteroid, *that* is why this is the proposed mechanism, not because Tyson is stupid...
Bet you feel a lot less like a genius now, smarty-pants?
No, I'm not religious at all, don't believe in any gods, but if a big ass asteroid was coming to hit earth, it is obviously God's fault.
After all, this is all according to God's plan, and if he wants to destroy the earth, who are we to complain?
Seriously, though, if a big ass Asteroid is going to hit earth, it's going to hit earth, no shit you will think of will change that. Start worrying about problems that affect us, not shit that might, maybe, in a small chance in hell, happen.
Be seeing you...
If we worry about a 2 km dia asteroid (rough sphere) it weighs 15 BILLION TONS.
Putting enough energy on over a year or two to pull the asteroid say 10,000 miles is going to be one hell of an amount of energy every second of the year. We don't have that sort of energy source we can deploy that I'm aware of.
Orson Scott Card appreciates your use of his imaginative solution to a similar - albeit far-fetched - threat.
Browsing at +1 - no ACs, I ignore their posts. So refreshing!
Do you work for a for-profit, or even well-known non-profit? Then you too work for advertisers...
Browsing at +1 - no ACs, I ignore their posts. So refreshing!
The whole idea is conceptually idiotic. You spend a strong force of reaction mass ejection to maintain a weak force of gravity at a constant distance from the target mass producing a microscopic tug on the object.
I pity the cranially impoverished people who modded this up as "Insightful". Go back to high school, would you? The two forces you're referring to are exactly equal in size, as per Newton's third law. The probe gets positioned at a distance at which the thrust of the engine is equalized by the asteroid's gravity, and the probe consequently pulls the asteroid with identical force (modulo its sign) while keeping a stationary position above its surface.
What you get here is exactly what you'd get by putting the probe onto the asteroid and pushing it, but you're avoiding the potentially dangerous contact with the asteroid. Moreover, the probe is likely to be powered using solar arrays, and asteroids sort of tend to rotate, which would severely complicate your attempts at creating a sustained thrust, not to mention the fact that your thrust vector would also rotate. Separating the probe from the asteroid and acting gravitationally upon it gives you constant insolation of the panels and the ability to exert constant thrust in a single direction.
Ezekiel 23:20
The only reason this ridiculous gravity pull method is even considered is that the asteroid may actually be a loose pile of rocks or snow/dust, not holding together strong enough to be pulled directly by pushing/pulling in one spot. Actually I see one problem with this method, the mass ejected from the station keeping thrusters would hit the asteroid and cancel the effect of the gravity pull. It's like getting into a basket and trying to lift yourselves up. They would have to fire multiple thrusters at an angle away from asteroid lowering the effectiveness of it all which is unfortunate because this is what translates into actual orbit change of the asteroid. It may be harder than it looks to stay very close to a big asteroid and keep position in a way that does not affect the asteroid. For gravity effect you need to be as close as possible, while it becomes harder and harder not to hit the asteroid with your thruster plumes. Maybe put the engines on a long cable so that they are far enough to fire at a smaller angle and let the heavy part of the spaceship hang towards the asteroid?
What about the rotation? Those rocks are usually spinning on multiple axes.
I mean hearing him talking about racism and such on one epsiode of Nova Science now I made the mistake of actually looking up his background for all the racism he had to overcome. Let's see, he's the son of 2 college graduates who helped get him noticed with his interest in astronomy.(Since that's the sort of thing where parents can make a big difference.) Because of this he went to Bronx Science and when he went to college he got heavily recruited specifically because of his background, even attracting the interest of Carl Sagan when he was picking his undergrad school. Of course getting all this extra attention probably gave him a huge leg up with college profs actually giving a shit about his education and eventually lead to him going on to a PhD program. As far as I can tell his main experience with racism is sometimes he has trouble hailing a cab.(Yeah, this'll get modded down.)
.... I'm confident that we have little to worry about. Asteroids will tend to avoid our planet out of sheer embarrassment.
I don't care if it's 90,000 hectares. That lake was not my doing.
Why don't we just tell the approaching asteroids that we want a committed relationship, they will veer off course very fast.
If the asteroid is a pile of rubble, then it would seem to be a collection of objects at similar but different distances. This would seem to induce a different gravitational pull on the parts of the asteriod. Could this pull it apart? It would seem likely over the months or years of time spent pulling on the rubble that it would separate into multiple objects resulting in a slower version of the problem from pushing the asteroid. I can imagine that spinning asteroids would require either gravitational pulling or explosions. I think we need a variety of tricks to cope with asteroids and we need to study these objects before deciding the appropriate plan. If we are too slow in discovering a threat, then explosions might be the only choice. We are currently not prepared with any actual equipment to repel any asteroids. We should get busy and start working on smaller objects to work on the technology. Maybe clearing out the debris around Earth would be a good place to start.
Ray Seyfarth, ray.seyfarth@gmail.com, http://rayseyfarth.blogspot.com
for being noncontributing zeroes.
A few comments on your comments. Firstly, the compressive strength of NEOs is not well understood. Many may be little more than self-gravitating rubble-piles, in which case your reaction engine will simply dig itself into a pit whilst ejecting boulders around it. Net result, multiple impactors on the same heading as the original body - which is Not Good. The mathematics is simple to perform for a gravity deflector. Here the displacing force is dispersed over the whole body - no single point stresses to accommodate. What is not so simple to gauge is the mass of the inbound body. And knowing that quite well is crucial to the success of a gravity tractor. You are at least correct in estimating the need for multi-year duration burns to deflect plausible objects. That is neither impossible nor impractical.
Yeah, but he's wrong. The scheme described in the summary would not work. Maybe there was some technical detail in the article, but setting down on the far side and pushing would work much better. If it spins, set down on both sides and stabilize the spin before pushing. The spin doesn't even "need" to be stable, so long as you only push in the same direction. Pulling by firing retro-rockets in the direction of the item you are trying to pull will push it away. You'd do better firing your retro rockets at higher power and retro-retro rockets on the far side to keep you close for the push to work.
Hell, more sensible than his plan is to catch the comet in a net and pull the net with a rocket. In a more interesting angle, I'd want to see whether it would make sense to "try to miss" or "try to hit something else". What if we tried to catch them in orbit. Help the space mining industry with captures of stray rocks. Or aim them at the moon to guarantee they'll never come around again. Maybe with enough of them, we could aim them to the back side of the moon and end up pushing the moon a little faster and get the lunar and solar calendars in sync.
Learn to love Alaska
The effect of gravity is multitudes more predictable that an explosion on an asymmetric tumbling object. A small tug around Jupiter may all we need to keep something from ever hitting us.
"When life gives you lemons, don't make lemonade. Make life take the lemons back!" -- Cave Johnson
Except your maximum thrust is tiny if you are holding yourself in place with gravity. And what's the fix for your gravity pulling it away from a collision, but your exhaust pushing it into a collision course?
Learn to love Alaska
Except your maximum thrust is tiny if you are holding yourself in place with gravity.
It would be tiny anyway, because you need high Isp, and you only get that with low-thrust engines.
And what's the fix for your gravity pulling it away from a collision, but your exhaust pushing it into a collision course?
The solution is to have the exhaust *not* pushing it into a collision course. Isn't that obvious?
Ezekiel 23:20
I think you may need to consider feasibility when coming up with your plans. It's a lot easier to just fly somewhere and hover than to land, or to make and deploy a gigantic asteroid net.
Hell, more sensible than his plan is to catch the comet in a net and pull the net with a rocket.
First, how did a comet get into this discussion? Second, a net big enough to hold securely a large meteor? Third, it's actually more sensible to bolt a few jet assist (JATO Bottles) onto the side of it and just accelerate it. Once it hits aphelion, pulverize it into dust.
"Tongue tied and twisted, just an Earth bound misfit
If by box of Crackerjacks you meant Columbia University, then sure.
A free mass spinning in a vacuum only ever spins on one axis. A temporary force applied will change the axis, but the mass will *never* "tumble".
Hell, more sensible than his plan is to catch the comet in a net and pull the net with a rocket.
*That* would be stupid. Do you have any idea how difficult is it to work with lines and nets of this size? Any tension changes propagate through the fibers at the speed of sound. If the whole thing becomes larger than, say, 10-20 km, you start having serious problems with not tearing the whole thing apart because you didn't notice a rising tension in one part of your dynamic system. Just controlling a single tether in LEO is difficult enough, you want a fully autonomous probe (light minues away from Earth) control a *net*? Wrapped around a celestial body with significant angular momentum? You're crazy.
Ezekiel 23:20
First, how did a comet get into this discussion?
I'm not an astrophysicist, and the dictionary definition of meteor is orthoginal to whether it's from a comet or other body of another name, and in any case, none of this applies to a meteor, only to a potential meteor.
So what was the point of your "correction"?
Learn to love Alaska
if the observations and calculations were a teensy bit off, and altering the asteroid's trajectory changed it from a very near miss...to a hit?
The solution is to have the exhaust *not* pushing it into a collision course. Isn't that obvious?
The net thrust *must* be at the object. Isn't that obvious? That, and the closer you are, the stronger the effect, complicating diverted exhaust. By the time you fix all those issues, the other solutions don't look so problematic.
Learn to love Alaska
And what's the fix for your gravity pulling it away from a collision, but your exhaust pushing it into a collision course?
The solution is to have the exhaust *not* pushing it into a collision course. Isn't that obvious?
What he meant was: you place the tug on one side to bend the trajectory of the asteroid that way, but in order to keep the tug away from the asteroid, it has to fire its engines towards it. The exhaust will hit the asteroid and exert a force in exactly the opposite direction from what you are trying to achieve with the gravitational pull. If the entire exhaust hits the asteroid, the net trajectory change will be precisely zero. The only solution for that is to fire thrusters diagonally from a far enough distance so that the exhausts will miss the asteroid. But this will obviously reduce the amount of tugging you're going to achieve.
Huge asteroid is found which will wipe out humans in two years. Scientists and engineers come up with a brilliant and very expensive plan to save humanity. US politicians argue about whether to fund it by tax cuts or tax hikes right up until impact.
If Slashdot were chemistry it would look like this:Cadaverine
gravitational force between a manmade spaceship and an asteroid won't be large enough to make that much of a difference, depending upon the SPEED of the incoming asteroid and the time it takes for us to build a ship, train a crew, and launch it into space. blowing it up could have dire consequences if the asteroid gets close enough to the earth or the moon. but if we can stop it by the time it reaches the asteroid belt, we might be ok.
the last thing we need is some tricky pool shot where you think you're going to hit the right stones but we end up tugging the earth into the corner pocket, game over.
Remember kids, if you're not paying for the service, YOU ARE THE PRODUCT THAT IS BEING SOLD.
Great. Now how do you propose to launch enough mass and enough fuel to sway an asteroid the size of Kansas? Remember, it takes 62 pounds of Saturn V to deliver 1 pound of payload to translunar injection orbit.
Help stamp out iliturcy.
You don't control a net. You spread a mesh in front of an object, and it snags in it. You have a single tether, and it doesn't matter how it spins. When you start gently pulling, it will waste a good bit of energy stabilizing the whole thing. It's inherently stable - the only issue is if our materials science is enough to support getting to that stable point.
Learn to love Alaska
Photons have momentum, and momentum is conserved. If you had a coherent enough laser, you just beam the thing when it's still far enough out and the momentum transferred from the photons to the asteroid will change its velocity.
Change it enough, and it'll miss Earth.
I say we do it old school and throw clumps of poo at it.
How exactly does it not matter how it spins? Do you propose to provide the probe with an infinite length of tether to compensate for what the asteroid winds up onto itself?
Ezekiel 23:20
He's a 'Scientist'.
People like Tyson make my head hurt.... The likelihood of us having enough time to use his method is probably somewhere near 0.. deflection.. certainly as opposed to ablation... but... Seriously? His idea would likely take YEARS to move the path a significant amount unless the object we're trying to mvoe is fairly massive (and the ship we're using is too) and it's actually a -solid- object.... What a Maroon.. anyone actually pay attention to this guy?
First, how did a comet get into this discussion?
I'm not an astrophysicist ...
Nor am I.
... and the dictionary definition of meteor is orthoginal to whether it's from a comet or other body of another name ...
My understanding is that comets and meteors are quite different things. Comets are made of ice and dirt/rock but, more importantly, comets generally are on elliptical orbits beginning as far out as the Oort Cloud, so when they come in, they've had a lot more time and distance to accelerate than meteors. The latter may burn up coming through the atmosphere. Comets are going fast enough to punch right through.
Of course, I could be mistaken.
"Tongue tied and twisted, just an Earth bound misfit
I agree, he's great for explaining stupid shit to proles, but as far as a professional scientist goes he has very little credibility in my book.
I bet you, as a complete fucking nobody AC, have tons of credibility in his book.
I find myself wondering if you'd find someone white significantly more credible.
I do not want your cheap brainburning drugs. They are useless for work. And I am a working man today.
Maybe there was some technical detail in the article, but setting down on the far side and pushing would work much better. If it spins, set down on both sides and stabilize the spin before pushing.
Fuel. Delta V and fuel. Your suggestion is less feasible as it requires bucketloads of propellant.
I do not want your cheap brainburning drugs. They are useless for work. And I am a working man today.
Why not send up a swarm of micro ships, each of which attach to a smaller asteroid, and then use their collective mass to affect the meteor's path?
Comets come from the outer solar system and they come in much, much faster than near earth asteroids or asteroids from the belt. If a comet is coming in on a collision course with us, forget it. We're fucked. We don't have time to do anything. That's the difference. Also, a meteor is a rock that falls through the atmosphere. If it hits the ground it's a meteorite. To do with the greek word for air, like meteorology.
I do not want your cheap brainburning drugs. They are useless for work. And I am a working man today.
Yeah the general rule of thumb is an asteroid might give us decades of notice if we're on the ball enough. A comet headed for us will give us maybe weeks. Comets are much less common thankfully.
I do not want your cheap brainburning drugs. They are useless for work. And I am a working man today.
we know that shit
*You* don't know a fucking thing.
I do not want your cheap brainburning drugs. They are useless for work. And I am a working man today.
I think you may need to consider feasibility when coming up with your plans. It's a lot easier to just fly somewhere and hover than to land, or to make and deploy a gigantic asteroid net.
And its a lot easier to fly somewhere close and send in a rocket powered Bunker Buster bomb.
Most of the rocky bodies we've investigated and photographed are loose creations of material which would most likely burn up in the atmosphere if you simply spread them out a bit. Even a solid rock of extinction size would do less damage if you break it up into more than one piece, and in doing so deflect significant chunks of it such that they would not even hit the earth. 2/3rds of the remaining pieces would land in the oceans as widely dispersed smaller chunks.
In other words, the entire premise of trying to finesse a miss by micromanaging the orbit doesn't put you in any better position than going nuclear. Because you have to have a great deal of time to change the orbit, the ability to predict future orbits, and technology of sufficient size and durability to actually be able to work, and if it fails you still have to have a plan "B". And waiting for a gravity solution to work would mean Plan B, would be a point blank nuclear strike.
The blowing things up bit, while sounding crass and inelegant, is actually the more sensible approach. Do it early, (preferably years in advance) evaluate your results, have another delivery vehicle pre-deployed for a later intercept, rinse, repeat until everything is smaller than a house, then simply take your chances.
Playing with orbit adjustments is an exercise in hubris.
Sig Battery depleted. Reverting to safe mode.
The whole idea is conceptually idiotic.
Large explosions will also fragment the mass, if they are placed so explosive force is trapped and bursts the object from within.
You call the idea idiotic, then you talk about blowing the asteroid up with explosions. Thanks for the giggle at the irony. The notion that someone might know more about something than you genuinely never occurs to slashdot armchair experts. But hey you did some math, well done. I'm impressed. So do some math on the kind of explosive force needed to take apart a large asteroid (into small enough bits) Here's a clue - it's waaaaaay more than the entire planet's nuclear arsenal.
The dismissiveness at the beginning of your post is what made me feel instantly hostile to the rest. Also, learn some SI units. Not interested in how many furlongs per fortnight a damn asteroid goes.
I do not want your cheap brainburning drugs. They are useless for work. And I am a working man today.
Find it early enough and a gnat's fart will change the angle enough to make it miss the earth. The larger the body - the further we can detectit - the more time to change the angle to miss the earth.
When he espouses the concept of hovering on thrusters to use the force of gravity to move the mass, I then know enough to dismiss him and his purported degree as idiocy.
Any rock of large side spinning even slowly will simply drill a hole though the net. There's nothing you can do about it.
There are solid asteroids, both rocky and metallic. Rocky asteroids are brittle and can be shattered by a high brisance explosive. The particles produced will diverge and the velocity imparted will be greater than the escape velocity and they will diverge - some will impact the earth and some will miss. To get the best effect the center of explosion should be at the center of mass. Depending on how far away the event occurred, most will miss the earth and impacts will be of smaller pieces spread over time instead of one lump at one place.Metallic asteroid are tougher and harder to break and will not shatter in the same way as a rocky mass. You may have to drill a number of holes and fill each one with explosive and set them off in a timed manner to break the metallic mass into pieces. A nickel-iron asteroid would be the worst case - hardest to break and more likely to reach the surface on impact - maximum impact damage.
There are also the loose gravitationally aggregated asteroids, that are weakly held together. To blow these up you need a less brisant, or low explosive that creates a large volume of escaped gasses that push the particles apart so each one diverges from the impact path into one that either misses or hits another place on the earth. Spread the impact of a million tons into one million separate one tone impacts will result in most melting and scattering before impact. Each case will differ. Some may be 2 or 3 large metallic ones and thousands of smaller rocky masses, all bound by gravity. So a large bang will scatter the small ones, but you may then have to deal with the metal ones - by thrusters or blow them up.
In any event Tyson will soon be dismissed as a fool by far more eminent minds than mine
And any reasonable size rock spinning as they tend to do will wind up your cable like a yo-yo and your rocket will have a short but very exciting life.
No, you only need to "waste" as much thrust as needed to counter the weak and gradual force of gravity --- you aren't spending any *more* energy in this situation than you would with a direct push. Just think of gravity as a rubber-band between the spacecraft and the space-rock --- you're effectively tethered to the rock already. Conveniently, the "tether" uniformly and predictably pulls the whole mass, instead of just shearing off a layer of rubble at an impact point.
Well, I think a more saner way would be to fire some astronauts up close enough and feed them a lot of beans. We can fund a fart cannon to connect up to their hineys. As an added benefit, we can substitute it for a rail gun here on Earth.
Iranian General: What the hell happened (fire, destruction, troops fleeing in terror)?
Iranian Colonel: Sir, they have resorted to Weapons of Mass Ejection?
Iranian General: You don't mean...they wouldn't...that's below the belt.
Iranian Colonel: That's exactly where we think they fired from, Sir.
you would have to bag a loose asteroid with something like a loose net, with, say 3 inch holes and you them use your 10-100 pounds of thrust on the gathering point of the net with the thrusters pointed so that they do not impinge on the net or the asteroid. 200 pounds of net will gather quite a large mass. and since forces are slow, on impacts or tears in the net will occur, and the net will be a slightly elastic material to avoid tears and the thrust will be gradually imposed to allow a proper gather.
Why would you push it one earth diameter? At the worst, you'd need to shove it one earth *radius*. And anyway, you're not pushing or pulling it out of the way, you're changing its trajectory. The tiniest nudge early enough on will change the trajectory enough to make it fly by with millions of miles to spare. It's not like you're pushing it those millions of miles.
All your math may make you look smart, but you're missing the fundamentals.
I agree, he's great for explaining stupid shit to proles, but as far as a professional scientist goes he has very little credibility in my book.
It's scientists like him that are personable and able to "explain stupid shit to proles" that help keep people interested in science and help make sure the scientists in your "credibility book" get enough funding from the proles to do their work.
There are two side to every coin. Yes, he may keep people interested, but by so over simplifying what is the real problem he gives the false sense that this could really work. So, by being personable and getting the funing from the proles, he is actually taking funding away from potential solutions that have a much higher probability of being successful.
The whole gravity tether concept is silly and non valid.
I can not see any way for it to ever work.
Only a fool would espouse it.
I think you may need to consider feasibility when coming up with your plans. It's a lot easier to just fly somewhere and hover than to land, or to make and deploy a gigantic asteroid net.
That may be true, but while hovering, you are going to have to exert enough gravitational pull to offset the inertia that is already in place. While it is true that all bodies exert gravitional forces upon each other, in practice, there has to be enough force to actually do something. When we landed men on the moon, the gravitational forces between earth and the moon were altered, but not enough to change their positions in space relative to each other. Likewise, a rocket, unless it contains extreme mass, is unlikely to change the trajectory of an asteroid or comet because of the combination of the gravitational forces and the inertia. And, if said rocket does contain enough mass to effect this change, then how in the hell are we going to get it there in the first place?
You don't control a net. You spread a mesh in front of an object, and it snags in it. You have a single tether, and it doesn't matter how it spins. When you start gently pulling, it will waste a good bit of energy stabilizing the whole thing. It's inherently stable - the only issue is if our materials science is enough to support getting to that stable point.
What exactly would such a mesh be made out of that could withstand the impact from how ever many metric tonnes of material traveling at however many thousands of meters per second? There would be no gently pulling involved as the same distructive force that would be applied if such an astral body hit the earth would be applied hitting the net.
Pomposity? How dare you!
And I can find your new breakthroughs in gravitational physics published in which journal? Apparently, a lot of decently competent scientists (who can certainly calculate the impact of gravitational forces implied by known physics) disagree with you, so it would be useful for you to point out which of your amazing new discoveries would invalidate this simple and robust mechanism.
he's wrong
pushing the moon a little faster
Comments on the internet in 2013. Aren't they awesome?
The escape velocities of many asteroids are very low and the exhaust velocity for high Isp engines are very high. The difference is at least 100 fold. For a net momentum change, it would be enough to not aim exhaust directly to the asteroid. The gravitational capture of propellant is impossible. No special diversion mechanisms are necessary.
Gentlemen, you can't fight in here, this is the War Room!
And its a lot easier to fly somewhere close and send in a rocket powered Bunker Buster bomb.
Where do you get your ideas that blowing up a giant rock is a good idea. I'm talking giant, because the smaller ones, while being a problem for whoever's head they land on, don't pose an Extinction Level Event.
If you blow up a big rock, you will end up with a lot of smaller rocks that will still have the same basic trajectory. So we pretty much guarantee that there will be lots of medium to largish impacts and a shitload of smaller ones. These will be spread all over the earth.
The dictionary indicated that an object that hits the atmosphere is a meteor, whether asteroid, comet, or stray (in fact, the definition didn't exclude man-made satellites from that definition).
An "asteroid" was an object in orbit around the sun. A "comet" was an object in orbit around the sun. But, given what I know about each, I would assume an un-stated "highly eccentric" in the second definition.
Learn to love Alaska
Comets are also cyclical in stable orbit. We "could" identify and map all of them, and if any would eventually pass close enough to be a danger, adjust them millenia before they are an issue. So with a comet, we have more time than anything else. The interstellar strays would be harder to detect and leave us with the least time. Second is a collision in the asteroid belt that sends an asteroid at us, and third, a gravity re-direct of something around the sun or Jupiter which adjusts it into a collision course.
Learn to love Alaska
No, the asteroid can't infinitely wind on itself. That's an unstable case. The tow ship will slow the spin by accelerating away. Perhaps there isn't enough tether to do it, but that's implementation, not theory. You are attacking the theory because you see problems with the implementation as you'd do it. That you can't see the answer doesn't mean the answer isn't there.
Learn to love Alaska
You pull the net tight so the rock is not spinning within the net, but spinning the net itself. The "spin" is transfered to the tether, not the net.
Learn to love Alaska
There would be no gently pulling involved as the same distructive force that would be applied if such an astral body hit the earth would be applied hitting the net.
No, it wouldn't. Take a hammer. drop a feather. While the feather is falling, hit it with the hammer. Oh my, that feather was destroyed by the sheer might of the hammer. Now, take the feather and put it on the ground (preferably on a rock). Hit it with the hammer.
See the difference now? The "desreuctive force" of the astral body can't exceed the destructive force of a light net gently settling on the surface. Though if it doesn't work and it hits the earth anyway, yes, the net will be destroyed.
Learn to love Alaska
Where do you get your ideas that blowing up a giant rock is a good idea. I'm talking giant, because the smaller ones, while being a problem for whoever's head they land on, don't pose an Extinction Level Event.
Maybe because the full rock DOES pose an extinction event?
And you might also want to look up the definition of "burn up in the atmosphere". And also you might want to supply some actual backup about your claim that they will have the same basic trajectory after a nuclear warhead scatters the big rock into much smaller pieces. Placed close to center, at least half the rock would get a significant retro acceleration. Another significant portion gets a forward acceleration. When you do this early enough there is no reason to suppose that all the parts have the same basic trajectory.
Even if a significant portion did stay on their collision course, they would be spread out, and the shitload of smaller ones represents a far less deadly potential than one giant big one. Because small ones burn up in the atmosphere.
Sig Battery depleted. Reverting to safe mode.
If you are being that gently, pushing it with a laser or the exhaust itself seems to be simpler.
Learn to love Alaska
I haven't checked for Earth, but some of the Endor Holocaust sites indicate that too much material entering spread out will cause atmosphere problems sufficient to kill everyone.
The rest of the plans mostly work in parallel. Blow it up, then pull it, while pulling on it, land on it and push it. Do them all, see what works best, then do that for the next one.
Learn to love Alaska
But Tyson's pomposity sort of makes it hard for me to "like" him..
They're fine as long as they don't get uppity, eh?
Pushing it requires propellant, but pulling it doesn't? I don't understand how that constraint applies any more to one over another. But yes, it will need more fuel because it will use it up faster for much much faster results.
Learn to love Alaska
The gravity tether fails on first principals. Those guys jumping on the bandwagon of asteroidal impact are simple populist fools.
Let us say the tether ship weighs 200,000 Kg and the rock it ispulling weighs 100,000,000 Kg . the force bewen them would be 133452000E -11 Newtons
which is 0.0003000120298690324 pounds.
What that means the maximum pull on the rock by your ship is 0.0003 pounds, if your ship was 10,000 times as big = 3 pounds is all the thrust you can pupp with. Any more and you fly away.
A net around the asteroid with a 100 pound ion thruster would be a lot better. Just have the ion thruster nozzles a little diverted to make the straight line ions miss is.
use this http://easycalculation.com/physics/classical-physics/newtons-law.php
Gravity is a VERY weak force,
Look here http://en.wikipedia.org/wiki/Fundamental_interaction
gravity is by far the weakest force
Yes, I know gravity is an f****ng weak force, but that's all you need over enough time. If you only locate the asteroid two weeks out from impact, then you're probably screwed anyway, and a last-ditch brute-force effort might be justified. However, deploying a "net around the asteroid" is a terribly complicated and risky engineering challenge --- gravity is dead simple, and requires nothing more than "being there." From a safety and engineering perspective, the slow but 99.99%-reliable solution (after the initial launch phase) is far preferable to a much more expensive and complicated 90%-reliable fast one.
Purported. So, you dispute his having the degree in the first place. How about this. You read his complete article, then show (with math and illustrations) why it can't possibly work.
Well, in his defense, he never said who was going to prosper; I see no disagreement between the two statements.
For a specific example, consider a spacecraft of mass m1 and an asteroid of mass m2.
The force on (F) and acceleration of (a) the asteroid when the craft is distance r away is F = G*m1*m2/r^2 = m2*a => a = G*m1/r^2.
The asteroid is deflected sideways by the force over time t by a distance of (a*t^2)/2.
Assuming a 2000kg craft (100x smaller than your example) at a distance of 10m from the asteroid, the acceleration is a = 1.33*10^-9 m/s^2. Not much, right? Now, consider applying this over 3 years: the deflection is 5982km --- pretty close to the 6371km radius of the earth. Adjust numbers as necessary for the time interval and necessary amount of deflection, and the gravitational tether is quite plausible (especially if you had 100x more spacecraft mass, as in your example, so the deflection time would be 11 days instead of 3 years).
The gravity idea can never ever work. Best intercept is years out, then small forces will work, however, gravity can never ever work, it is far too weak. Just calculate the force needed to move 100,000 tons by 10,000 miles over an incoming orbit to impact one year long. We find it one year from impact. It weighs 100,000 tons. .5 A t t we know that a one pound thruster will do this, with s = feet, t = seconds and A = 1/200,000,000 feet per second per second = low gravity = 9 million feet or 1700 miles. To get 8000 miles of earth movement we will need about 5 pounds of thrust.
from s =
Thus the mass of your tug will be 1,666,516,800. Kg and since your asteroid is 200,000,000 Kg the ship, which is also on an impact trajectory with the earth and weighs moire than 8 times as much = which is the greater danger? Fools like Neil De Nitwit Tyson and those who fail to analyze the interinsic errors in their theory.
I have not seen any such reputable article, all I have seen is fool's work,please show me one - if you can.
Forexample, this scenario has errors in their basic math. 1 newton of thrust will quickly move their tug away from the target mass, because the mutual attraction is far smaller.
http://arxiv.org/ftp/astro-ph/papers/0509/0509595.pdf
At this distance, the asteroid will fill about ~175 degrees of the visual field, thus the vector of the thrust will be 99% wasted
I'm surprised, (particularly because the discussion has broken down into push vs. destroy) that nobody has mentioned the Orion Project: http://en.wikipedia.org/wiki/Project_Orion_(nuclear_propulsion)
This seems like an elegant solution to the problem, with the added bonus of keeping both camps happy.,
Assuming a reasonably spherical asteroid, your statement is utter rubbish. The gravitational force on a sphere integrates out to the equivalent of the pull on a point mass (of the same mass) at its center (though the nearer parts of the asteroid are pulled more strongly than those distant). Did you fail intro freshman physics, by any chance?
No, the asteroid can't infinitely wind on itself. That's an unstable case. The tow ship will slow the spin by accelerating away.
If you attach a tether to a rotating celestial body that any asteroid or meteoroid is (no exceptions), said celestial body will end up coiling the tether (not itself!) into a loop around its surface. In addition, the spin change will be imperceptible and completely unnecessary. What the fuck is "an unstable case"? Stop babbling incoherently!
Perhaps there isn't enough tether to do it, but that's implementation, not theory. You are attacking the theory because you see problems with the implementation as you'd do it. That you can't see the answer doesn't mean the answer isn't there.
Not "perhaps", there simply isn't. For a 5km sized body and 10h rotation period (a comparatively slow one!), you'd end up winding almost 40 km of tether per day. With a 200 mN class electric thruster, you'd be able to impart a daily momentum of only ~20 kNs. That's very little. The probe would have to work for hundreds of days, which would mean carrying tens of thousands of km of tether. That's completely unworkable. And the sooner you realize that people *don't care* whether you can toy with an asteroid like with a yo-yo or not, they care about workable solutions to the deflection problem, the better for you.
Ezekiel 23:20
The thrusters must aim about 175 degrees away from each other to avoind the ion stream from impinging on the asteroid - you can not have that. The ion thrust can not impact the towed body
Not everyone needs to be stuck in front of a computer calculating orbital paths all day. Some people choose to try and spread knowledge, only an idiot couldn't see the value in that. So I think that makes you an idiot. There I said it.
The smarter option is not hiring people like you to engineer the mission. I think the typical proposed flight profile is to lead the asteroid in a "zigzag" path: aim the craft so it slowly drifts a bit past behind the asteroid; fire the thrusters (now clear of the asteroid) so the trajectory orbits around a bit forward; repeat as necessary. On average, you're still deflecting the asteroid sideways (at a slightly reduced rate from hanging out directly at its side, compensated by a bit more mass and/or time).
It might be possible to perturb an asteroid's trajectory with a pulse laser. When you hit various materials with very short, intense pulses of light at a wavelength that the target material tends to absorb, it causes such rapid localized heating that it either vaporizes a little bit of material, turning it into very hot gas, (a tiny little rocket,) or it causes a tiny, rapidly expanding piece of material to spall off the surface, (a higher-mass, lower velocity rocket.) Repeat a few thousand times per second and you will basically turn the asteroid into a crappy rocket, using the asteroid's matter as the working mass. The biggest problem I can see with this is that the mass ejected from the asteroid will have a tendency to hit the laser. It might be possible to avoid this simply by aiming the laser slightly off-normal.
... then there would be no way to stop these asteroids. And nobody would even KNOW about them. Because blacks' IQ is too low for them to ever discover and understand ANYTHING about space.
Does that bother you? It should, if there are blacks in your country. Why are they there? Why don't they want to live around their own people, in their own country?
If you attach a tether to a rotating celestial body that any asteroid or meteoroid is (no exceptions), said celestial body will end up coiling the tether (not itself!) into a loop around its surface.
So space elevators are impossible. Not to mention that if you attach the tether at the pole, it will still coil? How does that work?
What the fuck is "an unstable case"? Stop babbling incoherently!
Ah yes, idiots who don't know the difference between stable and unstable equilibrium are, and take out their frustration for their ignorance on others. A stable equilibrium is where you put a ball in a bowl. It rolls to the bottom and stays there. If you poke it, it returns to the bottom. Now, turn the bowl over. Balance the ball on top. That's an unstable case. If you disturb it, it will fall.
Not "perhaps", there simply isn't. For a 5km sized body and 10h rotation period (a comparatively slow one!), you'd end up winding almost 40 km of tether per day. With a 200 mN class electric thruster, you'd be able to impart a daily momentum of only ~20 kNs. That's very little. The probe would have to work for hundreds of days, which would mean carrying tens of thousands of km of tether.
Repeat the question with a tether length of 5 km and report the results. Also, examine the case where you hook the tether to the pole, rather than the equator. Even if you missed the pole and got the equator (but were still above the pole), with a 20 km tether for your 5km body, please describe what would happen. Hint: as long as your tether mount articulates, you'll get the tether spinning about once every 10h, but it would otherwise have no effect on the exercise.
No, I don't see how any of your objections apply to the situation. They just indicate you inability to understand and unwillingness to try.
Learn to love Alaska
There would be no gently pulling involved as the same distructive force that would be applied if such an astral body hit the earth would be applied hitting the net.
No, it wouldn't. Take a hammer. drop a feather. While the feather is falling, hit it with the hammer. Oh my, that feather was destroyed by the sheer might of the hammer. Now, take the feather and put it on the ground (preferably on a rock). Hit it with the hammer.
See the difference now? The "desreuctive force" of the astral body can't exceed the destructive force of a light net gently settling on the surface. Though if it doesn't work and it hits the earth anyway, yes, the net will be destroyed.
But there is not light net gently settling on the surface, unless you are going to try and catch the asteroid from the back side, which of course won't do you any good. As long as you are approaching the asteroid from the front or some angle off center from the front, you have to deal with the inertia of the asteroid against your net.
I guess it would be possible to land on the asteroid and somehow deploy your net running around the surface and at some point on the back side launch rockets in the opposit direction, but at that point, the rockets and cords attached to the net have to be able to deal with the inertia of the moving asteroid.
Put it this way, prior to launching the shuttle, it was bolted to the pad, to allow it to build up thrust. If your methodolgy worked, everytime they launched the shuttle, the earth would have been nudged out of it's normal orbit. It simply doesn't work that way because there is too much mass involved (earth) versus the thrust of the rocket (shuttle). Catching an asteroid hurtling toward the earth in space would not be any different, other than whatever you are catching it with has to be able to withstand the mass and inertia or at a minimum get drug along for the ride.
But there is not light net gently settling on the surface, unless you are going to try and catch the asteroid from the back side, which of course won't do you any good. As long as you are approaching the asteroid from the front or some angle off center from the front, you have to deal with the inertia of the asteroid against your net.
No, you don't. Did you hit the feather with a hammer as I instructed? If so you'd have noticed that the feather was unharmed. And the feather didn't even have to approach the hammer from the night side.
The net will hold no more weight than the weight of the net itself, no matter how big the object. At least until you turn the engine on. But that will be a coparitively small and gently pull, nothing "violent".
The net is light, it has low inertia. The asteroid will instantly accelerate it to asteroid speed. But the relatively light weight of the net make that a non-event, like hitting a feather floating in air with a hammer.
Put it this way, prior to launching the shuttle, it was bolted to the pad, to allow it to build up thrust. If your methodolgy worked, everytime they launched the shuttle, the earth would have been nudged out of it's normal orbit. It simply doesn't work that way because there is too much mass involved (earth) versus the thrust of the rocket (shuttle). Catching an asteroid hurtling toward the earth in space would not be any different, other than whatever you are catching it with has to be able to withstand the mass and inertia or at a minimum get drug along for the ride.
It doesn't work that way because 100% of the exhaust of the shuttle was captured in the atmosphere. The net push on the planet was zero, because there was no unbalanced force. When you finish 6th grade and understand what a "force" is and can draw a free body diagram (why yes, I was doing free body diagrams in the 6th grade, we just didn't use the "official" term for them until college engineering classes). And yes, the idea would be that it would be drug along for the ride. Now you are getting it, but only in your "throw away" joke at the end. Too bad you don't even listen to yourself, or you'd get it.
Learn to love Alaska
Not all the mass will impact the atmosphere. We'd be gaining ground -- some portion would be deflected to a great enough degree that it would miss the Earth.
Now, y'see that's where it gets fun, because if anything is still large enough to NOT burn up in our atmosphere?
We've got more than one bomb! We've got all KINDS of bombs! That's kinda.. sorta.. I mean, we humans! We're the fucking TITS at bombs! I mean *really really good* with 'em, and we have SO MANY just SITTING AROUND.
Reach out, and make space our bitch. With bombs. Bombs with profane language scrawled across them. We're humanity, that's just how we roll. No, seriously, the rocks that we hurled at each other thousands of years ago were scrawled with nasty words too -- now quick somebody quote Fallout.
... still waiting for this free-as-in-beer free beer I keep hearing about.
Lead weights? A mini-neutron star?
Even though this works in theory, the asteroid is going to be many orders of magnitude more massive than the rocket in order to cause an extinction event, so this idea is basically like trying to get a flea to pull an elephant by tugging at its tail.
It's the job, the monitor was invented to do,more or less.
*Repent!Quit Your Job!Slack Off!The World Ends Tomorrow and You May Die!
I would imaging that asteroids would make *one* legitimate use for nuclear weapons.
http://cpusupply.com - discount netbooks and tablets
Before we can really take any meaningful steps toward defending ourselves, we need to get all of the "screw science - let them hit us and kill us all in a bath of fire, so baby jesus can come take us to heaven after the apocalypse!" nutjobs that make up such a huge chunk of our political representatives and their constituents. The first step to finding a way to defend yourself against something is getting rid of the people who want that thing to actually happen.
There is literally nothing we could do about a Kansas-size (500km) asteroid but that scenario is highly unlikely, there isn't any evidence that such an impact happened anywhere in the solar system in the last 3.5b years.
A realistic scenario is an asteroid between 100m and 1km, and ion thrusters and nuclear propulsion have a high enough efficiency that they can influence that category.
The Neil deGrasse Tyson of AstroPsychology.
The dictionary indicated that an object that hits the atmosphere is a meteor ...
I just did "dict meteor", and you're right. It can be pretty amorphous. The word comes from French:
things in the air, fr. ? high in air, raised off the ground; ? beyond + ?, ?, a suspension or hovering in the air, fr. ? to lift, raise up.
1. Any phenomenon or appearance in the atmosphere, as clouds, rain, hail, snow, etc. [1913 Webster]
Then it offers this (emphasis mine):
Note: The term is especially applied to fireballs, and the masses of stone or other substances which sometimes fall to the earth; also to shooting stars and to ignes fatui. Meteors are often classed as: aerial meteors, winds, tornadoes, etc.; aqueous meteors, rain, hail, snow, dew, etc.; luminous meteors, rainbows, halos, etc.; and igneous meteors, lightning, shooting stars, and the like. [1913 Webster]
Finally, there's also this:
n 1: (astronomy) any of the small solid extraterrestrial bodies that hits the earth's atmosphere [syn: {meteoroid}, {meteor}]
Which I think is the definition we ought to be going by here.
"Tongue tied and twisted, just an Earth bound misfit
Just like it did when it saved the planet from global warming.
I bet you can't swing a hammer through the air with as much force as a celestial body on a collision course with Earth. Also, you left out the part where someone is holding the feather, and then lining up it's trajectory with that of the swinging hammer, and then catching the hammer and tugging it off course. I think you're oversimplifying the problem. What was wrong with making micro corrections to the celestial body's path again?
Even a solid rock of extinction size would do less damage if you break it up into more than one piece, and in doing so deflect significant chunks of it such that they would not even hit the earth. 2/3rds of the remaining pieces would land in the oceans as widely dispersed smaller chunks.
Mmm... no, don't think so. You've got to deal with the atmosphere heating up by that amount of rock dropping through it, big or small. If anything, the surface to volume ratio would mean we'd simply fry the atmosphere directly, rather than indirectly via the shock wave of impact. Kinetic energy is kinetic energy. We can be killed off by an amount of gravel equivalent to the full-sized rock.
Do not mock my vision of impractical footwear
This one is a comet, estimated up to 50km. It's retrograde and hyperbolic, giving a good inertial multiplier and ensuring that it's a one time only event. It may hit Mars. If it was headed for us, there's nothing we could do about it.
Help stamp out iliturcy.
Discovery Channel already covered this option, or maybe one of the BBC documentaries. And instead of saying stupid things like "feel each other" they spoke about the "long term gravitational effect, however miniscule it would be" - that's what would slowly nudge the asteroid from its existing path and hopefully not into us.
The massive limitation (no pun intended) is that the asteroid in question needs to be detected when it's really really really far away, to give enough time to
a) launch a spaceship designed for this,
b) have it reach the asteroid and then
c) still have enough time/distance for the gravitational effect of the ship to affect the asteroid significantly enough to have it adequately deviate from its path.
While it's the most realistic option from the perspective of current space technology, it's only likely to be useful for asteroids which we already know are likely to hit many many years from now. It would have been more useful to give some sort of indication of time/distance required to actually have it work, relative to the mass and velocity of likely asteroids.
Nobody is "holding" the net. And the net isn't doing any "tugging" when applied. That comes after. The pull is gentle and doesn't pull it off course in a manner you can see, but 1/1,000,000th of a "tug" spread out over a year.
Learn to love Alaska
Am I the only one who thought of Project Valkyrie (not the World War II project, the interstellar one) as being a comparatively cheap and easy solution for deflecting or destroying meteors headed for Earth with little advance time?
With only a few modifications (most notably, removing the passenger compartment), a rocket-propelled antimatter delivery system with sufficient antimatter (say, 10 Kg, magnetically isolated) dragging a tungsten shield (20cm thick, say a 20ft diameter disk) a fair distance away (50 meters) would produce upon impact a matter-annihilating explosion of gamma radiation with a yield of approximately 400 megatons (depending on the annihilation percentage), with most of that force being diverted away from the Earth (the tungsten shield absorbing what heads for Earth due to tactical trajectory placement (alignment before impact with the shield being directly between Earth and the meteor creating an umbra).
Another side effect: that much ionizing gamma radiation would undoubtedly weaken the meteor's base components on a molecular scale, making the object much more susceptible to break-up and frictional heat destruction if any of it hit the atmosphere.
Having that much antimatter on hand may be an issue, since, according to the last news article I read about it, 10Kg would be about half of the antimatter currently available on Earth, but the parts already exist, and casting a tungsten disk that size is only a matter of cost, not time. The Newtonian backlash on the tungsten disk would propel it back towards the Earth, but I would rather have a 20ft diameter disk coming at the Earth instead of a house-sized chunk of iron and nickel, wouldn't you?
I don't really see a downside to the plan except lead time.
Any comments would be appreciated.
How about a rocket with a wide flat nose of some sort that can push against the rock and move its orbit so it heads to the sun, and so completely destroys it.
When we landed men on the moon, the gravitational forces between earth and the moon were altered
Yes they were. Only for a few days total, and get this, at an absolute fraction of the effect the earth has on it. Hence it didn't actually do anything. Also, the men compared to the moon are much much much much much smaller than the satellite will be to the asteroid; even a civilization killer. If something the size of the moon is going to hit us, we are well and truly fscked :)
The asteroid on the other hand, you do need months if not years of hovering because it's a small effect. The difference is there isn't anything else acting on the asteroid of significance. The Sun does somewhat but since gravity falls off exponentially with distance(I'm totally guessing but it's something like this I think), the closer satellite will exert a statistically significant force on the asteroid compared to the Sun.
And, you don't have to do much at all. Just a few miles per hour difference over a few years starts to mean the asteroid won't be the earths path at the time the earth passes by. We don't have to send the thing out at a right angle, just retard it enough that it passes through the same point an hour later or something like that. The earth passes by and there's no collision, yet both objects are still relatively on their same orbints.
People in cars cause accidents....accidents in cars cause people
setting down on the far side and pushing would work much better.
So rather than use physics in your favor by slowly gravitationally altering it over time, you'd rather work AGAINST physics by trying to push it? Do you realize how much more energy that would require?
The gravity tractor idea is exceptionally sound physics, as is blowing something up, as is pushing something with rockets. Two solve the problem but one costs significantly less...the third just creates lots of new 'hopefully' smaller problems - but there's no guarantee of that.
And then if the thing is tumbling, you can only push at certain times since it has to be aligned properly...if you can find a stable platform on the asteroid that can adequately resist your rockets force...
People in cars cause accidents....accidents in cars cause people
1 planet killer is bad. 15 continent killers is still just as bad.
People in cars cause accidents....accidents in cars cause people
We're the fucking TITS at bombs
Looks up at the Sun exploding with the force of a bajillion bombs...figures we aren't all that great really...
People in cars cause accidents....accidents in cars cause people
Howser himself has gone downhill since he changed his name a little and later developed a vicodin addiction.
Put in a sail and plunder the universe! Seriously, use a sail to steering it?
Red een boom, Eet een bever!
If you propose that, to push the asteroid, you first stop most of its spinning, then the pushing scenario requires huge amounts of additional fuel before you even begin talking about changing its trajectory. Landing and firmly attaching a rocket to an asteroid or comet is not a trivial undertaking - what works for some bodies may not work for others.
The big benefit of the gravitational tether is that it matters not a whit if the asteroid is tumbling wildly, or off-gassing (i.e., a comet), or is held together too loosely to attach to - you are simply applying force to this civilization-threatening mass by using another mass: action at a distance. The "at a distance" part circumvents a lot of thorny challenges.
An extinction level event via asteroid might interupt the extinction level event currently unfolding through man made processes.
Could we hope for a positive outcome as a negative plus a negative (or X) are equall to a positive, thereby cancelling each other out.
Or would it introduce a race condition between alternate realities where the outcome would be influenced by locking and freezing events?
You are hovering nearby so your gravity pulls the rock toward you. You fire your retro rockets to push yourself away from the rock, in the process pushing the rock away from you, back towards it's original destination.
Cheap storage VM.
Burning up in the atmosphere means the atmosphere gets hot, right?
Burning up an extinction level asteroid in the atmosphere makes the atmosphere so hot, it extinguishes all live.
Hence the name ... next try?
Cost free eBook I read (by iBook/Kobo/Amazon/ObookO/Gutenberg etc.): "The Green Odyssey" by Philip Jose Farmer.
Direct a strong enough laser at the inbound meteor/asteroid and as the incident energy warms the material increasing the rate of sublimation from the surface, the remaining body will be propelled in the opposite direction to the ejected material. Thus "paint" one side of the asteroid and you can expect to alter its path. Other bonuses include it won't really matter if the target is spinning, and the beam will reach the target at the speed of light, so you can keep the laser platform near earth and start altering the course of the inbound object almost as soon as you detect it is on a collision course with earth. With a small constellation of these orbiting laser platforms you can probably always have a firing solution.
I take it you've waved the magic want that stops the asteroid's rotation first? Or is there some sort of mobile 'gathering point' that you haven't mentioned?
"Think about how stupid the average person is. Now, realise that half of them are dumber than that." - George Carlin
I would say the "idiot" is you. Your discussion partner corrected you several times and you seem not to grasp it. If the tether is at the pole, guess what happens? You can easy figure that your self. ... I guess everyone knows what a stable equilibrium is, however likewise no one here understands what you mean with "unstable" in your post ... is there an equilibrium between your probe and your asteroid?
Regarding stable and unstable
Even if you missed the pole and got the equator (but were still above the pole), with a 20 km tether for your 5km body, please describe what would happen. Hint: as long as your tether mount articulates, you'll get the tether spinning about once every 10h ... what did you expect? Oh ... you think the centrifugal power is strong enough to let the probe rotate stringed to the asteroid, what a laugh.
After 5 spins the tether is winded up and the probe has a hard landing
Cost free eBook I read (by iBook/Kobo/Amazon/ObookO/Gutenberg etc.): "The Green Odyssey" by Philip Jose Farmer.
No, it wouldn't. Take a hammer. drop a feather. While the feather is falling, hit it with the hammer. Oh my, that feather was destroyed by the sheer might of the hammer. Now, take the feather and put it on the ground (preferably on a rock). Hit it with the hammer. ;D
This shows how less you understand of physics
I as a mere man perhaps lack the muscle power to smash a falling feather in mid air, however it is only a question how fast the hammer is. If I have a hammer flying with the speed of sound, hitting a feather, the feather is smashed, regardless whether it is floating or laying on a rock.
Cost free eBook I read (by iBook/Kobo/Amazon/ObookO/Gutenberg etc.): "The Green Odyssey" by Philip Jose Farmer.
Rocky asteroids are brittle and can be shattered by a high brisance explosive.
Really? Someone blew up a rocky asteroid? When was this research carried out, because I seem to have missed it. The particles produced will diverge
Until their mutual gravity pulls them back together again. This isn't like when you played 'Asteroids' in the video game parlor in the '70s.
Spread the impact of a million tons
A million tons? I didn't realize you were talking about such small rocks. Anything actually civilization-threatening is an order of magnitude larger. But I suppose such an eminent mind as your realized that.
one million separate one tone impacts will result in most melting and scattering
You don't see a slight problem with a frelling million almost-simulteneous air bursts covering one side of the planet? Dunk a basketball under water and pull it out. That sheen of water? If Earth were the size of the ball that water would be thicker than our breathable atmosphere. Now imagine ONE MILLION grains of sand scattered across that face of the basketball. I don't think you really have much of an idea what you're talking about, certainly not as much as you think you do.
"Think about how stupid the average person is. Now, realise that half of them are dumber than that." - George Carlin
The net will hold no more weight than the weight of the net itself, no matter how big the object.
That is nonsense.
The net has to hold the "weight" of its own impulse and on top of that the "weight" of the impuls of the asteroid.
As the asteroid likely moves with several 10k km per second spanning a net in front of it will just evaporate the net.
Cost free eBook I read (by iBook/Kobo/Amazon/ObookO/Gutenberg etc.): "The Green Odyssey" by Philip Jose Farmer.
You seem not to understand basic physics.
I take a wip and hit you ... you guess that will hurt.
Now I let the wip float and accelerate you to the same speed the wip had above and let you hit the wip.
In your world nothing will happen as the wip is floating, in my world (which happens to be the real world) you get hit equally hard.
It does not matter "who" is standing and who is moving, only the speed of impact matters (in fact there is a small difference ;D ... regarding impulse and such ... but it is likely beyond your grasping so I spare me that)
Cost free eBook I read (by iBook/Kobo/Amazon/ObookO/Gutenberg etc.): "The Green Odyssey" by Philip Jose Farmer.
You pull with gravity.
That means you only move your probe every few weeks one yard away from the asteroid, using a milligram of propellant.
Pushing means you land on the asteroid (landing alone costs awful lot of fuel I assume). Now guess: how many milligrams of propellant do you need to push an asteroid with the mass of a few billion tons equally fast?
Cost free eBook I read (by iBook/Kobo/Amazon/ObookO/Gutenberg etc.): "The Green Odyssey" by Philip Jose Farmer.
If you aimed your rockets directly at the asteroid, yes you're correct. And yes that would be stupid and counterproductive.
you aim your rockets at a diagonal, so that you get some vertical thrust to counteract the gravitational pull of the asteroid and some horizontal thrust which is counteracted by the opposing rocket.
It's very similar to how Curiousity's 'backpack' of rockets worked. They couldn't fire straight down because it would kick up too much dust and cover the rover...not to mention fry it as they lowered it. So they aimed them out at some angle so the blast wasn't near the lowered rover but was still providing enough vertical thrust to support it during the lowering operation.
People in cars cause accidents....accidents in cars cause people
http://www.facebook.com/neil.degrasse.tyson.snl.host
If the engines are sufficiently removed from the attracting mass, such as by a tether several kilometers long, the angle of thrust of the engines can be quite close to the desired direction of movement and still miss the asteroid. Absolutely nothing says that the engines have to be at the rear of the spacecraft pointing directly backwards.
"Think about how stupid the average person is. Now, realise that half of them are dumber than that." - George Carlin
So rather than use physics in your favor by slowly gravitationally altering it over time, you'd rather work AGAINST physics by trying to push it? Do you realize how much more energy that would require?
It would take much less to push than pull. I realize how much energy it would take to pull than push. At least 3 times as much to pull than push.
And then if the thing is tumbling, you can only push at certain times since it has to be aligned properly...if you can find a stable platform on the asteroid that can adequately resist your rockets force...
Yes. That's why I added another contact option. Put a net around it and tow it to where you want it. That way, no matter how the object spins, the thrust will always be aimed in the correct direction.
Learn to love Alaska
You pull with gravity. That means you only move your probe every few weeks one yard away from the asteroid, using a milligram of propellant.
And you get worse results than landing a probe and using that same milligram every few weeks to push. And, if you are pushing, you have no upper bound on pushing power, other than the stability of the asteroid and the design of the craft.
Learn to love Alaska
Neil, I realize there's a need to dumb things down sometimes, but you're going to provoke suggestions that we criticize the asteroid's weight so that it'll run away crying.
Here's a more useful idea: Use asteroids to improve our situation on Earth. Deflect otherwise-colliding asteroids to pass by us in front of our orbit, not behind us. Let gravitational pull add to our speed around the sun. Let it add to our rotational speed. We need a higher orbit around the sun and less baking when we're facing the sun. I realize the relative masses assure that it won't noticeably help. But it would help more than deluding folks who don't know any better than to believe that asteroids have emotions.
I agree that the *only* redeeming quality of the "pull with gravity" plan is that it works for all bodies. My issue with it is that for any one body, the solution is likely something else. The Best Solution (tm) is to design one craft for multiple capture types, and have gravity for the last option, if nothing else worked. Any mechanical connection allows thousands times more force to be applied. How long do we have until impact? Oh, not enough time? Then gravity pull won't work. What else is there? Nothing, because so many on Slashdot insisted "gravity is the Best Solution (tm)" so we didn't design any other backups.
Likely the government won't build anything to be ready to go, but having an idea of responses isn't a bad thing. We've spent billions on scenarios for WWIII, so why not this? In which case there should be multiple solutions depending on the object type.
Learn to love Alaska
You are quite right, except that "translunar" and "injection orbit" are two different things ;D
Cost free eBook I read (by iBook/Kobo/Amazon/ObookO/Gutenberg etc.): "The Green Odyssey" by Philip Jose Farmer.
You apparently have no experience with reality. Ever have a housefly draw blood? Ride on a motorcycle in a t-shirt. A housefly, standing still, will hit you with enough force to draw blood. Yes, you will be hurt just as much by a stationary whip as one moving at whip sped, though you don't know how a whip works. Ever watch the whipper? There's a bit of wrist action as you hit something. You aren't just striking them with the inertia of the whip, but transferring energy from the arm of the holder at the same time.
Your analogy is wrong on two very fundamental issues, proving you don't know basic reality, even if you think you know more physics than me (and you are wrong on that count too).
Learn to love Alaska
Even if you missed the pole and got the equator (but were still above the pole), with a 20 km tether for your 5km body, please describe what would happen. Hint: as long as your tether mount articulates, you'll get the tether spinning about once every 10h
After 5 spins the tether is winded up and the probe has a hard landing ... what did you expect? Oh ... you think the centrifugal power is strong enough to let the probe rotate stringed to the asteroid, what a laugh.
You are trying so hard to prove me wrong you aren't even reading what I write. If you are above the pole and hit the equator, the tether will rotate under you, around the equator. If your tether wasn't articulated, you'd rotate every 10h with the object. With it articulated, you can begin the tow, no issues, other than the object is moving under you, and that doesn't matter. In addition to never having used a whip or had a small object be in your way while you are traveling high speed (stick your hand out the window of your can next rainstorm, at 100mph gentle rain can hurt), you also have never used a yo-yo. One of the "failure modes" of a yo-yo is to spin under your hand at the end of the string. It doesn't wind itself up again.
Learn to love Alaska
Cotton cloth can stop a bullet at faster than the speed of sound (some earlier bullet-proof vests were multi-layer cotton, and worked). Again, your ignorance is showing. You are changing a physics question to a materials science question because you know you lost the physics discussion, and it was just a discussion, until you got aggressive and stupid.
Learn to love Alaska
I suppose in reality both options take the same amount of energy technically speaking.
Perhaps my take isn't explained properly and that what I'm actually saying is that the gravity method is much simpler to implement than a net that is 4 square miles or a rocket on a tumbling object without necessarily a stable platform on which to put the rocket.
Likewise the net option doesn't work if the asteroid is tumbling since it would just wind up the net and now your 'pulling' rocket is right against the surface.
People in cars cause accidents....accidents in cars cause people
You are hovering nearby so your gravity pulls the rock toward you. You fire your retro rockets to push yourself away from the rock, in the process pushing the rock away from you, back towards it's original destination.
Isn't a more likely scenario to be you are hovering nearby so the gravity of the larger asteroid pulls your rocket towards the asteroid. You fire your rockets to push yourself away from the asteroid while the asteroid continues on its merry way.
Otherwise, when the various lunar lander crafts launched from the moon, the moon would have been pushed further away and that didn't seem to happen, at least not that could be measured.
If you are going to need years of hovering for this to work and you are going to have to reach the asteroid while it is still years away, so you have time to launch a rocket and travel to it in time to make a difference, That means, first you are going to have to be able to detect said asteroid while many decades away, if not possibly a century or more.
Now, lets say there is an asteroid detected early enough that this might work and that it is relatively small enough where it would make a difference, say the size of a football stadium. Assuming it is mainly solid rock and iron, exactly how much fuel is going to be needed to hover long enough to make a difference. Then once that is known, how much fuel is it going to take to transport the hovering fuel there in a timely fashion. And finally, how much to get it out of earth's gravity well. Sounds like one pretty damn big rocket is going to be needed, just to transport the fuel.
Of course, if it works and it would safe earth, that would be worth it. OTOH, we still have to get past being able to detect it far enough away where there would be time to get there and do all of this hovering.
Now, on the other hand, instead of a football stadium, the asteroid is the size of a volkswagen (which would be far more feasible to divert in this manner), and it is on the right trajectory where it will hit the earth's atmosphere at a steep enough angle that it will penetrate it instead of glancing off, we will never know in time to do anything about it, because at that size, it won't be detected until it is too close to alter the trajectory.
Yeah, I don't think this plan would work very well with our current lightweight spacecraft.
Cheap storage VM.
Yes, Rocky asteroids are indeed brittle and most break up when they enter. Rock is brittle, metals is not.
Yes, the escape velocity of the fragments is very low and most will achieve escape velocity from their original mass.
Remember,the breakup of the asteroid will have most of them miss the earth and the number that hit the earth will be of various sizes, most will break up, being rocky. There may well be larger ones that impact? Recall the one that broke up over Russia recently was about 10,000 tons. They will be of all sizes.
The earth gathers a few thousand tons per day of mainly small sizes. The temporal spread will mitigate the damage as will the size and type of rock.
a million one ton rocky masses - none would reach the surface.
A volkswagen sized asteroid burns up in the atmosphere. The object that created meteor crater was 50 METERS across.
Civilization killers are bigger yet. The dinosaur one was 10 km in diameter.
Yes we need to find these things years in advance.
Fortunately asteroids are mostly going in the same direction we are and are fairly close by which makes it likely we'll have significant warning. Take Apophis, we know it will come very very very close in 2029 and again in 2036. That's over a decade away and that one is just a few hundred yards wide.
Comets on the other hand are real threats because we only get notice of them a few months in advance and they are coming in at right angles (generallishly). And since they are coming from the edge of the solar system...there's no way to get something out to them quick enough.
But asteroids we will almost always have plenty of warning. And since we don't have to deflect it much, it's extremely feasible to do this. Let gravity do the work for us. All we need to do is slow it down so that it's an hour 'late' for it's crossing of our path and the problem is fixed. Or divert it a fraction of a percent of a degree. When done multiple years in advance...it has big enough effects to solve the problem.
People in cars cause accidents....accidents in cars cause people
You're seriously calling Douglas Adams a bad writer?
Persistent Volume manager for Kubernetes - https://github.com/dwimsey/openshift-pvmanager
Depending on which version you read. There isn't a single definitive version of the HHGTTG, I have at least 3 different versions on my bookshelf at home.
Persistent Volume manager for Kubernetes - https://github.com/dwimsey/openshift-pvmanager
Which is better: Getting hit by Mt Everast or a Volvo?
Which is better: Half of Mt Everast burning up in the atmosphere because most of it is broken down into the size of a Volvo or the whole thing hitting the planet because someone forgot that the gravity tether's retro rockets ... are thrusting AGAINST THE OBJECT TRYING TO BE MOVED EFFECTIVELY CANCELING ITS OWN FORCE OUT.
Persistent Volume manager for Kubernetes - https://github.com/dwimsey/openshift-pvmanager
In order for this 'gravity tether' rocket to have enough time to pull the asteroid's course enough to make a difference, it would be far more effective to break it up into tiiny peice and let the debris spread out over the next 50 years it takes to reach Earth.
The problem with the gravity tether is the time required to exert any sizable amount of force on it, with that sort of forewarning, blowing it up becomes logical. The debris will spread out and have its course effected by the rest of the solar system in new ways. Sure, we'll still get SOME bits, but not all.
You'd need decades of time for a gravity tether to do even a noticeable change, forget useful.
Persistent Volume manager for Kubernetes - https://github.com/dwimsey/openshift-pvmanager
I'm not sure where you got Mike from? The only relation I see is that Mike is black ... but so is Neil so I don't get the insightful mod?
Persistent Volume manager for Kubernetes - https://github.com/dwimsey/openshift-pvmanager
most will achieve escape velocity from their original mass.
May I borrow your crystal ball for a while? I assume you must have one, since there is absolutely no way you would know that with any certainty at all otherwise.
a million one ton rocky masses - none would reach the surface
You must be pretty amazingly good to be able to shatter a rock into a million roughly equally-sized pieces. Or maybe you really don't know squat about blowing up rocks at all. (Hint: real miners can't blow up a boulder into equal-sized pieces.) Assuming the extreme best-case scenario, a homogeneous asteroid without any major cracks, internal stresses, voids or veins, perfect knowledge of the internal structure, and unlimited time to drill many thousands of holes all over it to varying depths, and unlimited explosive to fill them with, yes, I guess your plan might possibly work. Then we just have to deal with the equivalent of several thousand nuclear weapons all exploding in the lower atmosphere at once.
On the other hand, we can just tow the damn thing out of an intercept path and be done with it.
"Think about how stupid the average person is. Now, realise that half of them are dumber than that." - George Carlin
http://www.amazon.com/dp/B00BMU2W9O
even discloses how to build a better replacement for rockets
How exactly are you calculating gravitation force without any separation distances?
Persistent Volume manager for Kubernetes - https://github.com/dwimsey/openshift-pvmanager
You sir, are a racist fuck.
You know nothing about the AC, you assume he/she is a racist just because they are saying something to disagree with a black man.
You're projecting your own ignorance and racism on others and its as obvious as it gets.
Crawl back in your hole and keep your fake liberal posture put away so it doesn't make it so obvious you're a tool.
Persistent Volume manager for Kubernetes - https://github.com/dwimsey/openshift-pvmanager
Tyson killed Pluto damnit! He's evil!
(Note: I could care less that he got Pluto demoted, just making a bad joke)
Persistent Volume manager for Kubernetes - https://github.com/dwimsey/openshift-pvmanager
So, the earth is not "tumbling"? ...
That is new to me
Cost free eBook I read (by iBook/Kobo/Amazon/ObookO/Gutenberg etc.): "The Green Odyssey" by Philip Jose Farmer.
Sorry, the only one who is wrong is you.
For the tip of the wip, which is around speed of sound, it does not matter if it was accelerated by swinging arm, a magnetic field or a rocket engine.
It only matters with which speed you are hit or with which speed you hit the wip.
Cost free eBook I read (by iBook/Kobo/Amazon/ObookO/Gutenberg etc.): "The Green Odyssey" by Philip Jose Farmer.
and it was just a discussion, until you got aggressive and stupid.
Do you mix me up? Where was I aggressive? Where was I stupid?
You lost the physical discussion as you ignore the material science issues.
For man made material it is impossible to have a free floating net catching an asteroid without destroying the net ...
Cost free eBook I read (by iBook/Kobo/Amazon/ObookO/Gutenberg etc.): "The Green Odyssey" by Philip Jose Farmer.
You are trying so hard to prove me wrong you aren't even reading what I write. Perhaps you should read what I wrote as well? I covert this point: If you are above the pole but I left it for you to figure what will happen ... the tether breaks ofc after enough rotations.
If you are above the pole and hit the equator, the tether will rotate under you, around the equator. This btw makes no sense ... you can not have the tether at the pole and hit the equator ... or what do you mean with hit?
Cost free eBook I read (by iBook/Kobo/Amazon/ObookO/Gutenberg etc.): "The Green Odyssey" by Philip Jose Farmer.
Which physical effect would it make "worse"?
On top of your claim: it should be obvious that pushing with a very low impulse engine into a sandy surface likely only heats up the sand and does not move a billion tons heavy asteroid at all.
Cost free eBook I read (by iBook/Kobo/Amazon/ObookO/Gutenberg etc.): "The Green Odyssey" by Philip Jose Farmer.
Pushing gently over a long time, without any contact is the idea. For rocky asteroids known to be structurally sound, non-contacting may not be important. But pushing with exhaust without landing is a very inefficient idea. To keep spacecraft same distance from the asteroid, you have to waste half of your propellant in the opposite direction.
Gentlemen, you can't fight in here, this is the War Room!
Of course, the time required will vary depending on the masses involved, but the point is a minor deflection compounds and results in a miss way down the line.
Once you don't have friction to worry about, it's not hard for small objects can push or pull heavy objects. Have you ever been at a science museum that had a crushed car floating on a compressed air truck? You can push several thousand pounds across the floor fairly easily despite inertia.
What if it's spinning on 3 axes?
simple, fast homepage with your links: http://www.ngumbi.com/
Ah, I think I read about this in a book of Galileo's lesser known achievements.
simple, fast homepage with your links: http://www.ngumbi.com/
You also need months if not years to distribute the debris in a way that it does not hit the earth all at once. So I don't see a big difference in the problem set. OTOH the solution set is quite different. How do you split an 1km diameter asteroid in enough tiny parts? How do you distribute them over space that is at least 2x the diameter of earth?
Cost free eBook I read (by iBook/Kobo/Amazon/ObookO/Gutenberg etc.): "The Green Odyssey" by Philip Jose Farmer.
Here-
http://neo.jpl.nasa.gov/neo/b612_report.html
The report is a word doc linked at the bottom.
Just a note, the thrusters are canted somewhat offline so that the exhaust mass doesn't hit the asteroid and negate some of the gravity attraction.
simple, fast homepage with your links: http://www.ngumbi.com/
most will achieve escape velocity from their original mass.
May I borrow your crystal ball for a while? I assume you must have one, since there is absolutely no way you would know that with any certainty at all otherwise.
LOL, the escape velocity from a one million tonne mass is 0.0000115536 meters per second (gravity = weak remember)
a million one ton rocky masses - none would reach the surface
You must be pretty amazingly good to be able to shatter a rock into a million roughly equally-sized pieces. Or maybe you really don't know squat about blowing up rocks at all. WHat a moron, you supplied the one tonne masses - did you forget?
Explosive fragmentation will produce randon masses from dust upwards - to large pieces, depends on the competence of the rock and shear it is subjected to, and the number of holes and blasting material you used.
The rock will break where the local shear exceeds the strength. High brisance, like TNT with a velocity of detonation of several thousand meters per second will create a network of fractures. The more hole = more fractures = smaller pieces, I agree, surprise I have lots of experience in mining, drilling, fusing etc. With a large mass like this with expansion room to infinity, you might create a ring of holes 10 feet apart as a ring, and another one within it, and so on. The outer ring is detonated first, followed progressively by the inner ones, which will give you an expanding mass of fragmented rock. This is opposite to what you do to blast a shaft, where you create an expanding pattern from the middle out, the center if broken and ejected and then successive blasts break into the loosened area
On the other hand, we can just tow the damn thing out of an intercept path and be done with it.
Yes, I agree, but the best way to tow it is with an ion rocket mounted some distance from the asteroid with a number of nozzles directing the ions so they clear the asteroid (hitting it wastes it) and attached by a pull cable of sufficenet strength for the job. A sold metal asteroid can probably be moved by a post drilled into it and cemented. A one inch attachment will take many tons, bit if it is broken and goint to be moving through a gravitational gradient that might cause separation of pieces, you need to bag it. Seine nets 500 meters across are sold, in essence they can be made arbitrarily large - as long as they can be orbited and have the strength needed to be pulled by 1000 pounds. A large and light net could be extruded in orbit from the correct material. Nylon would work, so would polyester, as long as they were UV stabilized.A net 500 meters x 500 x 500 = 125,000,000 cubic meters - 400 million tons of rocks, more or lees, =depends on the density which a 1000 pound pull would move away from the earth in a few months or less. You could make a net 5 miles across, just balance the holes size, strength etc to suit it.
The gravity tug method is many thousands of times as wastefull of energy as ion rockets. Just thrust it away, do not use the microscopic force of gravity when you have the large force of thrust
Rotation would have to be dealt with. You might not want to stop it, if it in enough may toss loose pieces away with escape velocity - remember how very small the ev is, In my opinion, a loose aggregate will not have a large rotational speed for this reason. A metal one can have a high rate of rotation. A solid rock one that has a high rate of rotation will scatter when broken. Each case will differ, and various ways to accomodate any rotation will be used.
Our parent thinks it can't spin around 3 axes ;D
Well to be honest: if it spins around more than one axis, there is a resulting axis which expresses all 2 or all 3 spins. However our parent also claimed it could not tumble, which is ofc nonsense. You only need to watch a spinning top. The earth is tumbling as well, once every 24,000 years the polar axis makes one big circle. That is the reason why the north star is wandering (and we have a new north star every few thousand years)
Cost free eBook I read (by iBook/Kobo/Amazon/ObookO/Gutenberg etc.): "The Green Odyssey" by Philip Jose Farmer.
And to pull with gravity, the closer you are the stronger the pull, but when you get close, you have to make sure your exhaust doesn't hit the body, so you'll be directing your exhaust in an inefficient manner.
Learn to love Alaska
Yes, I see, it has limited merit, and is inferior to impactors and suited only to the bag of orbiting gravel and very long time frames because it is so very very weak.
i.e.
4. For our simulated test case, where the tractoring spacecraft was about 1000 kg, the total V imparted to the asteroid in one month was about 7 m/s.
so it would need decades tomiss the keyhole.
It also says, each case differs and impactors and direct thrust can be superior.
I would like to see a ssimilar report that rated other methods in more detail
I use online calculators that deal with m1, m2, and separation as point masses
http://easycalculation.com/physics/classical-physics/newtons-law.php
here is one that seems to do a good job
If you aim the connection point from the tether to the net to be at a pole, it will not wind up the tether. It would only wind if the connection point was at the equator, and your tug was also over the equator. Any other combination will not result in a wind (even if it causes stresses that would cause a failure, the failure would be in a different manner).
The gravity method is "simple" in that it is independent of the approaching body and never touches it. However, it is very very very slow. It's unlikely that we'll ever have enough time to identify the body, get a gravity tug out there, and have it have enough time left to make a difference. And if we did, we could still try 10 other more "drastic" attempts at the same time as using the gravity tug, for additional security and safety margins. A 3000 km variance in something far away isn't hard. But if our measurements at that range are within 0.01%, then we could be pulling it from a close miss east to a hit far west, when waiting would make the gravity useless if it were a hit, when other more aggressive actions could still work.
I never said it wouldn't work. I've just indicated that for most real-world cases, we'll not be able to wait the long time it takes for a gravity tug to work.
Learn to love Alaska
Why does your post make me think of testicles?
The new right fascists are bilingual. They speak English and Bullshit.
pushing into a sandy surface will be no different from pushing on a rock environment. When you finish 3rd grade physics, let us know. Having to teach you elementary physics to prove your ignorance is beyond my patience for some anonymous Internet user.
Learn to love Alaska
This btw makes no sense ... you can not have the tether at the pole and hit the equator ... or what do you mean with hit?
You were indicating the worst case, you are above the equator and attach the tether at the equator. I indicated that any modification of that will result in a "safe" result and no issues using a tethered tug. If you are above the pole and attach at the equator, it will work without issues. If you are at the equator and attach at the pole, you will also be successful. The "issue" is that you need to guess the spin correctly before you deploy the net. None of your irrational attacks on the scheme are valid.
Learn to love Alaska
You use physics to determine if it's "possible". Then you determine whether it's practical. Like space elevators. Possible, but not yet practical. A net to catch a comet/asteroid? possible, but practicality undetermined (not the same as impractical, just not determined). You are stupidly changing the topic back and forthe between possible and practical in an irrational attempt to prove me wrong. Why? If I'm wrong, why not just the first post and leave it? You haven't even supported your complaints with fact/physics
And you got aggressive when you objected to one of my complaints on one of your posts, and stalked me on 4 or more threads within this article. That's aggressive and indicates some irrationality. You aren't discussing the issue, but stalking me and complaining about my opinion in multiple places.
Learn to love Alaska
For the tip of the wip, which is around speed of sound, it does not matter if it was accelerated by swinging arm, a magnetic field or a rocket engine.
It only matters with which speed you are hit or with which speed you hit the wip.
So, your argument is "you are traveling the speed of sound towards a whip, will it hurt as much as standing still and being hit" I think hitting a stationary whip tip at that speed will feel exactly the same as the other way. You are implying the opposite, without any evidence to support your opinion.
If you are just going to make up untestable shit to support your point and imply that I'm wrong because you can't conceive of fast speeds means you are irrational.
I could post piles of equations to prove you wrong, but you'll never listen. So what's the point of continuing to prove you wrong?
Learn to love Alaska
most real world cases mean the asteroid is tumbling in all 3 axes making anything that requires contact with the asteroid will be severely problematic.
The 'connection point' still has the problem of not being stable enough to support the mass of the asteroid being diverted; i.e. weakest link. Most of these things are piles of dust and rocks loosely held together, you can't put a tether on it and pull, it would just pull off with any amount of pressure. Hence my understanding of your 'net' idea means we need to drape something over the object and pull in the ends of the draped material. It's a *really* big net, bigger than anything we've built previously. If it's draped over the surface it will wrap itself up eventually.
But to your 'most real world cases'; if we find a planet killer coming without years of warning, we aren't going to be able to do anything about it anyway. The less time you have the more force you have to impart over that lesser time. Even trying to put up pusher rockets is going to take months to get into position. Plus it's wildly more complicated and prone to failure.
Simplicity is the only way to do this reliably; since it can't possibly fail or we die. And yes it means lots of lead time. Better to fund finding those asteroids now before they become 2 months out.
People in cars cause accidents....accidents in cars cause people
It's a *really* big net, bigger than anything we've built previously.
Larger than any other net, maybe, larger than "anything" we've built previously, certainly not.
And, as I've said before, if it's a pile of dust, weakly held together, then you land a nuke on it, as far down as you can (should be easy, something like a bunker-buster missile with a nuclear explosive) and boom, send 5% of the mass one direction at super-high speed, and 95% of the mass goes the other way with a small moment imparted, and both sets of mass miss the earth. If it's harder, then the net won't suffer the issues you are complaining about. The gravity pull is useful only if you require a single sub-optimal solution that works in *all* cases, not just 99.9% of cases.
Learn to love Alaska
For more info on this topic, Google "non-principal axis (NPA) rotation asteroids"
All go back to the basic http://en.wikipedia.org/wiki/Precession#Torque-free for the physics about it, and it's a small effect because single-axis rotation is the stable state. Oh, I did find references to most known cases being ones that appear to be bifurcated bodies, where the two parts orbit each other, but the torque-free precession (tumbling) indicates the effect is small, and stabilizes into a single-axis rotation.
Learn to love Alaska
He said "black moran (sic)". Punchy Mike fits the bill.
If a bill fit you, you'd be a duck.
We don'ta hava no insightful mod, we gotta introspection mod, just sit and think about yourself a while.
*Repent!Quit Your Job!Slack Off!The World Ends Tomorrow and You May Die!
But Tyson's pomposity sort of makes it hard for me to "like" him..
They're fine as long as they don't get uppity, eh?
Excellent, I think you just summed up both the proles' and the actual people in power's feelings towards scientists.
Um, what are you going on about? There is nothing in Runaway1956's comment that is racist.
Sometimes I doubt your commitment to Sparkle Motion
Yes, but the point is that not all asteroids have stabilized their rotation - only the large ones have. The rest are tumbling, i.e. spinning on more than one axis.
Nukes are not going to work. We don't have anything big enough to deflect something that is KILOMETERS across.
And when we're talking about the survival of the human race, I'll take 'sub optimal' but 100% functional thanks. If you call the simplest, easiest and most cost effective solution 'sub optimal' that is...
People in cars cause accidents....accidents in cars cause people
A small nuke will move something KILOMETERS across. The gravity pull requires a very long time to get any effect, a nuke is much much more effective. The *only* redeeming quality of the gravity pull is that it works for *all* cases. It's slow. It's hard. It's risk-prone, but it's a one-size-fits-all solution, and that's apparently more important than effectivenes.
Learn to love Alaska
Are you unable to read or do you this with intention?
So, your argument is "you are traveling the speed of sound towards a whip, will it hurt as much as standing still and being hit" I think hitting a stationary whip tip at that speed will feel exactly the same as the other way.
That is exactly what I said, but you argued the rest of this thread it would not be true.
So now you agree? Your face feels the same regardless wether I smack you with the wip or wether I smash you into a stationary wip?
And if you agree now, why did you argue for a net in space trying to "capture an asteroid" it is different?
Cost free eBook I read (by iBook/Kobo/Amazon/ObookO/Gutenberg etc.): "The Green Odyssey" by Philip Jose Farmer.
(not the same as impractical, just not determined).
Of course it is determined. everyone here on /. told you so, you just don't listen/believe it.
To capture an asteroid with a net the net has to fly more or less the same speed, then you need to gently wrap it around and in the end you need to determine what to do, how to slow the spin or how to move the asteroid.
We never argued about "impossible" we argued about your brain dead idea that you simply can have a net float in front of the asteroid to let it smash into it.
That's aggressive and indicates some irrationality.
This is absolutely not agressive as this is an discusion forum and you treat everyone without respect and use verbal violence continuously.
I would suggest you get a good book about physics or get your lazy ass up and go to a collage / university and study the stuff.
Cost free eBook I read (by iBook/Kobo/Amazon/ObookO/Gutenberg etc.): "The Green Odyssey" by Philip Jose Farmer.
Man are you stupid and stubborn.
I suggest you take a 10 yards tether and bind it at a fixed point, like a tree.
Then you twist it until you no longer can twist it.
See what happens. Depending on the tether it will break at that point ...
BTW it will shorten during that, pulling you (or your space probe) closer to the tree (to the asteroid).
In case it does not break, you have now a probe very close to the asteroid, far closer than the length of the tether. Now the probe starts to rotate, first slowly, then with the speed of the asteroid, and then it starts to untwist the tether completely gaining speed and speed and speed and rotating faster and faster.
This process is repeated until the tether ruptures, which I guess is in 3 or 4 iterations.
If you ever had played es a child with simple toys, you knew that, and no one would need to explain it to you.
Cost free eBook I read (by iBook/Kobo/Amazon/ObookO/Gutenberg etc.): "The Green Odyssey" by Philip Jose Farmer.
Define pushing then :D
Sems you have a different idea of pushing.
If you push into a sandy surface a huge deal of your energy gets converted into heat (due to friction).
if you "impact" with a "momentum" onto a rocky surface a huge deal of your momentum gets deflected/reflected.
So about what are we talking? Pushing? You talked about pushing. Pushing on a sandy surface will let you lose lots of energy ... pushing the sand left and right instead of into the direction you want.
Or do we talk about the law of conservation of impulse? Then I would suggest we talk about "impact".
And no, I don't know which gradfes physic that is as I did my first exams 27 years ago and my bachelor equivalent 20 years ago, the law of conservation of impulse clearly states that it is not the same wether I impact on a pile of sand or on a rock.
If I hit a pile of sand the impacts impulse is completely transfered to the sand pile. If I hit a rock, I get reflected/deflected and only a part is transfered to the rock.
So, what did you say again? pushing into a sandy surface will be no different from pushing on a rock environment Just quoting it, so you can not again use my words and claim it where yours. No, there is a difference a huge one even. And pushing versus impacting are two different things anyway. If you push you soon are in the area of solid state physics ... which can become tricky ;D ... good luck in your arguments, I hope you don't plan to go into a job where physics knowledge is required.
E.g. lots of stuff you push is not moving but deforming
Cost free eBook I read (by iBook/Kobo/Amazon/ObookO/Gutenberg etc.): "The Green Odyssey" by Philip Jose Farmer.
That snippet, yes.
Written like a 12 year old.
Here's the original from The Restaurant at the End of the Universe (UK edition):
"Well what happened you see was," said the Captain, "our planet, the world from which we have come, was, so to speak, doomed."
"Doomed?"
"Oh yes. So what everyone thought was, let's pack the whole population into some giant spaceships and go and settle on another planet."
Having told this much of his story, he settled back with a satisfied grunt.
"You mean a less doomed one?" promoted Arthur.
"What did you say dear fellow?"
"A less doomed planet. You were going to settle on."
"Are going to settle on, yes. So it was decided to build three ships, you see, three Arks in Space, and ... I'm not boring you am I?"
"No, no," said Ford firmly, "it's fascinating." ...
"Yes, so anyway," he resumed, "the idea was that into the first ship, the `A' ship, would go all the brilliant leaders, the scientists, the great artists, you know, all the achievers; and
into the third, or `C' ship, would go all the people who did the actual work, who made things and did things, and then into the `B' ship - that's us - would go everyone else, the middlemen you see."
He smiled happily at them. ...
"Er ..." said Arthur after a moment, "what exactly was it that was wrong with your planet then?"
"Oh, it was doomed, as I said," said the Captain, "Apparently it was going to crash into the sun or something. Or maybe it was that the moon was going to crash into us. Something of the kind. Absolutely terrifying prospect whatever it was."
"Oh," said the first officer suddenly, "I thought it was that the planet was going to be invaded by a gigantic swarm of twelve foot piranha bees. Wasn't that it?"
Number Two span around, eyes ablaze with a cold hard light that only comes with the amount of practise he was prepared to put in.
"That's not what I was told!" he hissed, "My commanding officer told me that the entire planet was in imminent danger of being eaten by an enormous mutant star goat!"
"Oh really ..." said Ford Prefect.
"Yes! A monstrous creature from the pit of hell with scything teeth ten thousand miles long, breath that would boil oceans, claws that could tear continents from their roots, a thousand eyes that burned like the sun, slavering jaws a million miles across, a monster such as you have never ... never ... ever ..."
"And they made sure they sent you lot off first did they?" inquired Arthur.
"Oh yes," said the Captain, "well everyone said, very nicely I thought, that it was very important for morale to feel that they would be arriving on a planet where they could be sure of a good haircut and where the phones were clean."
"Oh yes," agreed Ford, "I can see that would be very important. And the other ships, er ... they followed on after you did they?"
For a moment the Captain did not answer. He twisted round in his bath and gazed backwards over the huge bulk of the ship towards the bright galactic centre. He squinted into the inconceivable distance.
"Ah. Well it's funny you should say that," he said and allowed himself a slight frown at Ford Prefect, "because curiously enough ... but they must be behind us somewhere."
we haven't heard a peep out of them since we left five years ago
He peered off into the distance again. Ford peered with him and gave a thoughtful frown.
"Unless of course," he said softly, "they were eaten by the goat ..."
"Ah yes ..." said the Captai
If you push into a sandy surface a huge deal of your energy gets converted into heat (due to friction).
Go to the beach. Stand on the soft dry sand (the worst case you are talking about. Wait 6 hours. How hot is the sand from your "pushing" on it? Yes, it's hot, but that's from the sun, you are on a beach after all.
Sorry, but reality proves you wrong on every count, every time you speak. If you are impacting sand, it reacts like a firm but deformable surface. Sandbags do a good job of absorbing bullets. But push on it more slowly with the sharp tip of a pencil, and you'll push the 50 lb sandbag off the pile.
the law of conservation of impulse clearly states that it is not the same wether I impact on a pile of sand or on a rock.
Where did you do your bachelors? For one, you call it an "equivalent" which indicates to me you got it outside the US. The other is it's "the conservation of momentum" in American English. And yes, the law says the same happens regardless of the surface, so long as you don't bounce off. Perhaps the issue is that you did that too long ago.
I hope you don't plan to go into a job where physics knowledge is required.
I already have a nice job where physics knowledge is used on a regular basis. Works well for me. Maybe you are working on the wrong physics. Where was it again you learned it?
Learn to love Alaska
If a small probe were twisting around the tree, the cable would work transfer torque to the probe and the probe would spin. That isn't a problem. That is expected behavior, and you can fix it with an articulating mount.
If you ever had played es a child with simple toys, you knew that, and no one would need to explain it to you.
Your children's toys were cheap. Go do the same with one with an articulating mount. Twist all you like, it won't do what you describe. And your "analogy" requires you have two fixed points at the ends of the tether. Neither is fixed in space, though we can assume the comet/asteroid to be so, but that still leaves one as a comparatively small body, which your examples don't allow for, which is why they are simply wrong. Like everything else you've said so far.
Learn to love Alaska
For all practical purpose a megaton or gigaton asteroid can be considered fixed like a tree.
As the probe is far heavier than you, my example with the tree and you and a tether made perfect sense. Only: you are unable to grasp it or to comprehend it.
I'm tired with you ... you seem to lack basic understandings and in other posts you are insulting ;D
Good luck in your "physics related" job.
Cost free eBook I read (by iBook/Kobo/Amazon/ObookO/Gutenberg etc.): "The Green Odyssey" by Philip Jose Farmer.
I still think you are neglecting the effect of the transfer of force/energy from the hand holding the whip. But I would also note that a whip striking you at MACH1 or you striking it at the same speed does not damage the whip in either case, and that was my original point you argued with. You've argued that me hitting the whip is fundamentally different because if you hit a whip at high speed, it won't hurt the whip, like if you hit a net at high speed, it won't hurt the net. And if "you" in the previous sentence is a rock the size of the moon, the effect doesn't change.
Learn to love Alaska
We never argued about "impossible" we argued about your brain dead idea that you simply can have a net float in front of the asteroid to let it smash into it.
So you are now asserting that it isn't "impossible" which means you think it possible, right? So, now that we've agreed on it being possible, the remaining issues are implementation details.
Learn to love Alaska
As the probe is far heavier than you, my example with the tree and you and a tether made perfect sense.
No, the probe is not heavier than me. The probe is unanchored in space. A 1N force will cause it to spin or move. a 1N force against me might get you slapped if I mistakenly take that as a bug landing on me.
you seem to lack basic understandings and in other posts you are insulting
You've stalked me to insult my idea with incorrect physics, then assert I'm the one that doesn't know what I'm talking about when I correctly rebuff all your incorrect physics statements. Again, I'd ask where you got your bachelor's equivelent, so I make sure to never hire someone from there, as they obviously don't educate, they de-educate, but given the way you ignored that question the first time, I assume you are ashamed of who you are and what you did.
Learn to love Alaska
You are both stupid and stubborn, and acting like children.
Why don't you go study some astrophysics and then argue about, you know, astrophysics?
As long as Bruce Willis is alive there's no need for a deflection-plan. He blew it up once, he'll do it again.
I still can't figure out who he survived the first time though...
Yes, I see, it has limited merit, and is inferior to impactors and suited only to the bag of orbiting gravel and very long time frames because it is so very very weak.
Thank you for that admission. However, your level of condescension detracts from that markedly.
I would like to see a ssimilar report that rated other methods in more detail
Then why don't you get on that right away, Bill? With your superior brain, they should be done in no time.
Please post them here when they're ready. And I promise I won't call them "fool's work".
Honestly.
Only if the thrusters are bolted onto the massive craft. They could be 10km away, cradling the probe with cables.
Think outside the box that is limiting you.
I don't see how that answered the question.
We know all km-sized asteroids including their trajectories for centuries...
Really? NASA disagrees with you and I tend to take their word for it over yours. We've discovered hundreds of kilometer sized near Earth asteroids in just the last decade.
The discussion is specifically about "extinction level" impactors. Get it wrong first time and you do not get a second chance.
This game doesn't have a "save" option. When you die, it's permanent. You don't get to do a rehearsal unless you spend some of your development budget and time on doing a rehearsal. There is no guarantee that you will have time to do a rehearsal. Or indeed, to actually do anything.
Nature doesn't care.
Birds are not dinosaur descendants;birds are dinosaurs, for all useful meanings of "birds", "are" and "dinosaurs"
This is only a problem if your retro-rocket plumes impact on the rock you're trying to tow around. So, you arrange your retro rockets to fire in pairs at (say) pi/4 radians to the desired line of thrust, and at sqrt(2) of the required power.
(Exact angles and forces will need refinement for the exact circumstances. How big is the asteroid ; how close do you need to get ; how much time do you have to achieve the deflection. In practice, I'd suspect that you'd use 3 thrusters on orthogonal axes, which is a common configuration on satellites already for these very reasons.)
Birds are not dinosaur descendants;birds are dinosaurs, for all useful meanings of "birds", "are" and "dinosaurs"
If you've got years of warning, then you don't need to do things like throwing bombs around. You've got the time to use less drastic techniques.
The only important effect would be if you actually get some of the pieces to not hit the Earth. Which you can do if you've got years and multiple orbits of warning. If you've got a few days or weeks warning warning, then you're also not going to have time for the debris to disperse sufficiently.
But don't worry ; in that circumstance the gravity tow idea isn't going to work either. For days or weeks everyone on the planet who cares to know is going to be aware of the date and time of their death, to an accuracy of a few minutes.
Two issues arise from your characterisation : firstly, these "rubble piles" are not very good at transmitting shocks. If you plant your nuke on the surface, the rocks near the nuke are going to get a big shove, but as they project away from the explosion point, they'll cut through the rubble and impart relatively little energy to the rest of the pile. Which is why many of the imaged asteroids have seemingly gigantic craters on them from large impacts which should have disintegrated the asteroids. If they were rigid bodies. But they're not ; they're rubble piles which accommodate the impact energy by internal rearrangement.
(Incidentally, this structural weakness is part of the reason that you're nuke is going to detonate on the surface. You're not going to be able to dig a pit deep enough to get the bomb significantly (several kilometres) down into the rock. How you're going to anchor your drilling equipment to such a weak substrate is just one of the impossible things you need to do before breakfast.)
Secondly. you're missing a point about "burning up in the atmosphere". As you "burn up" each impactor, the air gets hotter. With a lot of impactors, all of the atmosphere gets hot. With enough (a multi-kilometre impactor disintegrating, or the ejecta from one such re-impacting on the rest of the planet), all of the atmosphere gets hot. Hot enough to burn. Hot enough to cause "flash-over" fires all around the planet. (Your fire-fighting training at work included "flash-over"? When the radiated heat from a fire in area causes the surface of other objects to start burning directly. Mine did. I've friends who lost parts of their faces to a flash-over fire at work; it's not nice. 167 of our colleagues died that night.)
The sums have been done - over a decade ago - and published. You have had a decade to disagree and prove them wrong. Where's your paper?
Birds are not dinosaur descendants;birds are dinosaurs, for all useful meanings of "birds", "are" and "dinosaurs"
So if you know something is going to kill you in 15 years time, you can't try one thing now, and another next year, and compare the results and base continued action based on the results of the first two attempts? Why not?
Learn to love Alaska
There is every chance of not even getting 15 months warning. Not all asteroids (and comets) are tracked, and not all orbit in the plane of the ecliptic (which is where the large majority of the searching has happened). So a no-warning or minimal-warning impactor is a real possibility.
Even if you do have 15 years warning, then you'd have to be really really really sure that your first attempt at fixing the problem isn't going to make the problem worse. Say, you spend you first year deploying a nuke ... which busts the threatening impactor into 20 major chunks, only one of which is not on a impacting course. Lovely!
Birds are not dinosaur descendants;birds are dinosaurs, for all useful meanings of "birds", "are" and "dinosaurs"
Good thing he didn't write it, then! That's just GPierce paraphrasing Douglas Adams, poorly.
I got a bit weary of Adams after reading 4 books, but when his style was fresh and new to me, I just loved him:
http://www.wowbagger.com/chapter1.htm