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The Space Garbage Scow, ala Cringely
An anonymous reader writes "Robert X. Cringely once again educates and amuses with his take on how we could clean up the garbage that's in orbit around Earth. I cannot vouch for his math, but it makes sense to me. Quoting: 'We’d start in a high orbit, above the space junk, because we could trade that altitude for speed as needed, simply by flying lower, trading potential energy for kinetic. Dragging the net behind a little unmanned spacecraft, my idea would be to go past each piece of junk in such a way that it not only lodges permanently in the net, but that doing so adds kinetic energy (hitting at shallow angles to essentially tack like a sailboat off the debris). But wait, there’s more! You not only have to try to get energy from each encounter, it helps if — like in a game of billiards or pool — each encounter results in an effective ricochet sending the net in the proper trajectory for its next encounter. Rinse and repeat 18,000 times.'"
That this doesn't break up any debris into more parts - or cause the "net" to break and provide additional pieces of junk circling the earth.
If builders built buildings the way programmers wrote programs, then the first woodpecker would destroy civilization.
Wouldn't it be bad catching all of the space debris in a giant net, when the net itself will eventually come back down to earth. Individual space junk coming out of orbit isn't as bad since it's not all falling in the same place and it's small enough to mostly burn up in the atmosphere, but if you've got this huge net there's a lot more junk to burn up with a much more localized crash site.
Plus this thing bouncing around like a billiard ball seems likely to catch something that isn't junk...
I thought they were just in the early stages of establishing a ring-world, in terrestrial orbit. Oh well...
There will of course, be no such mission, headed by NASA, or any other fraction of the Federal United States. That banana republic operates on such a scale, only when there is substantial room for contractor and supplier rip-off. If Cringeley can figure a way for DynaCor to pocket a billion on the side, instead of increasing fuel efficiency in spaceflight? It'd happen next year.
"Speaking the Truth in times of universal deceit is a revolutionary act." -- George Orwell
Perhaps Cringely doesn't have a clear idea what sort of debris we are dealing with here
There are, certainly, some big chunks out there; but unpleasant enough(and far more numerous) are the little flecks of paint, bolts, and general fragments of this and that zipping around at bulletesque velocities.
Either this "net" will be made of very close-woven unobtanium, of the sort that we don't yet have, despite decades of interest in the personnel armor industry, or it will have to be a vast spongy particle trap, of the sort whose volume would be completely prohibitive for any available launch mechanism.
Anyone remember Quark, a space garbage scow show from the 70's? :D
It's nice to see it's time...
Soulskill, why are you posting this crap from Cringely? Any article attached to that name is automatically shit.
I wish Roland Piquepaille had never died. At least his articles had some scientific basis to them, even if he was hated by many people here. Cringley articles, on the other hand, are bunk from top to bottom.
Only the timescale. "Sooner or later" can be in the decades to centuries range, which is minimally useful for most of us now living.
I'd love to mod the article as (-1, Cringely doesn't understand space). Where's the button for that?
The good news is, Cringely's article does not contain any math or physics. Without serious numbers to back it up, the idea is no more than a pipe dream. How do you catch a stone flying with a relative velocity of a few miles per second without getting blown to bits?
You could try reading the summary next time. His proposal was for one flight, not 18000. I imagine his plan is still impractical for lots of reasons (you probably can't get enough impulse from each piece to approach the next one at a low enough speed, etc.), but it's still not as bad as your suggestion of 18000 manned space flights.
your and idiot not cringley. even TFS mentions collecting items in sequence, not a single launch for each object..
someones been playing Osmos too much.
I don't know, maybe you are... how come all these planets including the Earth are still in the sun's orbit?
among the other holes in this idea the biggest is that when in orbit an increase in velocity means an increase in altitude, to decrease your altitude you must either slow the space craft down or you need an elliptical orbit with an eccentricity approaching 1.
If you catch something stationary while you move, you won't increase your momentum; nor will you increase your kinetic energy. I don't care how much you want it to be akin to tacking into the wind, it won't work.
Until something tragic happens because of a piece of space junk, no one will do anything.
I scream. You scream. I assume that means we're both acquainted with the problem. We proceed.
Wouldn't something like a big ass electromagnet be useful? I mean, compared to a net... or something along the lines of giant flashlight (to push crap into earth)
But I think that I would prefer a set of these, and dispense of them after a shorter time (burn it up or capture it for material studies). For starters, imagine accumulating a bunch of that junk together and then losing the ship. It could actually make things worst.
Also, this would be a good use for the tug concept. At some point, a tug will be useful for space. This could help push the concept.
I prefer the "u" in honour as it seems to be missing these days.
A better idea might be to use the concept of induction to our advantage. Create a satellite that creates a several kilometer diameter magnetic field bubble and fly it through the debris at high velocity. THe debris is most likely conductive and would have a current induced in it causing a drag force against the janitorial satellite. The orbits that cause the most drag are ones that run counter to the craft so they'll probably be nudged into a lower orbit by the drag. The janitorial satellite will use solar power and a space tether to stay in its current orbit. Any satellites that need to stay up there and aren't considered debris can be tracked much more easily and you could just shut the EM field down upon close encounter with them.
The craft would use very little propellant and would probably work better than a net anyway. Just have a few craft like these flying around and acting like an immune system that kills off targets that are a danger to other craft.
Sigs are too short to say anything truly profound so read the above post instead.
IF (and I know it is a big IF) it were possible to "manufacture" aerogels in space, this material could be ideal for capturing/de-orbiting small pieces of debris that would be too difficult/expensive to chase and capture the traditional way (via space tug or whatnot) but still poses a threat. Aerogels have already proven themselves as capable of capturing extremely fast (although tiny) particles moving at literally astronomical speeds without itself disintegrating. It was used precisely for this reason in both the "Stardust" and "Genesis" probes.
Now imagine instead of the small plates that were on these probes a very large slab tens or hundreds (thousands?) of meters on a side that would, over time, slowly intercept the smaller particles. Larger fragments would still go right through but might lose enough kinetic energy (without fragmenting and making the problem worse) so as to de-orbit themselves. The only thing that might make this remotely possible is the thought that the aerogel is so light (lighter than air) that a really huge piece could be put into orbit without spending billions in launch something heavy. Of course the only way to keep the launch volume reasonable is to MAKE it in space. Once in space, an ion engine would be required to counteract the atmospheric drag (and loss of kinetic energy from the impacts of the space debris).
By "manufacture" I mean the raw material (I guess it some sort of silicate compound) would have to be brought up from earth but since the resulting aerogel is 99.9% empty space, a little could go a long way. I understand that one way to produce it requires a super-critical liquid carbon-dioxide solution; obviously the CO2 would have to be recycled or better yet would be if a means of producing it directly in vacuum. Chemists, any ideas?
Did you even read TFS?
He's not proposing 18,000 spaceflights manned or otherwise. He's proposing a gigantic billiards shot where all the balls are in motion, salvaging the motion of some of the balls to line up the next one and eventually encounter and sink all the balls in one shot.
Then he's got some weird ideas about orbital energy this "net" concept that seems tricky (although a sufficiently strong, ductile net would increase the target area for intercept and it doesn't matter if the net gets torn to shreds as long as the shreds stay attached), but the underlying idea is interesting, and it certainly doesn't need to be so tricky as to sink all the debris in only one flight with no inter-object maneuvering.
Can you be Even More Awesome?!
And by massive I mean square kilometres and tens of meters thick.
Aerogel has been shown to be able to pick up even the smallest flecks of material for the Stardust project.
Since it's the smallest things that are the trickiest (huge bits are easily tracked), we need something that will not only absorb the energy of the impact, but also keep the debris in place. Thus, Aerogel is a good fit.
Does Cringely have some kind of seedy business relationship with Slashdot's parent company?
Software piracy is victimless theft.
Every velocity in space in orbit is super-bulletesque. It's the relative velocities that matter. I could catch the paint fleks with any old material, if, the relative velocities were reasonably close. Indeed, if you launched me out of a cannon next to a bullet fired out of a rifle, I'd almost be able to catch the bullet with no harm to myself. It's just the launching and the landing that would suck.
This is my sig.
What about some gel block, or even better some kind of foam?
It makes sense to capture and lose the small pieces. BUT, the large ones are lots of material in space that took a lot of fuel to get there. That would be a shame to lose those if they are together. Seems like we can push those into a higher orbit out of the way and then use them in the future.
I prefer the "u" in honour as it seems to be missing these days.
We can send convicts with bright orange space suits into space. Give each one a trash stick and a burlap bag. For obvious reasons, there's no need for shackles and chains.
That's not a bad idea. The real questions would be how much of a drag force could you create at a given distance? The junk is distributed in a cloud around the planet so encounters with junk could be hundreds of meters? Kilometers? Getting closer would require propellant. The field strength is limited by the amount of power you can generate, which ain't much from solar cells. The end effect is it may be completely infeasible because of scale. I wouldn't know how to work the numbers, but maybe someone else does.
AccountKiller
...means the net will lose speed every time it captures some junk. The author needs to take high school physics again.
Tacking on a sailboat works because the wind is blowing on the sail, adding energy to the whole craft.
Scooping stuff in a net is just an inelastic collision. The momentum gain of the junk will equal the momentum loss of the net. The net's orbit will decay as it captures more and more junk.
HCG 50a = 2MASX J11170638+5455016
11h17m06.4s +54d55m02s
I don't know, maybe you are... how come all these planets including the Earth are still in the sun's orbit?
Duh. God.
Particles the size of a grain of sand - assume 1 gram. Speed: 8333 metres per second. Kinetic Energy Formula: 0.5 * mass * velocity * velocity.
Kinetic Energy of grain of sand: 34,719 joules.
Small car travelling at 30mph, mass 1000kg. Speed: 13 metres per second.
Kinetic Energy of car: 84,500 joules.
Area to which impact of grain of sand occurs: assume 1mm square.
Kinetic Energy per square metre when grain impacts: 34 billion Joules/Sqm.
Area to which impact of car occurs at 30mph: assume 1 sq m.
Kinetic Energy per square metre when car impacts: 84 thousand Joules/Sqm.
this is why, if a dust particle the size of a grain of sand hits a spacecraft it would leave a micro hole on one side, vapourise and turn to plasma, cutting its way through absolutely everything in its path in a geometrically predictable and expanding pattern. net result is a gaping cone of missing spacecraft on the other side of the dot, significant additional debris, and some dead astronauts.
and that's just the dust particles.
Materials science is simply not up to the job of dealing with this kind of energy impact, which is why, instead, NASA tracks several tens of thousands of objects including an Astronaut's boot, and makes sure that everything that goes up stays well clear.
To drop from a higher altitude to a lower altitude you have to lose kinetic energy, not gain it. Furthermore, everything is not traveling in the same direction. There are many different orbits and junk is in all sorts of them. So some junk you'll never "net" since it's traveling in the same direction as the dejunker, and other junk is traveling exactly opposite and will slam into the net with twice the velocity of the denetter's current orbital velocity. Furthermore if the junk's orbit is 90 degrees to the dejunker, it will never be caught either. Even if the orbital paths crossed, it would probably just destroy or damage the dejunker satellite (paint fleck or rachet wrench).
So it wouldn't seem that his idea stands the common sense test (or physics for that matter). But this is just slashdot and I am not an orbital-mechanics expert. I failed that class at the starfleet academy (or was that temporal mechanics).
Unfortunately, the operation of a space garbage scow is fraught with danger.
Anyone remember Quark, a space garbage scow show from the 70's? :D
It's nice to see it's time...
Quark was the first thing I thought of when I saw the heading. Life imitating art.
Beta is broken and the link to classic doesn't work. Stop wasting our time or there won't be anybody left here.
He's still an idiot.
How much fuel is this thing going to have to hold to make tens of thousands of adjustments.
How much sensitivity does it have to have to actually get close to this stuff?
And, what if it screws up and gets tagged really hard. Orbital velocities of any object can smash just about any other object. What unobtanium is this thing going to be made of? A net? Are you fucking kidding? The stuff that can kill satellites is smaller than a grain of sand. If by "net" he means "bigass wall" then maybe. Plus, anything that is flexible (like a net) is going to be near impossible to move accurately. So it'll have to survive THOUSANDS of deployment and retraction cycles. They can't even get ONE FUCKING SOLAR PANEL to extend ONCE reliably for fucks sake.
It's a stupid idea, any one of the problems can make it a stupid idea, and there's dozens of problems with it.
They'd be MUCH better off just lifting lots of water and vaporizing it to produce drag on these objects so they fall in naturally on their own. If they do that from a NON orbital trajectory they might be able to catch a bunch of stuff easily.
Need i say more?
---- Booth was a patriot ----
It depends on how much debris you are deorbiting and how large the area you are using for solar power generation. If power is a problem, supplement the power generation with a nuclear battery or two and every time they ae exhausted, swap them out for fresh ones.
Sigs are too short to say anything truly profound so read the above post instead.
Bigelow has a small line to build Kevlar material for their space stations. It is suppose to handle 17000 mph pieces. Seems to me that BA might want to get in on this if funds were to be done. At the very least, it helps gets their line started with building items.
I prefer the "u" in honour as it seems to be missing these days.
cringely sounds more and more like a clever junior high school student. nothing wrong with that, if you're in 8th grade. but i mean seriously, the volume of 3-d orbital space determines among other things the energy and time required to sweep it "clean." be almost faster just to wait for the junk to re-enter. cheaper and cleaner certainly.
playing Katamari Damacy in Space!
Why a net? There's no resistance in space and no medium that needs to pass through the net! Make it a big metal cup like the back of a dump truck. Drawback would be increased payload for launch, but it helps remove a lot of the risks others are describing such as the net breaking or contents of the net breaking up into smaller pieces.
I'm a writer, a poet, a genius, I know it. I don't buy software, I grow it.
Funnily enough, that bag was released in LEO... and will therefore eventually decay of it's own accord. He'll have to be quick if he wants to snatch that up.
--- The key to knowledge is not to rely on people to teach you it ---
And as an added bonus, it'll accidentally take out all those pesky military satellites that don't officially exist!
Unfortunately Cringely has overlooked the principle of conservation of momentum.
Once each piece of junk lodges permanently in the net - assuming for the moment that the net is a good solution - the whole ensemble will by definition have the total momentum vector that the spacecraft+junk had beforehand. No amount of clever angling will help that.
Now, if he instead said that he was going to bounce off each piece of junk so that the junk was sent into the atmosphere and the spacecraft was also redirected usefully, then that would have been more plausible - except of course that he would then need to make the spacecraft itself pretty damn robust.
No, I'm much more inclined to consider small drones which can drift around with a little ion drive and attach to a few bits of junk each (at near-zero dV), and then deorbit themselves.
--- The key to knowledge is not to rely on people to teach you it ---
Let's look at your alternate proposal. Say you can put huge blocks of aerogel in orbit. Huge blocks of a cubic kilometer (or a cubic mile, whatever). And say you can put a hundred of them in orbit every workday. That's about 20.000 cubic kilometer of aerogel in orbit per year.
Seems a lot, doesn't it? Well, it's nothing, considering the size of the space you're trying to clear. Imagine a ring with an inner width of 100km (low orbit) and an outer width if 30.000km. You'd need at least half such a ring to be able to sweep the area. That's 1,5 billion aerogel cubes. Even when you're launching one hundred of them every workday, it would take 75.000 years to get them up there.
It can't be done.
And that assumes that a kilometer of aerogel is actually able to stop and trap the debris. Which isn't likely anyway.
I like it. A giant magnet - suck up all the metal particles, never mind the big chunks! Give the nuclear power an ion engine and let it sweep clean whatever orbit you want.
In the end, you get a big(ger) metal ball, which you can keep in orbit as a useful mass, or drop on your chosen enemy.
magnet nets, magnet nets!
Magnet Nets, Magnet Nets, Magnet Nets, Magnet Nets, Magnet Nets![/BALLMER]
Doesn't anyone realize that spacejunk is our only hope of deflecting the killer asteroid when it comes? Think of the children!
A word fitly spoken is like apples of gold in pictures of silver --Proverbs 25:11
I say we launch sharks with frikkin' frakkin' lasers to vaporize the stuff. Who cares if they'd conserve energy and momentum, they're sharks and they fry things!
Recommend people check out the series "Planetes" on this topic:
http://en.wikipedia.org/wiki/Planetes
Also, you're going to be waving a huge net around and hope to only get close enough to things that are traveling at speeds which are only slightly different. Somehow you have to not catch working equipment, and not get smacked by something in a path at 90 or 180 degrees. That's worse than praying for a magical 18,000 carom path.
When you do catch something, it's not going hit right in the center of gravity so your whole contraption goes spinning. The first time that happens, your net might close around what might be in it. But it won't stop without a lot of fuel. And if you don't stop it yet somehow manage to intercept something else the something else will hit the outside of your net purse and send it spinning in another direction. If you do stop the spinning and reopen the net, the movement of opening will push your catch out and away.
That's assuming you can actually catch anything. It's more likely that you'll blunder into the path of things moving in the wrong direction. Then the debris will be increased by bits of stuff that got hit, followed shortly by whatever is torn off by the stresses of the net trying to head off in another direction (assuming your net got hit and not your garbage trawler).
Go look up the designs which others have done. Nets which are intended to vaporize or slow debris, electromagnetic drives, including deorbiters on new satellites.
And, no, don't think Quark. Think Planetes.
Slowing or absorbing into something that itself is not that harmful is a much better idea! Aerogel is a brilliant idea!
I was thinking more along the lines of some sort of gun shooting bullets of something harmless... aerogel would be perfect. similar complex issue of proper aiming and avoiding using up all the fuel.
Another idea would be to use some sort of ION drive or something to try to stay in orbit; power source would be a problem and I'm not sure there are enough ions out there to do enough to counter a movement. Too bad the amount of power needed for a really strong magnetic pulse makes that unlikely as well (although it would have more range than a big block of aerogel.) Much of the stuff up there is partially magnetic... doesn't take much to mess up an orbit.
Essentially this problem has been figured to be prohibitive long ago and it will take a lot more progress before we can realistically solve it; possibly many generations from now. I doubt that we'll ever get to the point where 1 nation can afford to clean while another intentionally dirties the sky (sooner or later there will be war in space-- we already leverage it heavily enough to provoke that now. )
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with 18,000 destinations, all of them moving, and each with a different angle, trajectory, spin mass, etc...
http://en.wikipedia.org/wiki/Travelling_salesman_problem
so while the idea as a real world solution is obviously impractical, its a great way to exercise computer scientist minds to dizzying distraction
intellectual property law is philosophically incoherent. it is your moral duty to ignore it or sabotage it
"It won't always be possible, of course, to gain energy from each encounter, but that's why we start in a higher orbit, so as energy is inevitably lost it can be replenished by moving to a lower orbit."
Changing to a lower orbit will increase velocity, yes, so in a sense you're trading off potential and kinetic energy... but in the sense that matters... maintaining the ability to change your orbit... it doesn't matter if you go up or down, it matters only that you are changing your orbit. Any change in orbit requires you to shed reaction mass. And it's the mass that you need to conserve, not any fuzzily defined energy.
But wait, there is one possible solution, you could use conductive tethers. You could use them to raise your orbit by pumping current through them, or lower your orbit by running the current from them through a load, like a generator. You'd probably NOT want a polar orbit for this trick. And you'd need lots of big heavy solar panels to provide the power. Or maybe a radiothermal generator. No, that'll never fly.
The big problem, though, is that the operational lifetime of the device has to be large enough that it results in a net reduction in trash. And it's deliberately colliding with junk? Eventually it's going to mess up and hit something with the wrong part of the device, particularly if it's using tethers for maneuvering, and now you'll need to have another net handy to collect IT as well as the trash it collected.
Would it be possible to use that same gel-type stuff they used to collect tail material from that one comet? Use it almost like ballistic gel or the rubber backstop of an indoor pistol range?
The only thing necessary for evil to triumph is for it to be pitted against a slightly greater evil
I thought his idea is to use the momentum of Junk A to help shift into Junk B's orbit? The sequence of capture would be such that the smallest difference in orbit is selected for each item. It sort of reminds me of the Cassini Saturn probe: a moon's gravity is used to shift its orbit to fly by the next moon.
However, there's at least three problems. First, the mass of each junk item is not known well enough to rely on. Cassini had a little bit if this problem as nobody was sure of the some of the moons' mass until after the fly-by's. (Titan is used the most because it is the largest, and its mass was known from prior probes.) It's possible to make a rough guess based on brightness and/or diameter, but space junk may vary in density more than outer-planet moons. I'd say scrap the momentum-borrowing idea and just bring enough fuel, or ion engine solar panels, to shift orbit.
Second, computing Cassini's orbit to reduce fuel consumption was rather expensive. There's lots more space junk than Saturn moons (if you exclude the rings). Even without debris-momentum assist, the calculations are going to be tricky.
Finally as somebody else pointed out, the net would have a difficult time dealing with a potentially wide variety of velocities and shapes. It would take some fancy foot-work and/or strong net to pull that off. I wouldn't rate it as "impossible", but it will certainly tax the best engineering minds. A proof-of-concept trial run(s) may be the best way to start.
I would point out that the catcher wouldn't even have to come back. As long as the junk is collected in a single known location, it won't be a notable threat. A possible risk though is something coming by and tearing the net, releasing the hard-won bounty.
Table-ized A.I.
That's assuming all (or even the majority) of the debris is ferrous. Titanium, aluminum, ceramic, propulsion slag, and leaked coolant are at least some of the debris that's up there, and it would happily float past a giant magnet like it wasn't even there. Lets not forget rock debris that's been floating around up there since before we (humanity) had a space program.
Don't forget, attraction and repulsion work both ways too. So the satellite pulls the object out of orbit a little. The object in turn would be pulling the satellite too. It's an absolutely huge 3 dimensional space, so even at 18k mph, clearing one plain would take a long time. Clearing all the plains would take an eternity. We're not talking about a few miles. According to NASA, there's debris from 300km to over 10,000km. That'd take one mighty big EM field, that I don't believe we have the ability to produce any time in the near future.
Even the net, sheet, or garbage collecting satellite would spend an awful lot of time (and fuel) to try to collect them. The expended fuel would cause new debris too. Since we're talking about some huge orbital velocities, the impacts would make a bigger mess than they'd cure. Even something only 1kg at 18k mph at a glancing impact would likely leave fresh debris.
I do wonder what will happen over time. From what I know about astrophysics (which isn't all that much), I would have to assume that they would eventually drift into a equatorial orbit. Ahhh, the man made rings of Earth. :)
Serious? Seriousness is well above my pay grade.
Perhaps Cringely doesn't have a clear idea what sort of debris we are dealing with here.
No, he doesn't seem to have a clear idea of what debris is, or what orbital energy is, or how orbits work, or how BIG space is.
It is reasonable to clear debris up from Earth orbit... but not the way he proposes.
I'm afraid I have to agree with the people saying that this is not a workable idea. He needs to put some numbers to it. He's going to catch basketball sized objects in a net? Have he thought about what happens when a massive object hits something at several miles per second? I'd say, picture trying to catch a howitzer shell in a net, but, actually, artillery shells are snail-paced compared to orbital velocities. Here's a comparison: imagine that you're catching dynamite, and it explodes the instant you touch it, sending out shrapnel in all directions. Got that in your imagination? OK, it's a lot worse than that. (And if the answer is, well, make sure you come up on it at slow relative velocity... that means that you have to essentially match orbits with each piece of debris. This is unrealistically expensive in terms of delta-V.)
Also, has he thought about the relative size of the net needed to sweep out a few trillion cubic kilometers of space?
http://www.geoffreylandis.com
Exactly where are you getting thrust from the solar power? Solar panels are great for making electricity, but it's not like you can spin a propeller in space.
Serious? Seriousness is well above my pay grade.
I agree totally. He's an idiot. Most people who have read his stuff know that though.
There's way too much space to cover. I talked with some friends in the past about the same idea, but we realized it wouldn't work, without putting ourselves in front of the world to look like idiots. :)
I don't think putting water up would help much either. It may encourage some of the very low debris to deorbit sooner, but not the majority of the junk that's up there. The really low stuff is on it's way down already anyways.
Serious? Seriousness is well above my pay grade.
And as an added bonus, it'll accidentally take out all those pesky military satellites that don't officially exist!
Or at least those of the other side.
Loose lips lose spit.
The best solution is a ground based laser which simply shoots the debris, causing it to fall to ground. (If you think I don't know how orbits work, you're wrong). Anyway, google for Orion laser. It's not only feasible, it's probably pretty cheap. And it doesn't matter if access to space is not possible.
The Chinese pre-emptively launch a billion piezo electric pebbles into all the military sattelite paths just before they invade Taiwan and the petroleum rich areas of the Philippines, thus sweeping all comm links and observation platforms from the sky in a matter of an hour. As well as every other satellite. to re-build the world after the[a href="http://www.missilethreat.com/missiledefensesystems/id.13/system_detail.asp">Brilliant pebbles attack, we'll need a scow.
So it won't really matter if a few things break up. Space won't be habitable at all till some clean up is done.
Consider for a moment that the sphere of a high orbit is larger than the size of the earth. Then consider all the orbital altitudes (like layers of an onion) which need to be "scoured", and you're talking about an amount of space that is many times the total surface area of Earth.
That's a whole lot of territory to cover, even for a large army of scour-ers.
------ The best brain training is now totally free : )
Too late. That tool bag is already back to earth. http://en.wikipedia.org/wiki/Heidemarie_Stefanyshyn-Piper#Lost_tool_bag_during_spacewalk
engineers are all basically high-functioning autistics who have no idea how normal people do stuff
I say we just send Superman up there with a big net and let him make a bunch of trips around the planet to clean everything up. Then we don't have to worry about conserving the energy in the pieces or any of that crap, because Superman has energy to spare.
Not only is this faster and safer, but much more entertaining. I think they could actually make a profit on this, when they figure in the comic book sales.
One thing I have always wondered was why ice wasn't considered. It'd have to be something in a low orbit so the drag would bring it down, but wouldn't an ice projectile of an appropriate mass and velocity be sufficient to de-orbit some items? Or would the risk of shattering the target be too great?
Semper en excreta sumus solum profundum
As I had previously mentioned, the craft uses a technology otherwise known as Tether propulsion which only uses electrical energy to provide a propulsive force against Earth's magnetic field. It works like an electric motor in a way.
Sigs are too short to say anything truly profound so read the above post instead.
You may wish to refine your knowledge of inductance which is not dependant on a material being ferromagnetic. Also, the craft is designed to sweep through about 800km^3 of space (10 km diameter bubble) every second and would be capable of cleaning a layer of space covering the whole planet 30 miles thick in a single year. More if the size of the bubble is increased.
Sigs are too short to say anything truly profound so read the above post instead.
I think that would be like trying to hit a bullet with another bullet and it's been tried with the US missile defense system with far slower moving objects and it was a complete disaster. Also, you are correct that the target would probably get broken into several pieces and pose a hazard until it burns up.
Sigs are too short to say anything truly profound so read the above post instead.
Ion engines. Only a fraction of the propellant is exhausted, but with a very high impulse. Solar sails could provide the energy for EM acceleration.
because a net can fold up and fit inside a rocket capsule.
“Common sense is not so common.” — Voltaire
"I suppose you are strategy..." ? :-p
Oh I see, you meant "your".
(hee hee, captcha: nastily)
"Hey guys, look at me, look at me! I'm talking about crap I don't know a goddamn thing about! Are you paying attention to me yet? Look, I'm even suggesting that in space you can go down in your orbit without losing any energy, as if it worked the same as with airplanes!! I TROLL U!!!"
You just got troll'd!
After reading Cringely's rant on faximile via VoIP (which exposed that he had extremely little knowledge of the underlying technical issues in the subject), I don't bother wasting my time reading anything from him that requires engineering and technical proficiency in a specialized field to intelligently discuss.
The whores get mad when the sluts give it away for free.
http://slashdot.org/comments.pl?sid=1353599&cid=29268653&art_pos=4
Mmmmmm... Bold, yet refreshing!
The idea of deriving some energy and momentum from the captured debris is interesting. But I'm pretty sure it will not stand up to critical analysis. The relative speeds of orbits crossing through the same area in space at different inclinations or eccentricities are faster than a bullet. Even if the net survives this many types of debris captured certainly won't - they will shatter and generate lots of smaller pieces of debris. If you somehow manage to choose only encounters with speeds low enough to survive the impact it will be too slow to derive any useful energy or momentum from. This idea might be sound in principle (though I wouldn't bet on it) but wrong by several orders of magnitude in practice.
And no, Cringely, you can't simply "trade altitude for speed" (potential energy for kinetic energy) in space to change to a different orbit. While it does not break the law of conservation of energy it definitely violates conservation of momentum. You could change momentum without spending energy via gravity assist with a third body (nothing available with enough mass in the vicinity but the moon) or using a tether. Otherwise you need to spend energy and reaction mass to change to a different orbit even if it has the same orbital energy. Space tethers are sometimes proposed for collecting space junk by people who actually understand a bit of orbital mechanics. Tethers are a very complex and mostly untested space technology we haven't mastered yet.
Capturing all 18000+ objects in a single net?!?!? What are you smoking? Have you any idea how much mass you are talking about? Moving all this mass to all the target orbits is an unimaginable waste of delta V. Even if you could somehow derive some momentum from the captured debris the 100th piece captured will barely change the vector of this huge collected mass.
Yes, as you say, this is a crazy idea. But it's not crazy in the "crazy enough that it might just work" kind of way. It's just plain crazy, dumb and ignorant.
Sorry, Cringely. You have just lost whatever remains of professional respect I still had for you.
Stop worrying about the risks of nuclear power and start worrying about the risks of not using nuclear power.
IANARS (I am not a rocket scientist), but have done much work-related research in the space junk population calculations.
Many other posts have already stated that most of the pieces of junk will never be able to be captured with way, due to small size and/or relative velocity issues.
We will never be able to effectively use space travel until we solve this. If the space junk population continues to increase, it is liable to set off a collision cascade effect (Kessler syndrome) - errant junk colliding with larger pieces to create more small pieces to collide with other objects, and so on. Kinda like a nuclear reactor, or the analogous 'room full of ping-pong-loaded mouse traps' demonstration... Space travel could be even more dangerous when this happens.
For the time being, we can steer our craft around the larger pieces of junk that we can track, put shielding on our craft to protect us from the small pieces. But there's a size range of pieces that are too small to be tracked, but too large to be effectively shielded.
The solution to this problem has to start at the top - take out the biggest pieces of space junk - that will reduce the chance of the collision cascade effect. A fleet of mini space tugs, each programed to safely de-orbit a specific piece of junk, should be able to put a significant dent in the problem. The use of lasers would complement the work. Hopefully, as our technology and experience increase with this, we'll be able to remove the smaller pieces as effectively.
Sorry but I dont understand how having to a lot of electricity through "solar power and a space tether" allows a satelite to "stay in its current orbit". For what I know you need action-reaction force to keep a satelite in orbit. In fact the reason satelites stop operating is becouse the run out of propelant.
Please explain.
A Space tether can be used to boots satellites acting like a dynamo circuit if a voltage potential is applied to the tether.
Sigs are too short to say anything truly profound so read the above post instead.
correction: the proper link would be this one.
Sounds like a cool idea for a video game.
FTA:
Dragging the net behind a little unmanned spacecraft my idea would be to go past each piece of junk in such a way that it not only lodges permanently in the net, but that doing so adds kinetic energy (hitting at shallow angles to essentially tack like a sailboat off the debris). But wait, there’s more! You not only have to try to get energy from each encounter, it helps if — like in a game of billiards or pool — each encounter results in an effective ricochet sending the net in the proper trajectory for its next encounter. Rinse and repeat 18,000 times.
There is a basic physics problem. The whole idea that you can capture the debris and control the space ship's velocity after the collision is a flawed.
His sailboat analogy breaks down because a sailboat does not capture the air; it deflects the air. If the space craft deflected the debris and controlled the way it "bounced off of the debris" it could control the velocity after the collision. Of course this defeats the whole point of the space craft.
However, if the space craft captures debris then it can't control it's resulting velocity. The resulting velocity will be governed by conservation of momentum.
Imagine playing pool with a sticky cue ball that stuck to any other balls that it struck. Because the cue ball was sticky, you'd loose the ability to control the direction of either ball after the collision. If the cue ball struck a ball that was at rest, the resulting velocity would always be 1/2 the cue ball's original velocity in the same direction.
Wouldn't a several km mag field require a lot of power? Much more than can be derived from the limited # of sq meters of solar panels available for a satellite?
Not really.
The objects pass through the field, get 'pulled' by the drag. They slow down, dropping orbit.
Slow them down enough and they spiral into the atmosphere to burn up.
For large sets, this will be our guide even unto death, for the LORD will work for each type of data it is applied to...
Magnetic sails use magnetic fields this large.
Sigs are too short to say anything truly profound so read the above post instead.
this is a perfect application for an evolutionary algorithm,
prepare the survey weasels.
Except they suffer from the slight drawback of neither actually existing, nor having particularly strong fields in the first place. Besides, that doesn't solve anything - you've just swapped a nasty field generation power problem for a nasty superconductor cooling problem.
Reality is the ultimate Rorschach.
Actually, what would make far more sense... would be to somehow capture the trapped mass, and then eject it violently to change course so as to be able to gently-enough encounter and capture the next piece of mass, and so on. Use the junk as reaction mass to change your velocity...
:)
...perhaps the relative delta-v needed to move from one piece to another (compared to the force one could realistically apply to launching a given intercepted mass) would make it difficult or unviable with current technologies... any thoughts?
:) )
To gain altitude, fire the current junk at an downward angle which also completely cancels out it's orbital momentum, it will then fall directly to earth, and your 'scow' will gain altitude (well, a change in orbital momentum as well due to angle you need to fire it at to cancel out it's own, but you get the idea). To descend, fire it straight up a speed exceeding terminal velocity so as to escape the earth's orbit altogether (here you would have more freedom to also adjust your orbital momentum as you saw fit, by firing it at different angles... also, you could effectively -only- change your orbital momentum by firing it an extreme angle essentially perpendicular to the earth's surface, such that it would still achieve terminal velocity).
All the thing needs is an energy source! (Well, and some serious computation) The reaction mass is already up there!
This then becomes an engineering problem of how to capture and relaunch the individual pieces of junk. First off, I'd imagine you would need a sufficiently low differential in velocity to the target during the intercept/capture phase. (Of course, once again, free reaction mass abounds, as long as you can 'throw' your last captured piece with sufficient energy). Which leads to the second engineering challenge; how to very energetically expel the mass you've just captured in any direction. Well, the direction part isn't hard, gyroscopes and all... but how a machine would grapple and then violently launch an arbitrarily sized and shaped object would be the challenge.
For ferromagnetic debris, I suppose electromagenetic coupling might allow capture, and then perhaps a robotic arm could appropriately position it's center of mass over a 'simple' extremely-high-speed piston?
But, I can't think of any reason this couldn't necessarily work!
(PS: This is still an engineering problem relating to the force you could realistically impart when relauching debris... for even a single atom would be more than sufficient mass if you could launch it at 99.99999999% the speed of light.
---
the pen is mightier than the sword, the sword is mightier than the court, the court is mightier than the pen.
synthesize the superconductor coil material in the form of a porous rope like structure that has a lot of surface area and pump superfluid Helium through it. The thermal conductivity of superfluid Helium is over 1,000x that of Copper and it has no measurable viscosity. It boils at its surface by virtue of its ultra high thermal conductivity leaving the rest of it cold enough to cool the superconductor material. combine that with a solar shade on the devide its self, a cryogenic liquification device and radiators and there shouldn't be that much of a problem with heat.
As for the magnetic sails, so what? It's been tried in the lab and the physics is pretty well understood, it's just a matter of building it.
Sigs are too short to say anything truly profound so read the above post instead.
The earth has a giant magnetic field. Induce a powerful opposing magnetic field in your satellite/space tether system that "pushes" against the earth's field. There's no reaction mass, but your satellite can then control its position in orbit. Most satellites don't use the space tether system, although I don't know whether that's because it's inherently impractical or merely too new/expensive/fancy.
Just another "DOJ fascist authoritarian totalitarian bootlicker" -- Zeio
for Half Section!
the little flecks of paint, bolts, and general fragments of this and that zipping around at bulletesque velocities.
"Bulletesque?" 17,000 miles per hour isn't "bulletesque" unless *railguns* are the norm.
Dissipating such energies with something make of small cross-section strands isn't going to be easy. Actually, I don't think it's going to be possible with normal matter.
The Space Colonization folks advocated huge ships in the shape of rings, trailing conical kevlar bags. (Mass catchers.) The Kevlar wasn't going to stop the incoming space-junk projectiles. (In this case, bags of lunar regolith launched into orbit from the Moon's surface.) Instead, the kevlar bags would rotate and hold a layer of Lunar regolith against its inner surface using centrifugal force. The incoming projectiles would be stopped the same way micrometeorites stop when they hit the moon.
The easiest way to dissipate highly concentrated energy, such as that possessed by projectiles at orbital velocity, is a lot of *mass*.
It's not a stupid idea. It has a stupid rationale, and many parts of it are ignorant (orbital mechanics is the biggie. You can't trade orbital energy for speed, at least not freely like an airplane. Every interaction changes the orbit. period. time them so they add up usefully if you can.) or outlandish (a net?? seriously?) but that doesn't mean it doesn't have a kernel of an interesting idea.
I wouldn't say that I think it's a great idea, but it's definitely worthy of an AIAA paper or so worth of effort. Even if it turns out to be completely unworkable, it would be a useful exercise to work out why.
Can you be Even More Awesome?!
The notion of capturing energy from objects already in orbit is intriguing - but I doubt that "tacking" is sufficient to explain how this works. Tacking occurs when two fluids are connected by airfoils; moreover, the essence of tacking requires the deflection, or bouncing, of the fluids - not the collection of same.
So, in what way could you approach an object and steal its energy. But before that question, what does it mean to steal energy from these captured items? If the trash ends up a part of the garbage scow's orbital dynamics, then "stealing" energy is moot - unless the trash is ejected into a less energetic orbit, the scow cannot end up with a more energetic orbit - which of course defined the solution. The desired "net" may be an electromagnet on a long wire. The intercept is made with a near miss, such that trash and the scow end up like a double-star, tumbling around a common axis - then the electromagnet is released in a moment when the trash is tumbling counter-orbital, leaving the trash in an inferior (and hopefully terminal) orbit - and the scow in a new trajectory of choice - based largely on the intercept angle (to establish the tumble plane) and the release timing to select the angular acceleration.
18,0000 items or not, some day it will need to be cleaned up,i just hope it doesn't take killing astronauts by space debris to get it started/done. But thats normally how things are done,someone has to die to get thing done way too many times
Jack of all trades,master of none
... a giant space vacuum cleaner.
This is such a good idea, I'm off to the patent office!
Have gnu, will travel.
You could try reading the summary next time.
You must be new here. We don't read the summaries, let alone the friendly articles. Hell, any day now I expect most /. readers will stop reading the headlines, too, and every article will be a homogeneous mishmash of vim vs. emacs arguments, libertarian propaganda, and goatse links.
Not that I have a problem with this, mind you.
"Destroy science and religion. Science would re-emerge exactly the same; but not religion." - Penn Jillette, paraphrased
Our planet's own tarbaby.
Why did you get "insightful"? The problem is that big parts hit each other and then produce A LOT of smaller parts. We need to get the big parts first. Then we can worry about small stuff. I heard they wanted to try and smoke those with "friggin lasers".
And that thing would be spinning like a top. Good luck trying to do guidance once that happens. I suppose it would be spin-stabilized, in an unpredictable way, but in practice it would make predicting the impact of the next piece that much harder. You'd have to spend fuel to remove the effect or have a configuration where uncontrolled spinning doesn't matter.
It's still not much different than trying to hit a bullet with a bullet, and then predicting the ricochet for that bullet to hit another, and another, and another, 18000 times. You'd have some time in between each to assess the impact and prepare for the next one, but it sounds immensely challenging, and each time you might have an impact that trashes your "net", the sensors and thrusters that guide it, and changes its dynamics. It's an interesting idea but it sure looks impractical to implement.
I know this is unmanned, but does anyone else look at this article and get nostalgia for Sierra's Space Quest series?
Treat it as an orbiting version of pinball. Each piece of garbage adding mass then a precise hit on a key piece of garbage to break it apart into further ricocheting pieces.
Ding ding ding ding: multiball!
This sounds like they want to roll all the things in space into a large ball, possibly visible in the night sky??
KATAMARI!
King of All Cosmos: We hope you can visit during the day's rolling. Like that's possible.
How about garbage collectors with bumpers that use spinning to match speed with garbage that is passing by. Objects made of metal or are valuable could be spun into a higher orbit, perhaps to intercept other garbage collectors that would slow the object down for capture. Objects with no value could be spun into lower, unstable orbits, if we are really clever, the stuff heading down could push the garbage collector higher at the same time or towards its next intercept or both.
The garbage collector itself would not have to match speeds, just plot intercepts and bumper speeds. Since we are tracking a lot of these objects already, it should be possible to figure out in advance a mission for a garbage collector. It would take a lot of missions, but I don't see why this would be impossible.
Also, it would look like a tie fighter and George Lucas will be forced to sponsor it...
\-------o-------\
Now where's my nobel prize?
The phrase 'Garbage Scow' brings to mind the Star Raiders rank 'Garbage Scow Captain'. I've never heard the phrase 'Garbage Scow' anywhere else.
...
Like so many college ideas...
Sounds good on the surface until you think deeply at all about the problem.
The net is guaranteed to break. Find out the difference between speed of orbiting objects. Calculate mass. Calculate density and material strength.
This if anything would cause a bigger problem than it solves.
Can I get some dumb ideas posted too!
I'm thinking we need a return of Adam Quark!
http://www.imdb.com/title/tt0077066
Cringely does realize if he replaces the word "garbage" with "another nation's military satellites" this is going to get a lot of DARPA funding :p
bash-2.04$
bash-2.04$yes "Don't you hate dialup connections?"| write USERNAME
The problem as I see it is that the Earth is going around the sun carrying a bunch of space junk with it. This space junk make it miserable for people who want to shoot more stuff into space. Therefore, all we have to do is get all our buddies together ( the moon and other satellites we want to keep), then just stop orbitting the sun for about 4 hours (distance to the moon/helocentric velocity). Then we should be in a nice clean portion of the orbit. Usually, it is heck of alot easier to litter and walk away than it is to pick it up and put it in the trash bin. http://www.wolframalpha.com/input/?i=distance+to+moon+%2F+speed+of+earth+orbit
-- Each tock of the Planck clock is a new world and here we are still life. --