As for my "relative close up view", picture this: If we're trying to, from Earth, see something at the L5 point, 60 degrees away in our orbit, we're trying to see something from 1 AU away, with only a sliver of visible crescent
If you want to see whatever has somehow accumulated in Earth-Sun L4/L5, or even L3, why not simply send a small probe to those specific places?
Then don't blow it up isotropically. That's an obviously bad idea. An anisotropic detonation could ensure that an appreciable portion of the mass will leave the asteroid in a cone with velocities spread in a spectrum in such a way that they won't meet the main mass again for centuries (in such a way that after a single orbit, they're already hundreds of kilometers apart, with the distance increasing every period). The remaining mass will have been nudged by the negative of the total momentum of all the fragments that left the main mass, divided by the remaining main mass. If you only manage to blow off 1% of the mass, and the conversion to kinetic energy is only 1% efficient, you will have impacted a delta v of 0.2 m/s onto the remaining mass. That is 200000000 MNs of impulse transferred onto the main mass, which is massively higher than the "nudging" capability of any other propulsion system we've ever had (gravity tractors with existing electric thrusters could hope for perhaps 100-500 MNs or so, limited by the total design thrust of their thrusters). I don't see a 10 km asteroid threatening us any time soon, though. The larger these objects are, the fewer of them exist, and also the lesser the chance we don't know about them yet in the first place.
Which is only useful if we are between the asteroid and the sun. That's my point. My shining a flashlight towards you doesn't help you see anything between us, except in silhouette. And there's no background in space for a silhouette to be visible against.
By your logic, we can't ever see Venus or Mercury. But we actually can, so your argument is flawed. Fucking Keplerian orbits, how do they work?
Worse, we're not actually looking. Current astronomy amounts to a few hundred people looking through drinking straws at the sky - the vast majority of the sky never gets looked at for long enough to spot any particular asteroid, even if it's perfectly visible in theory.
So send a dedicated telescope into space. With the new launch vehicles providing low launch costs in the future or even now, this is not going to such a problem.
Plus, near-Earth asteroids are the most persistent threat - and they spend their entire orbital path quite near Earth's orbit, mostly locked into a 1:1 orbital resonance with Earth
Which means they're almost never between Earth and Sun (defeating your reasoning above), but almost always in or near first or third quarter when they're in detectable range, to use lunar phase terminology.
It's not that they're hard to see - they're just hard to see *from here*. One of the proposals (several, probably), is to put asteroid spotting space-telescope(s) in a solar orbit inside our own, looking outward, so that they'll circle the sun independently from us, and every time they lap us around the sun, they will have had a chance to photograph the entire near-Earth asteroid belt in full sunlight. That, and some good software to spot the asteroids amongst the camera noise, and we could actually be fairly confident we spotted everything big (at least that's not extremely dark-colored). That strategy also has the benefit that the telescope stays very close (relatively) to what it's photographing, making it much easier to spot smaller still-dangerous asteroids.
Not quite sure how that makes sense. It will never get you closer to all the things you might want to capture, since the average distance to them is lowest when you're *at* Earth's orbit. It makes much more sense to look in the direction of Earth's velocity vector, for reasons related to the Yarkovsky effect - the retrograde hemispheres of asteroids have been recently heated, and therefore offer a larger IR signature in that direction, plus you still have the partially sun-lit disk to look for in the visible spectrum.
If size was the issue, you'd see them for just as long coming as going. The problem is light. An unlit object in space is completely black in the visible spectrum. And black also happens to be the exact shade of empty space.
Fortunately, there's also this 1360 W/m^2 light flux near 1 AU making things significantly easier for us.
The result being that anything coming at you from the general direction of the sun...
...would have been noticed before it got into such unfavorable position. Fucking Keplerian orbits, how do they work?
From what I've gleaned from business articles, Musk is pretty much just a rain maker for Space X - he's hands off of everything else. Vision? Yes. But day to day operations? No.
Really? So the micro-management stories from SpaceX are all lies?
You use stereo vision, stereo hearing, IMUs, touch/pressure sensing when driving, and knowledge/memories, including basic understandings and predictive knowledge of newtonian mechanics at our speeds and life experiences.
Obviously, the "just cameras" omitted information processing. I don't think it implied that you can remove the computer (or your brain).
Also EVs are falsely made cheaper because the government raises taxes on ICEs.
Considering that the raised taxes seem to be comparable to what carbon pricing would do to the price of ICEs, PLUS the existing difference in energy prices for vehicles between $7/US gal. gasoline and $0.15/kWh electricity, what's the big deal here?
So, yes, in cold areas up north, EVs are almost fucking useless.
Fortunately, almost nobody lives in cold areas up north, since EVs are not the only thing that hates cold. So saying that EVs don't work very much like saying that chemotherapy doesn't work. Just because something doesn't work for 100% of people doesn't mean that it "doesn't work".
Thermal radiation could do the same job. I.e., amplify the Yarkovsky effect with a set of large but lightweight mirrors. You can't beat the power/weight ratio of metallized foils.
Given a long enough lead time the method that seems coolest to me is the gravitational tractor method.
According to my (admittedly rudimentary) calculations, an underground nuke detonation forming a crater with maximal amount of ejecta would impact at least two orders of magnitude higher total impulse compared to a gravity tractor. It would also impact this impulse in a single point in time, a long time before the encounter with Earth, compared to a gravity tractor where effect of the impacted impulse would be diminished by virtue of a major part of it happening much closer to projected impact on Earth (therefore with decreased time for this impulse to make difference to the trajectory near Earth).
If it was "many smaller ones", depending on the time of fracturing, the vast majority of them might never hit Earth at all, with some hitting it initially and some of the rest potentially becoming a regular smaller meteor shower.
And burying a nuke greatly increases the odds of shattering the asteroid rather than deflecting it. And that's almost certainly a bad thing. You've just turned a predictable rifle slug impact area that could be easily evacuated, into a shotgun blast.that will pepper the Earth with nuclear-size impact blasts.
Even asteroids have their binding energy. So if you detonate the nuclear explosive at proper depth underground at a sufficient distance from Earth (months before the impact, at the very least), even if the asteroid as a whole initially shatters, it most likely mostly gravitationally re-coalesce into one mass with a momentum changed by the negative of the sum of momentum change of the parts that actually flew away, impacting an impulse of at least giganewtonseconds or tens of giganewtonseconds.
What about a sodium spray? It should be able to create a very thin, yet highly reflective surface practically on anything. High vacuum in unlimited amounts simplifies such processes.
I still don't understand how exploding one in space where there is no air is supposed to alter the trajectory of a hugely massive object
You explode it in a reasonable depth below the surface, so that the largest possible amount of the asteroid's mass is ejected at a speed somewhat higher than local escape speed (which is usually meters per second or so), to maximize the terminal momentum of the ejected mass. Bunker buster technology like the B61 Mod 11 bomb should be suitable; the cohesion of the asteroid's surface is unlikely going to be higher than Earth's regular soil.
Slashdot Mirror
As for my "relative close up view", picture this: If we're trying to, from Earth, see something at the L5 point, 60 degrees away in our orbit, we're trying to see something from 1 AU away, with only a sliver of visible crescent
If you want to see whatever has somehow accumulated in Earth-Sun L4/L5, or even L3, why not simply send a small probe to those specific places?
Then don't blow it up isotropically. That's an obviously bad idea. An anisotropic detonation could ensure that an appreciable portion of the mass will leave the asteroid in a cone with velocities spread in a spectrum in such a way that they won't meet the main mass again for centuries (in such a way that after a single orbit, they're already hundreds of kilometers apart, with the distance increasing every period). The remaining mass will have been nudged by the negative of the total momentum of all the fragments that left the main mass, divided by the remaining main mass. If you only manage to blow off 1% of the mass, and the conversion to kinetic energy is only 1% efficient, you will have impacted a delta v of 0.2 m/s onto the remaining mass. That is 200000000 MNs of impulse transferred onto the main mass, which is massively higher than the "nudging" capability of any other propulsion system we've ever had (gravity tractors with existing electric thrusters could hope for perhaps 100-500 MNs or so, limited by the total design thrust of their thrusters). I don't see a 10 km asteroid threatening us any time soon, though. The larger these objects are, the fewer of them exist, and also the lesser the chance we don't know about them yet in the first place.
Which is only useful if we are between the asteroid and the sun. That's my point. My shining a flashlight towards you doesn't help you see anything between us, except in silhouette. And there's no background in space for a silhouette to be visible against.
By your logic, we can't ever see Venus or Mercury. But we actually can, so your argument is flawed. Fucking Keplerian orbits, how do they work?
Worse, we're not actually looking. Current astronomy amounts to a few hundred people looking through drinking straws at the sky - the vast majority of the sky never gets looked at for long enough to spot any particular asteroid, even if it's perfectly visible in theory.
So send a dedicated telescope into space. With the new launch vehicles providing low launch costs in the future or even now, this is not going to such a problem.
Plus, near-Earth asteroids are the most persistent threat - and they spend their entire orbital path quite near Earth's orbit, mostly locked into a 1:1 orbital resonance with Earth
Which means they're almost never between Earth and Sun (defeating your reasoning above), but almost always in or near first or third quarter when they're in detectable range, to use lunar phase terminology.
It's not that they're hard to see - they're just hard to see *from here*. One of the proposals (several, probably), is to put asteroid spotting space-telescope(s) in a solar orbit inside our own, looking outward, so that they'll circle the sun independently from us, and every time they lap us around the sun, they will have had a chance to photograph the entire near-Earth asteroid belt in full sunlight. That, and some good software to spot the asteroids amongst the camera noise, and we could actually be fairly confident we spotted everything big (at least that's not extremely dark-colored). That strategy also has the benefit that the telescope stays very close (relatively) to what it's photographing, making it much easier to spot smaller still-dangerous asteroids.
Not quite sure how that makes sense. It will never get you closer to all the things you might want to capture, since the average distance to them is lowest when you're *at* Earth's orbit. It makes much more sense to look in the direction of Earth's velocity vector, for reasons related to the Yarkovsky effect - the retrograde hemispheres of asteroids have been recently heated, and therefore offer a larger IR signature in that direction, plus you still have the partially sun-lit disk to look for in the visible spectrum.
Of course then you bring in one of the articles' findings - if the cone is too small, the asteroid will re-coallesce.
Only if nothing reaches escape velocity, which is reasonably easy to prevent. In fact, it's very difficult to arrange for anything else to happen.
If size was the issue, you'd see them for just as long coming as going. The problem is light. An unlit object in space is completely black in the visible spectrum. And black also happens to be the exact shade of empty space.
Fortunately, there's also this 1360 W/m^2 light flux near 1 AU making things significantly easier for us.
The result being that anything coming at you from the general direction of the sun ...
...would have been noticed before it got into such unfavorable position. Fucking Keplerian orbits, how do they work?
From what I've gleaned from business articles, Musk is pretty much just a rain maker for Space X - he's hands off of everything else. Vision? Yes. But day to day operations? No.
Really? So the micro-management stories from SpaceX are all lies?
You use stereo vision, stereo hearing, IMUs, touch/pressure sensing when driving, and knowledge/memories, including basic understandings and predictive knowledge of newtonian mechanics at our speeds and life experiences.
Obviously, the "just cameras" omitted information processing. I don't think it implied that you can remove the computer (or your brain).
Also EVs are falsely made cheaper because the government raises taxes on ICEs.
Considering that the raised taxes seem to be comparable to what carbon pricing would do to the price of ICEs, PLUS the existing difference in energy prices for vehicles between $7/US gal. gasoline and $0.15/kWh electricity, what's the big deal here?
No, they don't work for MOST use cases. As in "a person buys a car for a lot of money and may go on a long trip once in awhile".
Ah, so it *does* work most use cases, then. ;)
So, yes, in cold areas up north, EVs are almost fucking useless.
Fortunately, almost nobody lives in cold areas up north, since EVs are not the only thing that hates cold. So saying that EVs don't work very much like saying that chemotherapy doesn't work. Just because something doesn't work for 100% of people doesn't mean that it "doesn't work".
EVs don't work. I grew up probably more north than you, with people that hunt with bows, and go ice fishing in the middle of nowhere.
Ah. That one again... There's a massive hole in your your argument.
Go take a look at the long list of asteroids that have passed frighteningly close to Earth, that we didn't see until they were already past.
In other words, asteroids that were too small to notice earlier...
It's in the to-do list right below Unicode support.
Who is feeding you those lines? Return to your carriage, sir!
Haven for The Troubles.
Thermal radiation could do the same job. I.e., amplify the Yarkovsky effect with a set of large but lightweight mirrors. You can't beat the power/weight ratio of metallized foils.
Given a long enough lead time the method that seems coolest to me is the gravitational tractor method.
According to my (admittedly rudimentary) calculations, an underground nuke detonation forming a crater with maximal amount of ejecta would impact at least two orders of magnitude higher total impulse compared to a gravity tractor. It would also impact this impulse in a single point in time, a long time before the encounter with Earth, compared to a gravity tractor where effect of the impacted impulse would be diminished by virtue of a major part of it happening much closer to projected impact on Earth (therefore with decreased time for this impulse to make difference to the trajectory near Earth).
If it was "many smaller ones", depending on the time of fracturing, the vast majority of them might never hit Earth at all, with some hitting it initially and some of the rest potentially becoming a regular smaller meteor shower.
And burying a nuke greatly increases the odds of shattering the asteroid rather than deflecting it. And that's almost certainly a bad thing. You've just turned a predictable rifle slug impact area that could be easily evacuated, into a shotgun blast.that will pepper the Earth with nuclear-size impact blasts.
Even asteroids have their binding energy. So if you detonate the nuclear explosive at proper depth underground at a sufficient distance from Earth (months before the impact, at the very least), even if the asteroid as a whole initially shatters, it most likely mostly gravitationally re-coalesce into one mass with a momentum changed by the negative of the sum of momentum change of the parts that actually flew away, impacting an impulse of at least giganewtonseconds or tens of giganewtonseconds.
Only the *largest* asteroid in the Solar System is anywhere near the size of Texas. All the remaining ones are vastly smaller than Texas.
For many asteroids, a 4km chunk is a significant fraction of the whole.
For most asteroids, you won't find a 4 km chunk in them because they're smaller than 4 km.
What about a sodium spray? It should be able to create a very thin, yet highly reflective surface practically on anything. High vacuum in unlimited amounts simplifies such processes.
I still don't understand how exploding one in space where there is no air is supposed to alter the trajectory of a hugely massive object
You explode it in a reasonable depth below the surface, so that the largest possible amount of the asteroid's mass is ejected at a speed somewhat higher than local escape speed (which is usually meters per second or so), to maximize the terminal momentum of the ejected mass. Bunker buster technology like the B61 Mod 11 bomb should be suitable; the cohesion of the asteroid's surface is unlikely going to be higher than Earth's regular soil.
Isn't it "Hydra" in Russian?
Except that what he wants is unlikely to *not* be an internetwork.