PDA

View Full Version : How to Clean up Space After a War??


Rhum Runner
05-29-2002, 02:17 PM
This thread (http://boards.straightdope.com/sdmb/showthread.php?threadid=117533) discusses some interesting ways to kill and maim in space. Cool stuff. I also remember seeing some stories a few weeks ago about a study that projected that even a very limited space conflict would result in so much debris that Earth orbit space would be more or less useless. So, the obvious question is “How do we clean up space?” How do you pick up millions of tiny pieces of material moving at tens of thousands of miles an hour spread over an enormous volume? Is there any way to do it? Big magnets might collect iron and other magnetic materials. That doesn’t do too much good for aluminum and ceramics etc.. What if N. Korea (insert favorite rouge state) develops a ballistic rocket or three and loads them with ball bearings and explodes them in Earth orbit? Would there be anyway to clean it up or would we just be SOL? No GPS, no comm sats, no spy sats.....no sat tv!!! The horror!

Triskadecamus
05-29-2002, 04:29 PM
The "sweep 'em up with magnets" idea has some major engineering hurdles to overcome, not the least of which is the fact that if your dredge satellite itself gets hit while on station, you are back where you started, plus the debris of the recovery system.

If someone has done this as an exercise in interdiction, that is, on purpose, it will include deliberately designed shrapnel that resists detection, or manipulation by magnetic fields. The most useful orbits are only a small fraction of the total sphere of Earth orbits. Objects put into highly elliptical orbits with perigees overlapping the geostationary positions, but with opposite inclinations would be very hard to eliminate, since they would not always be in the orbit you want to clear. Also, they would be moving forty thousand miles an hour the other way, when they went by.

The low orbits will clear themselves in a few years, mostly. But the high orbits, and the orbits only dropping into those high orbits at perigee will not clear for very long periods.

How clear is clear, anyway? One shuttle load of flying thumbtacks won't make it inevitable that your CommSat will be hit during its useful life. Of course it becomes a part of the cost estimate that it could happen at any time. Then Brightstar No. 14 becomes a cloud of new shrapnel, waiting for Brightstar 15.

A bucket of bolts, and a pound of Octal are a pretty cheap payload to orbit, relative to an entire system of military satellites which they effectively threaten. If someone gets tired of being second or seventh place in the space race, it's not all that difficult to make it look accidental, either. What do we do, Nuke 'em when their Moon Shot blows up on the way back? (the perfect trajectory, by the way, if you want a load of crap to periodically sweep by a set of useful orbits for a few hundred years.)

No one in the world has a better reason to support eliminating all military use of space than the United States. Count up the inventory of expensive stuff in the sky. Who doesn't like this game the most? Iran? Iraq? China? Uh huh.

The safest way to clean it up is to keep it from getting messed up.

Tris
--------------------------------
"For there has never been a protracted war from which a country has benefited." ~ Sun-tzu ~

Rhum Runner
05-29-2002, 04:59 PM
Originally posted by Triskadecamus
The "sweep 'em up with magnets" idea has some major engineering hurdles to overcome, not the least of which is the fact that if your dredge satellite itself gets hit while on station, you are back where you started, plus the debris of the recovery system. If someone has done this as an exercise in interdiction, that is, on purpose, it will include deliberately designed shrapnel that resists detection, or manipulation by magnetic fields.
I agree, the magnets clearly won’t work.

Originally posted by Triskadecamus
A bucket of bolts, and a pound of Octal are a pretty cheap payload to orbit, relative to an entire system of military satellites which they effectively threaten. If someone gets tired of being second or seventh place in the space race, it's not all that difficult to make it look accidental, either. What do we do, Nuke 'em when their Moon Shot blows up on the way back? (the perfect trajectory, by the way, if you want a load of crap to periodically sweep by a set of useful orbits for a few hundred years.)
Well, I don’t think that anyone would do it and make it look accidental. What would be the point? Clearly space (communication etc.) is valuable to everyone, so what would be the point in staging an accident to destroy satellites? Now, if you are in a war and you want to deny your enemy his fancy eyes in the sky, ok. That makes sense. Or, if you are a desperate spiteful dictator about to loose power, you might do it as a final shot. (Like blowing up a bunch of oil wells, right?)

Originally posted by Triskadecamus
No one in the world has a better reason to support eliminating all military use of space than the United States. Count up the inventory of expensive stuff in the sky. Who doesn't like this game the most? Iran? Iraq? China? Uh huh.

The safest way to clean it up is to keep it from getting messed up.

Just for clarification, What do you mean by eliminate military uses of space? Do you consider GPS a military use of space? or com sats? Agreed preventing the mess is always easier than cleaning it up, but is there any way we could clean it up if we had to?

rsa
05-29-2002, 05:01 PM
This article (http://www.space.com/news/debris_plea_020517.html) is mostly about prevention, but it has a lot of interesting info such as the fact that there is already 4 million pounds of space junk. :eek:

There is this brief bit about removing debris:

A handful of far-out and costly ideas have been put forth to collect or destroy existing smaller debris, such as mile-wide "Nerf" objects that slow the orbits of debris to send them into the atmosphere, or ground based lasers that evaporate materials.

SPOOFE
05-29-2002, 05:56 PM
Really, really, really, really, really, really, really, really, really, really, really big nets.

Tranquilis
05-29-2002, 06:05 PM
Large blocks or sheets of Aerogels might do the trick, or at least part of it. The debris would still punch through, but would lose some velocity with each pass, until they lost enough energy to assume orbits that intersect the atmosphere. Of course, you'd have to do this repeatedly (very repeatedly!), as your aerogels would become perforated and shredded (adding new, if low-density, projectiles to the mix), and space, as has been pointed out repeatedly, is vast.

Aerogels are also damned expensive.

Squink
05-30-2002, 12:26 AM
We might try moving a few dozen small asteroids, 10 km or so, into obits of varying heights and in the same plane as the moon. Like Jupiter's moons, or the planetismals during the formation of the solar system, the asteroid's gravitational fields would perturb anything orbiting in a different plane. Sooner or later, most of the space debris would be ejected from earth orbit, or entrained to the same plane as the asteroids.

Mangetout
05-30-2002, 04:43 AM
Wouldn't that effect also interefere with the orbits of artificial satellites (those not in orbits in the moon's plane) , requiring them to make more adjustments and using more of their finite propellant resource?

Squink
05-30-2002, 08:04 AM
It sure would. On the other hand, you could just use the asteroids themselves as impact resistant orbiting platforms upon which to mount instruments.

World Eater
05-30-2002, 12:22 PM
How would you mount the instruments, you wouldn't be able to get into orbit with all the debris floating around.

MannyL
05-30-2002, 01:28 PM
I always wondered why the shuttle can't extend a net to catch the floating junk. THe shuttle would be moving in the same direction and close to the same speed as the junk so it shouldn;t be too hard to snag it right?

Triskadecamus
05-30-2002, 01:54 PM
Unfortunately, Manny, space is just way to big for sweeping with a physical object. The size of your net would be unworkably high, long before you got the necessary sweep time down to human scales. Also the problem is not limited to stuff in the same orbit, it includes a lot of stuff in intersecting orbits. The difference in relative velocity between your shuttle/net and some of the debris is going to be very high. One of the shuttles had a crater in one window, almost all the way through. It was caused by a collision with a millimeter scale chip of paint in an intersecting orbital path. Now think about that wrench that got dropped while Skylab was being assembled. You're gonna need a stronger net.

Tris