space junk

I just read an article on Headline News’s webpage about space junk accumulating and was wondering if anybody figured out how to get rid of it all. It seems to me that if we could track it we could zap it with a Flash Gordon Ray gun or something. How do the folks on the space station protect themselves from these micrometeroids (is that the right word)?

IIRC, people working on the Space Station try to face and to position themselves relative to structures nearby so that they are shielded from particles overtaking them. But there’s no absolute way to protect yourself – stuff can come in from any direction.

Proposals for cleaning it up include using aerogel-type things – kind of like towing a big wad of fluff around and letting things embed themselves in it. You can find discussions of this in SDI material and in books about Space Elevators (see Clarke’s Fountains of Paradise and Schmidt’s Web Between the Worlds, for instance).

I can’t find the article again, now.

The space station is armored to a degree. It’s also oriented so that the most vulnerable surfaces are out of the most likely line of collision.

The prblem with getting rrid of the space junk is that if you zap it, you create smaller, still very dangerous, untrackable debris. The best bet is to allow it to de-orbit on it’s own, which is fine for LEO debris, and it works well enough, I guess. Stuff above LEO, however…?

I also read that article, and noted some inconsistancies or ommisions. It talked about interceptting missiles, and then implied that missile debris would stay in orbit forever. Ballistic missiles are suborbital, and their debris (or at least the vast majority of it) would share roughly the same trajectory: Back into the atmosphere. Ditto for most interceptor debris: It’d achieve higher apogee, but it’s meet the atmosphere on it’s way back down. The article also fails to mention that LEO debris tends to deorbit over time.

All that said, debris in Earth orbit is a serious issue, and I’m stunned to find the NASA office being closed for budgetary reasone

There are a couple of different strategies for dealing with space junk that the ISS uses. First off, for reasonably large stuff, you just drive the ISS out of the way. US Space Command tracks stuff bigger than about 10 cm (they can probably track things smaller than that, but 10 cm is the “advertised” size), so if something that big is headed your way, you can tweak your orbit to miss it. This is pretty rare - most of these orbital conjunctions end up not being an issue once they are mapped over a few revs. Secondly, the really small stuff (like the size of sand particles) you just take. The station is shielded for most of that stuff, but you still see little dings that look like BB holes every so often.

The danger is in the “middle ground” there, where the debris is too small to be tracked and too big to take on the shields. In those cases, the ISS uses the “space is big” defense, and hopes that it never gets hit. This has worked so far, but there were reports of a “fist-sized” hole in the Mir solar arrays that had some folks a little excited a few years ago.

The real danger comes from the cascade effect. Witch is when a peice of space junk hits a satalite and breaks it into many peices witch hit other satalites and so on untill LEO is filled with millions of micrometeorites. This would put and end to space use for many decades untill all the junk deorbits. Fortunatly this hasn’t happend yet,and hopefully we will find a way to clean it up before it does.

Judging from the session of the UK’s working group on space debris (an annual get-together of a couple of dozen government, military, academic and industry representatives) that I attended a couple of years ago, there’s very little interest at an international level in finding ways of actively reducing what stuff’s already there. Frankly, it’s difficult enough merely to establish what the risks are and that’s where most of the effort is currently directed. What is being done is the development of predictive models of the different effects of things like launch patterns. The hope is that, by taking action to minimise the amount of debris being added and with atmospheric drag removing some of the existing amount, the dangers can be reduced over a timescale of several decades.