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fortytwo
11-17-2005, 09:22 AM
I was reading about the delay in the Falcon 1 rocket launch which was going to carry the remains of James Doohan into orbit, and how it would be about 200 years before said remains would burn up in the atmosphere.
While I can understand the sentiment behind it- I'm a keen science fiction reader myself- it did start me thinking about how much debris was orbiting Earth and if it was a danger to other missions.
Apparently there are 8000+ objects up there above our heads right now.

You wouldn't think that humanity has been this busy in space - but there are over eight thousand satellites and other large objects in orbit around the Earth, along with many smaller objects. These objects include spent vehicle upper stages, separation bolts, lens caps, momentum flywheels, nuclear reactor cores, auxiliary motors and launch vehicle fairings. Material degradation due to atomic oxygen, solar heating and solar radiation produces particulate matter. Solid rocket motors used to boost satellite orbits leave motor casings, nozzle slag, solid-fuel fragments and exhaust cone bits. More than 124 satellite breakups have been verified; many more are believed to have occurred; these are generally caused by explosions and collisions. Satellites or other objects in orbit higher than 700 kilometers will stay there for hundreds of years; LEO satellites have an average working life of just five years.
Source (http://www.space.com/businesstechnology/technology/technovel_tether_041117.html)

Presumably the number of objects are increasing as time goes by, so is there a real chance that some multi billion dollar project could be ruined by a collision?

It would be rather ironical if the rocket launching Scotty into space was destroyed by the remains of Gene Roddenbury.

I guess this debris is spread out all around the earth but surely the danger must exist?

DarrenS
11-17-2005, 09:35 AM
It is a huge problem. Scientific American did an article on this about a year ago - you can read the first couple of paragraphs free here: http://sciam.com/article.cfm?chanID=sa007&articleID=00013F6C-6477-10A9-A47783414B7F0000

What Exit?
11-17-2005, 09:46 AM
I always thought that eventually someone would start gathering all the junk up as building materials for a larger station. A little far fetched, but we should be able to find a way to do this.

Jim

mks57
11-17-2005, 10:18 AM
Presumably the number of objects are increasing as time goes by, so is there a real chance that some multi billion dollar project could be ruined by a collision?


Yes. My memory is fuzzy on the details, but I've read several spacecraft post-mortem reports that listed collision with debris as a possible cause of failure.

Finagle
11-17-2005, 10:30 AM
I always thought that eventually someone would start gathering all the junk up as building materials for a larger station. A little far fetched, but we should be able to find a way to do this.

Jim

No way would this be cost effective. Even if the parts were actually useful instead of paint chips and bolts, the fuel required would be extravagant. Sort of like trying to assemble a free car by driving around the United States picking up car parts from the side of the road.

What Exit?
11-17-2005, 10:39 AM
No way would this be cost effective. Even if the parts were actually useful instead of paint chips and bolts, the fuel required would be extravagant. Sort of like trying to assemble a free car by driving around the United States picking up car parts from the side of the road.
Quite a bit of the junk is larger though. Dead Satellites and some Boosters I thought.
It should eventually be cheaper than boosting mass out of the gravity well and leaving the debris to total new equipment.
Eventually we could use Solar Sailed Bots to gather the debris.
If you donít like Solar Sail concept, that is fine but a low powered unit of some sort should be able to do a slow cleanup.
Feasible right now today, of course not, but maybe in 20 years we can start doing this.

Jim

minor7flat5
11-17-2005, 11:20 AM
Quite a bit of the junk is larger though. Dead Satellites and some Boosters I thought.
It should eventually be cheaper than boosting mass out of the gravity well and leaving the debris to total new equipment.
Eventually we could use Solar Sailed Bots to gather the debris.
If you donít like Solar Sail concept, that is fine but a low powered unit of some sort should be able to do a slow cleanup.
Feasible right now today, of course not, but maybe in 20 years we can start doing this.

JimI imagine that the most difficult part of this is the inherent challenges in rendezvous in space. I was surprised at the complexity of the problem: a nice article (http://inventionandtechnology.com/xml/2001/2/it_2001_2_feat_0.xml).
It takes substantial energy and finesse to chase something down if you are in precisely the same orbital plane. If you aren't, it takes huge amounts of energy to change the orbital plane enough. As you said, perhaps down the road; nevertheless, it seems less probable the more one looks at the details (e.g. the docking problem).

What Exit?
11-17-2005, 11:24 AM
I imagine that the most difficult part of this is the inherent challenges in rendezvous in space. I was surprised at the complexity of the problem: a nice article (http://inventionandtechnology.com/xml/2001/2/it_2001_2_feat_0.xml).
It takes substantial energy and finesse to chase something down if you are in precisely the same orbital plane. If you aren't, it takes huge amounts of energy to change the orbital plane enough. As you said, perhaps down the road; nevertheless, it seems less probable the more one looks at the details (e.g. the docking problem).

Wow, great article, Thanks.
I would have to say 20 years sounds way to optimistic.

Jim

power sawyer
11-17-2005, 02:18 PM
I think something like Reagan's Star Wars laser sattelite could sweep that junk out in a hurry. The smallest nudge from a laser beam and they would change orbit. If it changed higher, the thing escapes into deep space. If lower, it burns up.

Chronos
11-17-2005, 04:10 PM
I think something like Reagan's Star Wars laser sattelite could sweep that junk out in a hurry. The smallest nudge from a laser beam and they would change orbit. If it changed higher, the thing escapes into deep space. If lower, it burns up.Not nearly that simple. With a small nudge lower, the thing will eventually re-enter and burn up... But it'll do that eventually without the nudge, too. If it's only a small nudge, then it'll only make a small difference in how long it takes. On the other side, there's a lot of room before you'd send something escaping into deep space: It takes as much energy to get from an orbit to deep space as it took to get it from the ground to orbit in the first place.