>> Saturday, May 22, 2010
Well, I'm back from the conference and I think it went well. I think my own paper was well received and I saw a number of other presentations that were very nice or thought-provoking, particularly one that used lessons learned from a rather tragic sledging expedition in Antarctica. It might seem a stretch, to compare them, but I thought he had excellent points. When everything you need to survive has to be brought with you, when you might be stranded or cut off from your home base, you need to be prepared and think it through. Lessons learned from this I thought quite applicable to Moon or Mars EVA expeditions and missions.
Another interesting presentation was on EDDE, a proposed debris cleaning program for Low Earth Orbit. Now, I've been pretty skeptical that cleaning out the debris is a practical notion, but, I have to say, this idea was intriguing to me. Using a tethering system to gain energy as well as change altitude/inclination very quickly without propulsion - thanks to the electromagnetic field around the Earth (and I find that cool beans). It's not science fiction; tethers have been used several times in the past with considerable success.
According to the presentation, they could change hundreds of km a day in altitude, quite a bit in inclination and, theoretically, clean out all the cataloged debris up to an altitude of 2000 km in less than seven years with just twelve 100 kg units. Units could deorbit themselves or stay as policemen. Now, they claimed they didn't have to worry about uncataloged debris (I'm less sanguin about that) though I agree they could avoid the cataloged stuff. And I'd want more than a power point presentation before I was sold on the idea, but, it seemed like a fine idea.
Although all the small stuff doesn't get cleaned out this way, you limit the generation of more debris by taking out the big stuff. The smallest stuff is the most readily cleaned out by natural processes. They bring the stuff down to 330 km (pretty much below anywhere dangerous) and were natural atmospheric friction will bring it down in weeks instead of decades. As the electromagnetic field at geostationary is not strong enough to use this there, it's limited to LEO, but that is where many of our valuable assets are.
Even if it didn't completely solve the problem, if effective, it could make a real difference.
They have an animation of this that's well worth watching here. If it doesn't work, the link above (EDDE) has it there as well.