Projected increase
in space debris
if none at all were added
“Risks in Space from Orbiting Debris”
J-C Liou and N L Johnson, Science,
311: 340–341 (2006).
A few weeks ago, a US and Russian satellite collided, spreading debris around near-Earth space. The video below shows an animation based on a state-of-the-art model of the event and the resulting clouds of ultra-high-speed projectiles. Collisions like this can be expected to occur with increasing frequency.
The Economist just ran an editorial calling for countries to take care not to make a mess with abandoned satellites, spent rockets, exploding fuel tanks, and other junk. One might almost think that these measures would solve the problem. They won’t.
Every collision creates debris that raises the frequency of further collisions. The graph above from a 2006 article in Science , Risks in Space from Orbiting Debris, shows the projected increase of 10 cm+ space debris according to a model that was run with the optimistic assumption that nothing has been launched since 2004, and that this complete moratorium on adding junk in orbit will continue forever. This ends the steep climb, but doesn’t reverse it.
The effect of launching more satellites and associated junk — and of China’s messy anti-satellite missile test in 2007, and of the collision last month — is to speed the onset of a more-or-less exponential growth process. There are currently more than 9,000 pieces of substantial size, with a total mass of over 5 million kg, and each piece is moving far faster than the highest-velocity bullet. This is a particular problem for large targets with people in them, like the Shuttle and space station.
According to the Science article, no one has a good idea what to do about this problem. Actually collecting the stuff would require, for example, the ability to produce many thousands of small, inexpensive, automated spacecraft at low cost. (So many problems, when examined from the right angle of view, hinge on manufacturing — the ability to make things.)
{ 6 comments… read them below or add one }
Eric,
Is this meaning that over then next 20-30 years that all the satellites and junk in space is going to add up and crash down upon us?
I have heard very little lately about the idea of using a ground-based pulsed laser to carefully ablate and de-orbit much of this debris. This idea was studied some years ago, and seems like a very good technique for clearing out, without any need for vehicles at all.
@ Stephen Bauer — The problem isn’t what comes down (which is an insignificant amount compared to natural meteoritic material) but what stays in orbit and poses an increasing collision risk to near-Earth spacecraft. Many small pieces pose a greater hazard than a few large ones, hence the problem created by ongoing fragmentation.
@ Phil — The principle is sound, but to quote the Science article,
“The use of ground-based lasers to perturb the orbits of the satellites is not now practical because of the considerable mass of the satellites and the consequent need to deposit extremely high amounts of energy on the vehicles to effect the necessary orbital changes.”
Most of the debris are not entire satellites. I’m suspicious of an argument that says “We can’t do this thing that we don’t need to do anyway, so we won’t do the other thing that might help.” What are the political reasons for not developing lasers?
I think this a huge problem, and we should not be ignoring it and hoping for the best. we should be looking at any and all solutions.
all space faring nations should be helping to solve the problem.
maybe if we had some kind of robotic craft, that could attach, or push
junk into a declining orbit and have it burn up…
-nex6
Eric, will this interfer with space elevator type plans, if society actually went forth to build such a thing? What is your view on the idea of building diamondoid or fullerene space elevators and tower systems? Is it futile as compared to other means or does it have validity? There is a great new book out by the way all about solar sail systems, and there is a section on emerging technologies that gets into molecular manufacturing and nanomaterials and how they can be used for solar sail craft. Your work is ofcourse mentioned.