Built on Facts

Space Debris

Sometimes I watch Survivorman on the Discovery Channel. It’s a good show – much better than that other one – by virtue of the fact that the survival is real and he doesn’t have a camera crew around to help him out. Sure he has a way to contact rescue should something go wrong, but it doesn’t change the fact that he really is very good at wilderness survival.

One of the things he points out is that pretty much wherever on the planet you find yourself, you’re going to find trash. This is especially true in island survival. Years of trash washing up can be useful when surviving, though he very much deplores the damage the trash can do aside from its simple ugliness.

But you don’t even have to find yourself on the planet to find trash. Though there’s no ecosystem to damage and it doesn’t ruin any views, trash in space is a problem. In the news recently the ISS has had a few close calls with space debris – leftover junk from old satellites and who knows what else from the decades of the human conquest of space. Like most news, there’s good parts, bad parts, and ugly parts.

The Good: Space debris is mostly temporary. There’s very very little atmosphere at space shuttle and ISS altitudes, but there is enough to cause orbits to decay over a period of years. Most low-orbiting space debris will burn up in the atmosphere over a period of years or decades. The period gets longer as orbits get higher. Debris in geosynchronous orbit will be there indefinitely. But there’s more room in each orbital shell as you go higher and so the debris is thinner. Debris can also be tracked by radar. Your satellites and space stations can dodge most of the sizable pieces given warning from the ground.

The Bad: Those high orbits will have to deal with debris forever, or at least until we have cleanup spacecraft. That will not be technologically feasible for a long time, if ever. More debris is being added all the time. Every once in a while some nation gets the bright idea to try something explosive in space and adds massively to the problem.

The Ugly: It’s possible there’s a “critical mass” of debris, past which debris hitting and destroying other satellites causes a chain reaction of more and more debris destroying more and more satellites until orbit is impassable. This would of course be an economic and technological disaster. Such an event bears the ominous-sounding moniker of the Kessler Syndrome A recent satellite collision might be an indication that we’re not far from that point.

I’m afraid I have no policy proposal to deal with this. So long as there’s stuff in space, there’s the risk of collisions. New satellites tend to have end-of-life procedures that move them out of the way of occupied space, but really that’s about all that can be done at the moment. All I can suggest is keeping your fingers crossed until someone figures out a practical way of removing debris.


  1. #2 CCPhysicist
    March 17, 2009

    There is a new “Google Earth” that shows all of the objects in orbit around the earth.

  2. #3 Carl Brannen
    March 18, 2009

    Is it possible to write a post on this: Ant’s don’t have traffic jams? As to why, here are some guesses:
    (a) No highway patrol.
    (b) No vehicle insurance.
    (c) No damage from running into one another.
    (d) No bad (i.e. slow or fast) drivers.

    It’s only a matter of time before they make us use computers to drive our cars.

  3. #4 Astronomy Link List
    March 18, 2009

    This article has been added to the Astronomy Link List.

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