Tuesday, February 06, 2007

Accelerating the Cascade

Some time ago I wrote about the "Cascade", a chain reaction where a collision between two hunks of space debris sets off a chain reaction of so much space debris that, in short order, our satellite systems are lost.

In the last decade scientists concluded that there's now so much space junk racing about that the cascade is inevitable, just a matter of time.

That's why the recent Chinese anti-satellite weapon test was so worrisome. Now, the International Herald Tribune is reporting that the explosion created a mass of new space debris, 800 pieces detected already and that's expected to grow to 1,000 or more that will eventually be located:

"Today, next year or next decade, some piece of whirling debris will start the cascade, experts say.

"'It's inevitable,' said Nicholas Johnson, chief scientist for orbital debris at NASA. 'A significant piece of debris will run into an old rocket body, and that will create more debris. It's a bad situation.'

"Geoffrey Forden, an arms expert at the Massachusetts Institute of Technology who is analyzing the Chinese satellite debris, said China perhaps failed to realize the magnitude of the test's indirect hazards.

"He suggested that Chinese engineers might have understood the risks but failed to communicate them. In China, he said, 'the decision process is still so opaque that maybe they didn't know who to talk to. Maybe you have a disconnect between the engineers and the people who think about policy.'"

It is speculated the Chinese went for a high-orbit satellite to avoid endangering the International Space Station which orbits at 220-miles above earth.

Most of us don't appreciate how dependent our world has become on these satellites. They include the GPS or Global Positioning Satellite systems that we use for navigation. They include most of our long-distance telecommunication services, our network television programming, and a lot more.

During the Cold War the US and the USSR conducted about 20-tests of anti-satellite weapons but they chose targets at low earth orbits that would be re-entering the earth's atmosphere. The Chinese target satellite was at an altitude of 800 kms. which means that debris could remain in space for hundreds of years or more.

There are alternatives, hypothetical at this point, to respond to a cascade. One is launching armoured satellites designed to survive a 20,000 mile an hour impact with space junk. Another is to launch robotic satellites that capture the existing debris, in effect sweeping space.

The robot solution sounds intriguing until you consider the fuel problem.

2 comments:

ed said...

I propose a Space Zamboni. In fact, I hereby claim all ownership of the idea.

The Mound of Sound said...

And why not Ed? Put together a couple of sketches and run it through the patent office but do it quick. You've already divulged your idea, it's now open season.