Posted on 02/07/2007 5:13:16 PM PST by Fitzcarraldo
For decades, space experts have worried that a speeding bit of orbital debris might one day smash a large spacecraft into hundreds of pieces and start a chain reaction, a slow cascade of collisions that would expand for centuries, spreading chaos through the heavens.
In the past decade or so, as scientists came to agree that the number of objects in orbit had surpassed a critical mass - or, in their terms, the critical spatial density, the point at which a chain reaction becomes inevitable - they grew more anxious.
Early this year, after a half- century of growth, the federal list of detectable objects (4 inches wide or larger) reached 10,000, including dead satellites, spent rocket stages, a camera, a hand tool and junkyards of whirling debris left over from chance explosions and destructive tests.
Now, experts say, China's test Jan. 11 of an anti-satellite rocket that shattered an old satellite into hundreds of large fragments means the chain reaction will most likely start sooner.
If their predictions are right, the cascade could put billions of dollars' worth of advanced satellites at risk and eventually threaten to limit humanity's reach for the stars.
Federal and private experts say early estimates of 800 pieces of detectable debris from the shattering of the satellite will grow to nearly 1,000 as observations continue by tracking radars and space cameras. At either number, it is the worst such episode.
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.
Forden 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."
In April, Beijing is to play host to the annual meeting of the Inter-Agency Space Debris Coordination Committee.
Donald Kessler, a former head of NASA's orbital-debris program and a pioneer analyst of the space threat, said Chinese officials at the forum would probably feel "some embarrassment."
Cascade warnings began as early as 1978. Kessler and his NASA colleague, Burton Cour- Palais, wrote that speeding junk that formed more junk would produce "an exponential increase in the number of objects with time, creating a belt of debris around the Earth."
A solution to the cascade threat has been suggested, but it is costly. Johnson of NASA has argued that the only sure answer was environmental remediation, including the removal of large objects from orbit.
Mama always told me not to mount space junk.
I don't know what the current stats are, but at one time the Soviet Union was responsible for 90% of the mass in space and 99% of the debris. Soviets launch heavy and dirty.
I'm still more'n a wee bit skeptical that we could ever acheive "critical mass". Space is big, radiation pressure and residual drag effect smaller stuff more. The issue is probability of a spacecraft being damaged by debris prior to its "natural" age. I think the number of satellites that have died in that fashion is exactly 0. I suspect that if space becomes a couple of hundred times dirtier, the mortality rate of satellites might tick up 0.1% or so.
This may just be a backdoor way of trying to stop missile testing by the U.S., now that we are at the threshold of widescale capabilities, ahead of the rest of the world.
You obviously know more about this than I do.
Time will tell ... there is no low for any human being - of that I am confident to state.
I was, like, 10 years old when it was on; near the era of "The Love Boat".
1977 starring Richard Bejamin as Quark.
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