Earth flybys of a rogue asteroid…falling spysats. I’m opening a discount store on used hard hats.

There’s a feeding trough of news circulating about this errant U.S. spy satellite. My email is full of tidbits. Let me share with you a couple of things.

Seems like a consensus that we’re talking about USA-193 that went south. Ground controllers are unable to control the spacecraft. Of course, that’s a story too - why exactly it went nuts. A space debris hit? Bad spacecraft engineering by a contractor?

USA-193, if that’s the one, took off from Vandenberg Air Force Base in California in December 2006 on a Delta 7920 rocket and on assignment from the U.S. National Reconnaissance Office (NRO). But according to one secret satellite sleuth, the maximum payload for that kind of rocket, from that location, is no more than 10,000 pounds, perhaps even less than that - not the 10 tons that some stories report.

Even so, a five-ton satellite diving into the Earth’s atmosphere might well lead to debris making it down to home planet.

By the way, this “it’ll burn up” in the Earth’s atmosphere is suspect in my mind.

For one, spacecraft entering the Earth’s atmosphere leave a trail of chemistry of foreign substances in the process, from the top layer of the atmosphere down. I hope somebody out there is thinking about the environmental impact — not just from this wayward satellite — but also the daily dose of human-made detritus that assaults the upper layers of our biosphere on a daily basis.

That said, there’s also a need to be pushing for the release of orbital and spacecraft data particular to this satellite’s fall from grace so that independent analysts can access the potential risk and allow those who might be affected to take the necessary mitigating actions.

My buddies over at the Aerospace Corporation’s Center for Orbital and Reentry Studies advise me that some debris from reentering objects do survive the plunge and can strike the Earth. Certain materials, those with high melting points — such as stainless steel, titanium and glass — are more likely to survive reentry than are materials with low melting points.

Also, for orbit decay reentries, those unplanned and unmanaged, the exact reentry points and location of debris impact on Earth are unpredictable. But experience shows that the discovery of reentered objects is rare because most land in water…and water covers nearly three-fourths of Earth’s surface, or in uninhabited areas.

The Aerospace Corporation experts in this arena point out that nobody has ever been injured by space debris to date. Unless, of course, somebody has been pelted to death in some out-of-the-way remote spot, out of communication. There’s been only one reported case of a person “struck” by debris. This individual, a woman in Oklahoma, was brushed on the shoulder by a lightweight fragment of debris in 1997.

To date, there has been only one instance of hazardous materials surviving reentry and being encountered here on terra firma. In 1978, debris from the former Soviet Union’s Cosmos 954 fell into Canada. Some of the debris was radioactive and was cleaned up after the mishap. No injuries were reported, although Canada issued the Soviet Union a littering ticket.

Meanwhile, for now, heads up!

This entry was posted on Monday, January 28th, 2008 at 9:28 pm and is filed under Contributors, Society, Space & Astronomy, Technology, Uncategorized. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.