A view to a satellite kill
Posted: Thursday, January 25, 2007 8:30 PM by Alan Boyle
The effects of China's anti-satellite test are graphically seen in an animation showing the debris that it created, and how all that junk matches up with the orbits of the international space station and other spacecraft. A satellite-tracking expert created the video clip to draw attention to the potentially perilous traffic in low Earth orbit - a space jam that just got worse.
CSSI |
An animation shows the orbital
tracks of the international space
station and debris left behind by a
Chinese anti-satellite test. Click on
the image to watch the animation.
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Beijing's Jan. 11 missile strike didn't really hurt anybody ... yet. The only known casualty so far was an aging Chinese weather satellite, which was targeted to test the feasibility of knocking out spacecraft in orbit. It was the first test of an orbital space weapon since 1985 - and it worked.
"We know from past experience that these types of events, whether they're ASAT [anti-satellite] tests or unintentional collisions, typically generate at least hundreds of objects. Some models estimate numbers in the thousands," said T.S. Kelso of the Center for Space Standards and Innovation, the research arm of Pennsylvania-based Analytical Graphics Inc.
Kelso's animation pinpoints just a few pieces of that debris - the 33 objects that are being tracked publicly by the North American Aerospace Defense Command, or NORAD. The video traces the space station's orbit as well, showing the potential for a smash-up at an orbital intersection.
"It's just like two streets crossing. ... You don't need to have something the size of a truck hit the space station," he said. "You could have something the size of a BB, because of the orbital speeds."
The Chinese satellite shootdown adds new twists to an already-complicated orbital traffic pattern. Of course, NORAD and NASA keep a close eye on the potential debris risk to the space station, spy satellites and other government-owned spacecraft, but Kelso said thousands of additional objects in low Earth orbit have to be watched as well.
That's the rationale behind a project called Satellite Orbital Conjunction Reports Assessing Threatening Encounters in Space, or SOCRATES. Kelso maintains the 3,000-satellite SOCRATES database as part of his work for the center as well as for his CelesTrak satellite-tracking Web site.
"We do a twice-daily report where we take all the unclassified data that the Air Force releases, and we do predictions for every payload," Kelso told me. "We know some satellite operators go out and look at that. It's not perfect, but it's better than closing your eyes and pretending nothing's going to happen."
Kelso said SOCRATES typically picks up 1,000 events every day in which one orbiting object is estimated to come within 3 miles (5 kilometers) of another one. Today, for example, the Web site projected that two Russian Cosmos satellites would zoom within 100 feet (28 meters) of each other at a relative speed of 25,000 mph (11.121 km/sec).
If satellite operators see that their assets might be involved in a close encounter, they would usually run their own numbers to assess the potential threat and take action if necessary.
"For the overwhelming majority of stuff that gets up there, there isn't anybody who's going to call them up and say, 'Hey, something's getting close to your satellite. You may want to do some more analysis and see if you need to react,'" Kelso said.
As space becomes increasingly crowded, due to the addition of more satellites as well as smash-ups like the one reported this month, SOCRATES could set the stage for a more formal approach to orbital traffic management.
"It's our feeling that, at some point, somebody's going to need to step up," Kelso said. "What SOCRATES is intended to be is a proof of concept, to show that it can be done."
For more about Kelso's analysis of the satellite-killing test, check out this page on the Center for Space Standards and Innovation's Web site. You'll find a higher-resolution, downloadable version of the satellite-tracking animation. And if you download the free AGI Viewer software, you can play around with the orbital paths to your heart's content. Think of it as a 3-D mapper for Earth's high frontier.
