When Satellites Collide
Special Report for Space Daily Bethesda MD (SPX) Feb 11, 2009 We have been speculating that pieces of space debris occasionally hit active satellites, but we had no concrete evidence to confirm such a hypothesis. All that has changed in an instant. On February 10th, an active commercial satellite and an expired Russian Cosmos spacecraft apparently tried to cross the same point in space at the same time. Both vehicles were traveling at about 16,800 MPH (26,800 KPH). Since they were in different orbital planes, their relative closing speed must have been at least several hundred miles per hour. One of Iridium's mobile telephony nodes instantly became a cloud of space junk, as did the Russian spacecraft. The resulting debris field adds to the already vast quantity of space junk in low Earth orbit. Since the satellites collided at an altitude of 491 miles, this new debris will remain in orbit for decades, if not centuries. To compound the situation the Iridium satellite was part of a constellation of over 66 identical spacecraft, all in near-polar orbits. Therefore, this single event dramatically increases the probability of further collisions among Iridium satellites and many other commercial and government spacecraft. The critical question we should ask is, "Are we going to get serious about actively managing orbital debris?" There is a real possibility that this collision will initiate a chain of other collisions. Other Iridium satellites may collide with pieces from the February 10th event. The rate of collisions could then increase exponentially until all 66 active Iridium nodes and spares are rendered space debris. This series of collisions would then yield thousands of new debris objects that would then threaten other satellites. The average time between collisions could possibly be reduced from tens of years to a year or less. One thing is certain, whatever happened over northern Siberia on Tuesday will be detrimental to space flight. If there is any good news from this disaster, the International Space Station is in an orbit well below that of Iridium and does not appear to be immediately threatened by the new debris. However, it is likely that some fraction of the resulting debris field will intercept the station's altitude. A complete picture of the resulting debris distribution will not be available for several days. Results of initial tracking indicate that there are nearly 300 new detectable fragments, but experience tells us that there are probably thousands of small pieces that cannot be tracked easily. As the debris field spreads out around the globe various tracking networks will piece together the complete extent of this hazard. The unfortunate Iridium satellite weighed as much as 1,400 pounds and it collided with a spacecraft of similar mass. You don't have to be an expert to conclude that we have a problem. Now imagine what might happen if all 95 Iridium satellites that were launched between 1997 and 2002 collided with the resulting debris. At that point there would be a loud cry for action from all who use space. There soon could be no more direct-to-home satellite television, no more weather pictures from space, no more GPS navigation and no more access to space. Let's not wait until it is too late! Related Links Launchspace Space Technology News - Applications and Research
Eliminating Space Debris - The Quest Continues Bethesda MD (SPX) Dec 16, 2008 Launchspace has received approximately 100 ideas and suggestions on cleaning up space debris. Many of these are simply not realistic for reasons ranging from violation of physical principles to excessive collateral damage. Of course, many are just too costly when compared to other approaches. |
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