For the third time since September, eyes will be pointed skyward in early 2012 as yet another satellite falls to Earth. This time it is a Russian spacecraft—Phobos-Grunt
—that became marooned in Low Earth Orbit when its Earth-escape engines failed to fire after launch on November 9. The ambitious mission plan was for the craft to land on the Martian moon Phobos
, collect soil samples and return them to Earth for study. The satellite also carries a small Chinese Mars orbiter, a science experiment
and full tanks of hydrazine fuel.
Since the spacecraft became stranded
in its parking orbit, Russian and European Space Agency ground stations have only succeeded in talking to it a handful of times. Initially, engineers hoped to start the engines and send it to Mars before the two-week window of opportunity closed. After that, the planets would not be properly aligned for another 26 months. When the window for the journey closed, the Russian Space Agency continued to try to contact the probe to boost it to a higher orbit where atmospheric drag would not impact it, and eventually bring it back to Earth. As hopes for recovering the satellite dimmed, speculation turned to when and where the satellite would reenter.
As with the two other recent satellite deorbits—NASA’s UARS and Germany’s ROSAT—no one will know the actual time and location of the reentry until the final moments. Estimates will
become more accurate as the event draws nearer, however. Most of the spacecraft is expected to burn up at reentry, although some pieces may fall to Earth. While most of the world’s population lies beneath the +/-51 degree latitude swath of Earth that’s in the potential reentry zone, any debris that reenters would likely land in the ocean, since water covers nearly three-quarters of the Earth’s surface.
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