Malfunctioning Russian probe spotted hurtling through space backward (+video)
Veteran satellite watcher Thierry Legault filmed the wayward Russian Phobos-Grunt probe, which was intended to collect soil samples from a Martian moon but is instead heading toward a destructive plunge back to earth.
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Russia's Federal Space Agency launched the Phobos-Grunt probe in November, only to see it fail to depart for Mars shortly after reaching Earth orbit. It has been stranded in orbit ever since.
Legault reported on his website that his new video shows no sign of the spacecraft tumbling.
"The unexpected thing that I realized when I looked carefully at the video is that Phobos-Grunt is moving backwards," Legault said, "with its solar panels deployed but at the opposite of the sun. It's not surprising that it had no energy to communicate!"
Spotting the Phobos-Grunt Mars probe
Legault's observation spurred Ted Molczan of Toronto, a leader in the amateur satellite- spotting network, to study the spacecraft's orientation.
"The orientation revealed in Thierry Legault's video — propulsion module leading, solar arrays trailing — may possibly be explained by analogy with the shuttlecock used in the sport of badminton," Molczan told SPACE.com. [Photos of the Phobos-Grunt mission]
Shuttlecocks are roughly conical, consisting of a heavy mass at the tip (called the cork) and trailing feathers forming the cone. This configuration results in highly stable flight through the air, with the heavy end leading, Molczan noted.
Molczan said that most of Phobos-Grunt's massive 14-ton bulk consists of fuel, located in tanks in the main propulsion module at one end of the spacecraft, similar to the heavy cork of a shuttlecock.
"Although Phobos-Grunt does not have feathers, it does have solar arrays, mounted on the end opposite the fuel tanks, which may produce a similar effect," Molczan said. "An essential requirement for shuttlecock flight is the presence of air, of which there is exceedingly little in space; however, at the very low altitude of Phobos-Grunt, the combination of atmospheric density and high orbital velocity is sufficient for aerodynamics to dominate the forces affecting the orientation of a spacecraft."