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Russia's Phobos-Grunt satellite stranded in Earth orbit--UPDATED

By: kelso
Phobos-GruntThings are not looking good for Russia’s Phobos-Grunt mission, which was launched in early November on a journey to land on the Martian moon Phobos, obtain soil (grunt) samples and return them to Earth. While Phobos-Grunt and its passenger—China’s Yinghuo-1 orbiter—did make it to the intended Earth parking orbit, the two planned automatic burns meant to send them on their way to Mars do not appear to have occurred. Instead, Phobos-Grunt remains in Earth orbit, and it appears that all attempts to communicate with it to date have been unsuccessful. The window to send Phobos-Grunt to Mars closed yesterday—since it will no longer have enough fuel to cover the increasing distance between Mars and Earth. And while there have been discussions about alternative destinations—such as orbiting the Moon or going to an asteroid—if the Russians are unable to establish communications, atmospheric drag will pull Phobos-Grunt back to Earth. The latest available orbital data suggests reentry will occur sometime around Christmas Day—just 34 days from now. We will continue to monitor this situation and report it here. In the meantime, we wish the Russian Space Agency the best of luck in recovering Phobos-Grunt. UPDATE--Dec. 27, 2011 While some recent news reports suggest that USSTRATCOM knows the reentry time for Phobos-Grunt with precision, the latest published results available on their Space Track web site now show a predicted reentry time of Jan 13 @ 2228 UTC with an uncertainty of +/-264 hours (that’s +/-11 days). That means they are predicting Phobos-Grunt could reenter anytime between Jan 2 @ 2228 UTC and Jan 24 @ 2228 UTC—a timespan of 22 days. This prediction was released Dec 25 @ 2227 UTC. Using the latest available TLE (orbital) data, the central prediction time currently shows Phobos-Grunt reentering just south of Australia, but the uncertainty in the estimate still means it could reenter virtually anywhere on the Earth’s surface between 51.4 North and South latitude—as can be seen in the graphic. Phobos-Grunt could actually reenter anywhere along the green ground traces shown in the graphic. Our own current estimate shows a reentry on Jan 11 @ 0933, but we really won’t know with any certainty what time Phobos-Grunt will reenter until after it has already happened. Such is the current state of reentry predictions. Uncertainties in the attitude of the spacecraft and the state of the Earth’s upper atmosphere (yes, there is still a very thin atmosphere at 200 km altitude) make it very difficult to predict these events more than a day or two in advance. We will continue to update this graphic as new orbital data and predictions come out of USSTRATCOM.
Posted: 11/22/2011 6:56:22 PM


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