Phobos-Grunt Reentry Window Narrows-UPDATE

Phobos-Grunt Reentry Window Narrows-UPDATE

UPDATE (Jan. 14, 2012, 5:30 pm EST):’s current estimate of the reentry window is 15JAN12 1326Z-15JAN12 2302Z, which translates into tomorrow, January 15, between 8:26 am and 6:02 pm EST.  Russia’s main news agency, Itar-Tass, reports that Russia’s space agency Roscosmos is predicting it will fall on January 15 or 16, with the midpoint of the window at 21:51 Moscow Time tomorrow (or 1:51 pm EST), and that reentry will occur “off of Chile.”  Forecasting satellite reentry times and locations is a very imprecise science, so these predictions should not be considered definitive.

ORIGINAL STORY (Jan. 13, 2012):  Russia’s failed Phobos-Grunt (Phobos-soil) spacecraft is expected to reenter Earth’s atmosphere this weekend.   The reentry window continues to narrow, and Sunday, January 15, Eastern Standard Time (EST) appears to be the most likely day., a U.S. government website associated with the Joint Space Operations Center (JSPoC), currently lists “15Jan12 0804Z – 16Jan12 0304Z” as the predicted reentry window.   Z stands for “Zulu,” an alternate name for Greenwich Mean Time (GMT).   That would translate to 03:04 am – 10:04 pm EST on January 15, 2012. 

Russia’s space agency, Roscosmos, states on its website today that a precise time and point of impact of the fragments will be known 24 hours in advance and it will keep the Secretary General of the United Nations and countries on which debris may fall informed of the situation (as translated by Yahoo! Babel Fish).   Even 24 hours in advance, however, an exact time and location for reentry is difficult to predict.   A variety of government and amateur space observers are tracking Phobos-Grunt’s final days.  Bob Christy at has a table showing a number of the predictions, which focus on January 15 with varying bands of uncertainty.

Russia anticipates that 20-30 fragments weighing no more than 200 kilograms may survive the heat of reentry.  The Earth is 70 percent covered with water, reducing the likelihood of damage to people or property, but some risk remains.  The spacecraft is in an orbit inclined 51.4 degrees to the equator, so debris can fall anywhere between 51.4 degrees north and 51.4 degrees south latitude.

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