Postcard from a Comet

Philae has phoned home!  The first man-made probe ever to land on the surface of a comet is back in contact with Earth after seven months of silence.

I previously blogged about the project here and here.  Following a 10-year journey through space, the robotic spacecraft Rosetta entered orbit around the comet 67P/Churyumov-Gerasimenko in August 2014.  On November 12, the unmanned probe Philae was deployed to land on the surface of 67P.  The craft carries several pieces of Agilent equipment on board for direct analysis of the comet.

Unfortunately, the landing last November did not go as planned.  Philae’s landing gear failed to deploy properly, so the probe bounced off of the comet’s surface twice.  It ultimately landed a kilometer away from its original targeted site, coming to rest in a shaded area instead of direct sunlight.  Because it relied on solar batteries, Philae ran out of power and put itself into a “sleep” mode three days later.

But scientists at the European Space Agency remained optimistic.  They believed that once P67’s orbit brought the comet closer to the sun, there was a slim chance that Philae would be able to recharge its batteries enough to reawaken.  Sure enough, on June 13, Philae began communicating with Rosetta again.  Philae, Rosetta and the ESA are now exchanging packets of data.

The news gets even better.  If Philae had landed on its original site, its mission would probably have ended in March due to overheating from the high temperatures.  Because it is in a cooler spot, it should be able to function for much a longer period.  As a result, the Rosetta mission has officially been extended through September 2016.

Rosetta’s long journey will end on a high note.  As the comet moves farther away from the sun again and all solar batteries deplete for the last time, scientists plan to send Rosetta itself on a slow three-month spiral down to the surface of P67.  This will enable Rosetta to gather even more unique and valuable data about the comet.


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