Rosetta's Philae Looking to Land

Even with the Rosetta Spacecraft successfully caught up and in orbit of its quarry, the comet 67P/Churyumov-Gerasimenko, its mission is far from over. Experts involved in the Rosetta mission must now prepare to set a lander down on the comet - a task that will take a great deal of planning.

The Rosetta mission, headed by the European Space Agency (ESA) and assisted by NASA and other international space agencies, is now in the midst of its final chapter, called the "comet rendezvous" stage.

This has included the final approach and eventual close orbit around 67P/Churyumov-Gerasimenko, which was achieved at the start of this month. Now mission experts are working to identify viable landing spots for the Rosetta spacecraft's Philae lander on the comet's nucleolus.

According to a recent NASA release, analysts have already whittled down the number of candidates to five possible landing zones on the comet.

Despite its nickname as the "rubber ducky" comet, 67P is fairly massive, covering over two square miles of space - the size of a mountain or small city. Even so, its unusual shape and uneven ground makes it relatively difficult to select the safest possible place to land, especially since a lander has never touched down on the surface of a comet before.

"This is the first time landing sites on a comet have been considered," said Stephan Ulamec, Philae Lander Manager at the German Aerospace Center in Cologne, Germany.

He added that the five selected sites "all provide at least six hours of daylight per comet rotation and offer some flat terrain. Of course, every site has the potential for unique scientific discoveries."

However complex the landing zone process is, the mission leaders only have a limited window of time to make their final decision. The landing is slated to happen this November, giving the Philae lander adequate time to conduct analyses before next August, when 67P's shrinking orbit will bring it too close to the Sun for Rosetta to handle.

"We had to complete our preliminary analysis on candidate sites very quickly after arriving at the comet, and now we have just a few more weeks to determine the primary site," said Fred Jansen, Rosetta's mission manager from the ESA. "The clock is ticking and we now have to meet the challenge to pick the best possible landing site."