Never Mind Philae’s Topsy-Turvy Touchdown, Its Brief Mission Advances Comet Science
Even the lander’s missteps generated valuable data

11-19-2014 | Clara Moskowitz

For a mission that lasted two days instead of its planned one to six weeks, the scientists behind the European Space Agency (ESA)’s Philae comet lander are surprisingly cheerful. “We’re extremely happy with how the mission went,” lander control team member Valentina Lommatsch said during an ESA press conference November 14. “Beyond words,” gushed Matt Taylor, project scientist for the Rosetta mission, which launched in 2004 and released the Philae lander on November 12.

These reactions might be surprising, given that Philae failed to land on Comet 67P/Churyumov–Gerasimenko as intended. Instead of touching down on a safe spot on the comet and latching on with harpoons, it bounced off the surface twice before finally settling down next to a cliff that is blocking sunlight from reaching its solar panels. As a result, Philae won't be able to take long-term readings as planned; it has also had trouble drilling below the surface to collect samples for analysis, which is a disappointment. Still, the mission has been overwhelmingly successful, accomplishing between 80 to 90 percent of its main science goals, said Stephan Ulamec, lander manager at the German Aerospace Center. And even the elements of the mission that strayed from the plan, such as the bounced landing, have been useful. Because Philae technically touched down in three places before settling, rather than making a single landing, it was able to measure the magnetic field surrounding the comet at three different points, Taylor said.