Mission scientist reacts to historic first images from the surface of a comet

A few moments after the pirouette, battery voltage suddenly plummeted and engineers said the end was near. Trapped between a rock and a dark place beyond its ability to survive, Philae dutifully sent back stored data and even made fresh measurements until finally, just after 7:30 p.m. (EST-5), contact was finally lost.

Paolo Ferri, head of mission operations, describes the moment of relief when engineers confirmed the Philae comet lander separated from its Rosetta mothership. But anxiety is building over touchdown after telemetry data raised questions about the status of an important cold gas thruster designed to keep the lander from bouncing off the comet.

The Rosetta spacecraft neared its comet Saturday, targeting a close flyby within four miles of the tiny world’s jagged nucleus to gain new up-close views of the comet and taste the growing vaporous cloud surrounding it.