Philae, the first probe to land on a comet, bounded twice when it touched down on Comet 67P-Churyumo-Gerasimenko yesterday, and remained un-achored, confirmed the European Space Agency mission group on Thursday.
"The first analysis of the touchdown data suggests that the lander bounced twice before settling on the surface of Comet 67P-C-G," said the ESA in a statement sent from its operations center in Darmstadt, Germany.
Philae landed three times; at 3:34, 5:25 and 5:32 local time (0234, 0425, 0432 GMT) on Wednesday. "In other words, the lander bounced," ESA said.
Earlier reports cited Philae lander manager Stephan Ulamec as saying the lander might have leapt as much as 1 km high after its first landing on the comet nicknamed "rubber duck," and made another small jump thereafter.
ESA explained that a pair of harpoons on the bottom of Philae were supposed to have fired into the comet but failed to do so.
Checks before Philae's separation from its mothership Rosetta Wednesday morning also found that a cold gas thruster on top of Philae which was designed to push the lander onto the comet surface would not activate.
Experts feared Philae might float away as it was only able to rely on the three ice screws in its feet to anchor itself to the comet which has a very weak gravity.
"The lander remained un-achored to the surface, but the instruments are running and are delivering images and data," ESA said, adding that teams were working to confirm the location and the overall power and thermal situation on board.
According to ESA, Philae was intended to conduct various experiments during its stay on the comet. A full panoramic view of the landing site, 3D high-resolution images of the surface underneath the lander, analyses of the comet's surface composition materials and samples from a depth of 23 cm were expected to be sent back to earth during the primary phase of Philae's scientific mission.
Scientists hailed the touchdown of Philae as a great progress in space discovery.
"This is a big step for human civilization," said Jean-Jacques Dordain, Director General of the European Space Agency, "Our ambitious Rosetta mission has secured a place in the history books."