The mission of the first robotic probe to land on a comet reached a high point on Friday when the spacecraft radioed back to Earth that it had successfully drilled into the comet's body.
Scientists with the European Space Agency's Rosetta mission did not know if the small lander that touched down on the comet on Wednesday would have enough battery power to phone its findings back to Earth 500 million km (300 million miles) away.
Rosetta's lander, called Philae, failed to anchor itself as planned on the comet's body, causing it to bounce and reland at about 1 km (.62 mile) away from its original target.
Photos and other data later relayed by Philae indicate it is trapped in shadow, suggesting it ended up by a cliff wall or inside a crater. With battery power dwindling, scientists sent commands for Philae to attempt to use its drill to obtain samples from the comet's body.
Those results were still pending, but on Friday Philae made a belated radio call via the orbiting Rosetta mothership, reporting that its drill successfully operated.
"First comet drilling is a fact!" ESA posted on Twitter Friday night.
Scientists also decided to attempt to reposition the lander so its solar panels could recharge.
"Just started lifting myself up a little and will now rotate to try and optimize the solar power," ESA said on the Philae lander Twitter feed.
One of the most important tasks for the 100-kg (220-pound) probe was to obtain samples from inside the comet for chemical analysis.
Comets are believed to be pristine remnants from the formation of our solar system some 4.6 billion years ago. They contain rock and ice that have preserved ancient organic molecules like a time capsule and may provide insight into how the planets and life evolved.
Philae's drill descended more than 25 centimeters (10 inches) on Friday, penetrating the comet's surface.
Previous robotic probes conducted brief fly-bys. After a 10-year flight, Rosetta arrived at comet 67P/Churyumov-Gerasimenko in August for a mission that is expected to run at least through December 2015.
"This mission is fantastic, let's look at what we have achieved, not at what we would have done differently. This is unique and will be unique forever," said Andrea Accomazzo, the Rosetta flight director.
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