A misfire of harpoons, an ancient technology, may have spelled the end of one of the most advanced: Philae, the first spacecraft to send images from the surface of a comet. Unanchored to its comet, the spacecraft drifted into darkness, sending back scientific data even as its solar-powered batteries faded.

The lander successfully delivered data on the composition of the comet, before losing contact early Friday with the European Space Agency at the Rosetta Mission Operations Centre in Darmstadt, Germany.

"With its batteries depleted and not enough sunlight available to recharge, Philae has fallen into 'idle mode' for a potentially long silence," an ESA statement announced.

"It was a very successful mission; it has returned a lot of great data