Comet lander Philae fell asleep after its batteries exhausted, the European Space Agency (ESA) confirmed on Saturday.

Philae communicated with controllers on the earth for nearly two hours before it fell into "idle mode", in which all instruments and most systems on board were shut down, ESA said.

"Prior to falling silent, the lander was able to transmit all science data gathered during the First Science Sequence," said Philae Lander Manager Stephan Ulamec in ESA operations center in Darmstadt, Germany.

Contacts with the lander was lost at 00:36 GMT on Saturday, the ESA said, adding further contacts would not be possible unless Philae's solar panels received sufficient sunlight to generate enough power to wake it up.

Pictures sent back earlier showed that the lander rested in a shadow of a cliff after bouncing for twice when it made a historical touchdown on Comet 67P/Churyumov-Gerasimenko, some 500 million kilometers away from the earth.

At its current location, Philae's solar panels could only receive sunlight for 1.5 hours per 12.4 hour comet day, while in the original landing site, the illumination could be offered for nearly seven hours.

The agency said Philae accepted commands from controllers during the last communication and rotated itself for 35 degrees in order to expose larger solar panels to the meagre sunlight.

It also confirmed that Philae had deployed all the science instruments on board, including a drill which took samples from a depth of 25 centimeters.

Scientists are analyzing the data to confirm whether all the experiments were completed.

"This machine performed magnificently under tough conditions, and we can be fully proud of the incredible scientific success Philae has delivered," Ulamec said.

European spacecraft Rosetta, carrying Philae, was hoisted into space in 2004, and reached its target in August this year.

Philae landed on the comet on Wednesday after a 10-year journey aboard its mother ship Rosetta. It was hailed as the first human-made object landing, instead of colliding as NASA Deep Impact probe did in 2005, on a comet in history.

Since its touchdown on the comet, the lander has performed a series of tests and sent back significant data, including photos.
(Xinhua)