The fridge-sized robotic lab, which in November landed on comet 67P/Churyumov-Gerasimenko, last made contact on July 9 and efforts to reach it again have so far failed, said experts at the European Space Agency project.
The lander — the first mission to land on a comet — initially bounced and landed in a position too shadowy to power its solar panels.
It woke up in June as the comet moved closer to the sun. But latest data suggests something, possibly a gas emission, may have moved it again. Philae’s antenna may have been obstructed, and one of its transmitters seems to have stopped working.
There was no answer to a command sent to activate Philae’s ROMAP instrument to determine the comet’s plasma environment and magnetic field. Communications between Philae and its orbiter are tricky because dust thrown off by the comet as it approaches the Sun make it hard for the orbiter to stay close to the comet. Scientists have commanded Philae to use just one transmitter, and have started moving the orbiter to a safer distance from the comet.