Contact with the Philae lander was lost at 6:36 p.m. (CST) this evening November 14th. Without sunlight to juice up its solar panels and recharge the battery, the craft will remain in “idle mode” – maybe for a long time. All its instruments and most systems on board have been shut down.
“Prior to falling silent, the lander was able to transmit all science data gathered during the First Science Sequence,” says DLR’s Stephan Ulamec, Lander manager. Contrary to earlier reports and initial speculations, Valentina Lommatsch from the German Aerospace Center explained that all three of Philae’s legs are on the ground. But the lander appears to be tipped up at an angle because one of the scenes from the panorama (below) shows mostly sky.
No contact will be possible unless maneuvers by controllers on the ground nudge Philae back into a sunnier spot. On its third and final landing, it unfortunately came to rest in the shadow of one of the comet’s many cliffs.
This evening, mission controllers sent commands to rotate the lander’s main body, to which the solar panels are fixed. This may have exposed more panel area to sunlight, but we won’t know until tomorrow (Nov. 15) at 4 a.m. (CST) when the Rosetta orbiter has another opportunity to listen for Philae’s signal.
The battery was designed to power the probe for about 55 hours. Had Philae landed upright in the targeted region, its solar panels would have been out in the open and soaking up the sunlight needed for multiple recharges. There’s also the possibility that months from now, as seasons progress and solar illumination changes on the comet, the Sun will rise again over the probe.
We may hear from the lander in the coming days or not. But if not, the original plan of gathering as much science as possible in the first two days of landing was for the most part a success.
* UPDATE 7:30 a.m. Nov. 15: Some good news! Rosetta did get back in touch with Philae during the overnight pass. Data was received, but the batteries are expected to be completely drained sometime today.