ESA May Shift Philae Lander to Get More Sun

PARIS -- With Rosetta's Philae lander stuck in a rocky, poorly-lit area of Comet 67P/Churyumov–Gerasimenko, and time running out to complete the probe's primary science phase, mission managers are considering shifting the lander's position to afford more sun exposure and potentially extend its battery life.

For now, Philae remains untethered to the surface of the comet, and preliminary data suggest its bumpy landing may have left it perched on the rim of a large depression near a location previously analyzed as a potential secondary landing site.

High-resolution images, some of which are still stored on the Rosetta orbiter, have yet to confirm the lander's location. But its science instruments are functioning, including the MUPUS (Multi-Purpose Sensors for Surface and Subsurface Science) and APXS (Alpha X-ray Spectrometer) sensors that had been left inactivated due to concerns they might further destabilize the probe.

However, Philae mission manager Stephan Ulamec said the lander's drill has been deployed 25 cm below its base plate. But it is not yet known whether the device bore into the comet's surface, or what impact it may have had on Philae's stability.

Images from Philae's CIVA cameras indicate the lander is in a rocky corner facing a wall, with one of its three feet possibly in open space. In its current position, the lander's primary battery is likely to drain in the next 24 hours. Although a secondary battery exists, it is charged by solar panels on the probe that are receiving less than 1.5 hours of sunlight per 12.4 hour comet day, rather than the 6-7 hours afforded by the original landing site.

Ulamec said while the team is weighing the possibility of shifting the lander to a spot with more sun, it is unclear whether the battery has enough energy to achieve this.

“If we get contact again, and if we get the data down, we plan to rotate the lander a little bit so we have a slightly larger panel exposed to sun, to increase the chance that the lander could wake up again and start talking to us,” he said in a Nov. 14 briefing.

This evening the team will know more, he said, when the mission makes contact with the Rosetta orbiter around 6 p.m. eastern. In the meantime, he said despite Philea's awkward position, mission scientists have gleaned between 80-90% of the data and imagery that was expected at this point in the mission.