During the weekend the lander Philae resumed communications from the surface of the comet 67P/Churyumov-Gerasimenko. It’s been almost exactly seven months since Philae ran out of battery power and, because its position didn’t allow it to recharge them using its solar panels, went into hibernation. Now ESA is preparing new plans to try to make the most of the period in which the comet will be close enough to the Sun to provide the energy needed for Philae to work.
Philae’s mission was really chaotic and full of surprises. In November, it detached from the Rosetta space probe to land on the surface of the comet 67P/Churyumov-Gerasimenko, an achievement never attempted before. It did it but failed to anchor itself to the surface, bouncing on it a few times and ending in an area with little lighting.
Philae’s hibernation also caused a controversy for the European choice not to use nuclear generators to power ESA’s space probes. If Philae had that kind of generator, it could have kept on operating during recent months collecting precious data and sending them to Earth.
The choices at the political level were different so only now Philae managed to collect enough energy to be able to communicate. Due to the circumstances of its landing, its exact location hasn’t been identified yet. However, ESA identified the area where it stopped by using the radio signals exchanged between Philae and Rosetta as part of the CONSERT (COmet Nucleus Sounding Experiment by Radiowave Transmission) experiment in the short period when the lander was active.
During the weekend, Philae communicated twice with the Rosetta space probe, which relayed the signals to ESA’s ESOC (European Space Operations Centre) on Earth. The first contact was a welcome surprise that initiated new plans to resume the lander’s mission, stopped well ahead of schedule.
The first contacts weren’t very stable and the plan is to change the Rosetta space probe’s orbit to optimize its communications with Philae. Communications can take place only when Rosetta passes over Philae and therefore will still be limited.
If the contact with Philae will be stabilized, it will be possible to send it commands to carry out scientific surveys. ESA will have to decide which instruments to use and this will depend on Philae’s energy levels. They might not be able to use the SD2 (Sampling, Drilling and Distribution) drill developed by the Italian Space Agency (ASI).
The good news is that with a little luck they can use Philae in the period of maximum activity on the comet 67P/Churyumov-Gerasimenko. It will be reached around mid-August 2015, when it will reach the closest point to the Sun. ESA’s mission controllers will keep considerable flexibility in their plans because their developments could still be unpredictable. At this point one might hope for new success for Philae’s mission.