Amid triumphant cries of victory following the first ever landing of a spacecraft on a comet’s surface, the Philae lander missed its designated mark and after settling in a shady spot on comet 67P/Churyumov-Gerasimenko, ESA’s mighty lander was unable to recharge its solar batteries and eventually shut down. Now, ESA and NASA scientists are feeling jubilant with data showing Philae recently woke up for eighty-five seconds thanks to the comet’s approach to the sun.
How Philae is waking up again
Although the lander was awake for only a short period of time, ESA scientists are hopeful that this is just one of many such mini revivals on its way to a full energy recovery given comet Churyumov-Gerasimenko is headed for the sun, with its closest approach on August 13.
Comets also experience orbital and seasonal changes, and as Churyumov-Gerasimenko heads toward the sun, scientists are expecting the shady side where Philae currently resides will give way to more sunlight as the comet tilts. Even back in December, scientists were expecting this possibility. According to Philae’s lead scientist Jean-Pierre Bibring, “Pessimistically [a wake up]will be after Easter.” Although most scientists assume this will happen even sooner. “The conditions for Philae’s wake-up are becoming more and more favorable as the comet approaches the sun,” says lander project Manager Dr Stephan Ulamec. As the comet approaches the sun solar intensity also increases, which scientists are anticipating will sublimate (partially shrink) the ridge that’s responsible for keeping Philae in darkness.
Even though Philae was only 60 hours operational the first time, the lander’s onboard instruments still managed to collect troves of data that scientists will study for years to come. If all goes well, subsequent states of powering up will allow Philae to collect even more data from the dirt beneath it, which provide insight into the chemistry of dirt on the dark side of comet Churyumov-Gerasimenko.
During this most recent wake up, Philae was able to collect and send back 300 packets of data. “Philae is doing very well: It has an operating temperature of -35ºC and has 24 Watts available,” said Ulamec, “The lander is ready for operations.”