Last night, at 0:36 GMT, contact with Philae was lost, as the lander’s non-rechargeable battery drained and it entered hibernation. Considering the very low amount of sunlight available in the location it eventually ended up in at the end of the two jumps it made after first touching down on the surface, the odds of the solar panels producing enough energy to exit this state in the near future are just about zero, despite the fact that the lift and turn operation succeeded, lifting Philae by about four centimeters and rotating it about 35 degrees in order to place the larger solar panel in the one area that does receive at least some sunlight. Still, there is hope for later, as it is believed the lander will be able to withstand the low temperatures it’s currently facing and the power situation will obviously improve as the comet approaches perihelion.
Something that seemed strange to me is the timeline, however, as it was initially stated that the conditions will become too hot for Philae to continue operating in March, yet during yesterday’s Hangout it was said that the power situation should improve enough when the comet will be at less than 1 AU from the Sun, and they mentioned late summer, perhaps August or as late as September. Admittedly, being in the shade and receiving about one and a half hours of sunlight on one side and about 20 minutes on a couple of others per comet “day”, which lasts about 12.4 hours, instead of the planned six to seven hours, does definitely mean that it won’t get nearly as hot, but that’s quite a difference.
Either way, they said the one solar panel that receives some sunlight for about one and a half hours per comet day produced less than one watt and the peak, for the 20 or so minutes when a couple of others come partially out of the shade as well, was three to four watts. That may have increased slightly now that they moved the larger solar panel in the better position, but when they also said Philae requires 5.1 watts to boot up and, at the moment, 50 to 60 to heat the battery to the 0°C required to start charging, it’s clear it’ll be a long time before anything may happen, and even longer before enough power will build up to support other instruments as well and do some more science.
Now we could dwell on what went wrong, starting with the failure of the thruster and harpoons which should have made Philae stay where it first landed, continuing with the fact that some of the operations which should have been performed on the surface of the comet were actually performed some distance above it, as the instruments started gathering information as soon as the lander first touched down, and ending with this particularly unfortunate position Philae eventually stopped in, which prevents it from continuing to operate at the moment. However, an incredible number of things went well, and this is what allowed this insanely daring attempt to be a success, because this is precisely what it was.
More than 20 years since this mission started being planned and ten years after launch, a man-made spacecraft caught up to a comet, entered orbit around it and delivered on its surface a lander which managed to complete its primary mission and transmit the science data obtained before it entered hibernation. This was an unbelievably difficult endeavor and so much could go so wrong that the idea of it succeeding on the first attempt as much as it did was likely difficult to believe for many who had some grasp of what was involved.
So now we move on and see what comes next, as Rosetta will continue orbiting the comet throughout next year, gathering as much information as possible before, according to some recent statements, eventually finding its final resting place on the surface as well. And if, at any point during that time, Philae will wake up as well, things can only get better, and if its current sheltered position will help it survive the period of closest approach to the Sun and the comet’s activity won’t otherwise damage it too badly, there’s even a chance it may somehow hop away from that spot and find one where it’ll receive more sunlight on the way back, allowing for far more observations than initially hoped for.
I’m going to end this by simply saying congratulations to ESA and to everyone else involved, and let’s hope space exploration will continue to offer us as a species reasons to celebrate. Once again, I must point out that, considering how little attention and funding governments seem willing to spare for such efforts, this seems quite unlikely right now, and considering the amount of time that passes between the moment any such endeavor starts being planned and the final, visible triumph, the results of this current attitude will hurt us all for decades to come, but as long as we’ll still have groups of passionate, dedicated and absolutely brilliant people, miracles may still happen. And this obviously applies to any field one may think of.