It’d been months since anyone had heard from the comet lander Philae, and chances were that it would be lost forever, missing out on the completely unique opportunity to send its data from a comet moving in to the closest point to the sun in its orbit. But then, Stephen Ulamec, project manager at the German Aerospace Center, received a phone call in the middle of the night: “We have a signal from Philae!”
Philae was a lander launched form the Rosetta spacecraft, which ESA sent out back in 2004 with the mission to land on a comet – the first mission ever of this kind. After using the gravitational fields of Earth and Mars to make its way to the comet, Rosetta reached its destination, and in November 2014 the lander was launched and succeeded to land on the comet surface. For 60 hours after the bumpy landing, Philae managed to send out data, but then it went quiet, without its location being known to the scientists on Earth, and without the possibility for them to see what had gone wrong.
Ever since, the Philae team has worked with calculations and models to zoom in on the spot where the lander most likely would be located, and the theories have mainly focused on the problem being a lack of sun for the solar panels used for communication and data collection from the comet.
Ulamec says about the incoming message from Philae: “We only received data for about 85 seconds. The data are housekeeping and system data from the lander.”
Those 85 seconds were enough to ensure the Philae team that the lander now is receiving enough solar energy to keep up its communication, and that it’s still operational. It seems as if the probe must have been active for a few days before it made the call back home.
What awaits now is a change in Rosetta’s comet orbit to make a closer connection between the lander and the orbiter, to begin the command transmission and get all the job done, finally.