The European Space Agency's (ESA) Philae lander – the first spacecraft to land on a comet – has been found by its parent module Rosetta, wedged into a dark ditch on the icy surface of Comet 67P/Churyumov–Gerasimenko.
Philae ran out of power due to limited sunlight and went into hibernation mode two days after completing its successful landing, ten years after leaving Earth. Its exact whereabouts have remained a mystery until now, despite brief communication being made with Rosetta – which is in orbit around the comet – in June and July 2015 as the object moved closer to the sun and more light became available.
Luckily, Philae was spotted less than a month before the end of Rosetta's mission, using its high-resolution OSIRIS camera, as the orbiter came within 2.7 km of the surface. The lander's main body and two of its legs can be seen in the images. Its orientation makes it clear why establishing communication was so difficult.
"With only a month left of the Rosetta mission, we are so happy to have finally imaged Philae, and to see it in such amazing detail," said Cecilia Tubiana of the OSIRIS camera team, the first person to see the images when they were downloaded from Rosetta yesterday.
During Rosetta's search for Philae, radio data narrowed down its location to an area spanning tens of metres. However, a number of potential candidate objects, seen in relatively low-resolution images that were taken from large distances, could not be analysed in detail until recently. The finding was confirmed when OSIRIS zoomed in on one promising target.
"This remarkable discovery comes at the end of a long, painstaking search," said Patrick Martin, ESA's Rosetta Mission manager. "We were beginning to think that Philae would remain lost forever. It is incredible we have captured this at the final hour."
"This wonderful news means that we now have the missing 'ground-truth' information needed to put Philae's three days of science into proper context, now that we know where that ground actually is," said Matt Taylor, ESA's Rosetta project scientist.
"Now that the lander search is finished we feel ready for Rosetta's landing, and look forward to capturing even closer images of Rosetta's touchdown site," added Holger Sierks, the lead investigator of the OSIRIS camera.
In one month's time Rosetta will complete its mission by descending to the comet's surface itself, from where it will conduct a final investigation that will hopefully reveal secrets about the object's interior structure.