Philae Found! Rosetta Spies Dead Comet Lander
With only a month before its mission ends, the European Rosetta mission swooped low over Comet 67P/Churyumov–Gerasimenko to see the stranded Philae lander jammed in a crack.
Like a child's toy dropped haphazardly on a rocky beach, a small boxy object can be seen deep within a high-resolution image of a comet's landscape. Looking closer, that shape starts to look all too familiar. Yes, it's Philae. Rosetta has found Philae.
On Nov. 14, 2014, the small comet lander made its dramatic landing onto the dusty surface of Comet 67P/Churyumov–Gerasimenko after being released by the European Space Agency's Rosetta spacecraft. Philae failed to fire its anchoring grappling hooks as it made first contact with the comet, causing it to bounce off the surface, sending it on an uncertain trajectory. The gravity of the comet's bulk was just enough to prevent it from spinning into space, resulting in another series of bounces.
When the lander eventually came to rest, mission control was able to make contact, but Philae was in trouble. On its side and apparently nestled by a rocky ridge, the solar-powered robot was in shadow couldn't recharge. Engineers made possible rescue plans to right the vehicle, but as its batteries drained, mission scientists worked hard to collect as much data as possible before the inevitable loss of signal three days later.
As the comet approached the sun and rotated to allow more light to fall on Philae's solar panels, its batteries did recharge enough for the lander to briefly reestablish contact on June and July 2015. But then it fell silent, this time for good.
Now, in photographs taken by Rosetta's OSIRIS camera as the spacecraft zoomed within 2.7 kilometers (1.6 miles) of the comet's surface on Sept. 2, the guesswork of Philae's fate can be put to rest. The lander really did end up on its side, with two of its three legs awkwardly poking upwards. It seems to be jammed in a dark crack, proving why it was so hard to maintain contact with the robot after landing.
"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. These new images were downlinked on Sept. 4 and Tubiana was the first to see them.
"After months of work, with the focus and the evidence pointing more and more to this lander candidate, I'm very excited and thrilled that we finally have this all-important picture of Philae sitting in Abydos," added Laurence O'Rourke, Philae search coordinator, in an ESA statement.
A smooth region on the smaller lobe of Comet 67P was chosen as the landing site for Philae. It was named Agilkia. Though Philae did touch down there, its final landing spot had largely remained a mystery. By collecting telemetry data and carrying out a detailed search using high-resolution imagery from the orbiting Rosetta satellite, the mission was able to narrow Philae's final resting place to an area called Abydos, further around the comet's smaller lobe. But this is the first photo of the lander and finally we have closure on the fate of Philae.
"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 Rosetta project scientist Matt Taylor.
On Sept. 30, Rosetta will be commanded to approach the comet, eventually crashing down onto the comet's landscape. It will then join Philae as permanent human made features of the cometary landscape, monuments to an amazing mission.