Scientists have begun work on a last-chance manoeuvre to contact the long-silentPhilae probe, dropped more than a year ago onto the surface of a comet hurtling through the Earth’s solar system.
Part of the European Space Agency’s Rosetta mission, the probe has yieldedspectacular scientific results – and a few moments of high drama – since its near crash-landing onto comet 67P/Churyumov-Gerasimenko in November 2014.
But it has been six months since mission control engineers at the German Aerospace Centre in Darmstadt have been in communication with Philae, and the odds of reestablishing contact are diminishing fast as the solar-powered probe speeds away from the sun.
“The last clear sign of life was received from Philae on July 9, 2015,” the GermanSpace Agency said. “Since then it has remained silent.”
On Friday, scientists sent a command to the fridge-sized robot to spin up its flywheel, initially used to stabilise the probe when it landed.
The hope is that so doing will “shake dust from its solar panels and better align it with the sun”, explained technical project manager Koen Geurts.
It is also possible, however, that the command – routed through the Rosetta spacecraft orbiting the comet – will never even reach Philae. Several further attempts to send the command will be made, Geurts added.
Philippe Gaudon of the French National Space Agency said: “It’s an admittedly desperate move. It is very unlikely the robot will become functional again.”
Mission managers believe one of the lander’s two radio transmitters, and one of its two receivers, have failed. Even the remaining ones may not be fully functional.
The window of opportunity for making contact with Philae will close definitively toward the end of January, when the comet and its companion hardware will be 300m km (185m miles) from the sun.
At that point the temperature is likely to fall below -51 degrees Celsius (-60 degrees Fahrenheit), the threshold beyond which Philae can no longer operate.
The robot-probe – packed with nearly a dozen instruments – landed on 67P after a 10-year, 6.5bn km (4bn -mile) journey piggybacking on mothership Rosetta.
It bounced several times on the craggy surface before ending up at an angle in deep shade, where it sent home 60 hours of data before going into standby mode on 15 November 2014.
The lander’s power pack was recharged as 67P drew closer to the sun on its elliptical orbit, and Philae woke up on 13 June. After that, it made intermittent contact, uploading data, only to fall silent again on 9 July.
The ground-breaking mission was conceived to learn more about the origins of life on Earth.
Comets are pristine leftovers from the solar system’s formation 4.6bn years ago. Many experts believe they smashed into our infant planet, providing it with water and the chemical building blocks for life.
Philae has found several organic molecules, including four never before detected on a comet.