Has time run out for the comet lander Philae?
The robotic spacecraft’s silence since July 2015 is feared to be for good, as it has not yet responded to any attempts of contact from Earth. By the end of this month, Comet 67P/Churyumov-Gerasimenko where Philae is located will have travelled so far from the sun that it will be too cold for the lander to function.
On Sunday, the German Aerospace Center (DLR) tried to activate the Philae flywheel via blind commanding in order to change its position. Unfortunately, the team received no feedback from its move, which is considered one of the last efforts at bringing the lander back to life.
"We have not gotten any feedback on its success, but this could also be the signal going from Philae to Rosetta,” said a DLR spokesman speaking from the Lander Control Center in Cologne, Germany.
The spokesperson added that the Osiris camera on the Rosetta spacecraft, which is Philae’s mothership, took a couple of images that are now being analyzed in search of a dust cloud that could have been caused by Philae changing its position.
When it touched down on Comet 67P in November 2014 (a good 317 million miles away from Earth), Philae was easily one of the biggest successes of the European Space Agency. However, there was no honeymoon period, so to speak, for the lander, as it was immediately hit by issues.
Philae bounced a number of times, which scraped the crater rim.
“[It was] on a landing site that was so [harsh] that we would never have dared to land there,” recalled DLR’s Stephan Ulamec of the mission.
It went to safe mode when its batteries ran low because of scarce sunlight and an unexpected landing location. Inspite of the setbacks, scientists said Philae had been a survivor for being able to communicate great results.
It was when the comet came closer to the sun and allowed for the so-called sleeping beauty to recharge. The lander woke from a seven-month sleep in June 2015, sending a message home. Using the Rosetta space probe as a relay, it sent a “Hello” that lasted for 85 seconds.
The comet lander unfortunately retreated back to silence in July.
‘Time Is Running Out’
In a blog published on Friday, Ulamec and the mission center expressed concern over Philae’s silence, as the comet has been straying further and further away from the sun each day. Conditions have then become more and more “lander-hostile” or too cold for the lander.
In a hopeful scenario, Philae technical manager Koen Geurts explained that the spacecraft might shake dust from its solar panels to better align itself with the sun.
On the other hand, Philae may be completely unable to respond, which was what occurred on Sunday.
Now, the team hopes the lander has not tilted over or become enveloped in excess dust, a particularly grim situation on an active comet that ejects gas and dust into the outer space.
By the end of January, Comet 67P will be over 300 million kilometers (about 186 million miles) away from the sun, which is a fatal temperature of -51 degrees Celsius on the comet lander. Rosetta is also intended to be operational until September this year, but its solar panels and battery levels will be affected by the comet's movement.
Despite the “small chance,” as predicted by Philae operations manager Cinzia Fantinati of DLR’s control team, Rosetta’s communication unit will stay switched on and continue tuning in to Philae after January.