Likelihood of contacting Philae "getting close to zero"
According to Rosetta's science team, hostile surface conditions prevailing on the comet 67P/Churyumov–Gerasimenko (67P) have rendered any hopes of re-establishing communications with the Philae lander negligible.
"The chances for Philae to contact our team at our lander control centre are unfortunately getting close to zero," explains Stephan Ulamec, Philae project manager at the German Aerospace Center, DLR. "We are not sending commands any more and it would be very surprising if we were to receive a signal again."
Philae's silence comes as a result of its initial descent to the surface of 67P on Nov. 12, 2014. Alongside coping with a faulty thruster, the onboard harpoon stasked with driving into the ground and securing the lander on the comet's surface failed to fire.
This resulted in Philae bouncing off the comet and impacting a further four times over a two hour period, before finally coming to rest over a kilometer away fromits designated landing point in the Adybos region of 67P.
Unfortunately, it soon became clear that the probe's resting place left it lacking the necessary sunlight needed to power itself, and a frantic race against the clock began as Philae's science team attempted to squeeze as much data as possible from a host of onboard experiments before the primary battery died.
Philae succeeded in completing an impressive 80 percent of its initial planned scientific activities before slipping into a deep hibernation on Nov. 15, 2014.
Despite this set back,the team at ESA remained cautiously optimistic that as 67P drew closer to the Sun, Philae may receive enough sunlight to warm up the little lander and allow it to recharge its depleted batteries.
Philae awoke once more on Apr. 26, 2015 but was unable to contact the Rosetta orbiter untilJune 13. A series of sporadic communications followed, however due to a combination of suspected complications including dust obscuring the solar panels and failure of the lander's transmitters and receivers, Philae fell silent for what is most likely the final time on July 9, 2015.
As the comet activity stirred up by perihelion recedes, Rosetta can once again approach close to the comet's nucleus, potentially allowing the orbiter to pinpoint the location of its silent partner.
However, as ESA is no longer sending commands to the Philae, and the comet's increasing distance from the Sun lowers surface temperatures below the operational threshold, it is incredibly unlikely that the probe will re-establish contact.
Even so, Rosetta scientists are planning to have the orbiter listen out for its silent companion leading up to the finale of its mission, which will culminate in the spacecraft attempting to perform its own landing on the surface of 67P in September this year.
Scroll down to view a computer rendering of Philae's traumatic journey to its final resting place.