Darmstadt, Germany (dpa) – All is not lost yet for the European Space Agency (ESA) robotic lander Philae, which is now inert with its batteries depleted on the icy surface of a comet more than 500 million kilometres from Earth.
Philae touched down in November after being delivered by the Rosetta space probe, which is continuing to orbit and observe comet 67P/Churyumov-Gerasimenko.
The four-kilometre-wide comet is arcing ever closer to the sun, its closest approach expected in August.
The increasing heat will cause it to spew dust and gases forming a giant luminous tail, a spectacle never before photographed up close.
It is hoped that come April or May, Philae, a mini-laboratory the size of a washing machine, can recharge its batteries and resume its experiments.
Making the first-ever controlled landing by a spacecraft on a comet on November 12 after a 10-year flight, it bounced twice in the ultra-low gravity before coming to rest in the shadow of a cliff. Its batteries went dead after about 64 hours.
Comets are primitive objects left over from our solar system’s creation 4.6 billion years ago, and the German Aerospace Centre (DLR) is hopeful that the comet will reveal secrets about the origin of life on Earth.
“The warmer the little fellow gets in the vicinity of the sun, the more gases will come out of its interior,” said Gabriele Arnold, a scientist at the DLR Institute of Planetary Research in Berlin.
“The comet will become a lot more active as it nears the sun,” said Andrea Accomazzo, Rosetta flight operations director at the ESA mission control centre in Darmstadt, Germany. “It’ll be interesting.”
Data from the Rosetta probe have already revealed that the comet, the shape of which has been likened to a giant rubber duck, smells like rotten eggs (hydrogen sulphide) and a horse stable (ammonia). Accomazzo said Rosetta had instruments on board that were able to “taste” the emissions.
This month, scientists reported that the composition of water vapour coming off the comet greatly differs from that of the water on Earth.
This suggests that when our earth was forming, its water was not supplied by comets such as 67P, as had sometimes been hypothesised.
In all, Rosetta and Philae are carrying 21 instrument packages. One of those on the mothership Rosetta is the DLR’s VIRTIS (visible and infrared thermal imaging spectrometer), meant to measure the composition and temperature of the comet’s surface and examine the gas molecules in its coma, the cloud of gas and dust surrounding the comet’s nucleus.
VIRTIS discovered that the surface is covered not only by ice, but also dark dust.
While Philae’s position doesn’t expose its solar panels to enough sunlight to recharge its batteries at present, the position also means there is less danger of the lander being destroyed by heat as it nears the sun.