Scientists at the European Space Agency say they are hopeful of receiving new messages from the Philae comet lander as early as Wednesday.
No new data was received overnight — as expected — but the next available “window” is approaching fast, and experts say it could offer the best chance since of communication with Philae since last weekend.
On Saturday, the dormant lander transmitted a message to its comet-chasing mothership that was translated to Twitter as: “Hello @ESA_Rosetta. I’m awake!”
It was the first contact since it went into hibernation after running out of power seven months ago.
In the ensuing 85-second “conversation” with Rosetta, Philae sent back more than 300 packets of data from Comet 67P, the astral body it was sent to investigate.
It made brief contact again on Sunday, but the link did not last long enough for it to transmit further.
Mark McCaughrean, ESA’s senior science advisor, explained that the chance to hear from Philae comes around approximately every 12.5 hours — but the lander isn’t always able to send back information.
Speaking to CNN after a briefing at the Paris Air Show on Wednesday morning, McCaughrean said: “The next opportunity is in a couple of hours. Not all are created equal — it depends where Rosetta is in relation to the comet’s rotation.
“We knew last night’s wasn’t good, but the one coming up is a good candidate,” he said.
The Rosetta team knows that Philae has collected much more data while it’s been out of contact — they just have to wait until they can get a strong enough link that stays connected for long enough to allow it to transmit.
“It works like a mobile phone signal, dropping out and coming back,” said McCaughrean. “But when you’re hoping to squirt data down the line, you need it to stay up, or you have to start again and again, many times.
‘Dodgy signal’
“We’ve got a dodgy signal — we’re a long way from the nearest mast, and occasionally, we go into a tunnel.”
Once they can establish a strong enough link, the team will be able to tell Philae to begin carrying out a host of scientific experiments, including “sniffing” the atmosphere around it, and sampling the ground beneath its feet.
Because of its perilous position — after a brief touchdown, it is thought to have skipped across the surface of the comet before coming to rest at the foot of a cliff when its anchors failed — scientists have had to reschedule the tests they want it to do, categorizing them from simple to risky.
But they hope that by analyzing the materials the comet is made of, they will be able to find out more about how the planets — and life on Earth — were formed.
“Comets are more than just beautiful things,” said McCaughrean. “They’re treasure chests of information locked up from the birth of the solar system, clues to the origins of Earth.”
Thanks to information already gathered by Rosetta, they have found a host of intriguing features in Comet 67P’s landscape, including “bizarre pits” from which jets of material stream out.
‘Dragon comet’
“This is not a ‘dead’ body,” said McCaughrean. “It’s a living, breathing dragon of a comet.”
That “dragon” is expected to become more and more active as it approaches the perihelion, the point at which it is closest to the sun, on August 13.
And it now appears that Philae may be able to report back on all that activity, thanks to the happy accident of its troubled landing; had it come to rest as planned, it would have stopped working months ago.
“The comet itself is cooperating with us,” said Jean-Pierre Bibring, the lead scientist on the Philae project. “At the normal landing site, we would have been dead by March.”
The lander’s systems could not have survived temperatures on the comet’s open plains, but shaded by the cliff it was able to go into hibernation and wake up in time for all the excitement.
ESA’s Rosetta team is bracing for a busy few months analyzing all the data that has already come in — and the results of tests they now hope to be able to carry out.
The mission was originally due to end on December 31, but plans are being made to extend it until September 2016. Philae will be long dead by then — it’s expected to run out of power for good in October — but Rosetta can keep working for almost another year.
Once it begins to run out of fuel, the team will use what little remains to send the satellite spiraling slowly down to its final resting place on the surface of the comet it has spent years studying.
“It will be sad, but all good things come to an end,” said McCaughrean.