This article is from the source 'bbc' and was first published or seen on . It last changed over 40 days ago and won't be checked again for changes.

You can find the current article at its original source at http://www.bbc.co.uk/news/science-environment-30055383

The article has changed 7 times. There is an RSS feed of changes available.

Version 3 Version 4
Comet lander: Future of Philae probe 'uncertain' Comet lander: Future of Philae probe 'uncertain'
(about 1 hour later)
The Philae lander has attempted to drill into the surface of comet 67/P, amid fears that its battery may die in hours. The Philae lander has attempted to drill into the surface of Comet 67P, amid fears that its battery may die within hours.
Researchers at Esa say the instrument is being deployed to its maximum extent despite the risk of toppling the lander. The European Space Agency (Esa) says the instrument is being deployed to its maximum extent, despite the risk of toppling the lander.
Scientists hope they will also be able to capture some samples for analysis in the robot's onboard laboratories. Scientists hope the tool will be able to capture some samples for analysis in the robot's onboard laboratories.
If the battery dies the results may not make it back to Earth. If the battery dies, the results may not make it back to Earth.
Esa reported that the drill has extended 25cm from the lander to try to start collecting samples. It is not known precisely where on the comet Philae is located, but the pictures it has returned indicate it is in the shadow of a cliff.
Stephan Ulamec, Philae lander manager, said: "The drill has been active today, whether it will sample and will succeed in bringing these samples to ovens we shall know this evening. The limited sunlight the robot receives means its solar panels cannot keep the battery systems properly topped up.
Engineers doubt the probe, in its current position, can stay powered beyond Saturday.
The dwindling energy reserves have therefore prompted the mission team to deploy the drill now.
Although the activity is among Philae's key objectives, it is also highly risky, because the torque on the tool could destabilise the delicately placed lander.
But Esa believes that the closing power window makes that risk worthwhile.
Commands were uploaded on Friday morning to deploy the tool, and early telemetry indicated it had extended 25cm from the base of the lander.
However, it was then that the orbiting Rosetta satellite, which has been relaying telecommunications from the probe, passed over the horizon and out of contact.
The results of the drilling will not now be known until Rosetta tries to re-establish the radio link on Friday night.
Stephan Ulamec, the Philae lander manager, said: "The drill has been active today, whether it will sample and will succeed in bringing these samples to ovens - we shall know this evening.
"This would be fantastic but it is not secured - maybe the battery will be empty before we get contact again.""This would be fantastic but it is not secured - maybe the battery will be empty before we get contact again."
The Esa team says that the solar panels on the lander are getting small amounts of sunlight, but not enough to maintain operations beyond Saturday. Engineers are working on potential solutions to boost the power available to the lander.
"We plan to rotate the lander a little bit so that at the position where we have now this one panel that gets sun, we'll have a slightly larger panel and this would increase the chance that at a later stage the lander could wake up again and start talking to us again," Dr Ulamec added. "We plan to rotate the lander a little bit so that at the position where we have now this one panel that gets sun, we'll have a slightly larger panel and this would increase the chance that at a later stage the lander could wake up again and start talking to us again," Dr Ulamec explained.
Valentina Lommatsch from DLR, the German Space Agency, added that she hoped Philae could bounce its way out of its dark spot More extreme ideas are also being considered.
"It's very unlikely, we're just throwing around ideas right now. Hopefully, we'll get the link; that's the most important thing. What happens after that... is cream on the top right now." One involves firing up Philae's flywheel - a mechanism that was used to keep it stable during its descent to the comet on Wednesday.
Prof Monica Grady of the UK's Open University works on an instrument on Philae called Ptolemy - a shoe-box-sized laboratory. Another would shift the legged landing system in such a way that a small amount of upwards momentum could be generated.
"One of the other things about the drill, they are hoping it will move the lander but they don't know how much it will move it, and they don't know if it will bring it out to get more sunshine," she told BBC News. Because Comet 67P is only 4km wide, it has very little gravitational attraction, and so even small motions could be enough to bump the probe out of its dark spot.
Scientists wanted to test the idea that comets like 67/P may have delivered water to the early Earth billions of years ago. Philae had been due to sample some of the comet's ices to see if their chemical signature matched the water found in our planet's oceans. "It's very unlikely; we're just throwing around ideas right now," conceded Valentina Lommatsch from the German Space Agency.
But researchers told the BBC that attempts to test the isotopic content of water were power hungry and they are concerned that there will not be enough energy left for the analysis to be carried out. And for such a strategy to work, Friday night's radio connection is needed to upload the necessary commands.
Two other instruments were deployed overnight, including a thermometer (MUPUS). "Hopefully, we'll get the link; that's the most important thing. What happens after that... is cream on the top right now," lander team-member Lommatsch added.
It is designed to probe the top layers of the comet to measure the temperature and other properties. The other instrument, APXS, is a mass spectrometer, which uses the mass of atoms to understand their chemical composition. Meanwhile, the hunt for Philae's exact location goes on.
The team is still not sure where on the surface the probe came to rest after bouncing upon landing on Wednesday.
Scientists have been examining radio transmissions between the orbiter and the lander to see if they can triangulate a position.Scientists have been examining radio transmissions between the orbiter and the lander to see if they can triangulate a position.
This work has now produced a "circle of uncertainty" within which Philae almost certainly lies.This work has now produced a "circle of uncertainty" within which Philae almost certainly lies.
It is believed that Philae is sitting in the shadow of a cliff, and will not get enough sunlight to work beyond Saturday. The Osiris camera team on Rosetta is also looking through its latest high-resolution images for any sign.
Launched in 2004, the European Space Agency (Esa) mission hopes to learn about the origins of our Solar System. One intriguing prospect is that the camera may have caught Philae in the act of bouncing during Wednesday's landing. The probe is known to have rebounded several hundred metres back up from the surface at the moment of first contact.
It has already sent back the first images ever taken from the crumbling, fractured terrain of a comet. "We know that at about 500m above the ground, we should see the rebound and the rebound direction, which should give valuable information for the search team," Osiris team leader Holger Sierks said.
Philae got to the icy 67P/Churyumov-Gerasimenko on the back of Esa's Rosetta satellite after a 10-year, 6.4 billion-km (4bn-mile) journey, which reached its climax on Wednesday with a seven-hour drop to the surface. Esa's Rosetta mission, with its piggybacked Philae lander, was launched in 2004.
The pair covered 6.4 billion km to reach Comet 67P out near the orbit of Jupiter.
Scientists hope the investigations at the giant "ice mountain" can provide fresh insights on the origins of the Solar System.
Comets are believed to hold materials that are largely unchanged since the formation of the planets 4.6 billion years ago.
One theory holds that comets were responsible for delivering water to the early Earth.
Another idea is that they could even have "seeded" our world with the chemistry needed to help kick-start biology.
Researchers say the data they have acquired through Rosetta's observations from orbit, and now from Philae's work on the surface, will re-write the textbooks.