text: Lander rotates into slightly sunnier position but apparently too late to charge batteries and keep systems running 
   
   Rosetta mission: Philae goes to sleep on comet as batteries run out 
   
   The Philae lander sitting on Comet 67P/Churyumov–Gerasimenko has run out of power after a successful last-ditch attempt to nudge it into better sunlight apparently came too late to charge its batteries and keep systems up and running. 
   
   
   
   Mission controllers for the Rosetta mission had said on Friday that they were preparing to “hop” the robotic probe in a hope it would settle in a sunnier spot on the comet’s surface. 
   
   Later came a promising announcement. “My rotation was successful (35 degrees). Looks like a whole new comet from this angle,” read a message posted on the lander’s official Twitter account. Earlier the scientists tweeted: “First comet drilling is a fact!” 
   
   But afterwards the Philae mission tweeted: 
   
   Philae Lander (@Philae2014) .@ESA_Rosetta I'm feeling a bit tired, did you get all my data? I might take a nap… #CometLanding 
   
   Philae had apparently been successful in shifting position to gives its shaded solar panels a better chance of catching sunlight. But the moment of success was followed by an announcement that it would have to use up its last battery power in sending a final burst of data back to Earth. 
   
   
   
   If the batteries are not charged the lander goes into hibernation. Without sufficient sunlight on the solar panels the mission shuts down. 
   
   The lander’s legs have a built-in spring action. Commands were uploaded on Friday night to fire them, scientists said, warning there was no guarantee of success. Another strategy under discussion was to spin up an internal flywheel that could make Philae cartwheel out of its predicament but also risked soaking up the last of its battery power. 
   
   Early on Saturday came an announcement that Philae was on the move: 
   
   
   
   Philae Lander (@Philae2014) I just started lifting myself up a little and will now rotate to try and optimize the solar power! 
   
   Since its triple touchdown on Wednesday the spacecraft had been resting on its side, lodged in the shadows of a cliff or large boulder. On Thursday the lander sent back historic first images taken from the surface of a comet. These showed that after its bumpy landing one of its legs was sticking up into space rather than in contact with the surface, raising doubts about whether there was enough spring in Philae’s step to achieve the hop. 
   
   The landing had left Philae surrounded by rocks with only a sliver of light reaching one of its smaller solar panels. Philae was receiving just 1.5 hours of sunlight instead of the expected 6-7 hours. “We are unlucky, in a corner, surrounded by rocks,” said Valentina Lommatsch from DLR’s lander team. 
   
   Despite the akward orientation, the lander’s science package deployed a 1.2 metre arm and a drill. 
   
   Philae Lander (@Philae2014) I confirm that my @RosettaSD2 went all the way DOWN and UP again!! First comet drilling is a fact! :) pic.twitter.com/eE3xL8CGk0 
   
   Philae’s primary mission was always designed to last around 60 hours on its initial battery charge. But engineers covered the spacecraft in solar panels in the hope that sunlight could charge a set of secondary batteries and extend the mission for months. 
   
   Despite the awkward landing, by Friday Stephan Ulamec, Philae lander manager, estimated that 80% of the science Esa was hoping for had been achieved. If the drilling operation succeeded in delivering samples to onboard instruments it would rise to 90%, he said. 
   
   The COSAC (Cometary Sampling and Composition experiment) instrument was chosen to study the first samples rather than the UK-built PTOLEMY instrument. COSAC detects and identifies complex organic molecules from their elemental and molecular composition. 
   
   Ulamec said the choice was made because COSAC uses less power than PTOLEMY, and provided data that could be more easily compared to that taken from the Rosetta orbiter. 
   
   PTOLEMY still generated data by working in “sniffing” mode. Essentially the instrument detected and analysed molecules of gas that naturally drift off the surface of the comet. 
   
   “We juggled everything so that every instrument got to do a measurement, so we are very happy with the mission so far,” says Lommatsch. 
   
   Despite the lander shutting down for now, all might not be lost forever. 
   
   The comet is currently out beyond the orbit of Mars, heading for its closest approach to the sun in August 2015. This will bring it as close to the sun as Earth’s orbit. There the sunlight will be brighter and may just allow Philae to reboot and power up. To that end, the Philae mission tweeted: 
   
   Philae Lander (@Philae2014) My #lifeonacomet has just begun @ESA_Rosetta. I'll tell you more about my new home, comet #67P soon… zzzzz #CometLanding 
   
   “Cross your fingers, or press your thumbs if you are a German, that we hear something from the lander again,” said Lommatsch. ||||| Media caption Esa told an online news briefing the drill has been active 
   
   The Philae lander has attempted to drill into the surface of Comet 67P, amid fears that its battery may die within hours. 
   
   The European Space Agency (Esa) says the instrument is being deployed to its maximum extent, despite the risk of toppling the lander. 
   
   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. 
   
   Philae made history on Wednesday when it was dropped by Esa's Rosetta satellite to the surface of 67P - the first time this feat has been achieved. 
   
   The probe has been returning pictures and other scientific data ever since. 
   
   Key objective 
   
   It is not known precisely where on the comet the robot is located, but the pictures it has returned indicate it is in the shadow of a cliff. 
   
   The limited sunlight the probe receives means its solar panels cannot keep the battery systems properly topped up. 
   
   Engineers doubt Philae 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. 
   
   Power possibilities 
   
   Commands were uploaded on Friday morning to deploy the drill, 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 comes back around and tries to re-establish the radio 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 [laboratory] 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." 
   
   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 explained. 
   
   Image copyright ESA/Rosetta/MPS Image caption One remarkable image taken by the "mothership" Rosetta shows Philae as a tiny speck, headed for history 
   
   More extreme ideas are also being considered. 
   
   One involves firing up Philae's flywheel - a mechanism that was used to keep it stable during its descent to the comet on Wednesday. 
   
   Another would shift the legged landing system in such a way that a small amount of upwards momentum could be generated. 
   
   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. 
   
   "It's very unlikely; we're just throwing around ideas right now," conceded Valentina Lommatsch from the German Space Agency. 
   
   And for such a strategy to work, Friday night's radio connection would be needed to upload the necessary commands. 
   
   "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. 
   
   Image copyright Esa/Rosetta/Philae/CIVA Image caption Several images have been taken on different sides of the lander, illustrated here with the pictures arrayed around a diagram of the probe 
   
   Image copyright ESA/Rosetta/MPS Image caption Where did Philae actually touch down? Images from the Osiris camera on Rosetta show the area surrounding the original target site (red cross) 
   
   Meanwhile, the hunt for Philae's exact location goes on. 
   
   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. 
   
   The Osiris camera team on Rosetta is also looking through its latest high-resolution images for any sign. 
   
   One intriguing prospect is that Osiris 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 - before then falling back down. 
   
   "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. 
   
   Image copyright ESA/Rosetta/Philae/ROLIS/DLR Image caption This picture was taken by the lander itself just 40m from its bumpy touchdown 
   
   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. ||||| BERLIN (AP) — The good news: The spacecraft that landed on a comet has begun drilling beneath the surface to see what secrets the celestial body can reveal. 
   
   This five-image montage of Rosetta's OSIRIS narrow-angle images , released by the European Space Agency ESA on Thursday Nov. 13, 2014 , is being used to try to identify the final touchdown point of... (Associated Press) 
   
   The combination photo of different images taken with the CIVA camera system released by the European Space Agency ESA on Thursday Nov. 13, 2014 shows Rosetta’s lander Philae as it is safely on the... (Associated Press) 
   
   This image released by the European Space Agency ESA Thursday Nov. 13, 2014 was taken by Philae's down-looking descent ROLIS imager when it was about 40 meters (131 feet) above the surface of Comet 67P/Churyumov-Gerasimenko... (Associated Press) 
   
   The bad news: Scientists at the European Space Agency still don't know exactly where the lander is on the comet and are anxiously hoping its batteries hold out long enough for them to get the mining data and adjust the spacecraft's position. 
   
   It was a race against time Friday for the Philae lander, which on Wednesday became the first spacecraft to touch down on a comet. Since then it has sent astonishing images from the icy, dusty comet, 67P/Churyumov-Gerasimenko, and generated some data from instruments such as one that measures temperatures. 
   
   All this is taking place 311 million miles (500 million kilometers) from Earth on a comet hurtling 41,000 mph (66,000 kph) through space. 
   
   Material beneath the surface of the comet has remained almost unchanged for 4.5 billion years, making those mining samples a cosmic time capsule that scientists are eager to study. 
   
   Mission controllers said Philae was able to bore 25 centimeters (10 inches) into the comet to start collecting the samples, but it's unclear whether it has enough power to deliver any information on them. 
   
   The lander has an estimated 64 hours of battery power but has to rely on solar panels to generate electricity after that. Scientists were relieved to learn the batteries still had some juice when the lander resumed contact. Communication was re-established, the ESA said in a tweet late Friday night. 
   
   "Lander now performing a 'lift & turn' of the main body on the landing gear - will last about 10 mins. Telecomm link is good," the agency said in a second tweet. 
   
   Philae bounced twice on the comet before coming to rest Wednesday after two harpoons that should have anchored it to the surface failed to deploy. Controllers still haven't been able to pinpoint its position, but photos indicate it's next to a cliff that is largely blocking sunlight from reaching two of its three solar panels. 
   
   "Maybe the battery will be empty before we contact again," said Stephan Ulamec, head of operations for Philae. 
   
   If the batteries are still running and scientists can extract the scientific data from the craft, they will rotate the lander slightly so that it might capture more sunlight. 
   
   "That would increase the chance that, at a later stage, the lander could wake up again and start talking to us again," Ulamec said. 
   
   After the batteries run out, Philae will remain on the comet in a hibernation mode for the coming months. The comet is on a 6 1/2-year elliptical orbit around the sun. Philae could wake up again if the comet passes the sun in such a way that its solar panels catch more light. 
   
   Meanwhile, the Rosetta — Philae's mother ship, which is streaking through space in tandem with the comet — will use its 11 instruments to analyze the comet over the coming months. 
   
   Scientists hope the $1.6 billion (1.3 billion-euro) project that was launched a decade ago will help them answer questions about the origins of the universe and life on Earth. 
   
   Communication with the lander is slow, with signals taking more than 28 minutes to travel between Earth and Rosetta. 
   
   No matter how long Philae keeps talking to them, scientists say they already have gathered huge amounts of data and are calling the expedition a roaring success. 
   
   "Let's stop looking at things that we could have done if everything had worked properly," said flight director Andrea Accomazzo. "Let us look at things that we have done, what we have achieved and what we have on the ground. This is unique and will be unique forever." 
   
   As for pinpointing Philae's position, Holger Sierks, the principal investigator for the Rosetta's camera systems, said the cameras should have captured the lander's rebound, yielding valuable information on where it came to rest. 
   
   That data has not yet come in, however. Specialists still need to comb one and two square kilometers (0.4 and 0.8 square miles) on the comet to find Philae. 
   
   ___ 
   
   Online: www.esa.int/rosetta 
   
   ___ 
   
   David Rising contributed to this story.
target: – The spacecraft that landed on a comet yesterday is still talking to scientists, but its battery is expected to conk out soon. In what could be a last-ditch effort to save the mission, scientists with the European Space Agency say they'll try to make the Philae lander essentially hop to a different spot—one in which it might get more juice in the form of sunlight for its solar panels, reports the Guardian. Researchers still don't know exactly where the lander is, only that it's surrounded by rocks blocking most sunlight, perhaps next to a cliff, reports the BBC. In the meantime, the lander has begun drilling about 10 inches deep into the comet to collect samples that scientists would love to analyze, given that they are presumably billions of years old, reports the AP. The question is whether the battery will hold out long enough to transmit any data, while the very act of drilling is draining it further. "Maybe the battery will be empty before we contact again," says Stephan Ulamec, head of the lander mission. The battery isn't expected to last beyond tomorrow, but if ESA is able to shift the lander to a sunnier locale, the data collection could go on for months. (The landing hit a few glitches, including anchoring harpoons that didn't fire.)