It’s hard to drill with one leg in the air… (Image: ESA/Rosetta/Philae/CIVA)
The Philae spacecraft has attempted to drill into the surface of comet 67P/Churyumov–Gerasimenko, but may not have enough battery left to beam the results back to Earth. The European Space Agency’s probe, which made its historic landing on the comet on Wednesday, 12 November, has not moved from its landing spot and so its solar panels are not getting enough sunlight.
Mission managers at the European Space Operations Centre in Darmstadt, Germany, made contact with Philae at around 0930 GMT this morning, downloading data from experiments conducted overnight and uploading new commands, including starting the lander’s drill.
“It started to drill but then we lost contact again,” said Philae manager Stephan Ulamec during a press conference this afternoon. This was expected, as the data link goes down as the mother ship Rosetta moves behind the comet. The link should be working again by 2100 GMT this evening, but it will take two more hours to actually download the data.
Philae may not be able to make contact at all. The team estimates that the lander needs 80 watt-hours of energy in its battery to complete its operations and upload the results. Simulations suggest Philae has around 100 watt-hours left – a tight margin. The team tried to switch the spacecraft to a low-power mode, but the command did not upload before they lost contact. “If we do not receive an update it is probably because the battery is flat,” said Ulamec – or an asteroid fell on Philae, he joked.
Even if Philae survives to report back, its drill might fail. Data received before the cut-off suggests the drill had reached 25 centimetres below the spacecraft, but with Philae standing in a precarious position, with one leg in the air, the drill may not make it to the surface to take a sample.
Since there will probably only be one chance to dig into the surface, the team had to decide which instrument on board Philae would get the sample. The pristine cometary material will be heated in an oven and passed to Philae’s Cometary Sampling and Composition Experiment (COSAC), which can analyse organic molecules and identify whether they are left or right-handed. Life on Earth contains only left-handed molecules, so the results could tell us more about our origins. Another instrument called Ptolemy, which was designed to sniff the gases trapped in the comet, will miss out on a sample, because it uses more energy and Rosetta can conduct similar experiments from orbit.
If ESA does make contact with Philae again and it has some juice left, the agency might make a last-ditch attempt to move the craft to a better location, perhaps by rotating its body, re-triggering its landing gear or spinning up an internal fly wheel. They still don’t know exactly where the probe is on the comet’s surface, but Holger Sierks, who is in charge of the OSIRIS camera on Rosetta, said they should have a picture of Philae’s 1 kilometre-high bounce after landing, which will help pinpoint its final resting spot.
There is also a small chance Philae could wake up as comet 67P nears the sun, but the spacecraft needs energy to heat up its batteries before they can start charging, so that may not be possible. Even if we never hear from Philae again, the team are very happy with the mission and say they have achieved 80 per cent of their initial science goals. “Let’s stop looking at things we could have done if everything had worked properly,” said Rosetta flight director Andrea Accomazzo. “This is unique and will be unique forever.”
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