European scientists are planning a risky maneuver to get their Rosetta spacecraft closer to the comet it is orbiting, so it can communicate with its robotic lander on the surface and start experiments that could unlock some of the universe's secrets.
The lander, called Philae, surprised scientists over the weekend by waking up and sending a signal to Earth. Its historic landing on comet 67P/Churyumov-Gerasimenko in November was marred when it bounced into a position too shadowy to power its solar panels.
With the comet moving closer to the sun, scientists hope Philae will be able to generate enough power to resume its pre-programmed experiments.
But in order to receive the data, Rosetta will have to get closer to the comet - to an orbit of about 180 km (112 miles) compared with about 220-240 km now.
That is a risky move as the comet approaches the nearest point of its orbit to the sun on Aug. 13 and throws off dust that could block the equipment Rosetta uses to orient itself.
"The comet is a very, very active object at the moment, it's a bit as if you were to imagine taking your car through a snowstorm," Elsa Montagnon, Rosetta deputy flight director at the European Space Agency, told a press briefing at the Paris air show on Wednesday.
"We reckon it should be safe but as soon as we see activity coming back we may have to retreat further," Montagnon added.
Scientists hope samples drilled from the roughly 3 x 5 km comet by Philae will unlock details about how the planets - and possibly even life - evolved. The rock and ice that make up comets preserve ancient organic molecules like a time capsule.
The plan is to start with the least risky experiments, such as using instruments to "sniff" the atmosphere before moving the lander and drilling into the surface to analyse samples, probably over the next months, rather than weeks, said Philippe Gaudron, Philae project manager.
Had it landed in the chosen spot, Philae would have been out of action by now as temperatures in its surroundings would have been too high for its systems to work, Jean-Pierre Bibring, Philae lead scientist, told the briefing.
"Thanks to the shadow, we have the capability now to wake up and have a very long-term activity. Now we are in a position not only to wake up but to resume science to an extent that might go beyond our expectations," he said.
Funding for the Rosetta project is secure until the end of the year, but the team has asked for an extension to September 2016, at which point they will let Rosetta spiral toward the comet, taking pictures as it goes, until it ultimately collides with it.