Probe makes history but faces an untimely death
THE PROBE is perched on the surface of a comet more than 480 million kilometres away and sending home pictures. That’s the thrilling news about the decade-long Rosetta space mission.
But in the jubilant hours after the Wednesday touchdown, it became clear that the landing had been far from perfect. The bumps the Philae craft took along the way may turn out to be disastrous because it is not at the best landing site and is not anchored.
The scientists at the European Space Agency’s mission control in Germany now know that the lander probably bounced when it reached its target landing site, maybe even for about a 1km into the air, and just as far across the ground.
“The lander may have lifted off (the comet) again, so maybe today we didn’t land once, we even landed twice,” said lander manager Stephan Ulamec.
Philae has already done some incredible things. The probe has sent home a panoramic shot of the comet’s terrain. It has begun analysing the comet’s composition and is sending data back to Earth. Its mission team is cautiously turning on more of its instruments in order of the degree of risk they pose to its position.
Comets, the Rosetta team has said, probably contain the elements present in the earliest days of the solar system, frozen in time. By digging into the mysterious ice, Philae is helping scientists learn more about the origins of the solar system and the planets.
But Philae may not last for its projected four-month run.
At a Thursday news conference, Ulamec announced the probe had bounced not once, but twice. “We landed three times, so there is an inflation of landing somehow,” he joked. All kidding aside, these jumps could end up being catastrophic.
Because Philae has failed to settle upright and anchor itself, which it was supposed to do by firing harpoons into the comet, it might get jostled into a position it cannot right itself from – or it might even bounce right off into space. The big question is not whether Philae can stand still, but whether the part of the comet it is on is a good place to be. Based on the image that Philae sent back to Earth, the landing team thinks it might be at the edge of a deep crater – but they aren’t sure.
“I can’t really tell you much more than what you interpret yourself from looking at these images,” Ulamec said.
A concern is that Philae’s solar panels are not getting enough light in the lander’s position. During the course of the comet’s rotation, which takes 12 hours, the panels are exposed to light only for about an hour-and-a-half, instead of the seven hours they would get at the optimal landing site.
That is not nearly enough to keep Philae operational. The lander left Earth with only a 60hour back-up charge.
The mission team is working to get a better idea of the lander’s position which could conceivably shift back to something more favourable on its own. The team could try to figure out a way to reposition the probe, but with the batteries dying they may end up racing against the clock.
And anything they do runs the risk of bouncing Philae into a worse position.
Philae was never meant to be a long-term data collector. No matter what happens to it in the next few days, it has a life expectancy of about four months. Rosetta scientists predict that in March, when the comet nears the sun, the surface will grow too hot for Philae to continue operating.
The Rosetta spacecraft will keep working and following the comet until December next year. But the team had hoped Philae would have more than a few days to go digging through the comet’s molecular treasure. The scientists had also hoped the probe would observe what changes the comet undergoes as it approaches the sun. – Washington Post