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Philae’s rough landing turns Rosetta mission into a race against time

Philae’s rough landing turns Rosetta mission into a race against time

The momentous event of landing on a high-speed comet for the first time in history is a bit tempered the day after touchdown, as the Philae spacecraft appears to have come to rest sideways in the shadow of a large cliff.

The small satellite initially touched down on comet 67P/C-G at about 10:30 am EST yesterday after its release from the Rosetta orbiter.

However, the lander actually bounced twice, at least once high as one kilometre, and took two hours to finally descend back to the comet. And now it appears to be sitting on the comet – about a kilometre away from where it was supposed to be – on its side in a hand-stand position, with only two of its three foot pads touching the surface.

While European Space Agency (ESA) mission operators in Darmstadt, Germany were initially elated, concerns began growing as incoming telemetry from the lander showed that the probe’s harpoons, which were supposed to anchor Philae to the comet, had not fired, thus explaining the unexpected, big bounce.

The harpoons are located on the underbelly of the washing machine-sized lander and were designed to burrow into the ground and firmly secure the lander. This was considered a vital manoeuvre for it to remain stable on the comet, which has a very weak gravitational field. In fact, it is estimated the mountain-sized, dirty snowball only has about 1/60,000th the gravity that’s on Earth, making Philae weigh just a few grams at most on its surface. This means that operators have to be extremely careful with the commands they beam to the lander so as not to inadvertently allow it to float off into space.

Making matters even more tense, Philae appears to have come to rest in the dark shadow of a nearby towering cliff.

Expectations are that the onboard batteries will last for just 3 days. However, according to mission scientists Philae only gets about 1-1/2 hours of sunlight instead of the expected seven, which means, even if they cut back on the science, its solar panels may not be able to offer much of a life extension for the hapless probe beyond a few extra days.

This is a far cry from the original plans, which called for the solar panels to recharge the batteries on a daily basis allowing Philae to say alive for weeks, perhaps even months, and well into next year.

Not surprisingly, now ESA scientists are working feverishly to figure out what happened and see exactly how this misfire and awkward positioning may affect the mission and its science moving forward. They are working against the clock, however – expectations are that the lander’s power will run out sometime Saturday.

The one jackpot science experiment everyone was really hoping for was to drill into the comet and retrieve samples to analyze the comet’s chemical DNA. It appears this project will be nixed unless they figure out a way to right the lander, because the craft’s drill is now oriented horizontally to the ground.

But all is not lost. At the very least, ESA officials say that they should be able to carry out some of the major science experiments it had planned. Already the on-board cameras are showing amazingly detailed and close-up portraits of the craggy and dusty landing site, including the face of the large cliff less than two metres away from the lander.

ESA officials will try and attempt to squeeze as much science out of Philae in the next few days while it has enough energy, and then perhaps attempt to reposition it.

Possibilities include firing either the harpoons or the small thruster at the head the craft. The danger is that with the super-low gravity, these manoeuvres may topple the lander over, push the craft away from the comet’s surface altogether, sending it floating away into space forever.