ESA lands Philae on Comet 67P

In a first for humanity, the European Space Agency (ESA) has successfully landed the Philae probe on Comet 67P/Churyumov-Gerasimenko on November 12. The landing is part of the overall mission for the Rosetta orbiter, which arrived at the comet earlier this year after being launched over 10 years ago, and its search for the possible cometary origins of Earth's water and complex organic molecules.

Philae in fact landed not once, but three times, as the harpoons which were meant to secure it to the comets' surface failed to deploy. Even though its approach was a stately 1m/s, the tiny gravitational pull of the comet (several hundred thousand times weaker than Earth's) sent the lander bounding about 1km back into the cometary sky, eventually landing it away from the intended landing area. Philae ended up at a steep angle in the persistent shadow of either a cliff or boulder.

The lander was built with a limited store of battery life before the solar panels were designed to start charging the batteries. With its unconventional landing angle though, Philae gets a fraction of the sunlight it was supposed to receive. ESA's mission controllers therefore re-organized the order of scientific activities to make sure each instrument got a chance to run at least one measurement before the lander went into hibernation.

The mission scientists are hoping that as Comet 67P moves closer to the sun, the increased solar radiation will be strong enough to charge Philae's solar panels again and return it to operational status. And even if that doesn't happen, it has already provided a wealth of intriguing data about the makeup of the comet, and the Rosetta orbiter will continue to provide more interesting data as it heats up.

Read more: ESA, Space 101

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