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Monday, December 10, 2018

By Deborah Netburn, Los Angeles Times (MCT)

The Philae probe is alive and well a day after the first successful spacecraft landing on a comet, but scientists are still trying to figure out exactly where it is on its new home.

Officials at the European Space Agency mission control in Darmstadt, Germany, confirmed Thursday that the lander, launched from the Rosetta spacecraft circling comet 67P/Guryomov Geraskimenko, is busily sending back data from the surface — including the first images ever taken from the surface of a comet.

While it was touching down, the lander bounced twice — almost as if the comet were a trampoline. The first bounce was major. It lasted almost two hours and took the lander about two-thirds of a mile above the comet’s surface. The second bounce was smaller and lasted just a few minutes, said Stephan Ulamec, the Philae landing manager. The craft’s harpoons failed to attach it to the surface after touchdown Wednesday but it’s now stable, scientists said.

The lander then settled in a shadowy part of the comet near a cliff, where it is only getting 1 hour of sunlight a day. At its planned landing site, Philae would have gotten six or seven hours of sunlight. The difference is crucial because Philae will need to rely on solar power after its batteries run out, and this will affect how much work the probe can do on the surface, mission officials said.

Scientists also said Philae landed with two legs on the ground and one foot in the air during its final touchdown. Ulamec said the lander has the capability to make a little “hop” on the surface, which could help it get into a better position, but the maneuver would be risky and it is not likely ESA will try it.

And because Philae’s harpoons failed to keep it tethered to the comet, ESA officials are also wary of drilling into the comet as planned. Their concern is that the force of the drills on such a low gravity body could cause the lander to move again.

The ESA team conceived the risky Rosetta mission in the late 1980s to learn more about comets that formed from the same mix of gas, dust and other ingredients that would form the sun, Earth and other planets. Spacecrafts have slammed into comets before, but none had ever landed intact before Wednesday.

Photo: European robot probe Philae has made the first, historic landing on a comet after descending from its mothership on Tuesday, Nov. 12, 2014. It was designed to shine a light on some of the mysteries of these icy relics from the formation of the Solar System. The landing caps a 6.4 billion-kilometer journey that began a decade ago. (ESA/Rosetta/Zuma Press/MCT)