Europe Lands Spacecraft on Comet

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Europe’s Rosetta spacecraft today landed the first ever probe on a comet, part of a decade-long mission to the icy body between the orbits of Mars and Jupiter. It’s unclear whether it’s properly anchored.

Rosetta’s landing craft, Philae, successfully touched down on the comet shortly after 4:30 p.m. Paris time, according to a webcast on the European Space Agency’s website. The result of the maneuver was known 28 minutes later -- the time needed for the signal to reach Earth. The mission’s staff cheered and hugged each other for a second time after learning seven hours earlier that the lander had separated from its mothership.

“We are sitting on the surface and Philae is talking to us,” Stephan Ulamec, the lander’s project manager said to cheers and whoops from scientists and engineers at ESA’s operations center in Darmstadt, Germany. “We are on the comet!”

Philae’s landing didn’t go completely as planned. Once initial communications were established it became clear that its anchors were not deployed, according to Philae’s Twitter feed set up by the German Aerospace Center. Calls and an e-mail to the space agency weren’t immediately returned.

“I’m on the surface but my harpoons did not fire,” according to the Philae Lander’s twitter feed. “My team is hard at work now trying to determine why.”

Scientists hope to glean information about the early evolution of the solar system by studying the comet named Churyumov-Gerasimenko. Comets date back 4.6 billion years to when the planets were forming, and the icy bodies may have seeded Earth with the organic molecules that became the building blocks for life.

‘New Opportunities’

“This is the first mission that puts a lander down on a comet, so there are a lot of new opportunities to do science,” said Gerhard Schwehm, a consultant and manager of the mission from its liftoff until he retired from the space agency last year. “We will not find life, and we won’t be able to answer the question tomorrow how did life emerge on Earth. But if we see organic molecules, we can say ‘Oh, the comets could have brought very complex molecules to the early Earth.’”

Rosetta, launched in March 2004, has been orbiting the comet since Aug. 6, gleaning information about the mass of dirty ice, dust and gas, and scoping out a suitable site to place Philae. Researchers selected a site based on the perceived ease of landing, the exposure to sunlight to fuel Philae’s solar cells, and hints of interesting nearby activity that the lander could observe.

Monitoring Instruments

Rosetta’s 11 instruments have been monitoring the comet and gas and particles thrown off it. It’s scheduled to orbit the comet until the end of 2015. Philae, which has 10 instruments, will take pictures of the comet, as well as drill 23 centimeters below the surface to retrieve samples that can be taken up into the craft and heated. The molecules that are released will then be analyzed, said Schwehm.

“If you want to see what the comet is really made of, you have to go there, you have to land and study it,” he said. “It’s the cherry on the cake that gives the Rosetta mission extra taste.”

The comet is shaped like a rubber duck, with two lobes measuring a few kilometers across.

The 6.5 billion-kilometer journey has taken Rosetta as far as 1 billion kilometers from Earth. It’s now orbiting about 22.5 kilometers above the comet, more than 500 million kilometers from Earth and about 450 million kilometers from the Sun, between the orbits of Mars and Jupiter, according to the ESA website.

Astrium, now part of Airbus Defence and Space, was the main contractor for the spacecraft launched on March 2, 2004. The European Space Agency was formed in 1973 and has 20 member countries, including the U.K., Germany and France.