Rosetta's Lander Grabs Onto Comet and Lands

The European Space Agency’s Rosetta mission has succeeded in landing its tiny Philae probe on the surface of a comet. This is the first time in history that a soft landing on a comet has been attempted and, at 17:03 CET (11:03 a.m. EDT), Rosetta mission control at ESA’s Space Operation Center in Darmstadt, Germany, said that they had received a signal from the lander confirming touchdown.

Rosetta Flight Director Andrea Accomazzo was the first to announce the news: "We see the lander sitting on the road. We've definitely confirmed that the lander is on the surface."

"Touchdown! My new address: 67P!" said the official Philae Twitter feed.

Although a landing was achieved there is growing concern for the harpoon system that was supposed to fire, holding Philae in place. It appears this anchoring system did not operate as planned meaning the lander may not be fully stable on the comet's surface. Mission managers are now deciding whether or not to attempt re-firing the anchoring system.

Landing came after Philae successfully detached from the Rosetta satellite 7 hours earlier and began its descent to the icy surface. Images beamed back from Rosetta showed a lander, with lander feet and instruments deployed, indicating that the robot was in good health as it dropped toward Comet Churyumov-Gerasimenko.

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"You have all heard that Philae has landed and ... this is a big step for human civilization. Because this is science, knowledge," said Director General of ESA, Jean-Jacques Dordain shortly after landing.

"The problem with success is it looks easy. When you know the sum of expertise, the sum of dedication the sum of teams working ... when you know that you know that this type of success is not coming from the sky -- it comes from hard work and expertise."

"The only way to reconcile risk and success is expertise."

The landing gear is composed of shock-absorbing landing legs and a harpoon system that was triggered as soon at the robot came in contact with the cometary surface, allowing Philae to grapple itself in the extremely low comet gravity.

Critical to mission success is the lander’s ability to hold onto the rock, dust and ice at landing. As there was a real risk of the lander bouncing off the comet, harpoons, landing leg ice screws and thrusters needed to work in concert to ensure Philae stayed in place. Apart from the harpoon system failing, another component of the landing system did not operate -- the cold gas thrusters. These thrusters were designed to push the lander into the cometary surface on landing.

The lander's ice screws have deployed successfully, however, providing some hope for the lander remaining in-situ.

Even though there seems to be some uncertainty about the stability of the lander, science operations will begin immediately. Philae only has a limited battery supply, so all of the lander’s 10 instruments will be feverishly working to squeeze out all the observational data they can. However, Philae comes equipped with solar cells that can recharge its batteries, so mission managers hope that the lander can remain operational for the duration of Rosetta's mission until March 2015.

The first images from Philae on the comet's surface are expected to be released within hours of touchdown.

From Discovery News