After 10 years of waiting, the European Space Agency just landed on a comet


Credit: ESA

In a first for humanity, a spacecraft just touched down on a comet. The European Space Agency’s Philae probe has been traveling toward a comet orbiting our Sun since 2004, and today it finally made the 7 hour jump from its orbit to surface.

The 220-pound probe was traveling at a rate of about 2.2 miles per hour when it reached the surface and landed on its three legs, which absorbed the shock of the impact.  Three ice screws anchored the lander to the comet’s surface to combat its very low level of gravity.

Philae was also supposed to fire two harpoons into the comet’s surface, but they failed to. Thrusters meant to keep the lander from bouncing away from the surface also did not fire. Officials said at a press conference Wednesday morning that they believe Philae bounced away from the surface and then touched back down.

“Maybe we didn’t just land once, we landed twice,” mission scientist Stephan Ulamec said at the press conference.

Its lack of an anchor may become an issue when the comet moves closer to the Sun and its surface begins to change. Philae’s team is analyzing data about the landing now and will have a more thorough understanding by Thursday.

The Rosetta mission crew celebrates just after it touched down on the comet.

The Rosetta mission crew celebrates just after it touched down on the comet.

The first images from the surface of the comet, which on its wider end measures 2.5 miles across, are expected to arrive in a few hours. The ESA will use Philae’s 9-inch drill and sensors to collect data for at least 2.5 days. It could extend the mission to March if there is enough sunlight to use the probe’s solar battery. What the agency finds will help scientists understand the composition and structure of comets, which are composed of rocks, frozen gas and ice. Just how much ice is contained in a comet and how different they are from asteroids has been a matter of debate over the last decade.

Rosetta, the spacecraft that released Philae, also accomplished a first by being the first manmade object to orbit a comet. Rosetta will continue to monitor the comet’s environment and how it changes as it moves closer to and farther from the Sun.

Rosetta's path

The comet could answer questions about the earliest stages of our solar system.

“What were the conditions like at its infancy and how did it evolve? What role did comets play in this evolution? How do comets work?” ESA Rosetta project scientist Matt Taylor said in a release. “Today’s successful landing is undoubtedly the cherry on the icing of a 4 km-wide cake. …”

The Rosetta team announced Monday that the comet had already revealed a surprise: a “song” created by its oscillating magnetic field.

“This is exciting because it is completely new to us,” Rosetta Plasma Consortium principal investigator Karl-Heinz Glaßmeier said in a release. “We did not expect this and we are still working to understand the physics of what is happening.”

Photo by ESA/J.Mai. Graphic courtesy of ESA.

This story was updated at 8:30 a.m. PT with further details from the landing. It was updated again at 9 a.m. and 12 p.m. with news of the harpoon failure.

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