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ESA's Rosetta probe activated, sends pictures

On March 27, the European Space Agency announced that its Rosetta spacecraft has taken its first pictures of its destination since being activated from deep-space hibernation on Jan. 20.

Artist's impression of Philae riding on the Rosetta probe.
Artist's impression of Philae riding on the Rosetta probe.
ESA

The two images of Comet 67P/Churyumov–Gerasimenko were taken on March 20 and 21 by the Optical, Spectroscopic, and Infrared Remote Imaging System (OSIRIS) cameras. These cameras, a wide-angle camera for longer range images and a narrow-angle camera for covering a smaller field at high resolution, were developed under the leadership of the Max Planck Institute in Göttingen, Germany.

The Rosetta probe also carries 10 other scientific instruments to help it provide information about the atmosphere, geology, gravity, internal structure, mass, plasma environment, and shape of the comet.

Rosetta was launched on March 2, 2004 from Kourou, French Guiana, and has engaged in gravity assist passages of Earth from then until 2009. In June 2011, Rosetta was put into hibernation because it was too far from the Sun for solar panels to be effective, and no other power source was included in the design. The spacecraft is now close enough for the systems to begin to be switched back on, which will be done over the next six weeks.

“Finally seeing our target after a 10 year journey through space is an incredible feeling,” says OSIRIS Principal Investigator Holger Sierks from the Max Planck Institute for Solar System Research in Germany. “These first images taken from such a huge distance show us that OSIRIS is ready for the upcoming adventure.”

“This is a great start to our instrument commissioning period and we are looking forward to having all 11 instruments plus lander Philae back online and ready for arriving at the comet in just a few month’s time,” says Matt Taylor, ESA’s Rosetta project scientist.

The plan forward is to burn thrusters on May 21 and on eight subsequent occasions to put Rosetta into orbit of Comet 67P in the first week of August. These maneuvers will slow the spacecraft from 800 m/s to 1 m/s relative to the comet.

Rosetta is currently 655 million kilometers from Earth and about 3.8 million kilometers from Comet 67P, which is too far away to resolve with OSIRIS. The comet was observed by a series of 60–300 second exposures taken with the wide-angle and narrow-angle camera. Between May and August, the 4 kilometer-wide comet will gradually ‘grow’ in OSIRIS's field of view to well over 2000 pixels, which at a resolution of around 2 meters per pixel will allow the first surface features of Comet 67P to be resolved.

After Rosetta arrives in August, it will map the surface between August and November, at which point the Philae lander will be released. Due to the weak gravity of an object that is only 4 kilometers across, the lander will use harpoons and ice screws to attempt to attach itself to the comet.