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Rosetta's camera seeing more of cometary destination
BY STEPHEN CLARK
ASTRONOMY NOW

Posted: July 31, 2014


On course for an historic rendezvous next week, the European Space Agency's Rosetta spacecraft is revealing new details of the oddball comet the probe has pursued for more than a decade.


The nucleus of comet 67P/Churyumov-Gerasimernko as seen from a distance of 1,950 kilometers on July 29, 2014. One pixel corresponds to approximately 37 meters. The bright neck region between the comet's head and body is becoming more and more distinct. Credit: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA
 
New images released by scientists Thursday show the coma surrounding comet 67P/Churyumov-Gerasimenko, revealing the cloud of dust and gas around the tiny unexplored world.

The images from Rosetta's OSIRIS camera system also provide a sharper view of the comet's nucleus, which appears to be formed of two distinct lobes merged along a brightly colored saddle.

Scientists programmed Rosetta's wide-angle camera to image the comet's coma with a 330-second exposure, bringing out subtle sunlight reflected from the minuscule particles of dust and gas stretching hundreds of kilometers from the nucleus.

"Even though it sounds like a contradiction, imaging the comet's coma from nearby is more difficult than from far away," said Holger Sierks, the OSIRIS camera's lead scientist from the Max Planck Institute for Solar System Research in Germany.

Rosetta detected the comet -- known by the abbreviated name 67P/C-G -- putting off dust this spring. The coma will become more pronounced as the comet comes closer to the sun, with its closest approach expected in August 2015.


The coma of comet 67P/Churyumov-Gerasimenko as seen with OSIRIS covers an area of 150 kilometers across. This image was taken on July 25, 2014, with an exposure time of 330 seconds. The hazy circular structure on the right and the center of the coma are artifacts due to overexposure of the nucleus. Credit: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA
 
Rosetta will arrive within 100 kilometers, or about 62 miles, of the comet Aug. 6. A minor rocket burn will put the probe in an slow, looping orbit around 67P/C-G, making Rosetta the first spacecraft to ever accomplish a controlled low-speed rendezvous with a comet.

As of Thursday, officials said Rosetta was less than 900 miles from the comet.

Imagery from Rosetta indicates the comet spins around once every 12.4 hours, according to scientists.

ESA plans to release the first close-up view the comet during a special event to celebrate the Aug. 6 rendezvous at Rosetta's control center in Darmstadt, Germany.

By September, scientists hope to identify a prime landing site for Philae, a small craft riding piggyback on Rosetta that will descend to the comet's surface in November.

Follow Stephen Clark on Twitter: @StephenClark1.

The Planets
From tiny Mercury to distant Neptune and Pluto, The Planets profiles each of the Solar System's members in depth, featuring the latest imagery from space missions. The tallest mountains, the deepest canyons, the strongest winds, raging atmospheric storms, terrain studded with craters and vast worlds of ice are just some of the sights you'll see on this 100-page tour of the planets.
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Hubble Reborn
Hubble Reborn takes the reader on a journey through the Universe with spectacular full-colour pictures of galaxies, nebulae, planets and stars as seen through Hubble's eyes, along the way telling the dramatic story of the space telescope, including interviews with key scientists and astronauts.
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3D Universe
Witness the most awesome sights of the Universe as they were meant to be seen in this 100-page extravaganza of planets, galaxies and star-scapes, all in 3D!
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