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Rosetta spacecraft captures 1st images of 2014 target comet

June 9, 2011 - Washington

The European Space Agency's Rosetta spacecraft has succeeded in obtaining the first glimpse of its 2014 target - comet Churyumov-Gerasimenko - using its onboard camera OSIRIS, even though it is approximately 160 million km away from the comet.

Scientists from the Max Planck Institute for Solar System Research (MPS) in Germany said that the spacecraft has been put into hibernation after having travelled through space since 2004.

In the first images, Churyumov-Gerasimenko appears as a single point of light covering only a few pixels.

"But the pictures already give us a good idea of where we are headed", said Dr. Holger Sierks from MPS and OSIRIS lead investigator.

"In addition, they are a remarkable proof of the camera's performance. We had not expected to be able to create first images from so far away," he added.

Comet Churyumov-Gerasimenko is extremely faint. Its brightness is approximately a million times less then that of the faintest star that can be discerned from Earth with the n*ked eye.

Astronomers studying the comet from Earth use the European Southern Observatory's Very Large Telescope in Chile, one of the world's most powerful telescopes with a main mirror diameter of eight meters. OSIRIS's mirror measures only approximately 10 cm in diameter.

To make the comet visible despite these challenges, an exposure time of 13 hours was necessary.

"All in all, we took 52 images with OSIRIS, each exposed for 15 minutes", said Dr. Colin Snodgrass from MPS, responsible for data processing.

Since within a period of a few hours the comet moves relative to the background of fixed stars, the first step was to align all of the images and correct for this motion.

After further refined steps of data processing (for example subtracting the fixed stars) the researchers were able to catch a first glimpse of their destination.

Before they get a chance at a second glimpse, it will, however, be a long wait.

The systems onboard Rosetta will be powered down for approximately three years from Thursday. In this way the solar panel powered spacecraft saves energy while it is far from the Sun-until it reawakens in the spring of 2014 and takes a next look at 'its' comet.


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