* Astronomy

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Rosetta mission

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Mission to Land on a Comet

Europe's Rosetta spacecraft is en route to intercept a comet-- and to make history. In 2014, Rosetta will enter orbit around 67P/Churyumov-Gerasimenko and land a probe on it for a front row seat as the comet heads toward the sun

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Title: Photometric observations of asteroid 4 Vesta by the OSIRIS cameras onboard the Rosetta spacecraft
Authors: S. Fornasier, S. Mottola, M. A. Barucci, H. Sierks and S. Hviid

Aims. We report on new observations of asteroid 4 Vesta obtained on 1 May 2010 with the optical system OSIRIS onboard the ESA Rosetta mission. One lightcurve was taken at a phase angle (52°) larger than achievable from ground-based observations together with a spectrophotometric sequence covering the 260 to 990 nm wavelength range.
Methods. Aperture photometry was used to derive the Vesta flux at several wavelengths. A Fourier analysis and the HG system formalism were applied to derive the Vesta rotational period and characterise its phase function.
Results. We find a G parameter value of 0.27 ± 0.01 and an absolute magnitude H(R) = 2.80 ± 0.01. The lightcurve has the largest amplitude ever reported for Vesta (0.19 ± 0.01 mag), and we derive a synodic rotational period of 5.355 ± 0.025 h. The Rosetta spectrophotometry, covering the Vesta western hemisphere, is in perfect agreement with visible spectra from the literature and close to the IUE observations related to the same hemisphere. The new spectrophotometric data reveal that there is no global ultraviolet/visible reversal on Vesta. The Vesta spectrophotometry is well reproduced by spectra of howardite meteorite powders (grain size < 25 \mu m). From the Rosetta absolute spectrophotometry and from the phase function behaviour, we estimate a geometric albedo of 0.36 ± 0.02 at 649 nm and 0.34 ± 0.02 at 535 nm.

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On 10 July 2010, Rosetta made a close flyby of asteroid (21) Lutetia, at around 15:44 UTC (17:44 CEST).
This was the spacecraft's second asteroid encounter with an asteroid of the main asteroid belt between Mars and Jupiter.

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Rosetta comet chaser goes into deep sleep

Europe's Rosetta spacecraft, which is heading for a rendezvous with a comet in 2014, has been put into hibernation by its controllers.
The command was sent from Germany on Wednesday, instructing the probe to enter a deep sleep. Only heaters and an "alarm clock" have been left running.
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Rosetta comet probe enters hibernation in deep space

The final command placing ESA's Rosetta comet-chaser into deep-space hibernation was sent earlier today. With virtually all systems shut down, the probe will now coast for 31 months until waking up in 2014 for arrival at its comet destination.
Today's dramatic event marks the end of the hugely successful first phase of Rosetta's ten-year cruise and the start of a long, dark hibernation during which all instruments and almost all control systems will be silent.
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Rosetta's first glimpse of the comet

Three years before its arrival the camera system on board the space probe Rosetta renders the first images of its destination.

Credits: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

Approximately 163 million kilometres still separate ESA's spacecraft Rosetta from comet Churyumov-Gerasimenko, its 2014 target. Despite this remarkable distance, scientists from the Max Planck Institute for Solar System Research (MPS) in Germany have succeeded in obtaining the first images of the remote destination using the onboard camera system OSIRIS. These pictures were generated during the tests performed by the team during the last weeks. After the successful completion of these tests, Rosetta will now start its almost three year hibernation period: In order to save energy on the last part of the way offering only little sunlight, all systems will be powered down.