* Astronomy

Results from the Rosetta Encounter with Asteroid 2867 Steins

Last week, scientists on the OSIRIS camera team ESA's Rosetta mission published the peer-reviewed report on their observations of asteroid 2867 Steins. Steins is an E-type asteroid that was visited by Rosetta on September 5, 2008, with the closest approach taking place at 18:38:20 UTC at a distance of 803 kilometers. Rosetta's OSIRIS high-resolution camera system imaged about 60 percent of Steins' surface during the flyby. Unfortunately, due to stringent limits set on onboard fault protection software, the narrow-angle camera component of OSIRIS (the highest-resolution camera instrument on Rosetta) went into "safe mode" before closest approach, but the wide-angle camera returned photos throughout the encounter. The following description of the asteroid is based upon an article published in the January 8, 2010 issue of Science by H. Uwe Keller and numerous coauthors and on a related press release (in German).
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ESA researchers study Rosetta

Together with ESA colleague and orbital mechanics specialist Frank Budnik, Morley co-authored a scientific report in 2006 that studied the Rosetta anomaly during the 2005 swingby and listed possible causes.
These range from tidal effects peculiar to the near-Earth environment, atmospheric drag, or the pressure of radiation emitted or reflected by the Earth, to much more extreme possibilities, such as dark matter, dark energy or previously unseen variations in General Relativity, one of the most fundamental and well-tested theories of modern physics.
One American research team, led by ex-NASA scientist John Anderson, is even looking at the possibility that Earth's rotation may be distorting space-time - the fundamental fabric of our Universe - more than expected, thus affecting nearby spacecraft. But there is as yet no explanation how this could happen.
Before even considering such exotic explanations, all the usual causes of spacecraft speed errors have been thoroughly eliminated by numerous investigations conducted over the years at both ESA and NASA. Software bugs, calculation errors, tracking uncertainties and other, much more mundane, causes have all been systematically eliminated or accounted for, leaving the speed anomaly maddeningly unexplained.

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Ed ~  there was no anomaly detected with Rosetta's third and final Earth flyby.

Rosetta makes final home call
Europe's Rosetta spacecraft has made its third and final flyby of Earth, a manoeuvre designed to position the probe to chase down a comet in 2014.
The spacecraft's whip around the planet will have given it the extra speed it needs to take it out to the rendezvous location near Jupiter.

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This morning, mission controllers confirmed that ESA's comet chaser Rosetta had swung by Earth at 8:45 CET as planned, skimming past our planet to pick up a gravitational boost for an epic journey to rendezvous with comet 67P/Churyumov-Gerasimenko in 2014.
Rosetta passed over the ocean, just South of the Indonesian island of Java, at exactly 08:45:40 CET, at a speed of 13.34 km/s with respect to Earth an altitude of 2481 km. The swingby was pre-planned and fully automated, and the spacecraft was in direct communication with Earth at the time, via the ESa New Norcia Station. 

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