European probe slings past Earth on long trip to comet

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European probe slings past Earth on long trip to comet
BY STEPHEN CLARK
SPACEFLIGHT NOW
Posted: March 5, 2005

The one-year old Rosetta comet chaser made a return visit to Earth Friday, flying by the planet to receive a boost to begin the long process of eventually sending the spacecraft on a trajectory to intercept the comet Churyumov-Gerasimenko in 2014.


While approaching Earth for the first of a series of fly-bys, Rosetta turned its navigation camera to the Moon, half lit by the Sun. This image was taken at 1510 GMT Friday when Rosetta was 265,997 miles from the surface of the Moon. Credits: European Space Agency, ESA/ESOC

Launched last March 2, Rosetta has now completed one revolution around the Sun in an orbit similar to that of Earth. Over the past year, European controllers have put the craft through a number of tests to verify the function of key systems and instruments, and no major problems were reported.

Rosetta made its closet approach to Earth at 2209 GMT (5:09 p.m. EST) as it passed 1900 kilometers above Mexico. The fly-by will send the spacecraft into a larger solar orbit that will take it past Mars for another one of these "sling-shot" gravity boost maneuvers in February 2007, followed by two more passes by Earth.

These planetary fly-by's save fuel that would otherwise have to be spent to propel the spacecraft toward its target comet.

Controllers switched on some of Rosetta's scientific instruments in advance of the close approach to carry out calibration measurements of the Earth and Moon. Navigation cameras were also successfully tracked the Moon during the fly-by to test their ability to track objects in space. These cameras will be responsible for the rendezvous with Churyumov-Gerasimenko and for tracking as the probe passes by a pair of asteroids later in the mission.

Rosetta also captured images of the Earth and Moon near the point of closest approach, but those pictures will likely not be available for a few more days.

The European Space Agency also sponsored a contest for amateur astronomers to take pictures of Rosetta as it passed close to Earth. It was expected that small telescopes could distinguish the craft's 100-foot solar panels, and possibly its high-gain antenna.

The fly-by also put Rosetta in position to be able to observe NASA's Deep Impact probe as it fires a small projectile into comet Tempel 1. The impact will reveal the comet's inner structure, and Rosetta will turn its instruments toward the comet to make additional observations.

Rosetta is planned to be the first spacecraft to rendezvous with and enter orbit around a comet. These primordial relics from the formation of the solar system are believed to harbor materials dating back as far as 4.5 billion years. Rosetta will also release a lander to explore the comet at the surface.

http://www.spaceflightnow.com/news/n0503/05rosetta/