Mon, Feb 26, 2007 - Page 6 News List

Rosetta probe completes crucial Mars flyby


A European spacecraft carried out a close flyby of Mars yesterday, a crucial maneuver in its meandering, 10-year voyage through the solar system to make the first soft landing on a comet.

Applause broke out in the European Space Agency's mission control center in western Germany as the Rosetta comet probe's radio signal was picked up after 15 tense minutes of silence as the craft passed behind the Red Planet.

Rosetta used Mars' gravitational field to change course and head toward two similar flybys of Earth this year and in 2009, which will accelerate it toward its distant target comet.

"Rosetta is on its way," said Manfred Warhaut, ESA head of mission operations.

The craft passed barely 250km from Mars. The navigation had to be precise, as a mistake could not be corrected.

It was a maneuver the craft was not designed to make, taking it into Mars' shadow where solar panels could not generate electricity to keep its systems alive. The original Rosetta mission would have taken it on a course where it did not fly through shadow; but a launch delay forced a change to a different target comet.

ESA officials solved the shadow problem by shutting off many of the spacecraft's instruments and using batteries untested since launch almost three years go.

Rosetta passed the test, flying from shadow into a Martian sunrise at 3:40am yesterday and regaining solar power and a radio signal from the craft's instruments.

The successful flyby "is fundamental to the mission,"| said spacecraft operations manager Andrea Accomazzo. "It's a very big success, so we are very happy -- and we can go to sleep now."

Rosetta blasted off on March 2, 2004 from Kourou, French Guiana atop an Ariane-5 booster rocket. Its destination -- in 2014 -- is comet 67P/Churyumov-Gerasimenko, a 5km long irregular chunk of ice, frozen gases and dust named for its discoverers, Soviet astronomers Klim Churyumov and Svetlana Gerasimenko.

Rosetta will go into orbit around it and release a small lander that will touch down and seek to drill into the surface and radio back an analysis of its makeup.

Because the comet's gravity is so weak, the lander will use a harpoon and spikes to catch hold. Researchers hope it will be able to photograph the dramatic appearance of the comet's tail, a stream of gases and dust that arises when the icy body warms as it orbits nearer the sun.

Comets are among the most primitive objects in the 4.6-billion-year-old solar system and their composition is considered to hold clues about its early development. In 2004, NASA's Stardust mission flew by a comet, collected thousands of particles that came from it and returned them to Earth for analysis.

A year later, NASA's Deep Impact launched a probe the size of a coffee table that struck the comet Tempel 1 with tremendous force, excavating materials from deep within its interior. Instruments on the flyby spacecraft analyzed the resulting debris.

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