少妇无码精品23p_亚洲一区无码电影在线观看网站 _悠悠色一区二区_中文字幕亚洲无码第36页

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 (ESA)'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 250 kilometers 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 0240 GMT 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 five-kilometer-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.

 

(China Daily February 26, 2007)