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Mars ExpressA mission organized by ESA and the Italian Space Agency to investigate the geology and subsurface structure of Mars and the composition and circulation of its atmosphere. Launched June 2 2003 from Baikonur Cosmodrome, Kazakhstan, on top of a Soyuz-Fregat rocket, the 12000-kg probe was the first all-European spacecraft to explore Mars. Built in record time and for a fraction of the cost of other comparable planetary missions, it consisted of an orbiter, the Mars Express craft itself, carrying seven instruments, including radar, for remote-sensing observations of the planet, and a lander, Beagle 2, which would be deployed by the orbiter and touch down on Mars to make on-site measurements of Martian rock and soil. After a six-month journey, Mars Express reached the vicinity of Mars and released Beagle 2 for descent to the planet's surface in Dec. 2003. Beagle 2 was scheduled to land on Mars on Dec. 25 and send a signal back to Earth to show that it was safely down, but the signal was never received and the lander was assumed lost. Meanwhile, Mars Express successfully entered orbit around Mars on the same day and began its scientific investigations. Still functioning in Feb. 2005, it had already sent back a wealth of scientific data. That month ESA scientists announced that Mars Express had detected a vast frozen sea beneath the surface of the planet in the region of the Martian equator.
Collins Dictionary of Astronomy © Market House Books Ltd, 2006