Moscow ? An unmanned spacecraft built by the European Space Agency blasted off atop a Russian rocket Monday on a mission to Mars, where it will orbit the planet for nearly two years and search for signs of life.

The Mars Express spacecraft was launched by a Soyuz FG booster rocket from the Russian-operated Baikonur cosmodrome in Kazakhstan. The space vehicle, which cost $350 million, was initially put into Earth’s orbit, and about 90 minutes later was given the final push to send it on a six-month journey to Mars — the ESA’s first interplanetary mission.

Several days before the spacecraft reaches Mars in December, the British-built Beagle 2 lander is set to separate from the vehicle. It will parachute down to the Martian surface on Dec. 25. The tiny lander will head to Isidis Planitia, north of the Martian equator where traces of life could have been preserved.

Scientists think Mars once had plenty of water and appropriate conditions for life but lost it billions of years ago, possibly after being hit by asteroids. It is believed that water might still exist on Mars as underground ice.

The lander would dig into Mars to search for organic materials and check the atmosphere for traces of methane produced by living organisms — the first such search since 1976, when twin U.S. Viking landers brought inconclusive results.

NASA is sending its own twin Mars Exploration Rovers later this month in an $800 million mission to try to answer the same questions about water and life on the planet. A Japanese spacecraft launched in 1998 also continues its voyage toward Mars, despite some electronic troubles.

The launching of many spacecraft at once isn’t accidental: Celestial mechanics are bringing Mars and Earth closer together than they have been for a long time, helping save fuel and travel time.

Of 34 unmanned American, Soviet and Russian vehicles sent to Mars since 1960, two-thirds ended in failure.

The spacecraft that succeeded helped vastly expand human knowledge about Mars. Just 40 years ago, some experts still believed that thick vegetation grew on Mars — that belief was dispelled in the 1960s by NASA spacecraft which beamed back images of Mars’ barren surface.