The main aim of the Phobos-Grunt unmanned mission is to bring back the first ever soil sample from Phobos, the larger of Mars' two moons.

　　Russia had spent about 5 billion rubles (about 161 million U.S. dollars) preparing for the three-year mission, which would include drilling Phobos' surface and returning 200 grams of soil back to Earth, according to Russian state space agency Roscosmos.

　　The mission would also collect bacteria samples for two Russian and one U.S. biological experiments.

　　In the meantime, China's first Mars probe Yinghuo will go into orbit around Mars and observe the planet itself.

　　Phobos-Grunt is planned to reach Mars in 2012, then deploy its lander for Phobos in 2013 and return the soil sample back to Earth in August 2014.

　　The Chinese probe, which would not land on Mars nor return to the Earth, is expected stay permanently in the space and communicate with the ground control directly via satellites.

　　The Chinese probe is 75 cm long, 75 cm wide and 60 cm high. It weighs 115 kilograms and was designed for a two-year life to discover why water disappeared from Mars and shed light on other environmental changes on the planet.

　　Victor Khartov, chief designer and director general of Lavochkin Research & Production Association, told Xinhua that the three-year mission is highly complicated.

　　"It consists of eight sub-missions: launch, travel to Mars vicinities, separation with the Chinese probe YH-1, landing on Phobos, soil collection, launch from Phobos, way back to the Earth, and final landing. Failure of any one of them could doom the entire project," he said.

　　The launch of Phobos-Grunt and Yinghuo-1, originally scheduled for October 2009 on a Russian carrier rocket, has been postponed until 2011 due to "technical reasons" on the Russian side.