A European spacecraft programmed to sniff out atmospheric evidence of life on Mars has blasted into space.
Trace Gas Orbiter (TGO) was launched into orbit by a Russian Proton heavy-lift rocket to begin a seven-month, 300 million-mile journey to the Red Planet.
ExoMars 2016 is the first phase of an historic 1.2 billion euro (£924 million) joint European-Russian mission to search for biochemical "fingerprints" of past or present life high above Mars and on its surface.
TGO is equipped with highly sensitive instruments for detecting trace gases in the Martian atmosphere, including methane which can be a sign of life.
On Earth, the gas is chiefly generated by billions of bacteria, many of which live in the guts of animals such as cows and termites. But it can also be released by volcanic activity and other geological processes.
The European Space Agency (ESA) orbiter will tell scientists whether Martian methane is most likely to have a geological or biological source.
Accompanying TGO is a robot lander, Schiaparelli, that is due to parachute down on to a Martian plain in October.
Its main job will be to test the descent and landing technology for ExoMars 2018, the next stage of the mission which will send a British-built rover to Mars in two years' time.
Fitted with a drill that can burrow 6ft into the Martian soil, the rover will search for evidence of long-dead or still living microbes underground.
The rocket carrying the TGO and Schiaparelli combination "stack" took off from the Baikonur Cosmodrome in Kazakhstan at 9.31am UK time, vanishing into an overcast sky within seconds.