Europe and Russia have launched a joint mission to Mars, BBC News reports.
The satellite, called the ExoMars Trace Gas Orbiter (TGO), lifted off from Baikonur in Kazakhstan at 09:31 GMT.
The probe will investigate whether the methane in the world's atmosphere is coming from a geological source or is being produced by microbes.
If all goes well, the two space powers expect to follow up this venture with a rover, to be assembled in the UK, which will drill into the surface.
That could launch in 2018, or, as seems increasingly likely, in 2020.
It will take the carrier rocket more than 10 hours to put the satellite on the right trajectory to go to Mars, BBC says.
This involves a series of engine burns by the Proton's Breeze upper-stage to build up the velocity needed to break free of Earth's gravity.
These will fling the TGO away from Earth with a relative velocity of 33,000km/h.
The flight sequence is sure to strain the nerves of space agency officials.
For Russia especially, the Red Planet represents a destination of wretched fortune.
It has previously launched 19 missions to the fourth planet from the Sun, and most of those have been outright failures.
