A European and Russian spacecraft set off for Mars this morning on a mission aimed at determining one of science's great unanswered questions - whether or not there is life on the red planet.

ExoMars will search the planet's atmosphere for gases that indicate the presence of life and will test technologies to be used on a rover which will be dropped onto the surface in 2018.

ExoMars was launched from Kazakhstan at the start of a seven-month journey across space.

"Proving that life exists or has existed on Mars would show that Earth is not unique in terms of having life on it," Rolf de Groot, head of the European Space Agency's Robotic Exploration Coordination Office, said.

"That would make it much more likely that there are other places in the universe that also have life," he added.

The spacecraft has two parts.

The first is an orbiting satellite carrying equipment to sniff Mars' atmosphere.

The second - a lander - which will be dispatched to the surface to test landing technology and briefly run some experiments.

The satellite will be looking for small amounts of gases including methane in the Martian atmosphere.

NASA's Curiosity rover found spurts of that gas in 2014, which if it were produced by biological processes would indicate there may be or may once have been life on Mars.

But methane can also be caused by geology so scientists want to determine once and for all where any traces may have originated.

This first ExoMars mission is a precursor to a second in 2018 or later which will see the launch of a rover capable of drilling 2m into the surface of Mars.

"The radiation from space destroys all the biological material. If you go two metres into the ground you may be able to find places that were protected [from radiation]," Mr de Grootsaid.

Landing on Mars is a notoriously difficult task that has bedevilled nearly all of Russia's previous efforts and has given NASA trouble as well. The United States currently has two operational rovers on Mars, Curiosity and Opportunity.
              
The ExoMars 2016 mission is led by ESA, with Russia's Roscosmos supplying the launcher and two of the four scientific instruments on the trace gas orbiter.

The prime contractor is Thales Alenia Space, a joint venture between Thales and Finmeccanica.