Life on Mars: Spacecraft successfully blasts off in search of life on Red Planet
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.
Earlier, one of the British scientists involved in the mission spoke for all his colleagues waiting anxiously for the launch.
Dr Manish Patel, from the Open University, who is in charge of TGO's ozone-mapping ultraviolet (UV) spectrometer instrument, said: "This is a fantastic mission, massive.
"I spent the last 13 years of my life working on it so I am somewhat excited and nervous.
"You're strapping an instrument you've devoted your life to on top of a great big bomb.
"It's scary but it's why I'm in this business. There won't be many nails left on launch day."
Nine minutes and 42 seconds after launch, the rocket's Breeze-M upper stage containing the two spacecraft separated prior to entering a parking orbit around the Earth.
A critical moment will come at 2013 UK time when a final engine burn tears the spacecraft away from the Earth's gravitational field at 20,500mph (33,000kph). The "stack" is ejected from the upper stage and sent on course for Mars, coasting for the rest of the seven-month journey.
On October 16, shortly before reaching Mars, TGO and Schiaparelli will part company.
Three days later TGO will begin orbiting the planet. Meanwhile, Schiaparellli, travelling at 13,000mph (20,920kph), will start its descent through the Martian atmosphere, landing on the Meridiani Planum plain close to the equator.
TGO will spend a whole year making orbital adjustments in preparation for its part of the mission.
From January 2017 to December the probe will use friction with the atmosphere to "aerobrake" and lower itself to an altitude of 250 miles (402km). Only then will TGO's science operations begin.
Dr Patel watched the launch via a live link from the European Space Operations Centre (Esoc) in Darmstadt, Germany.
He said: "It was a bit of a numbing few minutes before the launch but I'm very happy, although it's not over yet.
"I won't be celebrating till we get final separation and the signal from the spacecraft telling us it's on its way."
Scientists hope TGO will help them solve the mystery of methane on Mars.
Earth-based telescopes, the European Space Agency (Esa) Mars Express orbiter, and the American space agency Nasa's Curiosity rover have all detected traces of the gas around the planet.
But methane is quickly broken down by the Sun's rays, and to persist in the atmosphere must be continually regenerated.
There are only two possible sources of Martian methane - ongoing geological processes such as volcanic activity, or life.
TGO's sensitive instruments will not only detect methane but give scientists a good idea of where it comes from.
Sue Horne, head of space exploration at the UK Space Agency, said: "We hope TGO will answer once and for all the question of whether the methane has a biological or geological origin.
"If it is shown to be biological, created by life, that would be amazing."
The discovery of a likely source of biological methane on Mars would be a dramatic curtain-raiser for the ExoMars 2018 rover mission.
The six-wheeled rover, built by Airbus Defence and Space at its UK headquarters in Stevenage, will analyse samples drilled from the Martian soil for biochemical signatures of life, either left by long-dead microbes or organisms still thriving beneath the planet's radiation-baked surface.
Confirmation of life on Mars would be a truly historic discovery, forcing humanity to reassess its place in the universe.
It would mean primitive bug-life at least is probably abundant among the stars, and increases the probability of their being complex or even intelligent life "out there".
Schiaparelli will pave the way for the rover mission by testing its Russian-designed descent and landing system, which involves aerobraking, parachute deployment, and retro rockets.
The 7.9ft (2.4m) diameter disc-shaped lander carries a small instrument package to take weather measurements, recording wind speed, humidity, pressure and the amount of dust in the air.
Airbus Defence and Space supplied the lander's heat shield, which has to withstand temperatures of up to 1,850C (3,362F) during its descent through the Martian atmosphere.
UK Space Agency-funded planetary scientist Dr Peter Grindrod, from Birkbeck, University of London, said: "It's incredibly exciting.
"This is a series of missions that's trying to address one of the fundamental questions in science: is there life anywhere else besides Earth?
"Finding that life exists elsewhere in the solar system would be a huge discovery, so the evidence has to be strong. As they say, extraordinary claims require extraordinary evidence."