The ExoMars 2016 mission, a collaboration between the European and Russian space agencies, is scheduled to blast off from Kazakhstan on Monday.
The spacecraft, which consists of an orbiter that will measure methane and other gases in the Martian atmosphere and a lander to study dust storms, will hitch a ride on top of a Russian Proton rocket that is expected to lift off at 3.31pm local time.
After a journey of seven months, the ExoMars spacecraft will arrive at Mars in October and begin its investigation of life on the planet.
Three days before arriving, the lander, named Schiaparelli after the 19th-century Italian astronomer Giovanni Schiaparelli, will separate from the orbiter.
It is to enter the atmosphere at 13,000 mph and will quickly decelerate on its way to settling down on the surface.
The main objective of Schiaparelli is to demonstrate its landing system.
The European Space Agency’s last attempt to land on Mars, the Beagle 2 spacecraft, which accompanied the Mars Express orbiter in 2003, failed.
Schiaparelli carries instruments to measure Mars’s atmosphere during the height of the dust storm season.
Its batteries are expected to last only two to four days.
The Trace Gas Orbiter is to operate much longer, until at least 2022, circling Mars at an altitude of 250 miles.
Its instruments will measure gases, like methane, water vapour and nitrogen, that exist in minute quantities but that could hold important clues about the possibility of life on Mars.
Methane
Methane is seen as the most intriguing trace gas. Sunlight and chemical reactions break up methane molecules in the atmosphere.
Any methane there must have been created recently, and the two possibilities for creating methane are microbes and a geological process requiring heat and liquid water.
Mars Express made tenuous detections of methane, but its instruments were not sensitive enough for definitive conclusions.
Nasa’s Curiosity rover also detected a transient whiff of methane in 2014.
"Methane is a hot topic," Jorge Vago, the project scientist, said in a European Space Agency video.
“So trying to understand the origin of the methane, and where on the surface of Mars, and when it’s being produced and how it is destroyed is very important.”
The ExoMars spacecraft was originally to be launched by Nasa, but tight budgets led Nasa to back out in 2012, and the Russians stepped in.
The second half of the European-Russian ExoMars collaboration, a rover, is scheduled to launch in 2018, but that mission is expected to slip to 2020.
New York Times service