The probe, for example, will be able to distinguish between methane produced by biological activity and gases due to naturally occurring geology, said mission systems engineer Carlos Cassi.
"If there has been life on Mars there has been periods where gases have been produced by the presence of this life that would have gone into the atmosphere," Cassi told Discovery News.
The orbiter also will scout for other atmospheric gases, which is of interest to scientists and also for eventual human missions to Mars. Most importantly, the satellite will double as a communications relay for the 2018 rover, which will undertake a direct search life.
Technologies needed to enter into the thin Martian atmosphere, maneuver to the landing site (which has not yet been selected) and parachute down for a rocket-assisted landing will be tested during a practice run in 2016.
If the 2018 rover lands successfully and remains in good working order -- a notoriously difficult task that has been pulled off only seven times and only by the United States -- it will spend the next six months using a radar sounder to probe beneath the planet's surface for water, drilling up samples and running the rock powder through a series of on board chemical laboratories.