NASA officials said on 3 March that the agency may pursue a 2016 launch of an orbital mission to scout for methane hotspots on Mars, in preparation for a 2018 lander mission that would perform astrobiological tasks.

The orbital mission, called the Mars Science Orbiter (MSO), would produce detailed maps of atmospheric methane plumes recently hinted at by Earth-based observations and by older evidence from the Mars Express orbiter, which is funded by the European Space Agency (ESA).

In an effort to pursue joint Mars missions, ESA and NASA are looking at ways to get the MSO and ExoMars, a €1.2-billion (US$1.5-billion) rover also slated for a 2016 launch, on the same rocket.