The first mission within the ESA-NASA ExoMars Programme, scheduled to arrive at Mars in 2016, consists in an Orbiter plus an Entry, Descent and Landing Demonstrator Module (EDM).

The ESA-led Orbiter will perform detailed, remote observations of the Martian atmosphere, searching for evidence of trace gases of possible biological importance, such as methane and its degradation products. Instruments onboard the Orbiter will carry out a variety of studies, including:

Highly sensitive measurements of trace gases from which the composition of the atmosphere can be determined. This will provide important clues to the possible origin of the gas source, for example, is it of volcanic or biogenic origin?
The measurement and low-resolution imaging of aerosols in the atmosphere, investigation of the temperature variations in the atmosphere, and the mapping of key trace gas species other than methane.
High-resolution imaging of gases in order to provide the geological context, if it exists, for sources that have been identified.

The payload will include European and American instruments.

The second mission within the ESA-NASA ExoMars Programme, scheduled to arrive at Mars in 2018, consists of two rovers: the Esa's ExoMars Rover and a Nasa's Rover.

The science objectives of the ExoMars Rover, in order of priority, are:

To search for signs of past and present life on Mars;
To characterise the water/geochemical environment as a function of depth in the shallow subsurface.

The ExoMars Rover mission will pursue one of the outstanding questions of our time by attempting to establish whether life ever existed, or is still active on Mars today. The Rover will carry a comprehensive suite of analytical instruments dedicated to exobiology and geochemistry research: the PASTEUR payload. The Rover will travel several kilometres searching for signs of past and present life, collecting and analysing samples from within rocky outcrops and from the subsurface, down to a depth of 2 m.

More information about ExoMars Rover science objectives