NASA and the European Space Agency have selected five instruments for a methane-sniffing Mars orbiter scheduled for launch in 2016, the first mission of a transatlantic partnership to reconnoiter the Red Planet.

Artist's concept of the ExoMars Trace Gas Orbiter. Credit: ESA

The payloads will seek methane and other trace gases in the Martian atmosphere and collect high-resolution snapshots of the planet's surface.

Since its discovery on Mars in 2003, methane has been a priority for planetary scientists. The presence of methane implies Mars still harbors microbial life or continues to be geologically active. Scientists say either explanation would prove Mars is not a dead planet.

Representatives from both space agencies selected two spectrometers, two cameras and a radiometer for the ExoMars Trace Gas Orbiter scheduled for launch in January 2016.

ESA leads the project and is building an entry, descent and landing demonstrator to piggyback on the spacecraft. NASA will provide an Atlas 5 launch vehicle to send the orbiter toward the Red Planet.

The agencies announced the winning payloads Monday after a six-month competition open to researchers in the United States and Europe. Scientists submitted 19 proposals, according to a joint press release.

The probe's two spectrometers will sniff out the chemical signatures of trace atmospheric gases, or compounds that comprise a tiny fraction of Martian air. A sensor led by a Belgian scientist will map the locations of trace gases on Mars, while a U.S. and Canadian spectrometer will detect very low concentrations of atmospheric components.

Paul Wennberg, a researcher at the California Institute of Technology, is leading one of the spectroscopy teams with help from the Canadian Space Agency.

The Mars Atmosphere Trace Molecule Occultation Spectrometer, or MATMOS, payload will look for methane at a sensitivity of parts per trillion, Wennberg told Spaceflight Now in an e-mail.

It will determine seasonal distributions of methane and potential sources of the gas.

"We did a calculation which shows that the microbial community found in three cows' bellies would produce an amount of methane that, in the Mars atmosphere, would be observable by MATMOS," said Mark Allen, principal scientist at the Jet Propulsion Laboratory and a visiting associate in planetary sciences at Caltech.

MATMOS can also detect water, carbon dioxide, carbon monoxide, formaldehyde, ethane, propane and a host of other nitrogen, sulfur and carbon-bearing compounds, according to Wennberg.

The instrument will take measurements as the ExoMars spacecraft goes through sunrise and sunset. MATMOS will collect scattered sunlight and look for microscopic variations in the light caused by specific molecules in the atmosphere.

A high-resolution camera aboard the trace gas mission will snap stereo images of the Martian surface.

Called HiSCI, short for High resolution Stereo Color Imager, the camera can spot objects as small as 6.6 feet across on Mars. HiSCI will follow up on the HiRISE telescopic camera on the Mars Reconnaissance Orbiter, which has a peak resolution of about 1 foot per pixel, according to Alfred McEwen, the camera's principal investigator at the University of Arizona.

McEwen also heads the HiRISE science team.

"What HiSCI does better is provide much more extensive coverage in color and in stereo," McEwen wrote in an e-mail to Spaceflight Now.

The prolific HiRISE camera, which has returned stunning Mars images since 2006, can only see less than one-tenth of a percent of the planet in color or stereo each year. HiSCI can see about 2 percent of Martian surface each year, McEwen said.

HiSCI will also gather context imagery of regions where the spacecraft's other instruments detect methane.

The ExoMars orbiter's final two instruments include a JPL-led sounder to provide daily global measurements of dust, water vapor and other chemicals in the atmosphere.

A wide-angle global imager from Malin Space Science Systems of San Diego will also take pictures to aid the analysis of results from other instruments.

The ExoMars Trace Gas Orbiter will also carry telecommunications equipment to relay data between Earth and two rovers scheduled to launch in 2018.