ExoMars 2016: the Search for Life
March 18, 2016
On Monday, March 14, a rocket blasted off for Mars. The joint mission of the European Space Agency (ESA) and the Russian Federal Space Agency (Roscosmos) will arrive at the Red Planet in October. When it reaches orbit, ExoMars 2016 will sniff the Martian atmosphere to see if it smells like life.
Mars is the fourth planet from the sun. Today, it is a cold, desolate place. It orbits some 142 million miles (228 million kilometers) away from the sun, about 1 ½ times the distance at which Earth orbits. Its atmosphere is about 100 times less dense than Earth’s. Water exists there only as ice or in small, briny, subsurface streams in the Martian summer. Mars has no global magnetic field to protect it from harmful solar radiation. It is hard to imagine life—even bacteria—eking out an existence in such a place.
For a brief time after it formed some 4.6 billion years ago, however, scientists think that Mars was a warmer, wetter planet, much like Earth. Since scientists think life emerged on Earth shortly after its formation, it is possible that life arose on Mars at this time as well, when conditions were more favorable. If it developed, this early life could have gone extinct as Mars cooled and its atmosphere was blown away by the solar wind. Some of it, however, could have survived, most likely as microscopic organisms living underground. Determining whether Mars has hosted or still hosts life is extremely important in figuring out how common or rare life is in the universe. If it developed twice in the same solar system, the odds are good that it developed elsewhere, too.
ExoMars 2016 consists of two modules: the Trace Gas Orbiter and an entry, descent, and landing demonstrator nicknamed Schiaparelli (after Italian astronomer Giovanni Schiaparelli). The Trace Gas Orbiter will scan Mars’s atmosphere for gases that might indicate the presence of life, such as methane. On Earth, such gases are usually formed as a byproduct of living things.
In addition to looking for possible signs of life in the atmosphere, ExoMars 2016 will pave the way for an even more ambitious future mission. If all goes according to plan, Schiaparelli will be the first successful lander for either the ESA or Roscosmos. (Both have made previous, failed attempts to land a probe on Mars.) With this experience, the ESA and Roscosmos plan to send a large rover to the planet in 2018. This rover will continue to look for signs of past and present Martian life. It will carry a drill able to bore up to 8 feet (2 meters) below the surface. If life is hiding out on Mars, the ExoMars missions just might find it.