The European Space Agency and Roscosmos’ ExoMars program is sending a series of spacecraft to Mars to find out if life ever existed on Mars. Besides looking to answer this scientific question, ExoMars will also test out possible technologies to return a sample of Mars back to Earth — something that has never yet been done.
The first part of the ExoMars mission arrived at the Red Planet on Oct. 19, 2016. It was composed of two spacecraft: the Trace Gas Orbiter (TGO), which was designed to look at gases from orbit, and the Schiaparelli demonstration lander, which was designed to test landing technologies. TGO arrived at Mars safely, but Schiaparelli was lost upon landing. The second part of the ExoMars mission, to launch in 2020, will include a rover that will include a drill and other instruments to probe the Martian surface.
Early program history
Early European studies for an exobiology station in the solar system were performed in 1996 and 1998, according to a 2002 Proceedings of the First European Workshop on Exo-Astrobiology conference paper, called “Study of a Mars exobiology multi-user facility.” It was written by three participants in what is now the ExoMars mission, and led by Wolfgang Schulte from German technology company Kayser-Threde GmbH. (The company was merged under the name OHB System AG in 2014).
The 1998 study focused on looking at life on Mars, and among its recommendations was creating an “instrument package” to land on Mars and drill for evidence of life below the surface. In 2000, a Phase A study for what was then called the Exobiology Multi-user Facility (EMF) — later renamed ExoMars — was issued with three main components: a sample acquisition, processing and handling system; a set of analytical instruments; and a service module.
Around the same time, ESA’s Aurora Space Exploration Programme had an eventual goal to explore Mars using robots and humans. A “preparatory phase” lasted from 2002 and 2005, with various members of ESA choosing to participate and contribute funds, according to a 2006 report from the program. ExoMars was approved for further development at a ministerial meeting in late 2005.
An initial launch date of 2009 was pushed back several times, and the choice of launch vehicle also changed a few times. NASA agreed to participate in the mission in 2009 after ESA’s ministerial council asked for international co-operation to do ExoMars. The agencies created a Mars Exploration Joint Initiative that was supposed to cover launches in 2016, 2018 and 2020.
At the time, NASA intended to launch ExoMars, but that changed in 2012 when the agency received big budget cuts to its planetary science division. At that point NASA elected to prioritize certain missions (such as the James Webb Space Telescope). NASA withdrew from ExoMars, and ESA went searching for another partner. Roscosmos, the Russian space agency, then signed on to provide the launch vehicles, the surface platform for the ExoMars rover, and some other pieces of the mission.
TGO and Schiaparelli
The Trace Gas Orbiter (TGO) is designed to look at the smaller constituents of gas in the Martian atmosphere. While Mars is dominated by carbon dioxide, less prevalent molecules such as methane could be instrumental in helping scientists understand if there is life on the surface.
Methane could be an indicator of biological activity, but it’s unclear how much methane there is – or its source – as varying amounts have been measured across different missions. In late 2013 and early 2014, NASA’s Curiosity rover saw a spike in methane abundance during the Martian autumn. When autumn returned to Gale Crater in 2016, however, the spike was not repeated. This shows that the methane may not be linked to seasonal activity.
TGO will search for trace gases such as methane, water vapor and nitrogen oxides with its suite of four science instruments. It will look at how the atmosphere’s composition and temperature change with the seasons, and will search for subsurface hydrogen as it seeks underground water-ice deposits. When the ExoMars rover arrives (which is expected to happen in 2021), TGO will also serve as a communications relay for the rover’s activities.
Riding along with TGO was a lander demonstrator called Schiaparelli, which was intended to test landing technologies and also to operate for a few days on the surface. Schiaparelli carried an instrument package nicknamed DREAMS (Dust Characterization, Risk Assessment, and Environment Analyzer on the Martian Surface) that was supposed to look at things such as wind speed, atmospheric temperature and atmospheric electric fields.
TGO and Schiaparelli both launched for Mars on March 14, 2016. The two craft separated a few days before their expected arrival on Oct. 19. TGO did a successful burn to go into orbit, and watched the Schiaparelli spacecraft as it attempted a landing. Schiaparelli, however, made it through the atmosphere and then stopped communicating moments before landing. The cause of Schiaparelli’s loss is still being investigated; luckily, there is data on its landing from TGO up until almost the last moment. NASA’s Mars Reconnaissance Orbiter also imaged the crash site a few days after landing.
Rover and surface platform
The second phase of the ExoMars mission will include a Russian-built surface platform and a European-built rover. The rover’s scope has changed a couple of times due to funding changes. After Roscosmos signed on, the ExoMars rover was expected to launch in 2018.
That date was pushed back two years to 2020 due to “industrial delays” on both the European and the Russian side, the European Space Agency said in May 2016. Mars missions are launched in a “window” that happens roughly every two years, when Earth and Mars are closest to each other and the least fuel is required to travel to the Red Planet. If a mission misses its window, therefore, it must wait until the next one is available.
When the rover reaches Mars, its science objectives will be to look for signs of life (in the past or the present) and to look at water and other elements just below the surface. Investigators say that Mars could be an easier location than Earth to look for ancient life because Mars does not have widespread plate tectonics. On Earth, plate tectonics tend to “recycle” old rocks and remove past indications of life.
ExoMars will also carry a drill so that it can look at the geochemical environment just below the surface. The drill is about 2 meters (6.5 feet) long, which (if successful) will make it the longest such drill ever used on the Red Planet.
It is believed that organic substances – a possible indication of life – could be preserved in the Martian underground, but only if it is far enough down to avoid penetrating radiation on the Martian surface, ESA said in a statement on the mission. Any life on the surface would likely be baked or swept away by Martian winds, although that hasn’t been established for sure.