– These decisions are made by consensus within the scientific community and of course we feel extremely happy to contribute to this international effort, says Javier Martín-Torres, Professor of Atmospheric Science at Luleå University of Technology who together with Maria Paz Zorzano, also a Professor of Atmospheric Science, have been part of a small group of experts invited by the European Space Agency, to be involved in the selection process.
The two chosen sites are in the northern hemisphere of Mars, and they are called Oxia Planum (18.3N, 335.3E) and Mawrth Vallis (22.6N, 16.5W). Both sites preserve a rich record of Mars’ geological history and traces from billions of years ago when the planet was much wetter; a crucial circumstance since ExoMars is about answering the eternal question of life on Mars.
Good sites for HABIT
On ExoMars 2020, ESA will send a rover and a Russian space platform to Mars. The rover will drive around and investigate the planet while the platform will remain stationary and investigate the local surface environment. One of the instruments on this platform is HABIT, an instrument designed and built at Luleå University of Technology in collaboration with Omnisys Instruments. The HABIT instrument is dedicated to investigating the habitability on present day Mars by quantifying the availability of liquid water, the thermal ranges and UV doses.
– From the HABIT point of view we are equally interested on both the proposed landing sites. With our present knowledge, and bearing in mind that we have never landed at the proposed landing sites and we do not know what the environmental conditions will be, we can only extrapolate from our models and orbiter measurements. And according to that, both proposed sites behave almost similarly.
No Earth life to Mars
One of the most important issues to take into consideration when choosing landing site is safety. For a safe landing, the ground must be plain without inclined surfaces or large rocks. Also, the local winds need to be predictable, ideally soft, such that they cannot deviate the trajectory during the Entry Descent and Landing phase (EDL). It also helps if the site is deep and if there is a larger mass of air (total atmospheric pressure) in order to slow down the landing module’s descent.
Another important thing is to keep Mars clean from biological contamination. If the ExoMars 2020 mission finds some kind of biological life it should undoubtedly come from the red planet and not from Earth. Hence it is extremely important that the rover and the platform are clean when leaving Earth.
– Earth life forms can survive the traverse, in the form of spores, and they may produce new generations with sufficiently mild temperatures, nutrients and liquid water, says Javier Martín-Torres.
– Also, there is the debatable fact about our right to contaminate another planet, with the consequences that this may have for any hypothetical life forms inhabiting the planet.
The two chosen sites will now be further evaluated and the final decision will be made around a year before launch.
Besides HABIT, both Javier Martín-Torres and Maria Paz Zorzano are involved in two more ExoMars instruments. They are co-Investigators of the Infrared Spectrometer for ExoMars (ISEM) instrument on the ExoMars rover and the Atmospheric Chemistry Suite (ACS) on the Trace Gas Orbiter.