Unravelling the Mars’ atmosphere Main Mysteries (MCUBE) – MCUBE

The work carried out within the project is essentially based on the Mars Express and Trace Gas Orbiter missions which are revolutionizing our understanding of the Martian atmospheric and climatic system. These two missions carry on board instruments that have been developed jointly by the two partners and whose collected data constitute the core of the analysis conducted by the two partners.
Associated with this analysis work, a three-dimensional theoretical modeling has been undertaken in order to give an interpretation to the observed data, in particular for the isotopes of water present in the atmosphere, notably HDO,
Thus, the consortium has an «end-to-end« arsenal to analyze in depth the data produced by the SPICAM and ACS instruments.
No other group currently offers such a comprehensive capability to analyze and understand the Martian atmosphere, which has already led to several major discoveries.

Among the most important results, we can mention:
-1st detection of HCl on Mars, the first halogen gas spotted in this atmosphere and associated with potential surface activity (outgassing) that our observations associate instead with chemical processes separating surface chlorine from rocks and dust grains ;
-Affirmation that methane is not present on a global scale at a level ten times lower than that reported by the Curiosity rover, implying an unknown chemistry to explain this discrepancy of results;
-Characterization of water vapor up to more than 100 km altitude and evidence of a dominant season in the ability of water vapor to project into a region of the atmosphere leading to its escape to space;
Evidence of the preponderant role of photolysis in the proportion of deuterium atoms in the population of hydrogen atoms in the very high atmosphere (see recent article on this issue: theconversation.com/pourquoi-ny-a-t-il-presque-plus-deau-sur-mars-163312).

With both missions still disposing plenty of resources, the M3 project is ensured of a continuous production of new data to be analysed by the ever improving 3D climate model that includes an HDO representation developed by our team.
The year 2021 has been exceptionally rich in publications, while another series of publications is expected by 2022, dealing with important consideration for Martian climate, in particular the year-to-year variability of dust storms and its impact on the water cycle. Several Martian years will be jointly covered by Mars Express and Trace Gas Orbiter that may eventually provide robust information on the deepest mechanisms controlling the fate of water on Mars, from its production near the surface up to its escape in space; a process that has probably shaped over aeons the Martian atmosphere into the form we know today.

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Mars exploration entered its golden age in the late 1990s with NASA's Mars Pathfinder and Mars Global Surveyor missions, 12 years after the last successful Martian mission: the short Phobos mission sent by the Soviets in the mid-1980s and the Viking mission on the verge of 80s. Since then, NASA and ESA have been sending probes to and around Mars, making Mars the most visited alien body in the solar system. Since then, Mars has gradually taken on a new face thanks to evidence of real activity such as the presence of rapid changes in the Martian landscape, the appearance of dust storms enveloping the entire planet, or the detection of atmospheric gases whose origin remains unknown. Despite this intense exploration of Mars, its atmosphere has remained a field of research where many unknowns remain. It is widely accepted that today's tenuous Martian atmosphere is only a remnant of a previously denser and probably warmer atmosphere that may have allowed the formation of vast expanses of perennial liquid water. However, retrieving the primitive state of the Martian atmosphere, that is, 3 to 4 billion years ago, which correspond to the oldest traces of liquid water on the surface, requires a complete characterization and understanding of the processes that control present-day Mars' climate. Without this essential step, any temporal extrapolation will remain only an academic exercise leaving more open questions than solved mysteries.
The MCUBE project is driven by the desire to promote one of the most productive partnerships in the Martian exploration community and is run by two laboratories in France (LATMOS) and Russia (IKI). These two laboratories are jointly engaged in space exploration through ExoMars Trace Gas Orbiter (TGO) and Mars Express (MEX), the two Martian missions led by the European Space Agency (ESA) and Roscosmos (the Russian equivalent) that currently orbit and operate around Mars to examine the composition and phenomena present in the atmosphere and on Mars' surface. The two laboratories share the scientific responsibility for one instrument for each mission: The French MCUBE leader is the principal investigator (PI) of SPICAM on MEX, while the Russian leader is the PI of ACS on TGO. Both are engaged in a close partnership to decipher the central enigmas of the Martian atmosphere and try to answer the following questions:
1. Is Mars still an active planet? Are there any indications of degassing gas emissions and/or volcanic or biogenic emissions in the composition of the atmosphere, such as the presence or absence of methane?
2. What governs the current water cycle on Mars and that of HDO, its main isotope?
3. How do aerosols interact and control the climate of Mars?
Trying to answer these fundamental questions is the very driving force behind the partnership set up by our consortium and these answers, MCUBE has access to them thanks to all the experiences (MEX/SPICAM and TGO/ACS) developed and exploited respectively by the French leader of MCUBE and its Russian partner. The scientific effort of MCUBE will be shared by a team of highly experienced researchers and engineers as well as by qualified non-permanent staff. The very nature of the existing cooperation between the French and Russian partners of MCUBE implies a balanced and harmonious distribution of the workload and the scientific/technical contribution. The historic cooperation between LATMOS and IKI guarantees that MCUBE will maximize the benefits that France can derive from its contribution to Mars exploration and make it as visible and beneficial to the scientific community as possible.