Organic carbon on Mars as explored by the Perseverance and Rosalind Franklin rovers

Organic molecules are one of the main building blocks of life as we know it.

The ability to detect and characterize organic molecules is therefore key for determining whether life ever existed on Mars. In situ measurements on Mars with rovers indicate the presence of indigenous organic molecules on Mars.

However, further analyses are needed to verify these tantalizing results and find the origin of the detected organic molecules.

Two missions to Mars provide opportunities for improved understanding of the carbon chemistry of Mars: the NASA Mars 2020 Perseverance and the ESA ExoMars Rosalind Franklin rovers.The NASA Mars 2020 Perseverance rover has since 2021 explored Jezero crater, which has been identified as lacustrine (lake)/deltatic/fluvial setting and a potentially past habitable environment.

One of the main goals of Perseverance, in addition to search for signs of past life, is to collect samples for future Mars sample return. Perseverance has up to date collected 24 samples within Jezero crater.

The next step is to collect samples at the crater rim which contain of some oldest rocks on Mars, when Mars was its most habitable (>3.8 Ga).

The crater rim contains several sites that could have potentially accumulated organic molecules and biosignatures, including phyllosilicates in the Noachian basement and potential hydrothermal features.

I have been selected, as an expert in production and preservation of organic matter in the solar system and in the analysis of organic molecules in samples related to Mars, to participate in Mars 2020 mission to help select and document the best targets and samples to be analyzed and collected by the Perseverance rover.

I will also help interpret data collected by the rover to improve our understanding of organic preservation on Mars.The ESA ExoMars Rosalind Franklin rover, due to be launched in 2028 and land on Mars in 2030, will search for signs of present and past life on Mars.

The landing site, Oxia Planum, which might have been habitable in the past, contains ancient (⁓4 Ga) wide-spread phyllosilicate deposits optimal for preservation of organic molecules including biosignatures.

The rover has the capability to drill up to 2 m cores, which allows for the analysis of subsurface samples, including organic molecules, unaltered by surface destructive processes such as radiation and oxidants. The main instrument for organic analysis on the rover is the Mars Organic Molecule Analyser (MOMA).

MOMA has two main modes of operation: a) pyrolysis-gas chromatography mass spectrometry (Py-GC-MS) and b) laser desorption ionization mass spectrometry (LDI-MS). These different modes will enable MOMA to analyze range of different polar and nonpolar compounds up to 1000 u.

As the flight model of MOMA has been delivered the focus of the MOMA team is to prepare for scientific activities on Mars. I am Co-I on the MOMA instrument and part of the ExoMars rover science operation working group (RSOWG).

Activities in the proposed project will include participating in the science activities of the MOMA instrument and the Rosalind Franklin rover and contributing to the MOMA and rover characterization campaigns.

The characterization campaign will focus on meteorites, kerogens and Oxia Planum analogues and the samples will be analyzed with both prototypes of the MOMA instrument, other rover instruments and commercial instruments.

This characterization data is critical for the success of the ExoMars mission.With my research focus, expertise in analysis of relevant samples, and mission experience, I am well prepared to participate in the science activities of the Perseverance and Rosalind Franklin rovers.

By participating in both missions, I will be able to combine the data/science from them and contribute to a better understanding of the carbon chemistry of Mars including the origin of any detected molecules, the past and present carbon cycle on Mars and the potential for life on Mars.