The quest for oceanic sediments within the Ancient Martian sedimentary record

The Martian missions have gradually revealed that Mars abounds with evidence of a full ancient hydrological system favourable to life emergence. If so, there is every reasons to believe that Mars has hosted a hemispheric ocean covering the northern lowlands. This hypothesis is as old as Mars exploration, but has been repeatedly challenged over the past two decades.

The case of primitive Martian ocean remains one of the planet’s most controversial and unsolved issue.

Recent discoveries are re-opening this question mainly highlighting that the main oceanic activity may be older than we thought with related deposits partly exhumed and two rovers (Mars2020/NASA arrived in 2021 and ExoMars/ESA-Roskosmos to be launched in 2022) have landing sites in the oldest terrains never explored on Mars, displaying sediments possibly linked with an ocean system.

To wind up the debate, the identification of ancient deposits of the same age, same composition with a global distribution in agreement with a possible ocean level is required.

But such clues are small scale exposures solved only by high-resolution orbital data set (>10 To of data) or by in situ exploration preventing a forward link to the global context.

Oceanid proposes to face this challenge by investigating at different scale: global, mesoscale and microscale using complementary dataset (orbital, in situ and experimental data).

Oceanid will also lie on innovative methodology of orbital data mining: geological object recognition by artificial intelligence, erosion/deposition evolution models, clustering from multi-type of data…Oceanid objectives are to describe the early Martian sedimentary record accumulated below possible global ocean levels, to establish a fine-scale chronology of primitive events, to contextualize Mars2020 and ExoMars missions within the global ancient hydrological system and to correlate the oceanic context, the transient water cycle, and the mineralogy observed both from orbit and in situ.