Abstract_EANA2025-116

Abstract EANA2025-116

Following the water on Mars

Eduardo Caetano Author (1), Pedro Machado Co-Author (1) and Zita Martins Co-Author (2)

(1) Faculdade de Ciências da Universidade de Lisboa, Portugal

Mars shows undeniable evidence of the presence of liquid water in its past; however, now only remnants of its aqueous past are left. When we look at the Martian surface, we see that, between the northern and southern hemisphere, there is a huge discrepancy in the number of impact craters. One possible attempt at answering this problem was done by the scientists behind the Chinese rover Zhurong [Xiao et al., 2023], which detected what could be sedimentary ocean floor rocks.

This means that there is a chance that the lack of small-medium sized impact craters is due to an ancient Borealis ocean. Another big question that this leaves behind is: what can we do to better understand this side of Martian history? Recent observations show that we do not truly understand the liquid past of our neighbouring planet, yet. In situ studies, such as the Zhurong rover, would provide the best data sets, however, it is a very costly and very meticulous process and it should not be the only method relied upon. Doing space-based reflectance studies of the martian surface has recently gained a lot more relevance with the discovery of low altitude hydrated silica (opals) as well as low-mid altitude water ice. Both ESA’s Mars Express (MEX) [Ruesch et al., 2012], and NASA’s Mars Reconnaissance Orbiter (MRO) [Ehlmann et al., 2009] are crucial for these kinds of studies.

In the framework of the present study, we used OMEGA (MEX) and CRISM (MRO) to study the reflectance of the surface of Mars, and look for opals, water ice and serpentines along the potential shore line of the Borealis ocean.

The areas of interest are: a deltaic deposit above the Ismeniae Fossae- Lat: 45.09275º, Lon: 38.18631º, and an impact crater centered at Lat: 18.13427º, Lon: 113.20802º.

Our work in short: 1. We identified and characterized morphological evidence related to fluvio-marine environments on Mars. 2. We used OMEGA (MEX) and CRISM (MRO) spectra data sets to do reflectance studies and identify different minerals present in these past fluvio-marine environments.