Future expedition will greatly benefit from new map of Mars waters

Using data from ESA’s Mars Express Observatory for Mineralogy, Water, Ice and Activity (OMEGA) instrument and the Mars Reconnaissance Orbiter Compact Reconnaissance Imaging Spectrometer for Mars (CRISM ) from NASA, scientists have created a new map of the waters of Mars that could change our understanding of the planet’s aquatic past. It shows mineral deposits across the planet and suggests where future landings should take place.

Specifically, the map shows the locations and abundances of water minerals from rocks that have been chemically weathered by the action of water in the past and have generally been transformed into clays and salts.

The big surprise is the prevalence of minerals such as smectite and vermiculite. About 1,000 outcrops on Mars were known to planetary scientists ten years ago. They become intriguing as geological oddities because of this. However, the new map has changed that by exposing thousands of these regions in the oldest parts of the planet.

Global map of hydrated minerals on Mars
Global map of hydrated minerals on Mars. Credit: ESA/Mars Express (OMEGA) and NASA/Mars Reconnaissance Orbiter (CRISM)

John Carter, Institute of Space Astrophysics (IAS) and Marseille Astrophysics Laboratory (LAM), Paris-Saclay University and Aix Marseille University, France, said: “This work has now established that when you study ancient terrains in detail, not seeing these minerals is an oddity.”

“This is a paradigm shift for our understanding of the history of the Red Planet. From the smaller number of aqueous minerals we previously knew were present, water could have been limited in extent and duration. Now, there is no doubt that water has played a huge role in shaping geology all around the planet.

Whether the water was persistent or confined to shorter, more intense episodes remains elusive. This new study doesn’t offer a definitive answer, but it does give researchers a better tool to search for the answer.

Water-rich minerals at Jezero Crater
Water-rich minerals at Jezero Crater. Credit: ESA/Mars Express (OMEGA) and NASA/Mars Reconnaissance Orbiter (CRISM)

John said, “I think we’ve collectively oversimplified Mars. Planetary scientists have tended to think that only a few types of clay minerals on Mars were created during its wet period, and then as the water gradually dries up, salts have been produced around the world.

It’s more complex than previously thought, according to this new map. The map illustrates many instances where there is an intimate mixture of salts and clays, as well as some salts, which are considered older than others, although many Martian salts are likely to have formed later than the clays.

John said, “The evolution from lots of water to no water isn’t as clear as we thought, the water didn’t stop overnight. We see a great diversity of geological settings, so no single process or timeline can explain the evolution of the mineralogy of Mars. This is the first result of our study. Second, if you exclude life processes on Earth, Mars exhibits a diversity of mineralogy in geological contexts, just like Earth.

The OMEGA and CRISM instruments are perfectly suited to this investigation. OMEGA provides global coverage of Mars with higher spectral resolution and better signal-to-noise ratio. CRISM uniquely provides high resolution spectral surface imagery (up to 15 m/pixel) for very localized areas of Mars and makes it best suited for mapping small regions of interest, such as sites rover landing gear.

This survey also provides mission planners with several excellent prospects for potential landing sites in the future for two factors. First, there are still water molecules in aqueous minerals. This provides potential locations for water extraction for in situ resource use, essential for building human bases on Mars, as well as known locations of subsurface water ice. Second, even before humans got to Mars, aqueous minerals provide fantastic places to do science.

Journal reference:

  1. John Carter et al. A Mars Orbital Catalog of Aqueous Weathering Signatures (MOCAAS). Icarus. DOI: 10.1016/j.icarus.2022.115164
  2. Lucie Riu et al. The M3 project: 3 – Global distribution of the abundance of hydrated silicates on Mars. Icarus. DOI: 10.1016/j.icarus.2021.114809

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