This mineral prevalence is a big surprise, the newly released map has revealed. It was estimated that Mars had 1000 outcrops ten years ago. As a result, they were interesting as geological oddities. It was found, however, that hundreds of thousands of such areas exist in the oldest parts of the planet, according to the new map.

In addition to shedding light on Mars’ watery past, the updated map shows where future missions should land.

Over the past decade, the map has been painstakingly constructed using data from NASA’s Mars Reconnaissance Orbiter Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) instrument and the Mars Express Observatoire pour la Mineralogie, l’Eau, les Glaces et l’Activité (OMEGA) instrument to show mineral deposits across the planet.

Aqueous minerals are shown on the map, along with their locations and abundances. Typically, these are chemically altered rocks transformed into clays and salts due to water action in the past.

Clays on Earth are formed when water interacts with rocks, giving rise to different types of clays. Smectite and vermiculite, for example, are clay minerals formed when relatively small amounts of water interact with the rock, and they retain most of the same chemical elements.
Vermiculite and smectite have the elements iron and magnesium. Water can alter the rocks more when there is a high amount of it. Aluminum-rich clays such as kaolin tend to be left behind as soluble elements are carried away.

This mineral’s prevalence is a big surprise. It was estimated that Mars has 1000 outcrops ten years ago. As a result, they were interesting as geological oddities. It was found, however, that hundreds of thousands of such areas exist in the oldest parts of the planet, according to the new map.

As a result of this work, John Carter, from the Institut d’Astrophysique Spatiale (IAS) and Laboratoire d’Astrophysique de Marseille (LAM), Paris-Saclay and Aix Marseille Université, France, says, “Not seeing these minerals is actually the oddity when studying ancient terrains in detail.”

The red planet’s history has changed in a paradigmatic way as a result of this discovery. It was possible that water’s extent and duration were limited due to the smaller number of aqueous minerals previously known to exist. The geology of the planet has been profoundly shaped by water, without a doubt.

It is now crucial to determine whether the water was persistent or brief and intense. Although the new results do not provide a definitive answer, they certainly give researchers a better tool to pursue it.

An illustration showing a global map of hydrated minerals on Mars. Image Credit: ESA/Mars Express (OMEGA) and NASA/Mars Reconnaissance Orbiter (CRISM).

The way we understand Mars has been oversimplified collectively, says John. According to him, planetary scientists had been taught that only certain types of clay minerals were created on Mars during its wet period, then salts were produced as the water gradually dried up.

Compared to what was previously thought, this new map reveals that it’s far more complex.

Some salts on Mars may have formed earlier than clays, but the map shows several exceptions, including some salts that are likely older than clays and intimate mixing of salts and clays.

“The evolution from lots of water to no water is not as clear cut as we thought. The water didn’t just stop overnight. We see a huge diversity of geological contexts so that no one process or simple timeline can explain the evolution of the mineralogy of Mars. That’s the first result of our study. The second is that if you exclude life processes on Earth, Mars exhibits a diversity of mineralogy in geological settings just as Earth does,” he says.

Mars’s past becomes more complex the closer we look at it.

This survey is well suited to the OMEGA and CRISM instruments. As they work in the same wavelength range and detect the same minerals, their datasets complement one another very well. CRISM provides highly localized spectral imaging of Mars’ surface (down to 15m/pixel) and is optimal for mapping small areas of interest, such as rover landing sites, due to its high resolution and spectral resolution. A rich variety of hydrated minerals can be found in Jezero crater, the area where NASA’s 2020 Perseverance rover is currently exploring.

Omega, on the other hand, provides a better signal-to-noise ratio and higher spectral resolution for Mars. Doing so is more suited to mapping and discriminating between alteration minerals at a global and regional level.

John, Lucie Riu, and colleagues have written several papers describing the results. In addition to working at ESA’s European Space Astronomy Centre (ESAC) in Madrid, Lucie worked at the Institute of Space and Astronautical Science (ISAS), Japanese Aerospace Exploration Agency (JAXA) in Sagamihara, Japan, at the time parts of the work was completed.

Once Lucie had gathered the basic detections, she quantified the amounts of the minerals detected. We can better understand how minerals formed if we know where and how much each mineral is present,” she says.

Additionally, this research provides mission planners with some great landing site candidates – for two reasons. First of all, water molecules are still present in the aqueous minerals. Together with buried water ice found on Mars, this provides locations where water can be extracted for In-situ Resource Utilisation, which is crucial to the establishment of human colonies. Earth’s building materials include clays and salts.

Aqueous minerals represent fantastic locations to perform science even before humans travel to Mars. Oxia Planum, a clay-rich site, was discovered during this mineral mapping campaign.

The ancient clays contain smectite and vermiculite, which are rich in iron and magnesium. As well as revealing Mars’ past climate, they are ideal for investigating whether life once existed on Mars. ESA’s Rosalind Franklin rover was to land on Oxia Planum as a result.