The More We Explore Mars, the More Fascinating It Becomes!
New Mars Map – revealing vast water-rich mineral deposits scattered across the Red Planet – is transforming our understanding of Mars’s watery past and highlighting potential landing sites for future human missions.
Scientists have never been more astonished by the history of water on the Red Planet. It turns out that Mars has a “priceless” history of water that is more relevant to Earth scientists than ever!
Mars is Closer Than Ever
Today, Mars is a dry planet, but there is ample evidence suggesting it once had flowing water across its surface. Water-bearing minerals can be found in rocks that have been chemically altered by water in the past, often transforming into clay and salts.
New discoveries indicate that water played a much larger role in shaping Mars’s geology throughout its history.
NASA and the European Space Agency (ESA) have contributed to an entirely new understanding of Mars by creating a global map of water-rich areas on the planet.
This invaluable map has been meticulously crafted over the past decade using data from the Observatoire pour la Mineralogie, l’Eau, les Glaces et l’Activité (OMEGA) instrument on ESA’s Mars Express and NASA’s Compact Reconnaissance Imaging Spectrometer for Mars (CRISM).
Specifically, the map displays the locations and abundance of water-bearing minerals. These minerals come from rocks that have been chemically altered by water in the past, often converting into clay and salts.
Data from ESA’s Mars Express and NASA’s Mars Reconnaissance Orbiter were used to create the first detailed global map of water-rich mineral deposits on Mars. (Source: ESA / Mars Express (OMEGA) and NASA / Mars Reconnaissance Orbiter (CRISM))
The data from these two Mars missions have been used to create the first detailed global map of water-rich mineral deposits on the Red Planet. These minerals are primarily clay and salts, which can narrate the history of water in various regions of Mars. Largely, clays formed on Mars during its early wet period, while many salts still visible today were created as water gradually dwindled.
Landing sites and other areas of interest are highlighted on the map (see image below):
- Mawrth Vallis is an ancient water channel rich in clay.
- Oxia Planum is a clay-rich area. These clays include iron and magnesium-rich minerals such as smectite and vermiculite, along with local kaolinite. Oxia Planum has been selected as the landing site for ESA’s Rosalind Franklin rover.
- Hydrated silica has also been mapped in an ancient delta in Oxia.
- Meridiani Planum lies along the Martian equator and was the landing site of NASA’s Opportunity rover in 2004.
- Valles Marineris is one of the largest canyons in the Solar System.
- Gale Crater and Jezero Crater were the landing sites for NASA’s Curiosity and Perseverance rovers in 2012 and 2020, respectively.
The types of clays displayed on the map include iron and magnesium phyllosilicates, zeolites, and aluminosilicate clays. The salts shown are carbonates formed by carbon and oxygen. (Image source: ESA / Mars Express (OMEGA) and NASA / Mars Reconnaissance Orbiter (CRISM))
On Earth, clays form when water interacts with rocks, with varying conditions resulting in different types of clays. For example, clay minerals like smectite and vermiculite form when relatively small amounts of water interact with rocks. Consequently, they retain most of the chemical elements similar to the original volcanic rock.
In the case of smectite and vermiculite, those elements are iron and magnesium. Rocks can undergo more alteration when larger amounts of water are present. Soluble elements tend to be washed away, leaving aluminum-rich clays such as kaolinite (a white, crumbly, fire-resistant clay).
Researchers were surprised by the prevalence of these minerals. Ten years ago, planetary scientists were aware of about 1,000 rock outcrops on Mars. However, the new water map has changed the narrative, revealing hundreds of thousands of such areas in the oldest regions of the Red Planet.
Planetary scientist John Carter from the Institute d’Astrophysique Spatiale in Paris, the lead author of the paper published in the journal Icarus, stated: “This new water map transforms our understanding of the history of the Red Planet. With this map, we no longer doubt that water played a tremendous role in shaping the geology across this planet.”
Jezero Crater and its surrounding environment on Mars display a variety of rich minerals that have been altered by water in the Red Planet’s past. These minerals are primarily clays and carbonates. Close-up data obtained from the global mineral map created by ESA’s Mars Express and NASA’s Mars Reconnaissance Orbiter. NASA’s Perseverance rover, which landed on Mars in 2020, is currently exploring Jezero Crater and its surroundings. (Source: ESA / Mars Express (OMEGA) and NASA / Mars Reconnaissance Orbiter (CRISM))
The critical question now is whether water existed persistently or was limited to shorter, more intense periods. While no definitive answers have been provided, the new findings certainly equip scientists with a more powerful tool to pursue these answers.
Professor John Carter remarked: “I think we have oversimplified Mars as a whole.” He explained that planetary scientists tended to believe that only certain types of clay minerals on Mars were formed during its wet period, and that as water dwindled, salts formed across the planet.
This new map shows that it is more complex than previously thought. While many salts on Mars may have formed later than clays, the map indicates numerous exceptions with a close mix of salts and clays. There are even some types of salts believed to be older than some clays.
“The evolution from a water-rich to a water-poor state is not as straightforward as we thought; water did not just stop overnight. We see a geological context that is so diverse that no single process or timeline can explain the evolution of mineralogy on Mars. That is the first outcome of our study. The second is that if you exclude terrestrial life processes, Mars exhibits a diversity of mineralogy in geological environments akin to Earth.”
In other words, the more we closely observe, the more complex Mars’s past becomes.
“The Right-Hand Man” of NASA and ESA
The OMEGA and CRISM instruments are exceptionally suited for this survey. Their datasets are highly complementary, operating across the same wavelength range and sensitive to similar minerals.
CRISM uniquely provides high-resolution spectral images of the surface (down to 15m/pixel) for localized areas on Mars, making it most suitable for mapping small regions, such as landing sites for rovers. For instance, the map reveals Jezero Crater, where NASA’s Perseverance rover landed in 2020, displaying a variety of rich water-bearing minerals.
As part of the global mineral mapping process on Mars, the Oxia Planum area was discovered to be rich in clay. Oxia Planum has been selected as the landing site for ESA’s Rosalind Franklin rover. (Image source: ESA / Mars Express (OMEGA and HRSC) and NASA / Mars Reconnaissance Orbiter (CRISM)).
On the other hand, OMEGA provides global coverage of Mars at higher spectral resolution and with better signal-to-noise ratios. This makes it more suitable for global and regional mapping while distinguishing between different altered minerals.
The results are presented in a pair of scientific papers authored by Professor John Carter, Lucie Riu, and their colleagues. Lucie Riu worked at the Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Sagamihara, Japan, during part of the work but is currently an ESA researcher at the European Space Astronomy Centre (ESAC) in Madrid, Spain.
With fundamental discoveries in hand, Lucie Riu decided to take the next step and quantify the minerals present. She stated: “If we know the location and the ratio of each type of mineral present, it will give us a better idea of how those minerals might have formed.”
This work also provides mission planners with excellent candidates for potential landing sites on Mars in the future.
Firstly, water molecules still exist within the mineral water. Along with the known locations of buried ice, this offers potential areas for extracting water for human use of in-situ resources, which is essential for establishing human bases on Mars. Salts and clays are often the building materials used on Earth.
Secondly, even before humans set foot on Mars, the minerals in water provide excellent locations for conducting scientific research. As part of this mineral mapping campaign, a clay-rich site in Oxia Planum has been discovered. These ancient clays include iron and magnesium-rich minerals such as smectite and vermiculite. They could not only help unlock the past climate of the Red Planet but also serve as the perfect site to investigate whether life ever existed on Mars. Consequently, Oxia Planum has been proposed and ultimately selected as the landing site for the European Space Agency’s Rosalind Franklin rover.
Lucie Riu remarked: “This is what I am passionate about, and I believe this type of mapping work will pave the way for future research. The more we learn about this planet, the more intriguing it becomes.”