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The search for Martian water

By Carlos Manuel Eusoya

PHOTO: Youtube

In 2011, American planetary scientist Lujendra Ojha theorized that water exists on Mars’ surface. Using satellite data, Ojha found patterned streaks in Martian soil and landscapes. He believed that these patterns were not created by ancient or frozen water. They were directly formed by flowing liquid water that can be unearthed in the Red Planet.

Ojha’s discovery had slowly set the stage for the decade-long search for Martian water.


Part I: The search begins

Remote sensing studies of Mars’ surface and previous analyses of Martian meteorites can be traced back to the 1980’s. Data from these reports suggest that Mars may have been once rich in liquid water.
Mars, which is 38.6 million miles away from our home planet, is located in the outer edges of the Goldilocks Zone.

The Goldilocks Zone, also known as the “habitable zone”, is the proper distance from a Sun or a star. If a planet is placed within this zone, the planet will have the sufficient temperature to keep its water as a liquid. If the planet is too close to the star, its water evaporates due to the extreme heat. If the planet is too far away, then its water freezes.

Water is the most vital compound for all known living organisms. It is the foundation of life and the criteria scientists use to identify potential Earth-like planets.

Scientists have been using remote sensing data to continually evaluate the presence of water in Earth’s neighboring planet. Remote sensing refers to the gathering of information about a subject without making direct contact. In the case of astronomy, it is the study of planets using satellite data.

In 2015, the Mars Reconnaissance Orbiter owned by the National Aeronautics and Space Administration (NASA) detected long dark spots on the Red Planet. The only possible explanation for the formation of these spots was water flow. This supported Ojha’s theory.

In the following years, the rovers Curiosity and Perseverance showed scientists clearer images of the Martian surface. Curiosity’s findings suggest that 2 percent of Mars may be covered by surface water. Meanwhile, Perseverance discovered ancient delta and river patterns in the craters of Mars.

Even with these breakthroughs, we are yet to detect the slightest trace of visible water in the Red Planet. Could it be that Martian water is found only on undiscovered craters yet? Or were the discoveries simply misleading us that Martian water exists?


Part II: The search encounters turbulence

“We now know Mars was once a planet very much like Earth with warm salty seas and freshwater lakes. Something has happened to Mars, it lost its water,” says Jim Green, NASA’s planetary science director.

For a few years, the once-hyped search for Martian water had been decreasing in popularity. Without an actual basis for the existence of water, most scientists have turned their focus on other issues and topics to study.

The turbulence only got worse. In 2017, Ojha’s theory and the rovers’ discoveries were disproved by the data of the Mars Reconnaissance Orbiter. It showed that water flow was not the only factor that could form patterns in Martian landscapes. Dust grains and sand flows are more believable explanations for these patterns.

NASA is still determined in their mission. They recently announced that they will be sending the Volatiles Investigating Polar Exploration Rover (VIPER) in 2023. VIPER’s goal is to find evidence of water in Mars’ South Pole.

The determination of scientists to continue searching for water in our neighboring planet is exemplary. However, will this determination succeed in detecting Martian water? Or will VIPER be another failed attempt, succeeding Ojha’s research?


Part III: A disappointing ending?

The search may be over soon.

A new study from Washington University has made it clear. Mars is too small to have water.

“There is likely a threshold on the size requirements of rocky planets to retain enough water to enable habitability and plate tectonics, with mass exceeding that of Mars,” said Kun Wang, an assistant professor of earth and planetary sciences in Washington University, and the senior author of the study.

Wang and his fellow researchers used potassium to evaluate the abundance of volatile elements in Mars. Through remote sensing, the study measured potassium in 20 Martian meteorites and found that the meteorites lost more volatile potassium than Earth.

Volatile elements, such as potassium and water, are easily evaporated. By measuring how fast potassium is lost, the researchers can also estimate how fast water is lost on the Red Planet. They found that the rate of water loss is very high.

“Martian meteorites are the only samples available to us to study the chemical makeup of the bulk Mars. Through measuring the isotopes of moderately volatile elements, such as potassium, we can infer the degree of volatile depletion of bulk planets and make comparisons,” Wang said.

Wang and his collaborators then theorized that the size of a planet is proportional to the volatile elements it loses. In other words, Mars is not able to contain water for long periods of time because of its small size.

Their research may be the conclusion of the search for Martian water, but their study also opens up new opportunities. Scientists can now better identify Earth-like planets. They will not only have to consider whether a planet is inside the Goldilocks zone; they will also have to take into account the size of the planet.

“These results will guide astronomers in their search for habitable exoplanets in other solar systems,” said Klaus Mezger, the co-author of the study.

The decade-long search for Martian water has been one tumultuous ride. Although the search was composed of many failed attempts, one can never call it a failure. It improved the criteria being used to identify Earth-like planets. It also showed new data about volatile elements. More importantly, it is a testament to the spirit of the scientific community.

The search for Martian water may be over, but the search for habitable exoplanets will still continue.