Water on Mars: What We Know So Far

The search for water has always been a major goal of Mars exploration. Water is necessary for sustaining organic life, so its presence could prove that the planet can support living organisms. Meanwhile, evidence of water in the planet's past could prove that it was once able to sustain living things.

Water is key to discovering past and present life on Mars, but it also impacts the future. Extended exploration and even human colonization will depend on the availability of water.

Here’s a closer look at what past expeditions discovered and how these findings impact present and future plans for the Red Planet.

What Happened to the Water on Mars?

Currently, liquid water can’t exist on the surface of Mars. It evaporates because of the planet’s thin atmosphere. However, evidence suggests that Mars once had large amounts of water. Mars rover missions have found ancient riverbeds, lake deposits, and minerals that typically form in water.

These findings actually led to more questions rather than providing finite answers. Scientists have turned their attention to finding out what happened to this water. Such inquiries look at the geological and climate histories of the planet.

Exploration is ongoing, with several countries on extended missions using orbiters and surface rovers. You can keep up with the latest missions to Mars and learn about new findings, which could offer insights into the possibility of humans visiting and exploring the planet themselves.

First Evidence of Water on Mars

The first direct evidence of water on Mars came from the Mariner 9 mission, which discovered dried-up riverbeds on the planet's surface in 1971. The images from this spacecraft proved that water once flowed across Mars and impacted its landscape.

Later missions, such as that of the Mars Global Surveyor, revealed further signs of ancient water. The evidence included valleys and gullies that were likely shaped by flowing water. The Curiosity rover found evidence of ancient water as well. It discovered minerals, such as clays and sulfates, that typically only form in water.

These discoveries point to a wetter planet that once had the conditions to potentially harbor life. These early findings are enough to warrant continued exploration of Mars to learn more about its hydrologic past.

Water Ice on Mars

Liquid water can't exist on the surface without evaporating due to the thin Martian atmosphere. However, there’s evidence of past and present ice on the planet.

Scientists found the first evidence of ice on Mars during the Odyssey mission in 2002. The orbiter saw evidence of ice caps, which the Phoenix lander confirmed as water ice a few years later.

It’s essential to make the distinction between water ice, made up of hydrogen and oxygen, and dry ice, which is solid carbon dioxide. Mars' poles are covered with a top layer of dry ice. On Mars, this ice turns from solid to carbon dioxide vapor and doesn’t become liquid. Unlike regular ice, it doesn’t contain water and can’t support life. However, the poles of Mars remain cold enough to keep water ice in a frozen state even as dry ice evaporates.

Water Trapped in Minerals on Mars

A portion of Martian water could be trapped in minerals in the planet's crust. Evidence of such minerals challenges previous theories about the fate of water on Mars. The presence of hydrated minerals, like various clays and sulfites, proves that all water didn't evaporate. Some water is still contained inside minerals.

Though mineral water provides one answer to why there’s no water on the surface, it also brings new questions. The next challenge for scientists is to find out how much water is in minerals. This can help them learn more about the role atmospheric changes had in evaporating surface water. It can also offer insight into the potential availability of water for future human use.

Subsurface Water on Mars

Water can't survive on the surface of the planet. It sublimates, which means it turns from solid to gas without becoming liquid. When the Phoenix lander uncovered the ice first spotted by Odyssey, it didn’t melt but sublimated within a few days after being uncovered.

The Subsurface Water Ice Mapping Project (SWIM) seeks to find ice under the surface of Mars in areas that are more accessible than the poles. This ice can play a vital role in Mars exploration. Astronauts can land on the planet in areas near known ice reserves and access them to provide water for drinking and to make hydrogen fuel. The ice would make long-term exploration possible because astronauts wouldn’t be limited by a finite water supply.

How Can We Use Martian Water?

The presence of water can enable more in-depth human exploration of Mars. However, the presence of subsurface ice has implications for human activity on Mars in the long term. If early exploration efforts are successful, Martian water could eventually enable colonization.

Theoretical possibilities, like terraforming Mars to make it habitable, could become realistic if there are enough usable water reserves on the planet. Though there’s a long way to go to reach this point, having access to one of the most necessary elements to sustain life can take human habitation on Mars from science fiction to reality.

Continuing the Search for Water on Mars

New technology is aiding in the search for water ice on Mars. The SWIM project relies on high-resolution cameras, including a new piece of equipment known as the High-Resolution Imaging Science Experiment (HiRISE). It collects information on areas impacted by meteors and can spot ice in newly made craters before it turns into vapor.

Such advanced equipment and ongoing orbital and rover missions by different countries mean that major discoveries can happen at any time. Efforts like the SWIM project demonstrate how space agencies are rushing to expand new knowledge about water on the Red Planet and build on each discovery.

You can keep up to date on NASA's latest plans for expanding its knowledge of Martian ice. Each piece of knowledge the space agency gains about the planet's water supply puts it closer to realistically sending astronauts to Mars.