NASA released a paper in Nature Geoscience on Monday, September 28, detailing the discovery of liquid water flowing on the surface of present-day Mars, though calling it flowing water is a bit of a misnomer.
Alfred McEwen, a co-author of the paper, said in the news conference that the discovery is only a thin layer of wet soil, likely only a centimeter deep. The discovery of water on Mars is nothing new; however, many in the scientific community believe that liquid water is necessary to support microbial life.
The discovery was made using NASA’s Mars Reconnaissance Orbiter, which has an imaging spectrometer that allowed researchers to determine the presence of hydrated minerals on the planet’s surface. Images of the planet show dark streaks, known as recurring slope lineae, flowing down slopes.
The reason water is able to be present in liquid form, instead of subliming, is the presence of perchlorates. These compounds, such as sodium perchlorate, magnesium chlorate, and magnesium perchlorate, can lower the freezing point of water by as much as 70 degrees Celsius.
Liquid water being present on the surface of Mars does not suggest that microbial life is any more likely to be found. The evidence suggests that the water might be as much as 95 percent salt which is, not optimal for most forms of life. There are microbes that have been studied on Earth that are able to survive in such harsh conditions. It is more likely that life, if any, would be found under the surface of Mars. At this time, NASA has no rovers equipped to search for life in this manner. In a Reddit Ask Me Anything, a user by the handle of RZ said, “These features are on steep slopes, so our present rovers would not be able to climb up to them.” He also said that NASA considers these to be special locations, meaning that any equipment sent to the location would need to be sterilized to a higher degree to prevent any contamination.
Even if no life is discovered, the presence of liquid water is an exciting one. The water and minerals could be used for future expeditions, significantly reducing the costs associated with rovers and even colonization of Mars. Water can act as both a way to store energy and a source of oxygen and hydrogen, which can be burned as fuel.
At the moment, the next steps are focusing on further data gathering. Only approximately three percent of the martian surface has been covered at high enough resolutions to identify the hydrated minerals. This leaves much undiscovered territory for possible future missions.