Evidence of Water on Mars

Evidence of Water on Mars

Researchers have found evidence of an existing body of liquid water on Mars.

Liquid water may still flow on Mars, but that doesn't mean it's easy to spot. The search for water on the Red Planet has taken more than 15 years to turn up definitive signs that liquid flows on the surface today. Almost all water on Mars today exists as ice, though it also exists in small quantities as vapor in the atmosphere. Abundant water ice is also present beneath the permanent carbon dioxide ice cap at the Martian south pole and in the shallow subsurface at more temperate conditions. What they believe to be a lake sits under the planet's south polar ice cap, and is about 20km (12 miles) across. Observations of the Red Planet indicate that rivers and oceans may have been prominent features in its early history. Billions of years ago, Mars was a warm and wet world that could have supported microbial life in some regions. But the planet is smaller than Earth, with less gravity and a thinner atmosphere. Over time, as liquid water evaporated, more and more of it escaped into space, allowing less to fall back to the surface of the planet.

 How was it found?

Understanding the extent and situation of water on Mars is vital to assess the planet’s potential for harboring life and for providing usable resources for future human exploration. For this reason, "Follow the Water" was the science theme of NASA's Mars Exploration Program (MEP) in the first decade of the 21st century. Discoveries by the 2001 Mars Odyssey, Mars Exploration Rovers (MERs), Mars Reconnaissance Orbiter (MRO), and Mars Phoenix lander have been instrumental in answering key questions about water's abundance and distribution on Mars. The ESA's Mars Express orbiter has also provided essential data in this quest. The Mars Odyssey, Mars Express, MRO, and Mars Science Lander Curiosity rover are still sending back data from Mars, and discoveries continue to be made.

What does this mean for life?

On Earth, all forms of life need water to survive. It is likely, though not certain, that if life ever evolved on Mars, it did so in the presence of a long-standing supply of water. On Mars, we will therefore search for evidence of life in areas where liquid water was once stable, and below the surface where it still might exist today.

Nothing definitive. Yet.

Dr Manish Patel from the Open University explained: "We have long since known that the surface of Mars is inhospitable to life as we know it, so the search for life on Mars is now in the subsurface.

"This is where we get sufficient protection from harmful radiation, and the pressure and temperature rise to more favourable levels. Most importantly, this allows liquid water, essential for life."

This principle of following the water is key to astrobiology - the study of potential life beyond Earth.

So while the findings suggest water is present, they don't confirm anything further.

"We are not closer to actually detecting life," Dr Patel told BBC News, "but what this finding does is give us the location of where to look on Mars. It is like a treasure map - except in this case, there will be lots of 'X's marking the spots."

The water's temperature and chemistry could also pose a problem for any potential martian organisms.

In order to remain liquid in such cold conditions (the research team estimate between -10 and -30 Celsius where it meets the ice above), the water likely has a great many salts dissolved in it.

"It's plausible that the water may be an extremely cold, concentrated brine, which would be pretty challenging for life," explained Dr Claire Cousins, an astrobiologist from the University of St Andrews, UK.