NASA scientists have found evidence of liquid water on the surface of the Red Planet.
The space agency announced today that after years of investigation, they have determined that water intermittently seeps from below ground and on to the Martian surface. The water appears to ebb and flow depending on the season and the weather.
NASA scientists had previously detected crystalized water in the Martian soil and traces of large ancient water flows millions of years old, but this is the first time they have found evidence of water flowing on present-day Mars.
"We're starting to put together a much more interesting picture of what Mars is really like," said John Grunsfeld, an astronaut and associate administrator of NASA's Science Mission Directorate, at a press conference. "Our instruments today are showing us a much more dynamic and complex planet, and that is very exciting."
Discovering the presence of water on Mars is a big step for scientists, but it also leads to other questions. Since water is a key element needed for life as we know it, could life have ever existed on Mars? And if it did, could life on Mars still exist, or could evidence of that ancient life be found?
Since NASA plans to send humans to Mars in the 2030s, could their habitat be built near one of the areas with water so astronauts could use it for drinking and to grow crops?
"When you look at Earth, water is a central ingredient," said Michael Meyer, lead scientist for NASA's Mars Exploration Program. "Everywhere you go, there is liquid water, even if it's deep in the Earth. We haven't been able to answer the question, does life extend beyond Earth? But now we have a much better idea of where to look … and now we can thoroughly look for life and make that positive identification."
The water seeping to the surface of Mars, scientists say, is extremely briny. It's much saltier than the Earth's oceans but that doesn't mean it can't be used by future human explorers.
"Our results may point to more habitable conditions on the surface of Mars than we had once thought," said Mary Beth Wilhelm, an astrobiology Ph.D candidate and a civil servant with NASA's Ames Research Center. "Water may be an important resource for future explorers and may decrease the cost and increase the activity of humans on the planet."
The discovery began when scientists noticed dark streaks that appeared and then mysteriously disappeared on mountainsides and slopes in different areas of the planet. The streaks seemed to show up in warm seasons -- when temperatures are above minus-10 degrees Fahrenheit -- and fade as the seasons cooled.
Researchers then began using the imaging spectrometer on the Mars Reconnaissance Orbiter to study the area and detected hydrated salts on the slopes where the streaks had been.
Scientists say it's likely a shallow subsurface flow, with enough water seeping to the surface to explain the dark streaks. Now scientists will explore further to find out if there is a substantial amount of water in aquifers close to the surface.
Alfred McEwen, a principle investigator with the Mars Reconnaissance Orbiter, said he's not only looking forward to finding out more about the amount and location of the water on Mars, he's also expecting to find evidence of present-day life there.
"I think the possibility of life in the interior of Mars is rather high," he said. "It's very likely, I think, that there is life in the crust of Mars – microbes. Maybe there's something we can find close to the surface."
NASA has sent robotic rovers, including Curiosity and its predecessor Opportunity, to study Mars. Next year, NASA is scheduled to launch a mission that will probe the interior of Mars. Scientists hope to learn whether the planet's core is solid or liquid, and why its crust is not divided into tectonic plates like the Earth's surface.
In 2020, NASA plans to launch its next super rover, that is designed to search for minerals, make oxygen on the Martian surface and continue NASA's search for signs of life.