Speed of Solar Wind Likely Stripped Water from Mars: NASA

The planet Mars showing Terra Meridiani is seen in an undated NASA image. NASA/Greg Shirah/Handout/Reuters

Most of the water from the atmosphere on Mars was likely stripped away by solar winds, making it the cold, red planet that it is today, NASA scientists said Thursday during a press event to discuss the results of recent studies.

Scientists sent the Mars Atmosphere and Volatile Evolution (MAVEN) orbiter to space in September 2014 to answer a number of questions. Their discussion today followed research revealed two months ago that seemed to confirm the presence of water on Mars.

MAVEN data has enabled researchers to determine the rate at which the Martian atmosphere is currently losing gas to space, by way of stripping by solar wind. The findings reveal that the erosion of Mars's atmosphere increases significantly during solar storms.

Unlike Earth, Mars doesn't have a magnetic field to shield its atmosphere from solar wind, which continuously blows from the sun, the scientists said. MAVEN measurements indicate the solar wind strips away gas at a rate of about 100 grams—or 1/4 pound—every second, according to NASA.

"We looked for water and we found it, but if you look at Mars today, it is a cold, dry, desert planet," said Michael Meyer, lead scientist for NASA's Mars Exploration Program.

Bruce Jakosky, principal investigator of MAVEN, comically compared the solar wind hitting Mars to when he steps out of the shower into the breeze, and water is stripped away from his hair.

The panelists' research is the result of the first six months of data analysis from MAVEN.