Mars’ atmosphere is so puny, it amounts to less than one percent of Earth’s.
Yet the Red Planet at one time apparently had rivers and lakes, which suggests a much larger layer of insulation. Where did this thick Martian atmosphere go? Solving that mystery is the first order of business for NASA’s Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft, which arrived in orbit around Mars Sunday evening.
“One of the really overarching questions about Mars is whether there was ever life,” Bruce Jakosky, MAVEN principal investigator at the University of Colorado, Boulder, told reporters last week.
Life, most scientists assume, would have required liquid water—as all life on Earth does. Maven’s measurements will aim to study its atmosphere now and extrapolate back in time, to understand what it might once have been and how it was lost. “We’re learning about the history of the habitability of Mars,” he says.