NASA Scientists Think They’ve Solved the Mystery of Mars’ Missing Atmosphere—and All Its Water

image via NASA/GSFC

2015 has been a pretty good year for Mars: In September, scientists announced they’d found evidence of liquid water on the Martian surface, and in October, fictional astronaut Mark Watney’s time there helped propel Ridley Scott’s space adventure, The Martian, to both box office success and critical acclaim. Now, in the waning months of the year, the red planet is once again in the headlines, as NASA today announced findings that shed light on one of the biggest planetary mysteries of all time:

What happened to Mars’ atmosphere, and all its water?

image via youtube screen capture // NASA

In a press conference held Thursday afternoon, NASA researchers described the process by which they now believe Mars went from warm and moist to cold and dry, some billions of years ago. Quoting Bob Dylan, one of the NASA representatives explained simply “the answer is blowin’ in the wind.” But not just any ordinary wind. NASA, as part of their Mars Atmosphere and Volatile Evolution mission (affectionately dubbed "MAVEN"), places the blame for the loss of Mars’ once-substantive atmosphere squarely on solar wind, the charged particles expelled by our sun, which blast toward planets at ultra-high speeds. In Mars’ case, the solar wind doesn’t often hit the planet directly, instead “stripping” ions off the very thin layers of Mars’ upper atmosphere. By measuring the rate of this ionic loss, researchers were able extrapolate that these winds essentially blew the bulk of that planet’s atmosphere away, eons ago. And, as the Martian atmosphere diminished so too did Mars’ ability to retain moisture, until it became the dry, desert planet it is today, capable of hosting miniscule amounts of briny water, but nothing more.

This NASA animation shows what the process of stripping Mars of its atmosphere looks like:

Explains John Grunsfeld, associate administrator for the NASA Science Mission Directorate, in an agency press release

“Mars appears to have had a thick atmosphere warm enough to support liquid water which is a key ingredient and medium for life as we currently know it. Understanding what happened to the Mars atmosphere will inform our knowledge of the dynamics and evolution of any planetary atmosphere. Learning what can cause changes to a planet’s environment from one that could host microbes at the surface to one that doesn’t is important to know, and is a key question that is being addressed in NASA’s journey to Mars.”

Here on Earth, we’re largely spared the Mars effect thanks to our planet’s strong magnetic field, which shields us from solar wind’s charged particles. Mars, on the other hand, having long since lost its geo-magnetic field, was left susceptible to solar elements. And even if Earth were to undergo some catastrophic planetary event which were to leave us without magnetic protection, researchers believe that we’d still be in better shape than Mars was, billions of years ago. That’s because the rate of atmospheric loss is related to the strength of the solar winds buffeting the planet, and the sun today is a much calmer, less volatile star than it was eons ago.

These new Martian findings are part of a renewed effort by NASA to focus interest and research on the Red Planet, ahead of an eventual manned mission to its surface. To that end, NASA announced this week that they would soon begin accepting applications to join a new class of Astronauts, to be announced in mid-2017. If the prospect of manned space travel—and the possibility of someday setting foot on a planet whose very atmosphere was stripped away by harsh solar winds—appeals to you, you can learn more about applying to be an astronaut on the NASA site.

[via NASA]