New NASA research released on Thursday appears to finally solve the mystery of how Mars transformed from an Earth-like planet to a rocky desert.
The research data, transmitted back to Earth from the Mars Atmosphere and Volatile Evolution (MAVEN) orbiter satellite, reveal that over time, solar winds – a high-speed stream of electrons and photons – stripped away Mars’s atmosphere at a rate high enough to significantly alter its composition. Charged particles from the sun erode Mars’s atmosphere by almost a quarter of a pound every second.
The MAVEN orbiter was launched into space in September 2014, with the intention of understanding where the water and CO2 in Mars’s early atmosphere went.
“Understanding what happened to the Mars atmosphere will inform our knowledge of the dynamics and evolution of any planetary atmosphere,” John Grunsfeld, astronaut and associate administrator for the NASA Science Mission Directorate in Washington, said in a statement.
“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,” he added.
Because Mars does not have a magnetic field, like Earth does, to protect it from solar winds, it is vulnerable to charged solar particles from nearly every direction. It is especially unprotected on its poles, where the solar winds flow in a “polar plume,” and from a “tail” of solar winds that flow behind the Red Planet.
Over time, the total impact of those solar winds gradually made Mars less hospitable to life forms, while still maintaining the conditions necessary to support water flow.
“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,” Dr. Grunsfeld said.
Other scientists who were involved in the project say they were kicking themselves that they hadn’t solved the riddle sooner.
“What we in hindsight were pretty foolish about was, what Earth’s magnetic field really does is prevent auroras from happening everywhere on Earth,” Dr. Nick Schneider, a planetary scientist at the University of Colorado and a member of the MAVEN team, told The New York Times.
“We sort of did this dope slap, saying, ‘Well, of course, what’s going to prevent these particles from the sun from slamming into Mars’ atmosphere anywhere and maybe everywhere?’”