Case of Mars' mysteriously vanishing atmosphere solved

Scientists have long wondered how Mars transformed into the cold, dry desert it is today when it once was very similar to Earth. But NASA published new research Thursday from its Mars-orbiting MAVEN spacecraft that might at last solve this scientific mystery.

Mars’ atmosphere leaks into space at about a half a pound a second. Although this might sound impressive, scientists say that even this rate over the solar system’s 4.5-billion-year history would not be enough to fully erode a thick Earth-like atmosphere.

According to research published in this week’s issue of Science, MAVEN’s data reveals stronger erosion rates of Mars’ atmosphere during solar storms. The "interplanetary coronal mass ejection," also called an aurora, causes “dramatic spikes in the number of oxygen and carbon dioxide ions spewing into space.” 

Jasper Halekas, a professor of physics and astronomy at the University of Iowa and a member of the MAVEN team, told The New York Times that the solar storm studied in early March “is the equivalent of a tsunami at Mars.”

Because Mars does not have a global magnetic field like Earth, its atmosphere is left unprotected and vulnerable to periodic solar storms from the sun, caused by high-energy blasts of the sun’s gas and solar ultraviolet radiation.

The storms are so powerful, that Professor Halekas said the energy hitting Mars’ atmosphere is comparable to a million tons of TNT an hour, or “one large nuclear weapon per hour, if you like.”

MAVEN scientists say we have Earth’s magnetic field to thank for our aurora-ignorance. 

“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 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?’” 

To better understand when Earth-like conditions were present on the Red Planet, scientists with NASA’s MAVEN mission want to understand how much of Mars’ atmosphere has been lost to space, including influence from such solar storms. 

“Solar-wind erosion is an important mechanism for atmospheric loss, and was important enough to account for significant change in the Martian climate,” Joe Grebowsky, a MAVEN project scientist explained in NASA’s press release. “MAVEN also is studying other loss processes – such as loss due to impact of ions or escape of hydrogen atoms – and these will only increase the importance of atmospheric escape.”

This report contains material from Reuters and The Associated Press.