An artist's conception of what Mars may have once looked like juxtaposed with the red planet's cold, dry environment today.
Scientists working with data gathered by the MAVEN spacecraft orbiting Mars have made some surprising finds about the red planet’s atmosphere, described in a quartet of papers published today in the journal Science. Related findings were also published online in the journal Geophysical Research Letters.
Since it entered Mars’ orbit a little more than 13 months ago, on September 21, 2014, MAVEN (Mars Atmosphere and Volatile EvolutioN) has explored Mars’ upper atmosphere, ionosphere, and magnetosphere to try to understand the history of the Martian climate, and how the planet lost its atmospheric gas over time. Billions of years ago Mars was warmer and wetter. So where did all the water and carbon dioxide in the early Martian climate go?
Early in the mission, MAVEN mapped the distribution of carbon, oxygen, and hydrogen as a cloud surrounding the planet. While the first two cling tightly to Mars, hydrogen extends well above the planet. Understanding its escape from the atmosphere is important because hydrogen is the primary ingredient in water. MAVEN’s orbit brings it close to Mars’ polar caps, while Mars’ daily rotation beneath the spacecraft exposes its east-west faces. This allows the spacecraft to observe the planet’s entire atmosphere.
Here are a few of the findings MAVEN’s scientists announced today, based on data gathered through that comprehensive coverage:
Its atmosphere is affected by solar events. Scientists found this by studying data collected by MAVEN during a burst of gas and magnetism from the Sun in March 2015. This interplanetary coronal mass ejection (ICME) sparked strong fluctuating magnetic rotations that threw rope-like tendrils more than 3100 miles into space. Because the escape rate of ions is enhanced during solar bursts, this may indicate how substantial atmospheric loss could have occurred in early Martian history.
Its thermosphere and ionosphere have large vertical temperature and density gradients. They are caused by a steady mixing of carbon dioxide, argon, nitrogen dioxide, and a lot more oxygen than researchers expected to find. These results will help scientists better understand the interactions between solar wind and the Mars atmosphere.
It has Northern Lights–like auroras that dip to just 37 miles above the surface—the nearest ever discovered. First detected last year in Mars’ northern hemisphere using an instrument that measures UV light, the aurora is similar to the Northern Lights in that the acceleration of particles in or out of the atmosphere along electromagnetic fields creates what would likely be a stunning visual—if you were standing on Mars, that is. But while the Northern Lights are driven by magnetism of the Earth’s poles, Mars’ auroras may be sparked by the remnant magnetic field of the crust, creating a more even and diffuse aurora. Sounds lovely.
Finally, dust in the atmosphere is otherworldly. Scientists detected evenly distributed dust way above the surface, from 124–621 miles up. If it’s Mars dust, they can’t explain how it got there, because there are no known processes that can lift significant concentrations of particles from a planetary surface to such high altitudes. The team suspects the dust is of an interplanetary origin.
What does this all add up to? At 2 pm ET, the scientists began discussing just that on NASA TV. If you can't tune in for details, make sure to return to mental_floss tomorrow, when we’ll have a more in-depth look at these discoveries by space journalist and regular contributor David Brown.