A type of Martian aurora first recognized by NASA’s MAVEN spacecraft in 2016 is the most typical form of an aurora occurring on the Red Planet, based on new outcomes from the mission. The aurora is named a proton aurora and might help scientists track water loss from Mars’ atmosphere.
At Earth, the aurora is generally seen as colorful shows of light within the night time sky close to the polar regions where they’re also called the northern and southern lights. However, the proton aurora on Mars occurs during the day and gives off ultraviolet light, so it’s invisible to the human eye, however detectable to the Imaging UltraViolet Spectrograph (IUVS) instrument on the Mars Atmosphere and Volatile Evolution spacecraft.
MAVEN’s mission is to analyze how the Red Planet lost much of its atmosphere and water, transforming its climate from one which may have supported life to one that’s cold, dry, and inhospitable. Because the proton aurora is generated not directly by hydrogen derived from Martian water that is within the process of being lost to space, this aurora might be used to help track ongoing Martian water loss.
When the MAVEN group first noticed the proton aurora, they thought it was a relatively unusual occurrence. The correlation with the southern summertime gave a clue as to why proton aurora are so common and the way they might be used to track water loss.
More hydrogen within the corona makes interactions with solar-wind protons more common, making proton aurora more frequent and brighter.