A solar storm on September 11 sparked planet-wide aurorae on Mars 25 times brighter than previous observations, doubling the ground radiation level. The consequences of this intense event were detected by the Curiosity Rover on the surface and by MAVEN in orbit.

"NASA's distributed set of science missions is in the right place to detect activity on the Sun and examine the effects of such solar events at Mars as never possible before," MAVEN Program Scientist Elsayed Talaat, program scientist at NASA Headquarters, said in a statement.

MAVEN stands for Mars Atmosphere and Volatile Evolution and is equipped with ultraviolet instruments that can study extremely faint Martian aurorae. Curiosity sports a Radiation Assessment Detector (RAD) which has monitored the planet’s surface since the mission started in 2012. The high post-storm reading lasted more than two days.

"This is exactly the type of event both missions were designed to study, and it's the biggest we've seen on the surface so far," RAD Principal Investigator Don Hassler of the Southwest Research Institute added. "It will improve our understanding of how such solar events affect the Martian environment, from the top of the atmosphere all the way down to the surface."

Mars doesn’t have a magnetic field like Earth, so aurorae are not limited to higher latitudes, instead they can form globally. Particles from the Sun hit the entire atmosphere which emits UV light. This particularly intense storm just made it much brighter.  

The solar event was so impressive that we were able to detect its effects even on Earth, although we were on the opposite side of the Sun at the time. It came just a few days after our planet experienced a sudden and unexpected burst of activity from the Sun.

"The current solar cycle has been an odd one, with less activity than usual during the peak, and now we have this large event as we're approaching solar minimum," explained Sonal Jain of the University of Colorado Boulder, a member of MAVEN's Imaging Ultraviolet Spectrograph instrument team.

Using both atmospheric and on the ground monitoring, it’s very important to prepare for future crewed missions to the red planet. Since Mars lacks a magnetic field, astronauts wouldn’t have much protection during a solar storm.

"If you were outdoors on a Mars walk and learned that an event like this was imminent, you would definitely want to take shelter, just as you would if you were on a space walk outside the International Space Station," Hassler clarified. "To protect our astronauts on Mars in the future, we need to continue to provide this type of space weather monitoring there."