The story begins in 2024 when NASA’s Perseverance rover became the first to photograph a visible light aurora from Martian surface. Now, Dr. Elise Wright Knutsen and her team from the University of Oslo has revealed a second successful image and, more importantly, the method her team developed to forecast when these Martian northern lights will appear.
“The fact that we captured the aurora again demonstrates that our method for predicting aurorae on Mars and capturing them works” – Dr. Elise Wright Knutsen from the University of Oslo.
Aurorae on Mars work similarly to Earth’s northern lights but with crucial differences. When a coronal mass ejection erupts on the Sun sending a burst of charged particles into space, these particles eventually slam into the thin Martian atmosphere. The collision causes oxygen atoms high above the planet to glow with an eerie green light that could be bright enough for future Mars astronauts to see with their naked eyes.
Four images from Perseverance’s Mastcam-Z. The left hand-side images show both detections of the aurora, on 18 March and 18 May 2024. On the right are non-detections with comparable sky illumination (from Mars’s moons) to show the contrast in colours between a night with aurora and a night with no aurora (Credit : Elise Wright Knutsen et al.)
This is somewhat unlike the auroral displays many of us have enjoyed on Earth, which are typically confined to the polar regions thanks to our planet’s magnetic field. Mars lacks this protective magnetic shield so the Martian displays can appear anywhere across the planet’s night side as a diffuse glow spreading across the entire sky.
Of course it is wonderful to see pictures of these stunning displays but it’s not just about capturing the pictures! The same solar radiation that creates these auroral displays poses serious risks to human explorers. Without advance warning of incoming solar storms, astronauts could face dangerous exposure to high energy particles. Having a reliable prediction system could literally be a matter of life and death for future Mars missions and that’s the real driving force behind the study.
NASA astronaut Bruce McCandless II using a Manned Manoeuvring Unit outside Space Shuttle Challenger on shuttle mission STS-41-B in 1984 (Credit : NASA)
Predicting Martian auroras, however, proves to be remarkably challenging. It’s tricky enough here on Earth to grab a few pictures of the elusive displays but the team had to plan their observations three days in advance, uploading instructions to Perseverance’s cameras before they even knew if a solar storm would actually create an aurora!
Between 2023 and 2024, the team made eight attempts to capture a display, succeeding only twice. The first three attempts yielded nothing, teaching the researchers valuable lessons about what conditions actually produce visible aurora on Mars. By analysing data from NASA’s MAVEN orbiter and ESA’s Mars Express, they discovered that the speed of the solar storm matters enormously. According to Dr. Knutsen, the faster the coronal mass ejection, the more likely it is to accelerate particles towards Mars that create aurorae. Armed with this knowledge, the team began targeting faster, more intense solar storms and that’s when they achieved their historic detections.
This growing collection of Martian aurora observations, combining both visible light detections from the surface and ultraviolet observations from orbiting spacecraft, is building a crucial database. Each new image helps us better understand how the aurora work on a planet without a global magnetic field, potentially revolutionising our knowledge of space weather throughout the Solar System.
Source : Predicting the green glow of aurorae on the red planet