NASA’s Perseverance rover has just crossed a remarkable milestone. In fact, it became the first spacecraft to capture a visible-light picture of a green aurora on Mars! This stunning observation from the rover was possible while it was parked in the Jezero Crater. This incident unfolded only days after a similar massive solar flare had taken place. The journal Science Advances today published a landmark study detailing this discovery. In the process, it tells us amazing stories about the otherworldly atmospheric mysteries unfolding over the Red Planet.
The green aurora was recorded by two instruments onboard the Perseverance rover, which successfully identified the exact shade of green illuminating Mars’ sky. Mars experiences a special kind of aurora, due to the planet’s irregular and diffuse magnetism spread out on the surface. Different from Earth, where auroras are created by solar particles interacting with a global magnetic field, Mars does not have that luxury. This special aurora on Mars is what scientists call a solar energetic particle (SEP) aurora. This happens when highly charged solar particles hit the Martian atmosphere head on.
Understanding Martian Auroras
The auroral phenomenon on Mars has been known for about 20 years, mainly through space-based observations. Compared to Earth’s magnificent light shows, Martian auroras are likely to be more modest. Dr. Elise Knutsen, a physicist at the University of Oslo and lead author of the study, talked about the significance of their findings.
“When we saw the strength of this one, we estimated it could trigger an aurora bright enough for our instruments to detect,” – Dr. Elise Knutsen.
Unlike Earth, Mars does not have a global magnetic field. Consequently, solar particles produce fewer photons when they impact the Martian atmosphere. This is in stark contrast to Earth’s more robust magnetic field that shields the planet and produces brilliant auroras. To pinpoint when and where the aurora would illuminate the Martian night sky, Dr. Knutsen’s team employed sophisticated computer models. They put a spotlight on the need to really know what’s happening in the atmosphere.
The Role of Solar Activity
Solar activity is a critical ingredient for producing these auroras. The recent solar flare was responsible for that green aurora being detected. This was another great reminder of the tight link between solar weather and Martian atmospheric processes. Dr. Schunker, a coauthor on the study, discussed the significance of solar maximum with regards to auroral activity.
“We’re approaching, or we’re in the middle of, solar maximum at the moment. We never know if we’ve reached solar maximum until we’re on the other side of it,” – Dr. Schunker.
This current solar cycle has a significant effect on both Mars and Earth. Particularly, it provides fresh clues on how solar flares might strip away planetary atmospheres. The purpose of the research is to advance theoretical models of coronal mass ejections and to better predict the patterns of solar weather.
Implications for Future Research
Overall, these observations by Perseverance add to a broader understanding of Martian atmospherics and solar interactions. Dr. Schunker’s work suggests that the Martian atmosphere would be able to exhibit detectable changes in response to auroras. These changes will be very small.
“There might be a detectable change in the atmosphere, but it would not be strong and it would not be very obvious to the eye,” – Dr. Schunker.
He went into detail on how auroras, even here on Earth, often don’t look like they do in photographs.
“The photographic images that are taken of the auroras on Earth are often exposed for some minutes, so you get these really bright, vivid colours. Whereas if you see it with your eyes, it doesn’t look quite so bright and quite so vivid, although still impressive,” – Dr. Schunker.
Additional research on Martian auroras will deepen our scientific understanding. It is expected to deliver unique and scientifically valuable data to support scientists in evaluating solar weather from multiple perspectives.
