On March 15th, 2024, the Sun released a powerful solar flare that coincided with a heightened period of solar activity.
This was accompanied by a coronal mass ejection (CME), a massive cloud of solar energetic particles (SEP) that led to auroras all across the Solar System.
This included Mars, where NASA’s Perseverance rover made history by capturing a visible light image of the event with its Mastcam-Z instrument.
This was the first time that an aurora was witnessed from the surface of another planet.
On Earth, auroras are a common phenomenon that occurs whenever solar particles interact with the global magnetic field.
This field channels these energetic particles towards the poles, where they interact with atmospheric gases to produce the famous Northern Lights (Aurora Borealis) and Southern Lights (Aurora Australis). While Mars does not have a global magnetic field like Earth, it has localized magnetic fields and a very thin atmosphere by comparison (less than 1% of the atmospheric pressure).
On Earth, the most common color associated with auroras is green, which is caused by the excitation of oxygen atoms.
For years, scientists predicted that Mars might also experience green light auroras, except they would be far fainter and more difficult to image. Hence why all previous observations of auroras on Mars have been by orbiters in ultraviolet wavelengths. This includes NASA’s Mars Atmosphere and Volatile EvolutioN (MAVEN), which observed an SEP aurora from orbit in 2014.
Consequently, capturing this image required serious coordination and timing. Elise Knutsen, a postdoctoral researcher at the University of Oslo in Norway, was the lead author of the study that reported the detection, which recently appeared in Science Advances.
Since SEPs typically occur during solar storms, especially during the peak of the Sun’s eleven-year solar cycle (aka solar maximum), Knutsen and her team planned their observations to coincide with the peak of the Sun’s current solar cycle.
They also created models that determined the optical angle for the Perseverance rover’s SuperCam spectrometer and Mastcam-Z camera to observe it. The next step consisted of waiting for the right type of CME to happen.
This task fell to NASA’s Moon to Mars (M2M) Space Weather Analysis Office and the Community Coordinated Modeling Center (CCMC) at NASA’s Goddard Space Flight Center. The former provides real-time analysis of solar eruptions to the CCMC, which uses the data to run simulations of CMEs and determine if they could impact NASA missions.
When their simulations predict a potentially hazardous CME, the M2M team sends out of alert. As Knutsen explained in a NASA press release:
“The trick was to pick a good CME, one that would accelerate and inject many charged particles into Mars’ atmosphere. When we saw the strength of this one, we estimated it could trigger [an] aurora bright enough for our instruments to detect. This exciting discovery opens up new possibilities for auroral research and confirms that auroras could be visible to future astronauts on Mars’ surface.”
The team included researchers from Colorado’s Laboratory for Atmospheric and Space Physics (LASP), UC Berkeley, NASA’s Goddard Space Flight Center, and Jet Propulsion Laboratory, which collaboratively oversee NASA’s MAVEN mission. By coordinating Perseverance’s observations with measurements from MAVEN’s SEP instrument, the teams helped determine that the light detected was the same emission line as green auroras on Earth.
“Perseverance’s observations of the visible-light aurora confirm a new way to study these phenomena that’s complementary to what we can observe with our Mars orbiters,” said Katie Stack Morgan, acting project scientist for Perseverance at NASA’s Jet Propulsion Laboratory.
“A better understanding of auroras and the conditions around Mars that lead to their formation are especially important as we prepare to send human explorers there safely.”
What’s more, future astronauts are likely to be able to see this type of aurora from the Martian surface.
Written by Matthew Williams/Universe Today.
