Mars Was Hit With a Solar Storm Days After Earth’s Aurora Light Show, NASA Says

Studying this event could hold lessons for scientists about how to protect astronauts from radiation on future trips to the Red Planet

Mars appears as a gray planet with purple light flashing across its entire left half
Purple squares illustrate auroras on Mars, as detected by NASA’s MAVEN orbiter between May 14 and May 20. The brighter the purple, the more auroras present. NASA / University of Colorado / LASP

Days after solar storms spurred widespread sightings of auroras across Earth in early May, a new bout of eruptions on the sun brought glowing skies to another planet: Mars.

From pole to pole, Mars was hit by a barrage of gamma rays and X-rays, followed by charged particles from a coronal mass ejection. These led to auroras that would have appeared, if any viewers were on its surface, as a deep green color, reports the New York Times Robin George Andrews.

But while humans were able to watch the Earthen spectacle safely—our planet’s magnetic field and atmosphere shielded us from the solar radiation and sent the charged particles toward the poles—such events would be more dangerous on the Red Planet, which lost its magnetic field long ago and has a much thinner atmosphere.

The storm hit Mars on May 20, offering researchers an opportunity to consider how solar radiation would impact potential future astronauts there.

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Typically, the Curiosity rover records an average of about 700 micrograys of radiation daily, writes’s Keith Cooper. But during the storm in late May, this jumped to 8,100 micrograys—the largest the instrument has detected in 12 years—and the equivalent of receiving 30 chest X-rays, all at once.

While not necessarily a fatal dosage, such a strong measurement prompts significant safety considerations for human missions to Mars in the future. The radiation was so powerful that the Mars Odyssey spacecraft was temporarily knocked offline. The instrument’s solar panels experienced about a year’s worth of degradation in a single day, and visuals captured by Odyssey and Curiosity were garbled with static. Though the data they collected were not impacted, it was a reminder that even technology isn’t immune to powerful energy bursts.

On Mars, this was “the strongest solar energetic particle event we’ve seen to date,” Shannon Curry, the principal investigator of NASA’s Mars Atmosphere and Volatile Evolution (MAVEN) orbiter, at the University of Colorado, Boulder, tells the New York Times. “These solar storms pack a punch.”

A gif from a video collected by NASA's Curiosity Mars rover during the solar storm on Mars, during which energy particles from the aurora hit the rover's camera.
Energetic particles from the sun hit the camera of NASA's Curiosity Mars rover during the solar storm, causing streaks and specks to appear in its view like static or "snow." NASA / JPL-Caltech

As NASA researchers consider a future with astronauts on Mars, they say humans could take a few protective steps to ensure their safety. Potential havens from space weather include cliff faces or lava tubes—hollowed-out volcanic chambers wherein astronauts could wait out a solar storm.

A solar storm of this magnitude was actually on Curry’s scientific wish list: “For humans and assets on the Martian surface, we don’t have a solid handle on what the effect is from radiation during solar activity,” she said in a NASA statement in April. “I’d actually love to see the ‘big one’ at Mars this year—a large event that we can study to understand solar radiation better before astronauts go to Mars.”

A pit crater, created by an empty lava tube, in Mars' Arsia Mons region. Captured by NASA's Mars Reconnaissance Orbiter in 2020.
A pit crater, created by an empty lava tube, in Mars' Arsia Mons region. Captured by NASA's Mars Reconnaissance Orbiter in 2020. NASA/JPL-Caltech/University of Arizona

Currently, the sun is in a period of high activity surrounding its solar maximum, during which surface explosions and radioactive flares occur more frequently than usual.

“There have been several solar events in past weeks, so we were seeing wave after wave of particles hitting Mars,” Christina Lee, MAVEN space weather lead, says in a statement from NASA.

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