The sun fired a volley of radiation bursts in May. When they collided with Earth’s magnetic bubble, the world was treated to iridescent displays of the Northern and Southern Lights. But our planet wasn’t the only one in the sun’s line of fire.
A few days after Earth’s light show, a new series of bursts screamed from the sun. This time, on May 20, Mars was hit by a huge storm.
Observed from Mars, “this was the strongest solar energetic particle event we’ve seen yet,” says Shannon Curry, the principal investigator of NASA’s Mars Atmosphere and Volatile Evolution orbiter, or MAVEN, at the University of Colorado, Boulder.
When the barrage arrived, it created an aurora that enveloped Mars from pole to pole in a shimmering glow. If they were on the surface of Mars, “astronauts would be able to see these auroras,” Curry said. Based on scientific knowledge of atmospheric chemistry, they and other scientists say, observers on Mars would have seen a jade-green light show, although no color cameras detected it on the surface.
But it is very fortunate that there were no astronauts. Mars’ thin atmosphere and the absence of a global magnetic shield meant that its surface, as recorded by NASA’s Curiosity rover, was irradiated with a dose of radiation equivalent to thirty chest X-rays – not a lethal dose, but certainly not pleasant for Human. constitution.
While last month’s auroras were mesmerizing, they served as a reminder that Mars can be a dangerous, radiation-smothered place and that future astronaut visitors will need to be careful. “These solar storms have a huge impact,” Curry said.
Lava tubes – long caverns formed by volcanic activity – could provide travelers on Mars with safe shelter from solar storms. But because the sun’s harmful particles sometimes reach Mars within minutes, Earthlings will have to tread lightly.
In other words, if you’re a Mars astronaut, “you better stay on top of your space weather forecasts,” says James O’Donoghue, a planetary astronomer at the University of Reading in England.
When the May 20 mega-eruption occurred, it was immediately clear that it was formidable. A powerful solar flare first reached Mars, bathing it in X-rays and gamma rays. Hot on its heels was a powerful coronal mass ejection – a shot of charged particles from the sun. “They seemed pretty fast to me,” says Mathew Owens, a space physicist at the University of Reading.
When particles from a solar burst reach humanity’s home, they are captured in Earth’s magnetic field and spiral toward the magnetic north and south poles. There they reflect various gas molecules into the atmosphere, temporarily energizing them and releasing bursts of countless visible colors.
Mars lost its magnetic field centuries ago when its iron-rich innards stopped churning, so May’s solar bombardment was not intercepted. “There’s nothing stopping these particles from plowing straight into the atmosphere,” says Nick Schneider, the lead scientist working on the Imaging Ultraviolet Spectrograph on MAVEN at the University of Colorado, Boulder.
Subjected to a global pummel, auroras ignited across the planet. The MAVEN orbiter documented a thunderous ultraviolet glow, while a pale green hue would have been visible on the surface as it emanated from the agitated oxygen atoms in the atmosphere.
Some robot inhabitants of Mars experienced the more unpleasant consequences of the storm. Charged particles hit Curiosity’s navigation cameras and the Mars Odyssey orbiter’s star tracker camera, flooding them all with static electricity like “snow.”
Solar storms can also damage a spacecraft’s solar panels. May’s maelstrom was no exception. “Everyone’s solar panels took a hit,” Curry said. She added that one solar storm like the one on May 20 “will cause about the same amount of degradation that we typically see in a year.”
None of the spacecraft were seriously damaged – and the scientific data they recorded was warmly received. But these orbiters may not always emerge unscathed when confronted with the sun’s wrath. “The science team is thrilled every time we see these events,” Curry said. “The spacecraft team, less so.”