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| The specks in this image are from charged particles of a solar storm hitting Curiosity’s camera, as it captures dust devils and wind gusts on Mars. |
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| Curiosity’s navigation camera captured black-and-white streaks and specks caused by energetic particles from a solar storm hitting the image detector. |
A recent extreme solar storm not only produced auroras but also provided insights into the radiation future astronauts might face on Mars. With the Sun entering a solar maximum earlier this year, Mars scientists have been expecting significant solar storms. Over the past month, NASA’s Mars rovers and orbiters have observed a series of solar flares and coronal mass ejections, leading to Martian auroras. This has offered a unique opportunity to study these events in deep space and assess potential radiation exposure for astronauts.
The most significant event occurred on May 20, with a solar flare estimated to be an X12 based on data from the Solar Orbiter spacecraft. This flare sent X-rays and gamma rays to Mars, followed by charged particles from a coronal mass ejection. Analysts at NASA’s Moon to Mars Space Weather Analysis Office tracked these events and predicted the arrival of charged particles.
If astronauts had been on Mars during this time, they would have received a radiation dose of 8,100 micrograys, equivalent to 30 chest X-rays. This was the highest surge recorded by Curiosity’s Radiation Assessment Detector since the rover’s landing 12 years ago.
RAD’s data will help scientists prepare for the highest radiation levels astronauts might encounter on Mars, potentially using the Martian landscape for protection. “Cliffsides or lava tubes would provide additional shielding for an astronaut from such an event. In Mars orbit or deep space, the dose rate would be significantly more,” said RAD’s principal investigator, Don Hassler of Southwest Research Institute. He anticipates more solar storms due to the Sun’s active region.
During the May 20 event, charged particles caused “snow” in Curiosity’s navigation camera images. NASA’s Mars Odyssey orbiter also faced a brief orientation issue due to solar particles but recovered quickly and continued to collect crucial data. This wasn’t Odyssey’s first encounter with a solar flare; in 2003, an X45 flare damaged its radiation detector.
Auroras Over Mars.
High above Curiosity, NASA’s MAVEN (Mars Atmosphere and Volatile EvolutioN) orbiter captured another effect of the recent solar activity: glowing auroras over the planet. Unlike Earth, which has a robust magnetic field that limits auroras to the poles, Mars lost its internally generated magnetic field in the ancient past. This lack of protection means that energetic particles can create auroras that engulf the entire planet.
During solar events, the Sun releases a wide range of energetic particles. Only the most energetic particles reach the surface to be measured by RAD, while slightly less energetic particles, causing auroras, are detected by MAVEN’s Solar Energetic Particle instrument. This data allows scientists to reconstruct a timeline of the solar particles’ impact.
“This was the largest solar energetic particle event that MAVEN has ever seen,” said Christina Lee, MAVEN Space Weather Lead at UC Berkeley’s Space Sciences Laboratory. “There have been several solar events in past weeks, so we were seeing wave after wave of particles hitting Mars.”
New Spacecraft to Mars.
Scheduled for a late-2024 launch, ESCAPADE’s twin small satellites will orbit Mars to observe space weather from a unique dual perspective, providing more detailed measurements than what MAVEN can currently achieve on its own.