Epic solar storm effects seen by Mars rovers

JPL originally published this article on June 10, 2024. Edits by EarthSky.

Epic solar flare seen from Mars on May 20

Mars scientists have been anticipating epic solar storms ever since the sun entered a period of peak activity earlier this year. This peak in the 11-year cycle is called solar maximum (watch a video here). Over the past month, NASA’s Mars rovers and orbiters have provided researchers with front-row seats to a series of solar flares and coronal mass ejections (CMEs) that have reached Mars, in some cases, even causing Martian auroras.

This science bonanza has offered an unprecedented opportunity to study how such events unfold in deep space, as well as how much radiation exposure the first astronauts on Mars could encounter.

The biggest event seen from Mars occurred on May 20 with a solar flare later estimated to be an X12. X flares are the strongest of several types of solar flares. The Solar Orbiter spacecraft, a joint mission between ESA (European Space Agency) and NASA, saw the flare. It sent out X-rays and gamma rays toward the Red Planet, while a subsequent coronal mass ejection launched charged particles. Moving at the speed of light, the X-rays and gamma rays from the flare arrived first, while the charged particles trailed slightly behind, reaching Mars in just tens of minutes.

Images of radiation hitting Mars

Analysts at the Moon to Mars Space Weather Analysis Office at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, tracked the unfolding space weather closely. They also flagged the possibility of incoming charged particles following the coronal mass ejection.

During the event on May 20, so much energy from the storm struck the surface that black-and-white images from Curiosity’s navigation cameras danced with “snow”. It showed white streaks and specks caused by charged particles hitting the cameras.

Similarly, energy from solar particles inundated the camera NASA’s 2001 Mars Odyssey orbiter uses for orientation. This barrage momentarily caused it to go out. (Odyssey has other ways to orient itself and recovered the camera within an hour.) Even with the brief lapse in its star camera, the orbiter collected vital data on X-rays, gamma rays and charged particles using its High-Energy Neutron Detector.

Also, this wasn’t Odyssey’s first brush with a solar flare. In 2003, solar particles from a whopping X45 solar flare fried Odyssey’s radiation detector, which was designed to measure such events.

Space weather on Mars affecting future astronauts

If astronauts had been standing next to NASA’s Curiosity Mars rover at the time, they would have received a radiation dose of 8,100 micrograys, equivalent to 30 chest X-rays. While not deadly, it was the biggest surge measured by Curiosity’s Radiation Assessment Detector, or RAD, since the rover landed 12 years ago.

RAD’s data will help scientists plan for the highest level of radiation exposure astronauts might encounter. Astronauts might be able to use the Martian landscape for protection.

RAD’s principal investigator, Don Hassler of Southwest Research Institute’s Solar System Science and Exploration Division in Boulder, Colorado, said:

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.

Auroras over Mars

Over the past month, NASA’s Mars rovers and orbiters have provided researchers with front-row seats to a series of solar flares and coronal mass ejections that have reached Mars. In some cases, they’ve even caused Martian auroras.

NASA’s MAVEN (Mars Atmosphere and Volatile EvolutioN) orbiter captured glowing auroras over the planet. The way these auroras occur is different from those seen on Earth.

A robust magnetic field is what shields our home planet from charged particles. And that magnetic field normally limits auroras to regions near the poles. The current solar cycle – maybe at maximum – is the reason behind the recent auroras seen as far south as Alabama.

However, Mars lost its internally generated magnetic field in the ancient past, so there’s no protection from the barrage of energetic particles. When charged particles hit the Martian atmosphere, it results in auroras that engulf the entire planet.

During solar events, the sun releases a wide range of energetic particles. Only the most energetic can reach the surface for RAD to measure. MAVEN’s Solar Energetic Particle instrument can sense slightly less energetic particles, including those that cause auroras.

Scientists can use that instrument’s data to rebuild a timeline of each minute as the solar particles screamed past, meticulously teasing apart how the event evolved.

Christina Lee of the University of California, Berkeley’s Space Sciences Laboratory, and the MAVEN Space Weather Lead, said:

This was the largest solar energetic particle event MAVEN has ever seen. There have been several solar events in past weeks, so we were seeing wave after wave of particles hitting Mars.

How MAVEN and Curiosity study solar flares

Watch this video to learn how NASA’s MAVEN and the agency’s Curiosity rover study solar flares and radiation at Mars during solar maximum, a period when the sun is at peak activity.

Bottom line: The sun lobs its particles into the solar system, and studying this space weather on Mars helps us understand what future astronauts might face there.

Via JPL