Mars Is About To Get Bombarded By Solar Flares - Here's Why Scientists Are Excited
May 2024 saw a series of dramatic events involving the sun, which caused notable effects here on Earth, like aurora sightings across parts of the U.S. and Europe far further south than the northern lights are usually visible. This was caused by huge outpourings of energy from the sun called solar flares and coronal mass ejections, which caused charged particles to head out through the solar system and hit Earth. As the particles interact with Earth's atmosphere, they create the famous auroras.
But Earth isn't the only planet in the solar system affected by the sun's activity. The sun will continue to become more active as it moves through its 11-year cycle, ramping up to its highest point of activity called solar maximum.
And scientists are particularly interested in how increasing solar activity will affect Mars. Increasing solar activity will affect the amount of radiation experienced on Mars's surface, an important factor for future human exploration of the red planet. They are hoping to see the effects of large solar storms on the planet.
"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," said NASA researcher Shannon Curry of the University of Colorado Boulder's Laboratory for Atmospheric and Space Physics. "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."
Why radiation at Mars is so important
On Earth, we're protected from radiation by the planet's magnetosphere, which forms areas called the Van Allen belts. These act like shields, bouncing radiation away from the planet and protecting us on the surface from its dangerous effects. With these belts, the radiation would cause danger to people and also to electronics like satellite communications.
On Mars, however, there are no Van Allen belts as it doesn't have a magnetic field like Earth. The planet also has a very thin atmosphere, just 1% the density of Earth's. That means that radiation is a big problem there, as the surface is bombarded by radiation. However, the exact details of this radiation changes over time and the degree of danger it poses to future astronauts is unknown.
To learn more about this topic, researchers will take advantage of the upcoming solar maximum to see the impact solar storms have on radiation at Mars. To measure this, they will use tools like the Mars Atmosphere and Volatile EvolutioN (MAVEN) orbiter and the Curiosity rover's Radiation Assessment Detector (RAD) instrument on the planet's surface.
"You can have a million particles with low energy or 10 particles with extremely high energy," said RAD's principal investigator, Don Hassler of the Southwest Research Institute. "While MAVEN's instruments are more sensitive to lower-energy ones, RAD is the only instrument capable of seeing the high-energy ones that make it through the atmosphere to the surface, where astronauts would be."
Mars had lost water
As well as learning about radiation for the sake of future astronauts, scientists are also interested in learning about how radiation impacted Mars's climate. Scientists know that billions of years ago, Mars once had oceans of liquid water on its surface, similar to Earth. But over time this water was lost until Mars became the dry, inhospitable place it is today.
Researchers using data from the MAVEN orbiter have found that particles from the sun could have contributed to Mars losing its water. As particles blow out from the sun, this creates a solar wind which can wear away atmospheres in a process of erosion.
"Solar-wind erosion is an important mechanism for atmospheric loss, and was important enough to account for significant change in the Martian climate," said Joe Grebowsky, MAVEN project scientist. "MAVEN also is studying other loss processes — such as loss due to impact of ions or escape of hydrogen atoms — and these will only increase the importance of atmospheric escape."
With the upcoming solar maximum, scientists are interested to learn about the relationship between Mars's dust storms, which can grow so large they cover the entire planet, and the solar storms. The two occurring together may have contributed to the historical loss of Mars's water.
Over the next few months as the sun ramps up to solar maximum, both MAVEN and the Curiosity rover will be collecting data to learn more about this timely phenomenon.