As the Sun becomes more active, more solar storms occur on its surface, releasing powerful bursts of radiation that hit the planets of the Solar System.
Earth has a magnetic field that, for the most part, shields us from the extreme effects of solar storms, but Mars lost its global magnetic field long ago, so how can future astronauts on Mars hope to be protected?
The Sun goes through an 11-year cycle of peaks and troughs of activity, known as the Solar Cycle, and is currently approaching a peak, throwing out more solar flares and sunspots.
This, says NASA, makes now an ideal time for two of its spacecraft to study how solar flares could affect robotic probes and human astronauts on the Mars.
“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,” says Shannon Curry of the University of Colorado Boulder’s Laboratory for Atmospheric and Space Physics.
Curry is principal investigator for NASA’s MAVEN (Mars Atmosphere and Volatile EvolutioN) spacecraft, which orbits the Red Planet to understand more about its upper atmosphere.
"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."
MAVEN and Curiosity
The MAVEN orbiter collects data on a range of phenomena as it orbits Mars, including radiation and solar particles.
And data from the Curiosity rover’s Radiation Assessment Detector, or RAD, reveals how radiation breaks down carbon-based molecules on the surface.
This process could affect whether signs of ancient microbial life are still on Mars to this day.
Curiosity's RAD instrument has also given planetary scientists data that could reveal whether astronauts might be able to hide from radiation on Mars by using caves, lava tubes or cliff faces for protection.
What happens when a solar flare strikes
When a solar event occurs, scientists analyse the quantity of solar particles released, and how energetic they are.
"You can have a million particles with low energy or 10 particles with extremely high energy," says RAD’s principal investigator, Don Hassler of the Boulder, Colorado, office 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."
Coordination between MAVEN in Mars orbit and Curiosity on the ground is key.
MAVEN detects a solar flare and Curiosity scientists observe RAD’s data to look out for changes.
MAVEN also uses an early warning system to let other Mars spacecraft teams know when radiation levels begin to rise.
This means other teams can switch off instruments that could be damaged by solar flares.
How did Mars lose its water?
Studying the effects of solar maximum on Mars could reveal why ancient Mars was warm and wet like Earth, but is now a freezing, barren wasteland.
When Mars is closest to the Sun, its atmosphere heats up and this causes dust storms to occur on the surface. These storms can even become global.
Could global dust storms be responsible for ejecting water vapour high above Mars, where the atmosphere gets stripped away during solar storms?
Perhaps this could explain why Mars lost its water.
If a global dust storm occurred at the same time as a solar storm, it would make for a good opportunity to test the theory.
