This coronal mass ejection, captured by NASA's Solar Dynamics Observatory, exploded onto the Sun on August 31, 2012, traveling at more than 900 miles per second and sending radiation deep into space. Earth's magnetic field protects it from radiation from solar events like this, while Mars lacks this type of protection. Source: NASA/SDO
The Sun will be most active this year, providing a rare opportunity to study how solar storms and radiation will affect future astronauts on the Red Planet.
In the coming months, two of NASA's Mars Spacecraft will have an unprecedented opportunity to study how solar flares – giant explosions on the surface of the Sun – affect future robots and astronauts on the Red Planet.
This is because the Sun is entering a period of peak activity called solar maximum, something that happens approximately every 11 years. During solar maximum, the Sun is particularly prone to fiery outbursts in a variety of forms – including… Solar flares And Coronal mass ejection – Which releases radiation deep into space. When a series of these solar events erupt, it is called a solar storm.
Learn how NASA's MAVEN rover and the agency's Curiosity rover study solar flares and radiation on Mars during solar maximum — the period when the Sun is most active. Credit: NASA/Jet Propulsion Laboratory– Caltech/GSFC/SDO/MSSS/University of Colorado
The Earth's magnetic field largely protects our home planet from the effects of these storms. But Mars lost its global magnetic field long ago, making the Red Planet more vulnerable to energetic particles from the Sun. How intense is solar activity on Mars? Researchers hope the current solar maximum will give them a chance to find out. Before sending humans there, space agencies need to determine, among many other details, what kind of radiation protection the astronauts will need.
“For humans and Martian origins, we don't have a solid understanding of the impact of radiation during solar activity,” said Shannon Curry of the Laboratory for Atmospheric and Space Physics at the University of Colorado Boulder. Curry is the principal investigator for NASA's MAVEN (Mars Atmospheric and Volatile Evolution) orbiter, operated by NASA's Goddard Space Flight Center in Greenbelt, Maryland. “I would actually like to see a 'big event' at Mars this year — a big event that we can study to better understand solar radiation before astronauts go to Mars.”
The radiation assessment detector on NASA's Curiosity rover is highlighted in this annotated Mastcam image of the rover. RAD scientists are excited to use the instrument to study radiation on Mars during solar maximum. Image source: NASA/JPL-Caltech/MSSS
Measure height and fall
MAVEN monitors radiation, solar particles, and more from above the surface of Mars. A planet's thin atmosphere can affect the density of molecules by the time they reach the surface, which is where NASA's Curiosity spacecraft comes into play. Data from Curiosity's radiation evaluation detector, or RadIt has helped scientists understand how radiation breaks down carbon molecules on the surface, a process that could affect whether signs of ancient microbial life are preserved there. The tool also provided NASA with an idea of how much protection astronauts could expect from radiation by using caves, lava tubes or cliff faces for protection.
When a solar event occurs, scientists look at the amount of solar particles and how active they are.
This artist's concept depicts the Martian atmosphere and NASA's MAVEN spacecraft near Mars. Credit: NASA/GSFC
“You could have 1 million low-energy particles or 10 very high-energy particles,” said RAD principal investigator Don Hassler, of the Southwest Research Institute office in Boulder, Colorado. “While the MAVEN instruments are more sensitive to lower-energy instruments, RAD is the only instrument capable of seeing high-energy instruments that can cross the atmosphere to the surface, where the astronauts will be.”
When MAVEN detects a large solar flare, the orbiter team tells the Curiosity team what it is so they can monitor changes in the RAD data. The two missions can also compile a time series that measures changes down to half a second when particles reach the Martian atmosphere, interact with it, and eventually hit the surface.
The MAVEN mission also drives an early warning system that lets other Mars spacecraft teams know when radiation levels start to rise. The alert system allows missions to turn off devices that may be vulnerable to solar flares, which can interfere with electronics and radio communications.
Lost water
In addition to helping keep astronauts and spacecraft safe, studying the solar maximum could also provide insight into why Mars changed from a warm, wet, Earth-like world billions of years ago to a frozen desert today.
The planet is at a point in its orbit when it is closest to the Sun, heating the atmosphere. This can cause rising dust storms that cover the surface. Sometimes the storms merge, becoming global (see image below).
Mars before and after the dust storm: Side-by-side movies show how the 2018 global dust storm covered the red planet, thanks to the Mars Color Imager (MARCI) camera aboard NASA's Mars Reconnaissance Orbiter. This global dust storm caused NASA's spacecraft to lose contact with Earth. Image source: NASA/JPL-Caltech/MSSS
While there is little water left on Mars — mostly ice under the surface and at the poles — some of it still circulates as vapor in the atmosphere. Scientists wonder if global dust storms help push out this water vapor, raising it high above the planet, where the atmosphere is stripped away during solar storms. One theory is that this process, repeated enough times over eons, may explain how Mars went from having lakes and rivers to being virtually waterless today.
If a global dust storm occurred at the same time as a solar storm, it would provide an opportunity to test this theory. Scientists are particularly excited because this solar maximum occurs at the beginning of Mars' dustiest season, but they also know that a global dust storm is rare.
More about missions
NASA's Goddard Space Flight Center in Greenbelt, Maryland, manages the MAVEN mission. Lockheed Martin Space built the spacecraft and is responsible for mission operations. JPL provides navigation and deep space network support. The Laboratory for Atmospheric and Space Physics at the University of Colorado Boulder is responsible for science operations management, public outreach, and communications.
Curiosity was built by NASA's Jet Propulsion Laboratory, which is operated by the California Institute of Technology in Pasadena, California. JPL is leading the mission on behalf of NASA's Science Mission Directorate in Washington. The RAD investigation is supported by NASA's Heliophysics Division as part of NASA's Heliophysics System Observatory (HSO).