Mars scientists have been anticipating epic solar storms since the Sun entered a period of maximum activity earlier this year called solar maximum. Over the past month, NASA’s Mars rovers and orbiters have given researchers front-row seats to a series of solar flares and coronal mass ejections that have reached Marsand in some cases they have even caused Martian auroras.
This scientific bonanza has offered an unprecedented opportunity to study how such events unfold in deep spaceas well as how much radiation exposure the first astronauts could encounter on Mars.
The largest event occurred on May 20 with a solar flare later estimated to be X12 (X-class solar flares are the strongest of several types) according to data from the Solar Orbiter spacecraft, a joint mission between the European Space Agency (ESA) and NASA. The flare sent 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 flare’s x-rays and gamma rays arrived first, while the charged particles followed slightly behind, reaching Mars in just tens of minutes.
The development of space weather was closely monitored by analysts at the Moon-to-Mars Space Weather Analysis Office at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. which pointed out the possibility of the entry of charged particles after coronal mass ejection.
If the astronauts had been with NASA’s Curiosity rover on Mars at that time, they would have received a radiation dose of 8,100 micrograys, equivalent to 30 chest x-rays. While not fatal, it was the largest increase measured by Curiosity’s radiation assessment detector, or RAD, since the rover landed 12 years ago.
RAD data will help scientists plan for the highest level of radiation exposure astronauts could encounter, that they could use the Martian landscape as protection.
“Cliffs or lava tubes would provide additional protection to an astronaut from such an event. In Mars orbit or deep space, the dose rate would be significantly higher.”RAD principal investigator Don Hassler of the Solar System Science and Exploration Division of the Southwest Research Institute in Boulder, Colorado, said in a space agency statement.
“I wouldn’t be surprised if this active region of the Sun continues to erupt, “which would mean even more solar storms on both Earth and Mars in the coming weeks.”
During the May 20 event, so much energy from the storm hit the surface that the black-and-white images from Curiosity’s navigation cameras danced with “snow”: white streaks and specks caused by charged particles hitting the chambers.
Similarly, the star chamber used by NASA’s Mars Odyssey orbiter in 2001 for orientation was flooded with solar particle energy and momentarily shut down. (Odyssey has other ways of finding its way and recovered the camera within an hour.) Even with the brief lapse in his star chamber, The orbiter collected vital data on X-rays, gamma rays and charged particles using its high-energy neutron detector.
This was not Odyssey’s first encounter with a solar flare: in 2003, solar particles from a solar flare that was eventually estimated to be Odyssey’s X45 radiation detector, which was designed to measure such events.
High above Curiosity, NASA’s MAVEN (Mars Atmosphere and Volatile EvolutioN) orbiter captured another effect of recent solar activity: bright auroras over the planet. The way these auroras occur is different from those seen on Earth.
Our home planet is protected from charged particles by a powerful magnetic field, which normally limits auroras to regions near the poles. (Solar maximum is the reason behind the recent auroras seen as far south as Alabama.) Mars lost its internally generated magnetic field in the ancient past, so there is no protection against the barrage of energetic particles. When charged particles hit the Martian atmosphere, auroras are produced that envelop the entire planet.
During solar events, The Sun releases a wide range of energetic particles. Only the most energetic can reach the surface to be measured by RAD. MAVEN’s Solar Energetic Particle Instrument detects slightly less energetic particles, which cause auroras.
The scientists They can use the data from that instrument to reconstruct a timeline of every minute as the solar particles screamed past, meticulously breaking down How the event evolved.
“This was the largest solar-powered particle event MAVEN has ever seen,” said MAVEN space weather lead Christina Lee of the Space Sciences Laboratory at the University of California, Berkeley. “There have been several solar events in recent weeks, so we were seeing wave after wave of particles hitting Mars.”
The data from NASA’s spacecraft will not only help future planetary missions to the Red Planet. It is contributing to a wealth of information collected by the agency’s other heliophysics missions, including Voyager, Parker Solar Probe and the upcoming ESCAPADE (Escape and Plasma Acceleration and Dynamics Explorers) mission.
Aiming to launch at the end of 2024, lESCAPADE’s twin small satellites will orbit Mars and observe space weather from a unique dual perspective which is more detailed than MAVEN can currently measure alone.
