Mars radiation levels are measured for the first time and will help astronauts prepare

A group of scientists has given us a view into the radiation environment around Mars, which will be crucial for future astronauts as they explore the Red Planet.

They have pieced together the first comprehensive energy spectrum of protons during a recent solar eruption event.

This accomplishment significantly deepens our understanding of the radiation conditions around Mars — a crucial step in ensuring the safety of astronauts on future exploration missions to the planet.

Solar radiation’s impact on space travel

Solar radiation poses significant challenges for astronauts venturing into deep space, which is why it’s important to understand the radiation levels the first Mars astronauts will be dealing with.

Without the Earth’s protective atmosphere and magnetic field, astronauts are directly exposed to high-energy particles and harmful ultraviolet rays.

This exposure can increase the risk of cancer, damage the central nervous system, and cause acute radiation sickness, making long-duration missions especially risky.

Even short-term exposure can lead to eye problems like cataracts, which have been a concern for many space travelers.

To combat these dangers, space missions incorporate various shielding techniques and develop advanced materials to protect crew members.

Scientists are also researching pharmaceutical countermeasures that could help mitigate the effects of radiation on the body.

Additionally, mission planners carefully monitor solar activity to schedule spacewalks and other extravehicular activities during periods of lower solar radiation.

Impact of solar radiation storms on Mars

Solar energetic particle (SEP) events are caused by solar eruptions and are among the most destructive space weather phenomena.

During these events, charged particles, including protons, that are emitted by the Sun, become accelerated and may fly through space and enter the atmospheres of planets.

The flux of high-energy, charged particles in space may thus suddenly increase during these solar radiation storms, imposing significant threats to spacecraft safety, technological equipment and, of course, the well-being of astronauts.

In contrast to our blue planet, Mars lacks a robust protective magnetic field and only boasts a very thin atmosphere. This renders its surface more susceptible to these high-energy particles and to other, secondary particles.

Studying the impact of SEP events on Mars is, thus, critical for radiation protection in future Mars explorations.

Monitoring the presence of high-energy protons

Back in November 2021, China’s Tianwen-1 orbiter stepped into its science mission orbit around Mars. Its onboard device, the Mars Energy Particle Analyzer (MEPA), began its job by measuring particle flux.

With the MEPA’s capacity to measure a wide energy range from 2–100 MeV, it is highly suitable for monitoring the presence of high-energy protons, both on the planet and in Martian space. This provided critical data for the study.

Detecting radiation on and around Mars

On February 15th, 2022, an exciting incident occurred. MEPA registered a solar energetic particle event that had remarkable intensity and energy.

The accelerated protons in this event had energies that were high enough to penetrate the Martian atmosphere and induce radiation enhancement on the surface.

The event was simultaneously detected by the European Space Agency’s Trace Gas Orbiter (TGO), NASA’s Mars Atmosphere and Volatile Evolution Orbiter (MAVEN), and the Curiosity rover on the Martian surface.

This marked the first time an SEP event was observed by so many different radiation and particle detectors focused on Martian conditions.

Constructing the proton energy spectrum

Harnessing data from these multiple detectors, the researchers painted a full picture of the proton energy spectrum during the SEP event.

The low- and medium-energy proton spectra were obtained by Tianwen-1 and MAVEN. The high-energy proton flux was deduced by merging observations from Curiosity with simulations of particle transport in the Martian atmosphere.

By fitting the observed and derived fluxes at different energies, the researchers made a breakthrough. They successfully constructed the complete proton energy spectrum of the SEP event, ranging from 1 to 1000 MeV.

A path for future research

Taking their findings a step further, these scientists used this spectrum to compute the radiation dose caused by the event, both in Martian orbit and on the Martian surface.

This calculation aligns with actual dose measurements, thus validating the reliability of the Tianwen-1 MEPA data and the accuracy of the Martian radiation transport model.

Beyond the immediate discovery, this study paves a path for future research on similar space weather phenomena.

The research highlights the necessity for continuous and coordinated radiation monitoring on Mars. After all, the more we know about our neighboring planet’s radiation environment, the safer that our future explorers will be.

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This significant research was supported by the Key Research Program and Strategic Priority Program of CAS, along with the National Natural Science Foundation of China.

This study was conducted jointly by researchers from the University of Science and Technology of China, the Institute of Modern Physics (IMP) of the Chinese Academy of Sciences (CAS), the Lanzhou Institute of Physics (LIP), and the University of Kiel in Germany.

The study is published in the journal Geophysical Research Letters.

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