NASA has its sights set on the Moon and aims to send astronauts back to the lunar surface by 2026 and establish a long-term presence there in the 2030s. However, the Moon is not a very habitable place for humans.
Cosmic rays from distant stars and galaxies and solar-powered particles from the Sun bombard the surface, and exposure to these particles can pose risks to human health.
Both galactic cosmic rays and solar energetic particles are high-energy particles that move at speeds close to the speed of light.
While galactic cosmic radiation trickles toward the Moon in a relatively steady stream, energetic particles can come from the Sun in massive bursts. These particles can penetrate human flesh and increase the risk of cancer.
Earth has a magnetic field that provides a shield against high-energy particles from space. However, the Moon has no magnetic field, leaving the Moon’s surface vulnerable to bombardment by these particles.
During a large solar particle event, the radiation dose an astronaut receives in a spacesuit can exceed 1,000 times the dose received by a person on Earth. This would exceed an astronaut’s recommended lifespan limit by a factor of 10.
NASA’s Artemis program, which started in 2017, aims to re-establish human presence on the Moon for the first time since 1972. My colleagues and I at the All-Clear SEP Forecast Center at the University of Michigan’s CLEAR headquarters have been working on forecasts. These ejections of particles from the Sun. Predicting these events could help protect future Artemis crew members.
11-year solar cycle
The Moon will face dangerous levels of radiation in 2024 as the Sun approaches its maximum point in the 11-year solar cycle. This cycle is driven by the Sun’s magnetic field, whose total strength changes significantly every 11 years. As the Sun approaches its maximum activity, as many as 20 massive solar particle events can occur each year.
Both solar flares, which are sudden bursts of electromagnetic radiation from the Sun, and coronal mass ejections, which are the ejection of large amounts of matter and magnetic fields from the Sun, can produce energetic particles.
The Sun is expected to reach its solar maximum in 2026, the target launch time of the Artemis III mission, which will land a team of astronauts on the lunar surface.
Although researchers can track the Sun’s cycle and predict trends, it is difficult to predict exactly when each solar particle event will occur and how intense each event will be. Future astronauts on the Moon will need a warning system that will more precisely predict these events before they happen.
Predicting solar events
In 2023, NASA funded a five-year space weather center of excellence called CLEAR, aimed at predicting the probability and intensity of solar-powered particle events.
Currently, forecasters at the National Oceanic and Atmospheric Administration’s Space Weather Prediction Center, the center that tracks solar events, cannot warn of an incoming solar particle event until they actually detect a solar flare or coronal mass ejection. They detect these by looking at the Sun’s atmosphere and measuring X-rays coming from the Sun.
When a forecaster detects a solar flare or coronal mass ejection, the high-energy particles usually reach Earth in less than an hour. But astronauts on the lunar surface will need more time than that to seek shelter. My team at CLEAR wants to predict solar flares and coronal mass ejections before they happen.
Although scientists don’t fully understand what causes these solar events, they do know that the Sun’s magnetic field is one of the main factors. Specifically, they study the strength and complexity of the magnetic field in certain regions on the Sun’s surface.
At the CLEAR center, we will monitor the Sun’s magnetic field using measurements from both ground-based and space-based telescopes and build machine learning models that predict solar events, hopefully more than 24 hours before they happen.
With the prediction framework developed at CLEAR, we also hope to predict when the particle flux will drop to a safe level. This way, we will be able to tell astronauts when it is safe to leave their shelter and continue their work on the lunar surface.
This article is republished from The Conversation, an independent, nonprofit news organization providing facts and authoritative analysis to help you understand our complex world. Written by: Lulu Zhao, university of michigan
Read more:
Lulu Zhao serves as principal investigator of CLEAR at the University of Michigan, which receives funding from NASA.