The sun can send out eruptions of energetic particles. Credit: NASA/SDO (via AP)
NASA has set its sights on the moon, aiming to return astronauts to the moon’s surface by 2026 and establish a long-term presence there by the 2030s. However, the moon is not a suitable place for humans to live.
Cosmic rays from distant stars and galaxies and solar energy particles from the sun impact the Earth’s surface, and exposure to these particles can pose a risk to human health.
Galactic cosmic rays and solar energetic particles are both high-energy particles that travel at speeds close to the speed of light.
Galactic cosmic radiation trickles toward the Moon in a relatively steady stream, but high-energy particles can come in huge bursts from the Sun. These particles can penetrate the human body and increase the risk of cancer.
Earth has a magnetic field that provides a shield against high-energy particles from space. However, because the Moon has no magnetic field, the Moon’s surface is vulnerable to collisions with these particles.
During large solar particle events, the radiation dose astronauts receive in their spacesuits can be more than 1,000 times greater than the radiation dose received by people on Earth. This would exceed the recommended lifetime limit for astronauts by a factor of 10.
NASA’s Artemis program, which began in 2017, aims to reestablish a human presence on the Moon for the first time since 1972. My colleagues and I at the University of Michigan’s CLEAR Center for Transparent SEP Forecasting are working on predictions. Emission of these particles from the sun. Predicting these events may help protect future Artemis crews.
NASA plans to return humans to the moon using Artemis. AP Photo/Michael Wyke
11 year solar cycle
The moon will face dangerous levels of radiation in 2024 as the sun approaches the maximum point of its 11-year solar cycle. This cycle is driven by the Sun’s magnetic field, whose total strength changes dramatically every 11 years. As the sun approaches its peak activity, as many as 20 large solar energy particle events can occur each year.
Solar flares, sudden bursts of electromagnetic radiation from the Sun, and coronal mass ejections, the release of large amounts of material and magnetic fields from the Sun, can both produce high-energy particles.
https://youtube.com/watch?v=w6C1_Qci8nQ%3Fwmode%3Dtransparent%26start%3D0
The sun is expected to reach solar maximum in 2026, the target launch time for the Artemis III mission that will land astronauts on the moon.
Although researchers can track the sun’s cycles and predict trends, it is difficult to estimate when exactly each event of solar energetic particles will occur and how strong each event will be. In the future, astronauts on the moon will need warning systems that better predict such events before they occur.
Prediction of solar phenomena
In 2023, NASA funded a five-year Space Weather Center of Excellence called CLEAR, which aims to predict the probability and intensity of solar energetic particle events.
Currently, forecasters at the National Oceanic and Atmospheric Administration’s Space Weather Prediction Center, which tracks solar phenomena, cannot warn of an upcoming solar particle event until they actually detect a solar flare or coronal mass ejection. They detect these by observing the Sun’s atmosphere and measuring the X-rays flowing from the Sun.
When forecasters detect a solar flare or coronal mass ejection, the high-energy particles typically reach Earth within an hour. But astronauts on the moon will likely need more time to find shelter. My team at CLEAR wants to predict solar flares and coronal mass ejections before they occur.
The Sun’s magnetic field is incredibly complex and can change throughout the solar cycle. On the left, the magnetic field has two poles and looks relatively simple, while on the right, the field changes during the second half of the solar cycle. When the Sun’s magnetic field becomes like the image to the right, solar flares and coronal mass ejections become more common. NASA Goddard Space Flight Center/Bridgeman, CC BY
Scientists don’t fully understand the causes of these solar phenomena, but 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 specific regions of the Sun’s surface.
The CLEAR Center uses measurements from both ground-based and space-based telescopes to monitor the Sun’s magnetic field and build machine learning models that predict solar events, preferably more than 24 hours before they occur.
We also hope to use the predictive framework developed in CLEAR to predict when particle fluxes will return to safe levels. This would allow astronauts to know when it is safe to leave the shelter and continue working on the moon.
Lulu Zhao, Research Assistant, Department of Climate, Space, Science and Engineering, University of Michigan
This article is republished from The Conversation under a Creative Commons license. Read the original article.
