As two NASA astronauts gear up for a months-long unplanned stay on the International Space Station (ISS), they may also be increasing their risk of radiation exposure.
Barry “Butch” Wilmore and Sunita “Suni” Williams, who performed the first crewed test flight of Boeing’s Starliner, took off on June 5 and were only supposed to be in space for about one week.
However, several problems have arisen with the spacecraft, pushing their return to February 2025 aboard Space X’s Crew-9 Dragon spacecraft.
Space radiation is different from radiation experienced on Earth. It’s made up of three kinds of radiation: particles trapped in Earth’s magnetic field, particles from solar flares and galactic cosmic rays, NASA said.
Earth is surrounded by a system of magnetic fields, called the magnetosphere, that protects people from harmful space radiation. However, the higher a person is in altitude, the higher the dose of radiation they are exposed to.
Space radiation exposure risk for astronauts compared to people on Earth over three months.
ABC News Photo Illustration
“It’s an order of normal magnitude,” Dr. Stanton Gerson, dean of the Case Western Reserve University School of Medicine in Cleveland, told ABC News. “As you move [into] the atmosphere, you have increased radiation exposure.”
Due to prolonged exposure, astronauts can be at significant risk for radiation sickness and have a higher lifetime risk of cancer, central nervous system effects and degenerative diseases, according to NASA.
“In low earth orbit where the ISS is, astronauts are at least partially protected by the magnetosphere that protects Earth from the radiation exposure of deep space,” Dr. Rihana Bokhari, acting chief scientific officer at Baylor College of Medicine’s Translational Research Institute for Space Health, told ABC News.
“However, they do have a greater radiation exposure than those on Earth because the ISS passes through areas of trapped radiation in their orbit,” she continued. “Butch and Suni, since they are on the ISS, will not be exposed to enough radiation to seriously cause large impacts on body systems but the long duration exposure to greater radiation than on Earth could lead to an increase in the risk of cancer.”
Crews aboard the ISS receive an average of 80 mSv to 160 mSv during a six-month stay, according to a 2017 NASA report. Millisieverts (mSv) are units of measurement for how much radiation has been absorbed by the body.
Although the type of radiation is different, 1 mSv of space radiation is roughly the same as receiving three chest X-rays, the federal space agency said.
By comparison, a person on Earth receives an average of 2 mSv every year from just background radiation, NASA said.
Gerson said it’s fair to take the NASA estimates and cut them in half. This means for a three-month stay, the astronauts have a cumulative average risk of receiving 40 mSv to 80 mSv.
What’s harder to determine is the episodic risk from factors including solar flares, he said.
“There’s spike risks because there’s episodic waves of solar radiation and deep space ionic radiation that come through the magnetic field, and luckily Earth has a strong magnetic field that blocks a lot of that,” Gerson said. “If you’re on the other side of the moon, you don’t have that.”
Gerson added that NASA has done a good job of checking up on astronauts after they return to Earth as the agency and other researchers have learned more about how radiation affects the body and what signs to look for.
The recent delay in the return of Boeing’s Starliner spacecraft has raised concerns about the potential radiation exposure that astronauts on board may face. As the spacecraft orbits the Earth, astronauts are exposed to cosmic radiation, which can pose health risks if exposure levels are too high.
Estimating the radiation exposure of astronauts during return delays is a complex process that involves taking into account a variety of factors, such as the altitude of the spacecraft, the duration of the delay, and the intensity of cosmic radiation at that particular time. NASA and other space agencies have developed sophisticated models to predict and monitor radiation exposure levels for astronauts on long-duration missions.
One of the key factors in estimating radiation exposure is the altitude of the spacecraft. The higher the altitude, the greater the exposure to cosmic radiation. During return delays, astronauts may be exposed to higher levels of radiation than originally planned, as they continue to orbit at higher altitudes for an extended period of time.
The duration of the delay is also a crucial factor in estimating radiation exposure. The longer astronauts are in space, the greater their cumulative exposure to cosmic radiation. Even short delays can result in increased radiation exposure, which can have long-term health implications for astronauts.
In addition to altitude and duration, the intensity of cosmic radiation at the time of the delay must also be taken into account. Cosmic radiation levels can vary depending on solar activity and other factors, so it is important to monitor these levels in real-time to accurately estimate astronaut exposure.
To mitigate the risks of radiation exposure during return delays, astronauts are equipped with dosimeters that measure their cumulative exposure over time. These dosimeters provide valuable data for researchers and medical professionals to assess the potential health risks associated with prolonged exposure to cosmic radiation.
In conclusion, estimating the radiation exposure of Starliner astronauts during return delays is a complex process that requires careful monitoring and analysis of various factors. By understanding and mitigating the risks of radiation exposure, space agencies can ensure the safety and well-being of astronauts on long-duration missions.
