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NASA’s uncrewed Artemis mission highlights radiation risk to astronauts

ABC, By science reporter Jacinta Bowler, Thu 19 Sep, 24

In short: 

Scientists analysed the radiation experienced by two ‘radiation phantom’ dummies on NASA’s November 2022 uncrewed Artemis I mission.

The results suggest radiation may not be an issue for short Moon missions, but could be on longer Moon layovers or missions to Mars. 

What’s next? 

Scientists are trying to design ways to minimise radiation on longer space missions, including radio-protective drugs and spacecraft magnetic fields. 

In September next year, astronauts will be strapped into the Orion spacecraft and rocketed around the Moon in the first human moon visit in more than 50 years. 

And thanks to two space-travelling test dummies we now know those astronauts will likely be protected against dangerously high radiation exposure on their short trip.

Known as “radiation phantoms”, the specially designed dummies Helga and Zohar were included on last year’s Artemis 1 uncrewed mission.

Helga and Zohar are recreations of female humans, complete with fake organs that allowed researchers to record radiation exposure throughout the journey, and analyse results from skin, lungs, stomach, uterus and the spine to understand how radiation moves throughout the body. 

The results are published today in Nature.

Stuart George, lead author and a member of the NASA Space Radiation Analysis Group, says the results suggest that radiation exposure won’t be dangerously high for short Moon missions, but problems may arise on longer Moon missions such as the “Gateway” lunar space station, and eventual trips to Mars.

“These measurements comprehensively showed we have a well-developed system for protecting the crew from radiation during Artemis I, but challenges still remain for longer duration missions such as Mars,” Dr George said.

Why is radiation an issue? 

………………………………………………Items in low-Earth orbit are under the protection of Earth’s magnetic field, which shields Earth from the vast majority of radiation produced by our Sun (or from background cosmic radiation). 

But outside of this field, in open space, it’s a different story.

“In general, radiation levels are higher outside of the protection of low-Earth orbit and the protection of Earth’s magnetic field,” Dr George said.

“In addition, the exposure of crew to space weather, specifically ‘energetic solar particle events’ can be much higher as the Earth’s magnetic field is very effective at shielding these.”

……………………………………………...What did the research find?

The Artemis 1 mission, which lasted for 25 days, flew 450,000 km to the Moon, looped around it and then almost 65,000 kms out into deep space before flying back to Earth.

The team used Helga and Zohar as well as radiation sensors called HERA (Hybrid Electronic Radiation Assessor) placed throughout the cabin of the Orion spacecraft to assess how radiation levels changed throughout the mission.

………………………………………………………………..it wasn’t all good news. 

“The inside of the cabin was full of X-rays during the transit of the outer Van Allen belt which was something we did not expect,” Dr George said. 

“The overall biological impact was minor, but this was still a fascinating observation.”

The health risk of ionising radiation is measured in millisieverts (mSv).

The research team suggested that a quick trip around the Moon, like in the Artemis I mission might set you back about 26.7 – 35.4 millisieverts (mSv), which is well below the amount that might cause damage to an astronaut.

……………………………………………………………………………. According to Dr George, travelling to, and then staying on Gateway would expose astronauts to much higher levels of radiation than what they would receive on the ISS. 

Then there’s Mars, a trip which may take around nine months each way, plus any radiation you might receive on the surface.  

When the team extrapolated out the Artemis results to a Mars mission, and combined it with measurements from Mars’ Curiosity rover, they found astronauts might scrape by under the NASA lifetime limit of radiation, which is 600 mSv, but not by much.

“A really big solar particle event (with appropriate sheltering) might also push you up by a few hundred mSv,” Dr George said. …………………………………………………………………..

……………………………………..further into the future, radiation protection might become significantly more high tech.

According to Anatoly Rozenfeld, a medical physicist at the University of Wollongong who specialises in space radiation, one line of research is trying to build a magnetic field for the spacecraft itself, but he warns that this is still very much in it’s infancy. 

“There’s a lot of different kinds of projects and some of them are realistic, some of them are less realistic,” Professor Rozenfeld said. 

“People are also developing radio-protective drugs. So when you take these pills, your cells will recover very quickly after radiation.”  https://www.abc.net.au/news/science/2024-09-19/nasa-radiation-artemis-mission-helga-zolar/104365924

September 25, 2024 - Posted by Christina Macpherson | space travel