In space, most of this radiation is high-energy particles streaming from the Sun - protons that can travel 93 million miles in less than an hour.
On Earth, the planet's magnetic bubble, the magnetosphere, protects us from most of this radiation.
But in space, spacecraft and spacesuits are much more vulnerable.
Ruthan Lewis, an engineer for NASA’s human spaceflight program, said: "The danger of radiation is always present, whether you’re in orbit, in transit, or on a planetary surface.
"From mitigation techniques to protection and enclosures, we’re considering this in every environment astronauts will be in."
Knowing how radiation on the Moon affects the body will be critical for long-term missions.
The next generation of US astronauts is expected to return to the Moon by 2024 under the guise of NASA's Artemis programme.