June 12, 2013
Moon Radiation Study Explores How To Reduce Health Hazards For Astronauts
April Flowers for redOrbit.com - Your Universe Online
A new study from the space scientists at the University of New Hampshire (UNH) and the Southwest Research Institute (SwRI) reports that data collected by NASA's Lunar Reconnaissance Orbiter (LRO) reveals that lighter materials like plastics provide effective shielding against the radiation hazards faced by astronauts during extended space travel. The findings, published in the journal Space Weather, could help reduce human health risks on future deep space missions.
Space craft construction has relied heavily on aluminum, which provides relatively little protection against high-energy cosmic rays. The metal can also add so much mass to spacecraft that they become cost-prohibitive to launch.
Cary Zeitlin of the SwRI Earth, Oceans, and Space Department at UNH says, "This is the first study using observations from space to confirm what has been thought for some time — that plastics and other lightweight materials are pound-for-pound more effective for shielding against cosmic radiation than aluminum. Shielding can't entirely solve the radiation exposure problem in deep space, but there are clear differences in effectiveness of different materials."
Previous ground based tests using beams of heavy particles to simulate cosmic rays were used to make plastic-aluminum comparisons. "The shielding effectiveness of the plastic in space is very much in line with what we discovered from the beam experiments, so we've gained a lot of confidence in the conclusions we drew from that work," says Zeitlin. "Anything with high hydrogen content, including water, would work well."
The team´s space-based results were acquired using the Cosmic Ray Telescope for the Effects of Radiation (CRaTER) on board the LRO spacecraft thanks to the device´s ability to accurately gauge the radiation dose of cosmic rays after passing through a material known as "tissue-equivalent plastic," which simulates human muscle tissue. The effects of thick shielding on cosmic rays had only been simulated in computer models and in particle accelerators, with little observational data from deep space before CRaTER and recent measurements by the Radiation Assessment Detector (RAD) on the Mars exploration rover Curiosity.
The models and ground-based measurements have been validated by the CRaTER observations, suggesting that if their structural properties can be made adequate to withstand the rigors of spaceflight, lightweight shielding materials could safely be used for long missions.
CRaTER has been measuring energetic charged particles from galactic cosmic rays and solar particle events that can travel at nearly the speed of light and may cause detrimental health effects, since the launch of LRO. Earth´s thick atmosphere and strong magnetic field, however, provide adequate shielding against these dangerous high-energy particles.