The Effects of 4-He Radiation on the Material Properties of Bone

Abstract

NASA has a long-term goal to go to Mars. The long duration spaceflight has many risks to astronaut health, including the risk of bone loss due to the absence of gravity and exposure to space radiation. There have been studies on the microstructures and structural properties on the effects of space radiation on bone, but not on the material properties. This project looks at the changes in the viscoelastic material properties of the effects of helium radiation on bone in rats using spherical micro-indentation testing. Long Evans Rats were exposed to whole body helium radiation of varying doses at Brookhaven National Laboratory. As a result, radiation dose and the time after exposure to helium-4 radiation (25cGy) were found to cause changes in bone material stiffness when assessed with spherical micro-indentation. There was a decline at 90-days post exposure, with a partial recovery by 180-days. This decline in bone stiffness, without any compensating increase in bone volume, would increase fracture risk.