Testing Cellular Cultures in Simultaneous Simulated Reduced-Gravity and Radiation Space Environments*

An apparatus was developed to test the effects of space-like reduced-gravity and radiation environments on biological cells. The modified rotary cell culture system (RCCS) has been used to expose mice muscle and skeletal cells to prolonged reduced-gravity and radiation, either separately or simultaneously, to simulate conditions during extended space travel. The apparatus has five cylindrical vessels rotated by a motor driven chain. The cells grown on polystyrene microspheres suspended in a viscous neutral-buoyant fluid within the vessels reach terminal velocity as they fall; the rotation of the vessels prevents the cells from ever settling, inducing a state of constant ``free-fall.'' Viscous drag and centripetal forces counter the effects of gravity and buoyant forces producing very little net force on the cells and thus simulating a low gravity environment. This apparatus is designed specifically for insertion in the USU Space Survivability Test (SST) chamber equipped with a 0.2 to 2.5 MeV beta radiation Sr$^{\mathrm{90}}$ source. Interchangeable graphite shielding produce specific average radiation dose rates cells. The simultaneous rotation of the vessels and exposure to the Sr-90 source provides a terrestrial method to observe space like conditions on cells.