Cavanagh PR, Rice AJ, Licata AA, Kuklis MM, Novotny SC, Genc KO, Englehaupt RK, Hanson AM. A novel lunar bed rest analogue. Aviat Space Environ Med 2013; 84:1191–5.
Introduction:
Humans will eventually return to the Moon and thus there is a need
for a ground-based analogue to enable the study of physiological adaptations to lunar gravity. An important unanswered question is whether or not living on the lunar surface will provide adequate loading of the musculoskeletal system to prevent or attenuate the bone loss that is seen in microgravity.
Previous simulations have involved tilting subjects to an approximately 9.5° angle to achieve a lunar gravity component parallel to the long-axis of the body. However, subjects in these earlier simulations were not weight-bearing, and thus these protocols did not provide an analogue for
load on the musculoskeletal system.
Methods:
We present a novel analogue which includes the capability to simulate standing and sitting in a lunar loading environment. A bed oriented at a 9.5° angle was mounted on six linear bearings and was free to travel with one degree
of freedom along rails. This allowed approximately 1/6 body weight loading of the feet during standing. “Lunar” sitting was also successfully simulated.
Results:
A feasibility study demonstrated that the analogue was tolerated by subjects for 6 d of continuous bed
rest and that the reaction forces at the feet during periods of standing were a reasonable simulation of lunar standing. During the 6 d, mean change in the volume of the quadriceps muscles was -1.6% ± 1.7%.
Discussion:
The proposed analogue would appear to be an acceptable
simulation of lunar gravity and deserves further exploration in studies of longer duration.