Medical considerations for extending human presence in space.

The prospects for extending the length of time that humans can safely remain in space depend partly on resolution of a number of medical issues. Physiologic effects of weightlessness that may affect health during flight include loss of body fluid, functional alterations in the cardiovascular system, loss of red blood cells and bone mineral, compromised immune system function, and neurosensory disturbances. Some of the physiologic adaptations to weightlessness contribute to difficulties with readaptation to Earth's gravity.

[Future thrusts in life sciences experimentation in space (USA)].

The major physiological problem areas confronting man in space are reviewed and major research questions that remain to be answered are identified. The need for thorough ground-based studies prior to the acquisition of inflight data is emphasized. Future experiments are seen to focus on mechanistic questions and on the development of preventive measures to disturbances in neurophysiology, cardiovascular physiology, skeletal physiology and radiobiology since these areas have highest priority in future manned spacecraft operations.

Spaceflight and the telltale heart.

Cardiac arrhythmias have not been a common occurrence during manned spaceflights. Cardiovascular deconditioning, on the other hand, is a universal finding both during and after exposure to microgravity. Exercise capability is reduced only in the immediate postflight period as is cardiac output.

U.S. manned space flight: the first twenty years, a biomedical status report.

In the last 20 years, the biomedical problems facing man in space have been brought into sharper focus. Space motion sickness is presently our most serious problem. Its etiology remains obscure, but the "sensory conflict" theory appears most plausible.