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Apollo Flight Crew Cardiovascular Evaluations (AP005)
Principal Investigator
Research Area:
Cardiovascular physiology
Species Studied
Scientific Name: Homo sapiens Species: Human

It has been sufficiently documented from Earth-based simulations of weightlessness, such as recumbency, water immersion, and from the space-flight environment itself, that orthostatic intolerance may result from relative inactivity or confinement. Potential problems of cardiovascular deconditioning were anticipated and thoroughly studied through various simulation techniques even before man first ventured into space. Cardiovascular deconditioning, or orthostatic intolerance, was consistently observed in crewmen during the early period of the Mercury and Gemini missions. With the advent of the Apollo Program, researchers were presented with new questions and uncertainties regarding this topic. The fundamental differences in the Apollo spacecraft and its operational environment, and in program goals, were expected to produce physiological responses that differed from those seen after the Gemini flights. The two-gas (oxygen and nitrogen) atmosphere and the capability to move about in the spacecraft led to speculation that returning Apollo crewmen might show little or no change in orthostatic tolerance. On the other hand, there was some concern regarding the ability of the cardiovascular system to withstand acceleration stresses associated with lunar descent and ascent (headward acceleration was imposed during lunar module descent after three to four days of weightlessness and a near 1-G force was produced by the ascent profile after a day or more of 1/6-G exposure).

The primary objective of the Apollo Flight Crew Cardiovascular Evaluations was to determine the response of the cardiovascular system to weightlessness. The results of postflight tests were expected to show differences in cardiovascular responsiveness between crewmen who walked on the moon and those who remained in weightlessness. These speculations and other unanswered questions emphasized the need to gain as much understanding as possible about the cardiovascular system and its adaptation, first to zero-G and later to 1-G. Then, as a countermeasure to orthostatic intolerance, a supplemental objective was addressed on the last two Apollo missions This objective was to evaluate the efficacy of an experimental antihypotensive garment. Though the Gemini and early Apollo missions revealed no need for such postflight support, planners of the 28- and 56-day Skylab missions envisioned the possible need for such postflight protection.

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Hoffler GW, Johnson RL. Apollo flight crew cardiovascular evaluations. In: Johnson RS, Dietlein LF, Berry CA, eds. Biomedical Results of Apollo. Washington, DC: NASA Headquarters; 1975:227-264. NASA SP-368. [NTRS]

Cardiovascular deconditioning
Orthostatic intolerance
Lower body negative pressure (LBNP)

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Data Information
Data Availability
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Ambient temperature
Blood pressure
Body temperature
Body weight
Calf circumference
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Mission/Study Information
Mission Launch/Start Date Landing/End Date Duration
Apollo 10 05/18/1969 05/26/1969 8 days
Apollo 11 07/16/1969 07/24/1969 8 days
Apollo 12 11/14/1969 11/24/1969 10 days
Apollo 13 04/11/1970 04/17/1970 6 days
Apollo 14 01/31/1971 02/09/1971 9 days
Apollo 15 07/26/1971 08/07/1971 12 days
Apollo 16 04/16/1972 04/27/1972 11 days
Apollo 17 12/07/1972 12/19/1972 12 days
Apollo 7 10/11/1968 10/22/1968 11 days
Apollo 8 12/21/1968 12/27/1968 6 days
Apollo 9 03/03/1969 03/13/1969 10 days

Additional Information
Managing NASA Center
Johnson Space Center (JSC)
Responsible NASA Representative
Johnson Space Center LSDA Office
Project Manager: Jessica Keune
Institutional Support
National Aeronautics and Space Administration (NASA)