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Blood Volume Changes and Red Blood Cell Life Span (M113)
Principal Investigator
Research Area:
Species Studied
Scientific Name: Homo sapiens Species: Human

Decreased red blood cell mass has been found regularly among astronauts returning from space flight. This observation was first documented in the crew of the 8-day Gemini 5 mission and confirmed in the crewmembers of the 14-day Gemini 7 mission. In addition, it was observed that the red blood cell half- life (the time for half of the total amount of tagged red blood cells to be removed from circulation) was shortened, suggesting that hemolysis combined with bone marrow unresponsive to stimulation of red blood cell production caused the decrease in circulating red blood cells and subsequent decreased red blood cell mass.

Red blood cell half-life was not shortened on the Apollo missions, although the crews of both Apollo and Gemini missions were exposed to at least four hours of 100% oxygen prior to launch and during flight. It was not clear whether inhibition of erythropoiesis (decreased production of red blood cells) caused by hyperoxia, or hemolysis of red blood cells (increased destruction) was the causative agent for the decrease in red blood cell mass. The Skylab missions offered the opportunity to rule out the hyperoxia hypothesis while testing whether changes in red blood cell mass are progressive with longer periods of weightlessness. Skylab experiment M113 was designed to (1) determine the effect of Earth-orbital missions on plasma volume and red blood cell populations (particularly red cell mass, life span, and production and destruction rates), and (2) provide baseline data for correlation with data from other hematologic and immunologic experiments.

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Johnson PC, Driscoll TB, LeBlanc AD. Blood volume changes. In: Johnson RS, Dietlein L, eds. Biomedical Results from Skylab. Washington, DC: NASA Headquarters; 1977; 235-241. NASA SP-377. [NTRS]

Johnson PC, Driscoll TB, LeBlanc AD. Blood volume changes. The Proceedings of the Skylab Life Sciences Symposium, Volume II, August 27-29, 1974.. pp. 495-505. NASA TM X-58154. [NTRS]

Johnson PC, Kimzey SL, and Driscoll TB. Postmission plasma volume and red cell mass changes in the crews of the first two Skylab missions. Acta Astronautica 1975 2:311-317.[]


Data Information
Data Availability
Archive is complete. Data sets are not publicly available but can be requested.
Data Sets+ Request data

Iron turnover rate
Red blood cell half-life
Red blood cell lifespan
Red blood cell mass
Reticulocytes, number of

Mission/Study Information
Mission Launch/Start Date Landing/End Date Duration
Skylab 2 05/25/1973 06/22/1973 28 days
Skylab 3 07/28/1973 09/25/1973 59.5 days
Skylab 4 11/16/1973 02/08/1974 84 days

Additional Information
Managing NASA Center
Johnson Space Center (JSC)
Responsible NASA Representative
Johnson Space Center LSDA Office
Project Manager: Pamela A. Bieri
Institutional Support