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Calcium Balance (M007)
Principal Investigator
Research Area:
Bone and calcium physiology
Metabolism and nutrition
Renal, fluid and electrolyte physiology
Species Studied
Scientific Name: Homo sapiens Species: Human

The primary goal of the calcium and nitrogen balance study was to measure total body metabolism as it relates to the musculoskeletal system in the microgravity environment. Carefully controlled ground-based studies of calcium metabolism under varying conditions of bed rest and water immersion demonstrated that significant changes in calcium excretion generally occur over long rather than short periods of time in some people. Researchers believed urinary calcium excretion to be an indicator of changes in bone metabolism and bone physiology. There were the two significant reasons for examining calcium metabolism. First, urinary calcium can be derived from either dietary calcium or from skeletal calcium; if urinary calcium increases excessively, it may come from the skeleton, and demineralization of the skeleton would then be expected. Secondly, increased urinary calcium predisposes some individuals to kidney stones.

Calcium losses would not be significant unless collections were carried out under controlled conditions for periods of at least two weeks. Therefore, mineral balance studies were not attempted in the Gemini program until the first long duration flight was performed, the 14-day Gemini 7 mission. Changes in the excretion of other body constituents were of interest because they demonstrated effects in the body systems under investigation.

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La Chance P, Lutwak L., Neuman W, and Whedon GD. Experiment M-7, calcium and nitrogen balance. NASA Technical Report. January 01, 1966. N66-29626 16-31.

Lutwak L, Whedon GD, LaChance PA, Reid JM, Lipscomb HS. Mineral, electrolyte and nitrogen balance studies of the Gemini-VII fourteen-day orbital space flight. J Clin Endocrinol Metab. 1969 Sep;29(9):1140-1156.[]

Lutwak L. Calcium and nitrogen balance studies during Gemini VII flight. In: Lectures in Aerospace Medicine. Sixth Series. Brooks Air Force Base, Texas: USAF School of Aerospace Medicine, 1967 Feb 6-9.

Lutwak L. Calcium and nitrogen balance studies during Gemini-7 flight. NASA Contractor Report: NAS9-5375: September 1966.

Lutwak L., Neuman W, and Whedon GD. Calcium and nitrogen balance. NASA Manned Spacecraft Center A Revision of Medical Results of Gemini 7 and Related Flights. August 1966, 127-165. N68-10181 01-04.

Whedon GD. Effects of weightlessness on mineral metabolism: experience to date. Acta Astronautica. 1972;17:119-128.

Bone demineralization, pathologic
Kidney calculi

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

Calcium: dietary
Calcium: fecal
Calcium: sweat
Calcium: urinary
Creatinine: urinary
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Mission/Study Information
Mission Launch/Start Date Landing/End Date Duration
Gemini 7 12/04/1965 12/18/1965 14 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
National Aeronautics and Space Administration (NASA)