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Energy expenditure in space flight (doubly labelled water method) (8-IML-1)The objective of the Energy Expenditure in Space Flight (ESS) experiment is to demonstrate and evaluate the doubly labeled water method of measuring the energy expended by crew members during approximately 7 days in microgravity. The doubly labeled water technique determines carbon dioxide production which is then used to calculate energy expenditure. The method relies on the equilibrium between oxygen in respiratory carbon dioxide and oxygen in body water. Because of this equilibrium, the kinetic of water turnover and respiration are interdependent. Under normal conditions, man contains small but significant amounts of deuterium and oxygen 18. Deuterium is eliminated from the body as water while oxygen 18 is eliminated as water and carbon dioxide. The difference in the turnover rates in the two isotopes is proportional to the carbon dioxide production. Deliberately enriching the total body water with both of these isotopes allows the isotope turnovers to be accurately measured in urine, plasma, or saliva samples. The samples are taken to the laboratory for analysis using an ion-ratio spectrometer.
Document ID
19920014377
Acquisition Source
Legacy CDMS
Document Type
Other
Authors
Parsons, Howard G.
(Calgary Univ. Alberta)
Date Acquired
September 6, 2013
Publication Date
February 1, 1992
Publication Information
Publication: NASA. Marshall Space Flight Center, First International Microgravity Laboratory Experiment Descriptions
Subject Category
Aerospace Medicine
Accession Number
92N23620
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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