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Physical dosimetric evaluations in the Apollo 16 microbial response experiment
G R Taylor1, J V Bailey, E V Benton
1Life Sciences Directorate, NASA-Johnson Space Center, Houston, Texas, USA.
Life Sciences and Space Research
|January 1, 1975
Summary
Nine species survived space conditions like vacuum, radiation, and UV light during Apollo 16. Genetic and somatic studies on these organisms revealed no major survival changes, enabling further research into space radiation effects.
Area of Science:
- Astrobiology and Space Radiation Biology
- Microbiology and Genetics
- Radiation Dosimetry
Background:
- Understanding the effects of space environments on biological organisms is crucial for space exploration and astrobiology.
- Previous studies have indicated potential risks from space vacuum, galactic radiation, and solar ultraviolet (UV) light to living cells.
Purpose of the Study:
- To assess the survival and genetic/somatic effects on nine biological species (viruses, bacteria, fungi, nematodes) exposed to space conditions during the Apollo 16 mission.
- To develop and test in-flight radiation monitoring instruments for accurate dose-response studies of UV and cosmic radiation.
- To quantify the mutagenic potential of the space radiation environment, particularly heavy particles.
Main Methods:
- Exposure of biological species to combinations of space vacuum, galactic radiation, and solar UV light.
- Utilized solar UV at specific wavelengths (254, 280, 300 nm) and energy levels for mutagenic studies.
- Developed and deployed a potassium ferrioxalate actinometer and an anaerobic photographic emulsion dosimeter for UV monitoring.
- Employed lithium fluoride thermoluminescent dosimeters and passive nuclear-track detectors (cellulose nitrate, Lexan, Ilford G5, silver chloride) to measure cosmic radiation components.
Main Results:
- No significant changes in the number of surviving cells were observed across the nine biological species.
- Developed and validated novel dosimeters for accurate in-flight UV and heavy particle radiation measurements.
- Measured incident heavy particle fluences at 19.3 +/- 1.8 particles cm-2 (LET>100 keV x µm-1), which was lower than expected, suggesting shielding effects.
Conclusions:
- Biological species demonstrated resilience to the combined space environmental factors tested.
- The developed dosimetry methods are effective for in-flight monitoring of space radiation.
- The measured cosmic-ray particle dose suggests that the spacecraft or experimental setup provided significant shielding.
Keywords:
NASA Experiment Number AP002