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Published on: May 27, 2016
Biological UV dosimeters in simulated space conditions
1Institute of Biophysics and Radiation Biology, Faculty of Medicine, Semmelweis University, Budapest, Hungary. Ronto@puskin.sote.hu
Advances in Space Research : the Official Journal of the Committee on Space Research (COSPAR)
|April 6, 2005
Summary
Polycrystalline uracil layers are stable in simulated space conditions and show reversible UV-induced dimerization. Monomerization efficiency varied between UV light sources, impacting biological dosimetry experiments.
Area of Science:
- Astrobiology
- Photochemistry
- Materials Science
Background:
- Uracil is a key component in biological systems and its response to space radiation is crucial for astrobiology.
- The phage and uracil response (PUR) experiment investigates uracil's behavior under extraterrestrial conditions on the International Space Station (ISS).
Purpose of the Study:
- To assess the stability of polycrystalline uracil thin layers under simulated space conditions (temperature, vacuum, UV-C radiation).
- To study the kinetics of uracil dimer formation and reversion induced by short-wavelength UV radiation.
- To develop a mathematical model for uracil monomerization-dimerization reactions.
Main Methods:
- Simulated space environment tests including vacuum exposure, temperature variations (-20 to +40°C), and UV-C irradiation (down to 200 nm).
- Kinetic analysis of uracil dimer formation (dimerization) and monomerization.
- Comparison of monomerization efficiency using a polychromatic deuterium lamp versus a germicidal lamp.
Main Results:
- Uracil samples demonstrated vacuum-tightness for 7 days and stability within the tested temperature range.
- UV radiation induced simultaneous dimerization and monomerization reactions.
- The polychromatic deuterium lamp exhibited higher monomerization efficiency than the germicidal lamp.
Conclusions:
- Polycrystalline uracil is stable under simulated space conditions relevant to the ISS.
- The non-additive nature of UV-induced dimerization-monomerization reactions necessitates specific modeling.
- Findings contribute to understanding uracil's role in biological dosimetry for space radiation.
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