Abstract
This work presents the design and characteristics of a new compact ultraviolet (UV) irradiator used in a biological onboard space flight experiment. The experiment, called DRM, took place in the International Space Station research facility (ISS-13 expedition), during the Centenary Mission (Russian-Brazil) in March-April 2006. The DRM main objective was to correlate the DNA repair mechanism and mutagenesis with microgravity. A compact irradiator apparatus was designed for DRM to allow in situ induced radiation in space. This apparatus, called CIM, uses UV-A Light-emitting diodes (LEDs) with 375 nm wavelength as molecular lesions inducers on four bacterial E. coli strains. The manned space mission restrictions were focused on during the CIM main parts design. The ultraviolet dosimetry is also described in this document as DRM experiment results and the CIM operational data are reported to certify the CIM design and DRM protocol compatibility in space application.
Highlights
During the last decades, experiments using different bacteria (e.g.: Bacillus subtilis HA 101, Echerichia coli B/r, Echerichia coli PQ37, Echerichia coli 3 cp, Deinococcus radiodurans type R, Deinococcus radiodurans type R+rec30) have been conducted and their preliminary conclusions point to no significant statistical difference existing in DNA repair mechanism responses to equivalent radiation doses under microgravity or terrestrial conditions
Memory Module data results: After an analysis of Irradiance follow-up data stored in the MM, it was noted that the sets of LEDs in the two slots turned off after 25 minutes, contrary to the 240 minutes programmed in the firmware, due to an undetermined
The above irradiation periods were recorded in the Compact Irradiator Modulus (CIM) memory module
Summary
Experiments using different bacteria (e.g.: Bacillus subtilis HA 101, Echerichia coli B/r, Echerichia coli PQ37, Echerichia coli 3 cp, Deinococcus radiodurans type R, Deinococcus radiodurans type R+rec30) have been conducted and their preliminary conclusions point to no significant statistical difference existing in DNA repair mechanism responses to equivalent radiation doses under microgravity or terrestrial conditions. The mission was launched to a 650 km Earth orbit, providing a total dose rate in the experiment 15 times higher than observed at the ISS (exposed to microgravity, ionizing radiation, and heavy-ion bombardment due to its high-inclination orbit), using living organisms (B. subtillis wild-type 168 and radiation-sensitive mutant WN1087 strains).
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