Radiation dosimetry for microbial experiments in the International Space Station using different etched track and luminescent detectors

Abstract

The laboratory of Microbiology at SCK.CEN, in collaboration with different universities, participates in several ESA programmes with bacterial experiments that are carried out in the International Space Station (ISS). The main objective of these programmes is to study the effects of space flight conditions such as microgravity and cosmic radiation on the general behaviour of model bacteria. To measure the radiation doses received by the bacteria, different detectors accompanied the microbiological experiments. The results obtained during two space flight missions are discussed. This dosimetry experiment was a collaboration between different institutes so that the doses could be estimated by different techniques. For measurement of the high linear energy transfer (LET) doses (>10 keV microm(-1)), two types of etched track detectors were used. The low LET part of the spectrum was measured by three types of thermoluminescent detectors ((7)LiF:Mg,Ti; (7)LiF:Mg,Cu,P; Al(2)O(3):C) and by the optically stimulated luminescence technique using Al(2)O(3):C detectors.

Experimental design and environmental parameters affect Rhodospirillum rubrum S1H response to space flight

“…0.16 mGy day À1 of g rays and 0.02 mGy day À1 of neutron rays, totaling ca. 1.8 mGy per 10 days, which is comparable with the actual space flights experiments (Goossens et al, 2006;Vanhavere et al 2008 (Bradford, 1976), according to the Bio-Rad Protein Assay kit (Bio-Rad, Hercules, CA, USA), with bovine g-globulin as a protein standard. Protein concentration of each sample was adjusted to 5 mg ml À1 and equal amounts of the three biological replicates were pooled before labeling.…”

“…After inoculation, Petri plates were sealed first with Parafilm (Pechiney Plastic Packaging, Chicago, IL, USA) and Kapton tape (3M, Cergy-Pontoise, France), next, individually packed in Ziplock bags, and then jointly packed in a second Ziplock bag and placed in a sealed jar. Radiation dosimeters (Track-Etch Detectors, Optically Stimulated Luminescence Detectors and ThermoLuminescent Detectors, described in Goossens et al, 2006) and temperature sensors (CUBE, Meilhaus Electronic, Puchheim, Germany) were added in the jar. This jar was then wrapped in protective foam and NOMEX fabric bags (DuPont, Richmond, VA, USA) and stored at room temperature (Supplementary Figure 1).…”

“…400 km altitude) indicated an average dose of ca. 180mGy day À1 (Goossens et al, 2006;Vanhavere et al, 2008). Thus, on board the ISS, organisms undergo radiation stress up to 80-fold higher than the background radiation levels on the Earth.…”

The Influence of Microgravity on Invasive Growth inSaccharomyces cerevisiae

“…infra). Alternatively, the stress could be caused by the high total absorbed dose of ionizing radiation recorded during the flight experiment, which was about 70 times higher than that on Earth for the same period (Goossens et al, 2006;Vanhavere et al, 2008). CMBSESA1 is an industrial brewer's strain adapted to stress conditions and has a polyploid genome, which is correlated to an increased fitness and may result in an increased stress resistance (Sliwa et al, 2004).…”

“…From that point on, the same procedures as for the BASE-A experiment were followed as described previously (Leys et al, 2009). Temperature and radiation were logged as described previously (Goossens et al, 2006;Vanhavere et al, 2008).…”