(Expose-R PUR) Expose – R Responses of Phage T7, Phage DNA and Polycrystalline Uracil to the Space Environment
ENVIRONMENT (EXPOSE-R PUR)
Research Area: Astrobiology
Expedition(s): 18- 26
Principal Investigator(s): ● Gy Rontó, Hungary Academy of Sciences, Budapest, Hungary
RESEARCH OBJECTIVES
The Expose-R facility hosts a suite of astrobiology experiments, some of which could help
understand how life originated on Earth. This suite of experiments are accommodated in 3
special sample trays, which are loaded
with a variety of biological samples
and exposed to the harsh environment
of open space for almost 2 years from
March 2009-January 2011. This
experiment studies the effect of solar
UV radiation on a type of virus (Phage
T7) and an RNA compound (uracil) to
determine their effectiveness as
biological dosimeters for measuring
UV dose in the space environment.
RESULTS
During the whole flight, the surface of
PUR experiment was exposed to the solar radiation for 2 687 hours, which corresponds to a
total UV (ultraviolet) dose of 1 100 MJ/m^2. The effect of the solar UV was evaluated by
spectrophotometry in the specific UV range: 200-400 nm. The so-called dark samples (not
exposed to the solar radiation) in the EXPOSE-R under the exposed ones did not change in the
flight (ie, the measured absorption spectra did not change under the influence of space
conditions). On the top of the exposed uracil and bacteriophage samples, magnesium fluoride
filters of various (4 orders of magnitude) transparency were applied, which aimed to
approximate dose effect relations for both targets. Based on the slope of the curves, higher
sensitivity of the uracil samples was found. The resulting curves indicated that both
bacteriophage T7 and uracil in thin layer form are suitable for the assessment of the biological
risk due to extraterrestrial solar radiation (Berces 2013).
PUBLICATION(S)
Bérces A, Egyeki M, Fekete A, Kovacs G, Ronto G. Biological ultraviolet dosimetry in low-Earth’s
Orbit. Astrobiology & Outreach. 2013;1:104. doi: 10.4172/2332-2519.1000104.
This investigation is complete; however additional results are pending publication.
Sample containers are opened after they are returned to
Earth for analysis. ESA image.