ICEXPOSE:ICY EXPOSURE OF MICROORGANISMS
2019
The cold, arid, remotely located and perennially ice covered environment of the Antarctic ice sheet is
the most hostile place on Earth. It has long been considered an analogue to how life might persist in the
frozen landscape of the major Astrobiological targets of our solar system such as Mars or the Jupiter’s
ice-covered moon Europa. In the frame of the ICExPOSE project presented here, the parameters outside the Antarctic Concordia station are utilized as a testbed for performed or planned long-duration
space flights and to study the survivability of selected test organisms in an extremely cold (with temperature swings) and highly variable UV environment. The most likely terrestrial organisms to endure such
an excursion are extremely tolerant and/or (multi-) resistant microbes-extremophiles- that have evolved
mechanisms to withstand such severe conditions. The survivability of a variety of human-, space-flight
and extreme-associated microorganisms from all three domains of life (plus viruses) will be investigated
using a multiuser exposure facility called EXPOSE that has already been successfully flown on ISS for
space exposure durations of up to 2 years. The EXPOSE Mission Ground Reference (MGR) trays are still
available and will be reused to accommodate the samples for passive exposure. Microbiological response to
single and combined extraterrestrial conditions including simulations of astrobiological relevant environments, like simulated Martian atmospheric conditions, will be tested. The scientific questions addressed
in ICEXPOSE are: how is the survival of human-associated and Polar Regions- derived microorganisms
compared to (other) environmental extremophilic microorganisms; which physiological state (i.e., cells,
spores or colony/biofilms) harbors the weakest or strongest viability and/or mutagenicity detectable after
exposure; what type of morphologic and molecular changes can be identified and to which extent does
the exposure conditions (e.g. UV-exposed versus UV-shielded) influence the microbial physiology (e.g.
pathogenicity, antibiotic resistance, and metabolism) of the exposed species. The results of the ICExPOSE experiment will provide valuable information on: the definition of the physical-chemical limits of
life as well as the potential habitability of other planetary bodies; the assessment of the risk of microbial
contamination inside human inhabited confined areas and consequent challenges for human health; how
to better monitor and control microbial contamination in spaceflight environments, as a key-factor for
the success of future space exploration missions; whether specific microorganisms pose possible forward
contamination risks that could impact planetary protection policy and will provide complementary results
for the two selected future ESA space experiments MEXEM and IceCold.
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