European Technology Exposure Facility - Exposure Experiment – Seeds (EuTEF-Expose-Seeds)
Research Area: Astrobiology
Expedition(s): 16- 20
Principal Investigator(s): ● David Tepfer, Institute National de la Recherche Agronomique,
Versailles, France
RESEARCH OBJECTIVES
The European Technology Exposure Facility -
Exposure Experiment exposes several
investigations outside of the International
Space Station (ISS) for 18 months on the
external surface of the European Columbus
Laboratory. Plant seeds have evolved to
conserve the species and its genome under
extreme stress conditions (cold, drought,
heat). EuTEF-Expose-Seeds determines the
resistance of plant seeds when exposed to
the open space environment. Plant seeds
have in fact frequently been tested in space,
mostly as part of microgravity and radiation
studies, but never with full exposure to solar
UV-C on a long-duration flight.
RESULTS
Of the 2 100 wild-type Arabidopsis thaliana
(cress plant) and Nicotiana tabacum (tobacco) seeds, 23% produced suitable plants after
exposure for 1.5 years to full space conditions including solar UV. The highest survival occurred
in tobacco (44%). These results indicated that a seed-like entity could survive exposure to solar
UV radiation unprotected during transport between Mars and Earth.
Full survival is attained in seeds shielded from solar light, demonstrating that a longer space
travel would be possible for seeds embedded in an opaque matrix. Survival is lower in the
Arabidopsis wassilewskija ecotype and in mutants lacking UV screens.
Chemical samples of seed flavonoid UV screens were degraded by UV, but their overall capacity
to absorb UV was retained. Nucleic acids (large biological molecules essential for life) were also
degraded by UV. However, a fragment was detected and the gene survived in space when
protected from UV. This showed that even if seeds do not survive, components (eg, their DNA)
might survive transfer over cosmic distances.
Expose allows long exposures to space conditions and
solar UV-radiation on the International Space Station.
Several trays filled with organisms were installed on the
outside of the European Columbus laboratory as one of
the 9 payloads of the European Technology Exposure
Facility (EuTEF). ESA image.