European Technology Exposure Facility - Exposure Experiment - Process (EuTEF-Expose-Process)
Research Area: Astrobiology
Expedition(s): 16- 20
Principal Investigator(s): ● Hervé Cottin, Universite Paris Diderot, Paris, 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. EuTEF-Expose-Process improves
our knowledge about the chemical nature and
evolution of organic molecules in various
space environments. Organic samples are
exposed to space conditions to simulate their
evolution on extreme places such as
asteroids, comets, and the surface of Mars.
RESULTS
A selection of the results from the EuTEF-
Expose-PROCESS experiment showed that
resistance to radiation depends on the
chemical nature of the exposed molecules and the wavelengths of the UV light. The experiment
also demonstrated the protective effect of meteorite powder. The most altered compounds are
the dipeptide, aspartic acid, and aminobutyric acid. The most resistant are alanine, valine, glycine,
and aminoisobutyric acid. All molecules, with or without meteorite powder, were affected when
exposed to solar radiation. Aspartic acid, an amino acid with a diacid group, is more sensitive to
UV radiation than amino acids with alkyl chains. The dipeptide with an amide bond degraded
almost completely when not associated with a mineral surface. In contrast, the amino acids with
a substituted chain, such as valine, are more stable than those with a linear chain, as in the case
of aminobutyric acid.
Aboard the ISS, the amino acids exposed in the free form degrade by more than 40%. The
quantity of the leucine dipeptide (Leu2) in the samples is too low to be quantified, but intact
molecules are present. More than 80% of the compounds associated with meteorite powder
are preserved, except for the aspartic and amino butyric acids and Leu2. The protective effect
of the meteorite powder is important, in particular for those compounds that showed the most
degradation when exposed in the free form. In these 2 forms, free or embedded in meteorite
powder, the most resistant compounds were the amino acids alanine, glycine, aminoisobutyric
acid, and valine; the most degraded were the dipeptides and the aspartic and aminobutyric
acids.
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.