The space experiments BIOMEX and BioSigN to prepare for in situ life detection missions and habitability studies

Kurzfassung

The search for life in our Solar System is at the centre of several current and future robotic missions to Mars and beyond, to the icy moons of Jupiter and Saturn. New instruments, in the context of space exploration, have been sent to Mars on recent rover missions, such as Raman spectrometers particularly suited for the fast and non-destructive identification of biomolecules embedded in minerals. International and national efforts have also been focusing on bringing samples back from Mars to be analysed with state-of-the-art laboratory instruments on Earth. And two missions en route to Jupiter will teach us more about the environment and potential organic content of another excellent target for finding life beyond Earth, Europa. However, little is known about the stability of putative biosignatures in the Martian or space environment. To support and prepare these current and future exploration missions to Mars, Europa and Enceladus, exposure experiments in low Earth orbit, using the International Space Station (ISS) are crucial. For instance, during the BIOMEX experiment (2014-2016), biomolecules and microorganisms were exposed for 16 months to a simulated Martian environment in LEO. This environment was provided in the EXPOSE-R2 module, outside the ISS and comprised of UV and ionizing radiation, a Mars-like atmosphere, extreme temperature cycles, and analogues of Martian regolith. Seven of those biomolecules were analysed post-flight using Raman spectroscopy; all remained detectable. The next ESA space exposure experiment BioSigN (Biosignatures and habitable niches) will follow in the next few years extending the range of samples to icy moons relevant organisms and molecules. These experiments, and the international efforts required to achieve them, are crucial to advance our knowledge on the detectability of putative traces of life outside of Earth, and on the potential habitable conditions of our neighbouring planets and moons. To maximize the scientific outputs, the space experiments are always connected to the results obtained on ground from planetary analogue field sites and planetary simulation facilities.