In the EXPOSE-R2 facility, organisms can be installed on the outside of the ISS in conditions similar to those on Mars or the Moon. To do so, the samples are placed on simulated Mars or Moon soils; corresponding atmospheres fill the interior, and filters adapt the strength and wavelength range of the radiation. DLR has contributed to the BIOMEX and BOSS experiments.
The samples in the EXPOSE-R2 facility from space are carefully removed under a protective atmosphere at the DLR Institute of Aerospace Medicine. The several hundred organisms have spent almost two years on the outside of the ISS. The researchers want to investigate which organisms have survived the conditions in space.
Several hundred organisms have spent for almost 530 days in the EXPOSE-R2 facility on the outside of the ISS. During spacewalks, the facilty was installed and again dismantled almost 2 years later.
The small containers that are currently being disassembled at the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR) are rather inconspicuous, yet they may contain organisms that have endured the conditions of space for over 530 days. Several hundred organisms, such as bacteria that form biofilms, fungi, lichens, mosses and archaea that live in especially salty environments on Earth, returned to Earth from the International Space Station (ISS) in the Soyuz spacecraft with astronaut Tim Peake. Whilst there, the DLR Biology and Mars Experiment (BIOMEX) and Bio Organisms Surfing Space (BOSS) experiments were attached to the outside of the Station and exposed to the vacuum of space and the strong UV radiation of the Sun. "We are now disassembling the individual samples and sending them to the international research groups for analysis," explains DLR radiation biologist Elke Rabbow. "The results will then reveal which organisms can survive in space."
Small-scale Mars and Moon
The organisms already demonstrated a good chance of survival in initial tests conducted on Earth. At the DLR Institute of Aerospace Medicine, all the organisms had to prove their will to survive. Here, in the space simulation facility, they were exposed to the conditions on Mars and in space. A vacuum, the Martian atmosphere and sunlight as it is in space or on Mars can be simulated there. Likewise, in the Mars Simulation Chamber at the DLR Institute of Planetary Research, several selected organisms such as lichens, cyanobacteria and biomolecules were exposed to the changing environmental conditions in the day and night cycle – with changing humidity, temperatures and radiation – as part of the BIOMEX project. The almost two-year stay in space was the next step in putting the organisms to the test in the most realistic conditions possible.
The researchers primarily selected candidates that already live under extreme environmental conditions on Earth – and so would presumably be capable of surviving the conditions on the Moon or Mars. To create these conditions, the scientists introduced their samples into the EXPOSE-R2 facility, in soils similar to that on Mars and the Moon, created an artificial Martian atmosphere for some samples and used various filters to alter the radiation in space. Furthermore, in addition to other biomolecules, pigments that are found in living organisms on Earth were exposed to Martian conditions. "If we can find out the conditions under which organisms survive on Mars or the Moon, and how to look for these signatures of life, we can develop a better idea of where on these celestial bodies we should look for life," stresses Jean-Pierre de Vera, DLR planetary researcher and scientific head of the BIOMEX experiment.
Protection against terrestrial life
In addition, the risk of terrestrial life accidentally reaching another celestial body on a space probe will also be easier to estimate using the results of the astrobiological experiments. "We need to guarantee as much as possible that other planets are protected against this," says DLR radiation biologist Rabbow. "To do this, we need to understand which celestial bodies terrestrial organisms can actually survive on." The coming analyses of the samples will show which ones have stayed alive in the harsh conditions of the stay in space, and what the pre-requisites are.
