28.02.17 12:54

Biology: Analysis of space samples starts

Antarctica – Space – Düsseldorf: The Long Journey of the Lichens

28.02.2017 – On 23 July 2014, Düsseldorf biologist Professor Sieglinde Ott sent the lichen Buellia frigida found in Antarctica to the International Space Station (ISS). This international and interdisciplinary project is examining the survivability and resili-ence of different organisms as well as the stability of biomole-cules under space and simulated Mars conditions. After months in space, the samples returned to Earth in June 2016. Analyses of the lichens and the biogenic substances have now com-menced. The objective is to understand how they have survived in space as well as how resilient and stable they are under ex-treme conditions.

Caption: The EXPOSE-R exposure experiment in the process of be-ing assembled on the Zvezda module of the International Space Sta-tion (ISS). Alongside other samples, lichen samples from HHU were exposed to space conditions for a total of 480 days. (Picture: ESA/ROSCOSMOS)

Lichens are not plants but symbiotic communities that live between a fungus (mycobiont) and one or several partners capable of photosynthesis (photobiont). Algae are typical photobionts. Lichens grow in all ecosystems around the globe and in polar regions can even be the dominant form of vegetation. They occur in very many forms: They grow flat on surfaces (crustose lichens) but also form plant-like structures (e.g. foliose or fruticose lichens). Due to their life history strategy, lichens are able to master extremely difficult environmental conditions. Types are known, for example, that can even survive high doses of radioactive radiation.

Düsseldorf biologist Professor Sieglinde Ott (Botany Institute, Symbiotic Interactions Work Group) is working, amongst others, with the lichen Buellia frigida. This is found in continental Antarctica where it braves extremely cold and dry conditions in an environment hostile to life. Professor Ott brought samples of this lichen back with her to Heinrich Heine University Düsseldorf (HHU) from an expedition to North Victoria Land in Antarctica during 2009/2010.

The biologists wanted to see how resilient Buellia frigida, as a symbiotic eukaryotic organism, proves to be when exposed to even more extreme conditions than the difficult ones in continental Antarctica. It was for this reason that Professor Ott took part in an international and interdisciplinary project run by ESA, the European Space Agency (Project Leader: Dr. Jean-Pierre Paul de Vera, German Aerospace Center (DLR), Institute of Planetary Research, Berlin). In the summer of 2014, the lichens and nine biogenic substances set off from Russia’s Baikonur cosmodrome on board a Soyuz spacecraft to the International Space Station (ISS). The samples were mounted in the EXPOSE-R unit, attached to the outside of the Zvezda module and exposed to space conditions as well as simulated Mars conditions for a total of 480 days.

The objective of this exposure experiment was to test both the survivability and the resilience of the lichens as well as the stability of the biogenic substances under the extreme conditions in space. In the vacuum there, not only do temperatures far lower than in Antarctica prevail, but the lichens are also unprotected and exposed to strong radioactive, x-ray and UV radiation. The question therefore was how stable the lichens’ biological structure and the biomolecules remain under these extreme conditions. The study of biomolecular stability has gained in significance in the field of astrobiology, since relevant findings can reveal to what extent biomolecules can signal the existence of life on Mars or in the oceans of Jupiter’s and Saturn’s icy moons. The work undertaken within this project is also laying extensive groundwork for planned expeditions to the Moon and Mars. During such long expeditions, astronauts are exposed to far higher doses of cosmic radiation than here on Earth.

In February 2016, the samples were brought back inside the space station, on 18 June they landed in the Kazakh desert and in July 2016 they finally reached the German Aerospace Center (DLR) in Cologne. From there it was just a short trip to HHU.

Back in Düsseldorf, the research work, funded by DLR’s Space Administration through the Federal Ministry for Economic Affairs and Energy, could commence. Professor Ott and her team will study the damage to the lichens caused by exposure in order to determine their survivability and resistance potential under the extreme conditions in space. The HHU researchers are also examining the stability of the nine biogenic substances and the degree of damage to them. These analyses are being carried out primarily by means of Raman spectroscopy. The team is also testing whether the exposed lichen samples are still capable of photosynthesis and attempting to cultivate isolated symbionts in the laboratory. This will reveal to what extent the symbionts of the exposed lichens still exhibit the ability to grow. Electron microscopy is being used for other analyses of the lichens’ survivability.

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