Astrobiology Group

Astrobiology is a natural sciences research area concerned with the origin, evolution, distribution, and future of life in the universe. Astrobiology is interdisciplinary and encompasses amongst other disciplines biology, chemistry, physics, geosciences, planetary sciences and astronomy. The aim of this research is to learn more about the origin and evolution of life on Earth, about the formation of planetary systems, about organic compounds in space and to find out, if life exists or might exist elsewhere. Our neighbor planet Mars, but also the icy moons in the outer solar system, here in particular Europa and Enceladus, are of astrobiological interest. These solar system bodies are the target of ongoing and future international space missions with substantial contributions from DLR.

The main astrobiological question is whether the origin of life is an inevitable process, i.e. if the laws of biology are universal such as the laws of chemistry and physics, or if the origin of life on Earth was a unique event. The most important questions in astrobiology are; (i) How can we define habitability? (ii) Is there life on other planets and moons in our solar system and beyond? (iii) Where and how should we search for sign of past or present life?

The Research Group ‚Astrobiology‘ in the Institute of Aerospace Medicine in Cologne (led by Petra Rettberg) is working on this subject since the Apollo era with a main focus on the biological aspects of astrobiology. The cellular and molecular reponses to extreme environmental parameters as they occur on other planets and moons in our solar system are studied in microorganisms. Examples for parameters relevant for habitability are ionising and non-ionising radiation, high and low temperatures, low pressure, vacuum, low water activity, oxidising compounds, high salt concentrations, different gravity levels. In addition, the microbiome of manned habitats like the International Space Station (ISS) and the microbiome of plants grown in a confined habitat in Antarctica (EDEN ISS - Ground Demonstration of Plant Cultivation Technologies for Safe Food Production in Space) are under investigation. One important component are activities in the area of planetary protection, here the determination of the bioburden and biodiversity of spacecraft and spacecraft assembly cleanrooms as well as contributions to international planetary protection rules and standards (PANEL ON PLANETARY PROTECTION (PPP)).

The experimental work of the research group is performed in microbiological labs, in planerary and space simulation facilities, by participation in field campaigns, in form of space experiments, e.g. on the ISS, and by contributions to international space missions, e.g. ExoMars2020. These activities are complemented by collaboration in the development of relevant technologies, e.g. plasma-decontamination of space hardware or optimisation of antimicrobial surfaces.

Links:

Planetary and Space Simulation facilities of DLR in Cologne - https://www.dlr.de/Spacesim

Current, future and completed space experiments of the Department of Radiation Biology

Mikroorganismen unter dem Eis? (Dr. Petra Rettberg in an interview with the television station HYPERRAUM.TV)

Examples of actual projects:

EDEN ISS Antarctic mission 2021 for future safe food production in space

In 2021, the second campaign was conducted in the EDEN ISS greenhouse in Antarctica. From January 2021 to January 2022, the greenhouse was successfully operated by NASA guest scientist Jess Bunchek. The Astrobiology group focused on microbial quantity and diversity in surface samples from the greenhouse and in liquid samples from plant nutrient tanks during the second campaign. In addition, the efficiency of cleaning procedures was examined from a microbial perspective. In April 2022, all samples (surface swab samples and liquid samples) arrived at DLR Cologne. A first set of samples has been evaluated in the meantime and corresponds to the data of the first campaign. The evaluation of the remaining samples is still ongoing.

Alien worlds – alien life? How to protect astrobiologically interesting planets and moons as well as the Earth? – Planetary protection

The internationally accepted COSPAR (Committee on Space Research) Planetary Protection guidelines were set into place to avert the contamination of other habitable planets and moon in our solar system and to protect Earth from potentially harmful extraterrestrial agents. To comply with these requirements the bioburden and biodiversity of spacecraft is routinely monitored and controlled at various stages of its assembly process. The Astrobiology Group is performing Planetary Protection Verification Assays on behalf of ESA since 2003, actually for the upcoming ExoMars 2018 mission in addition to bioburden measurements for other international missions and contributions to international planetary protection rules and standards. (see: PANEL ON PLANETARY PROTECTION (PPP) and The COSPAR Panel on Planetary Protection Role, Structure and Activities).

Cold and salty, is there a chance for life in the oceans of the icy moons? – The space experiment IceCold

The space experiment IceCold (Investigating Cold adapted organisms as model organisms for a Europa ocean environment in CubeSat based hardware, team coordinator Elke Rabbow) was selected by ESA for flight in 2020. IceCold utilizes the ESA EXPO external exposure platform on Bartolomeo, ISS, to test the hypothesis that extremophilic salt and cold adapted organisms from the three domains of life on Earth can survive and possibly grow in the harsh environmental conditions in space and on the icy moons, in particular ionising radiation, short wavelength solar UV radiation, low temperature / temperature oscillations, high salt concentrations. The test organism suite comprises of Halorubrum lacusprofundi, Rhodotorula JG-1b and Rhodococcus JG-3 provided by L. White, Canada, Halobacterium salinarum, Deinococcus radiodurans and geothermalis and the microbial space veteran Bacillus subtilis. Currently, space exposure hardware models are developed and tested and ground based basis data collected.

Is the DNA repair capacity influenced by microgravity? – The space experiment LUX-in-Space

Lux-in-Space (Kinetics of enzymatic repair reactions after irradiation under microgravity by use of a rapid bioluminescence-based bacterial genotoxicity assay, team coordinator Petra Rettberg) investigates radiation induced DNA damage repair in microgravity in the ISS with a bacterial reporter assay develop in the DLR Cologne as a fast genotoxicity test. Both, the radiation damage and the enzymatic repair are induced in space in weightlessness and the repair kinetics is quantified in comparison to in-space 1g controls and to ground 1 g controls. The space experiment is foreseen for the ESA Biolab facility in the Columbus module in the ISS. The respective hardware is under development, ground based test to collect basis data are performed.

Anaerobic microbes from Earth, can they cope with Mars? – The space experiment MEXEM

The space experiment MEXEM (Mars Exposed Extremophiles Mixture, team coordinator Petra Rettberg) is the continuation and complementation of the MASE project (Mars Analogues for Space Exploration, see also http://www.mase-eu.org/). The launch of the passive exposure experiment MEXEM in ESA’s new EXPO facility on the outside of the ISS is planned for the year 2023. MEXEM will test the hypothesis that organisms in oxygen depleted natural samples, artificial anaerobic communities, and isolated strains including ciliates and viruses from Mars analogue sites and from the ISS are not only resistant to the specific environmental conditions from where they originate but also to the combined Mars relevant environmental stress factors due to their highly effective cellular and molecular adaptation and repair mechanisms. Additionally, artificially fossilized strains will be examined. Currently, the selection of the investigated strains and the accompanying first preparation tests are in process.

Examples of previous projects:

The EDEN ISS project

The EU project EDEN ISS (2015 - 2019; EC-H2020, Grant agreement n° 636501) was successfully carried out by an international project team consisting of scientists and industrial partners. It dealt with the development and optimisation of plant cultivation technologies and operating procedures for safe food production in extreme locations, such as the international space station or in future habitats on the surface of other planets and moons. For this purpose, the semi-autonomous EDEN-ISS greenhouse was built and operated near the German Station Neumeyer III in Antarctica. During the active cultivation phase of several months microbial samples were taken systematically from the various grown plants, the nutrient distribution system and the greenhouse itself. The microbial bioburden and biodiversity of the pro- and eukaryotic organisms in these samples were analysed afterwards in Cologne to assess possible risks connected to the consumption of food which is produced in a confined greenhouse.

The MASE project

MASE (Mars Analogues for Space Exploration) was an EU-funded project over a period of four years (2014 - 2017; FP-7, grant agreement n° 607297). The international project team identified different Mars analogous environments in different European countries. The local conditions of the Mars analogous environments were investigated with respect to chemical, geological and mineralogical characteristics. The obtained environmental samples were subjected to metagenomic analyses and anaerobic microorganisms were isolated from the samples. During the project period more than 30 pure isolates were obtained and a selection was exposed to Mars relevant stress factors in the laboratory . The focus was on how the organisms react to the combined effects of different stress factors (e.g. drying, radiation, oxidizing substances) in the absence of oxygen. Some of these resistant organisms are still being studied in the MEXEM project.

Are microorganisms space survivors? The EXPOSE space experiments

Do microorganisms survive space and if so, what are the protecting mechanisms? Could they be transferred to other bodies in our solar system? Could life or precursor life forms have originated somewhere else in space? In order to come closer to an answer on these and related astrobiological questions, microorganisms and organic chemical compounds were exposed in three ESA EXPOSE space missions in Low Earth Orbit (LEO) on the ISS for more than 1.5 years each. The ESA EXPOSE hardware was utilized successful by international and interdisciplinary science groups. Because no living Earth organisms shall be distributed to other celestial bodies of astrobiological interest, e.g. to Mars as blind passengers on spacecraft, the EXPOSE results are also important for planetary protection considerations. Some moons of the outer solar system are also considered as possibly habitable. Therefore, the knowledge derived from the EXPOSE missions also supports planetary protection measures for missions to e.g. Enceladus, Europa or Ganymede.

Head

Dr. rer. nat. Petra Rettberg
German Aerospace Center
Institute of Aerospace Medicine, Radiation Biology
Tel.: +49 2203 601 4637
Fax: +49 2203 601 3726

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