Astrobiologische Experimente im Erdorbit und darüber hinaus

Astrobiologie ist eine interdisziplinäre Naturwissenschaft, die sich mit Fragen zum Ursprung und zur Entwicklung des Lebens auf der Erde befasst und herausfinden möchte, ob und wo Leben außerhalb der Erde existiert oder existieren könnte. Mikroorganismen waren die ersten Lebewesen auf der Erde. Auch heute besiedeln sie in einer sehr großen Anzahl und Diversität alle Lebensräume auf der Erde und stellen somit die erfolgreichste Gruppe von Organismen dar. In der Arbeitsgruppe Astrobiologie im Institut für Luft- und Raumfahrtmedizin wollen wir herausfinden, wie das Leben von Mikroorganismen durch äußere biotische und abiotische Faktoren beeinflusst bzw. limitiert ist und welche molekularen und zellulären Mechanismen für die Adaption an extreme Bedingungen wichtig bzw. notwendig sind. Daraus wollen wir ableiten, wo sich die möglichen habitablen Zonen innerhalb und außerhalb unseres Sonnensystems befinden. Neben mikrobiologischen Experimenten unter standardisierten Bedingungen im Labor und Felduntersuchungen an extremen Standorten auf der Erde sind Weltraumexperimente notwendig, um die Widerstandsfähigkeit und Anpassungsfähigkeit von Mikroorganismen gegenüber den Bedingungen des freien Weltraums oder denen auf der Oberfläche von anderen Planeten zu testen. Freifliegende Satelliten und Raumstationen bieten die Möglichkeit im Erdorbit astrobiologische Experimente durchzuführen. In den außen an der ISS angebrachten ESA Facilities EXPOSE werden Langzeitexperimente durchgeführt, in denen auch Mars-Bedingungen simuliert werden können. In den Experimenten ADAPT, PROTECT und SPORES konnte gezeigt werden, dass verschiedene Mikroorganismen mit Hilfe unterschiedlicher Strategien die lebensfeindlichen Bedingungen auf dem Mars, wie extreme Trockenheit, ein energiereiche UV-Strahlung, Temperaturschwankungen, teil-weise überleben können. Von dem aktuellen ISS-Experiment BOSS werden die Proben im Juni zur Auswertung auf die Erde zurückgebracht werden. Neben dem Planeten Mars sind auch die Eismonde, wie Europa, von großem astrobiologischen Inter-esse. In dem zur Zeit in Vorbereitung befindlichen Experiment IceCube soll unter-sucht werden, ob auch dort aktives Leben möglich ist. Darauf aufbauend kann später auf einem Satelliten in einem anderen höheren Orbit die Wirkung des Weltraumstrahlenklimas auf entsprechend angepasste Organismen untersucht werden. Der Weltraum stellt also ein wichtiges Tool für die astrobiologische Forschung dar

THE BOSS EXPERIMENT OF THE EXPOSE-R2 MISSION: BIOFILM VERSUS PLANKTONIC CELLS

In the BOSS experiment (biofilm organisms surfing space), which was performed in the context of the successfully finalized EXPOSE-R2 mission, an international consortium of scientists investigated the ability of a variety of organisms to survive in space and on Mars as a function of their life style. The question in focus is whether there are different strategies for individually living microorganisms (planktonic state) compared to a microbial consortium of the same cells (biofilm state) to cope with the unique mixture of extreme stress factors including desiccation, gamma-, ionizing- and UV radiation in this environment. Biofilms, in which the cells are encased in a self-produced matrix of excreted extracellular polymeric substances, are one of the oldest clear signs of life on Earth. Since they can become fossilized they might also be detected as the first life forms on other planets and moons of the solar system and are therefore ideal candidates for astrobiological investigations. As an example for the organisms that attended the EXPOSER2 mission the results of the ight and mission ground reference analysis of Deinococcus geothermalis are presented. Deinococcus geothermalis is a non-spore-forming, gram-positive, orange-pigmented representative of the Deinococcus family which is unparalleled in its poly-extreme resistances to a variety of environmental stress factors on Earth. The results demonstrate that Deinococcus geothermalis remains viable in the desiccated state over almost 2 years, whereas culturability was preserved in biofilm cells at a significantly higher level than in planktonic cells. Furthermore, cells of both sample types were able to survive simulated space and Martian conditions and showed high resistance towards extra-terrestrial UV radiation. Additionally results of cultivation-independent investigations of pigment stability, membrane integrity, enzyme activity, ATP content and DNA integrity will be discussed.To conclude, biofilms exhibit an enhanced rate of survival compared to their planktonic counterparts when exposed to space and Martian conditions. This seems to indicate an advantage of living as a biofilm when facing the poly-extreme conditions of space or Mars. The findings will contribute to the understanding of the opportunities and limitations of life under the extreme environmental conditions of space or other planets as function of the state of life and aims to contribute to the understanding of the adaptation mechanisms that allow microorganisms to survive in extreme environments, possibly including space and the surface of Mars

CHARACTERIZATION OF OUTER SPACE RADIATION INDUCED CHANGES IN EXTREMOPHILES UTILIZING DEEP SPACE GATEWAY OPPORTUNITIES.

Early integration of science and exploration concerns into the design of the Deep Space Gateway (DSG) is essential to maximizing its science and exploration potential. The proposed concept, characterization of outer space radiation induced changes in microbial extremophiles, requires the DSG as infrastructure supplying power, communications, etc. to otherwise autonomous systems. Survival and proliferation of life beyond low earth orbit (LBLEO) can be accomplished by exposing extremophilic microorganisms in outer space radiation (OSR) conditions using DSG system. Extremophilic microbial survival, adaptation, biological functions, and molecular mechanisms associated with outer space radiation can be tested by exposing them onto DSG hardware (inside/outside) utilizing the traditional microbiology methods and state-of-the-art molecular biology techniques

THE RELEVANCE OF MARS SAMPLES TO PLANNING FOR POTENTIAL FUTURE IN-SITU RESOURCE UTILIZATION.

Considerable recent planning has focused on the potential importance of Mars in-situ resources to support future human missions. While atmospheric CO2 provides a source of oxygen [1], the regolith offers other potential resources [2]. The most significant surface asset is water, which could be used for propellant generation [3], life support, habitat sustainment, and agriculture [4]. In regard to the latter, the regolith could also provide a source of nutrients to supplement terrestrial fertilizers and/or act as a substrate to buffer plant roots. Local material could also be used as feedstock for construction, including for structures, roads, and additive manufacturing [5]. Native salts (e.g. perchlorates or chlorides) in the Martian regolith could be used as water absorbents for closed loop life support systems or for capture of the limited atmospheric water. Any of these in-situ processes would require definition of the resources to influence equipment design and resource budgeting. Exploration via orbital and landed surveys as well as technical demonstrations would be necessary. Mars sample return could play a key role in supporting this planning, especially when considering possible long-term human presence. The goal of the International MSR Objectives & Samples Team (iMOST) is to define the objectives that could be met using returned martian samples, and identify the types of samples needed to meet those objectives. In-Situ Resource Utilization (ISRU) is one of the six iMOST objectives, and this document summarizes the needs specified therein

Implementing bioburden reduction and control on the deliquescent hydrogel of the HABIT/ExoMars 2022 instrument

The HabitAbility: Brines, Irradiation and Temperature (HABIT) instrument will be part of the ExoMars 2022 mission (ESA/Roscosmos) and will be the first European In-situ Resource Utilization (ISRU) instrument capable of producing liquid water on Mars. HABIT is composed by two modules: Environmental Package (EnvPack) and Brine Observation Transition To Liquid Experiment (BOTTLE). EnvPack will help to study the current habitability conditions on Mars investigating the air and surface thermal ranges and Ultraviolet (UV) irradiance; and BOTTLE is a container with four independent vessels housing deliquescent salts, which are known to be present on Mars, where the liquid water will be produced after deliquescence. In order to prevent capillarity of deliquescent or hydrated salts, a mixture of deliquescent salts with Super Absorbent Polymer (SAP) based on polyacrylamide is utilized. This mixture has deliquescent and hydrogel properties and can be reused by applying a thermal cycle, complying thus with the purpose of the instrument. A High Efficiency Particulate Air (HEPA) grade filter made of polytetrafluroethylene (PTFE) porous membrane sandwiched between spunbounded non-woven fabric stands as a physical barrier allowing interaction between the gaseous molecules of the Martian atmosphere and the salt mixtures, and at the same time preventing the passage of any potential biological contamination from the cells to the outside or vice-versa. In addition to the physical barrier, a strict bioburden reduction and analysis procedure is applied to the hardware and the contained salt mixtures adhering to the European Cooperation for Space Standardization protocol of microbial examination of flight hardware (ECSS-Q-ST-70-55C). The deliquescent salts and the SAP products need to be properly treated independently to adhere to the planetary protection protocols. In this manuscript, we describe the bioburden reduction process utilized to sterilize the salt mixtures in BOTTLE and the assays adopted to validate the sterilization. We also describe the construction of a low-cost, portable ISO 7 cleanroom tent, exclusively designed for planetary protection tests. The sterilization process involves Dry Heat Microbial Reduction (DHMR) of the deliquescent salts and the SAP mixtures. The performance of SAP after DHMR is validated to ensure its working efficiency after sterilization. A slightly modified version of the standard swab assay is used in the validation process and a comparison is made between samples exposed to a thermal shock treatment and those without thermal shock, to determine the best assay to be applied for future space hardware utilizing such salt mixtures for planetary investigation and In-Situ Resource Utilization (ISRU). The demonstration of the compatibility of these products with the processes commonly required for space applications has implications for the future exploration of Mars.The authors of the paper would like to thank the Institute of Aerospace Medicine, DLR , Germany for their support to analyse the bioburden assay of the HABIT BOTTLE salt mixtures. The authors would also like to acknowledge Roberto Mantas-Nakhai for his contribution during the bioburden assay validation. HABIT is an instrument of the Luleå University of Technology (LTU), led by J. Martín-Torres (PI) and M-P. Zorzano (co-PI). The HABIT FM and EQM were fabricated by Omnisys, Sweden, under advice of LTU as part of the HABIT project development and funded by the Swedish National Space Agency ( SNSA ). M-P. Z's contribution has been partially supported by the Spanish State Research Agency ( AEI ) Project No. MDM-2017-0737 Unidad de Excelencia “María de Maeztu” - Centro de Astrobiología (INTA-CSIC). We acknowledge the Luleå University of Technology, the Wallenberg Foundation and the Kempe Foundation for support of the Mars research activities. We thank the ExoMars project team, European Space Agency (ESA), Roscosmos, Space Research Institute (IKI) and Omnisys Instruments AB for their hard work on the ExoMars 2022 mission. We acknowledge the Luleå University of Technology, the Wallenberg Foundation and the Kempe Foundation for support of the Mars research activities. The SpaceQ chamber has been developed together with Kurt J. Lesker Company and was funded by the Kempe Foundation.Peer reviewe

UV-radiation-induced formation of DNA bipyrimidine photoproducts in Bacillus subtilis endospores and their repair during germination

The spore photoproduct (SP) is the main DNA lesion after UV-C irradiation, and its repair is crucial for the resistance of spores to UV. The aims of the present study were to assess the formation and repair of bipyrimidine photoproducts in spore DNA of various Bacillus subtilis strains using a sensitive HPLC tandem mass spectrometry assay. Strains deficient in nucleotide excision repair, spore photoproduct lyase, homologous recombination (recA), and with wild-type repair capability were investigated. Additionally, one strain deficient in the formation of major small, acid-soluble spore proteins (SASPs) was tested. In all SASP wild-type strains, UV-C irradiation generated almost exclusively SP (>95 %) but also a few by-photoproducts. In the major SASP-deficient strain, SP and by-photoproducts were generated in equal quantities. The status of the UV-induced bipyrimidine photoproducts was determined at different stages of spore germination. After a germination time of 60 min, >75% of the SP was repaired in wild-type strains and in the SASP-deficient strain, while half of the photoinduced SP was removed in the recA-deficient strain. SP-lyase-deficient spores repaired < 20% of the SP produced. Thus, SP lyase, with respect to nucleotide excision repair, has a remarkable impact on the removal of SP upon spore germination. [Int Microbiol 2007; 10(1):39-46

The microbial diversity of the Su Bentu cave, Italy and the influence of human exploration.

Introduction: The microbial diversity in the Su Bentu Cave (Sardinia, Italy) was investigated by means of Illumina MiSeq analysis. The hypogean environment is of great interest for astrobiological research as cave conditions may resemble those in extra-terrestrial regions. Furthermore, they hold high potential to identify novel, extremely adapted organisms to severely oligo-trophic habitats. However, the influence of human is not neglectable and in-depth investigations are needed to determine the impact of exploration on an otherwise mostly pristine ecosystem. The cave investigated in this study develops for several kilometres into the mountain, two hundred metres below the topographic surface and is characterized by a strong air circulation. Its structure is composed of huge passages carved in limestone where an ephemeral underground stream creates some lakes, close to which seven samples of visible calcite rafts, manganese deposits and moonmilk (a hydrated calcium carbonate speleothem), were sampled during an expedition in 2014. Other samples were re-trieved from a frequently used campsite and from some dry cave passages leading deeper into the cave

Investigation of the physiological response of cold-adapted microorganisms to extreme environmental stress factors.

Exploring the limits of life is one of the objectives for better understanding how organisms have arisen on Earth, how they tolerate extreme conditions and how they might survive on other planets or moons. These investigations could help with understanding which Earth microorganisms could survive on other celestial bodies, such as the icy Moons: Europa (Jupiter) and Enceladus (Saturn). Furthermore, it might help with indicating how life could have developed on Earth or on the icy Moons of the Solar system. This project focuses on the insights from prokaryotic, eukaryotic and archaea organisms which can tolerate the simulated subsurface ocean environment of Europa and Enceladus. The moons have been speculated to have subsurface oceans which are heated by tidal movements or hydrothermal vents. These combined factors could create an environment suitable for life. Furthermore, the mechanism of radiation, desiccation and temperature survival could help us understand whether the organisms could survive a hitchhike on spacecraft surfaces travelling to the moons. During space exploration it is essential to avoid the contamination of planets and moons of astrobiological interest by microorganisms from Earth. [...

Esa Caves: training astronauts for space exploration

The first spaceflight was several decades ago, and yet extraterrestrial exploration is only at the beginning and has mainly been carried out by robotic probes and rovers sent to extraterrestrial planets and deep space. In the future human extraterrestrial exploration will take place and to get ready for long periods of permanence in space, astronauts are trained during long duration missions on the International Space Station (ISS). To prepare for such endeavours, team training activities are performed in extreme environments on Earth, as isolated deserts, base camps on Antarctica, or stations built on the bottom of the sea, trying to simulate the conditions and operations of space. Space agencies are also particularly interested in the search of signs of life forms in past or present extreme natural environments, such as salt lakes in remote deserts, very deep ocean habitats, submarine volcanic areas, sulphuric acid caves, and lava tubes. One natural environment that very realistically mimics an extraterrestrial exploration habitat is the cave. Caves are dark, remote places, with constant temperature, many logistic problems and stressors (isolation, communication and supply difficulties, physical barriers), and their exploration requires discipline, teamwork, technical skills and a great deal of behavioural adaptation. For this reason, since 2008 the European Space Agency has carried out training activities in the subterranean environment and the CAVES project is one of those training courses, probably the most realistic one. CAVES stands for Cooperative Adventure for Valuing and Exercising human behaviour and performance Skills, and is meant as a multidisciplinary multicultural team exploration mission in a cave. It has been developed by ESA in the past few years (2008-2011) and is open for training of astronauts of the ISS Partner Space Agencies (USA, Russia, Japan, Canada, and Europe). Astronauts are first trained for 5 days to explore, document and survey a karst system, then take on a cave exploration mission for 6 days underground. A team of expert cave instructors, a Human Behaviour and Performance facilitator, scientists and video reporters, ensure that all tasks are performed in complete safety and guides all these astronauts\u27 activities. During the underground mission the astronauts\u27 technical competences are challenged (exploring, surveying, taking pictures), their human behaviour and decision-making skills are debriefed, and they are required to carry out an operational programme which entails performing scientific tasks and testing equipment, similarly to what they are required to do on the ISS. The science program includes environmental and air circulation monitoring, mineralogy, microbiology, chemical composition of waters, and search for life forms adapted to the cavern environment. The CAVES 2012 Course will be explained and the first interesting scientific results will be presented