Comparative Raman spectroscopy of astrobiology relevant bio‐samples and planetary surface analogs under UV–VIS–IR excitation

We investigated the potential of a laser selection in the broad optical range, from ultraviolet through visible to infrared (excitation wavelengths of 325, 532, 785, and 1064 nm) for combined analysis of Earth‐relevant extremophiles (Xanthoria elegans, Buellia frigida, and green alga of Circinaria gyrosa), carbohydrate molecules, as well as Mars and Moon surface regolith simulants as analog mineral mixtures (P‐MRS, S‐MRS, LRS, and JSC‐1). We show that the optimization of the laser photon energy provides (for at least one of the chosen excitation wavelengths) high‐end quality Raman spectra for each examined sample. In most cases, the infrared spectral range is advanced for biological samples, while an excitation in the visible and ultraviolet spectral range is often favorable or at least sufficient for accurate identification/resolution of mineral phases under the illuminated laser spot on the planetary surface simulants. Ultraviolet excitation does not always deliver significant contrast of the Raman Stokes responses to the induced photoluminescence in the studied biomolecules. Most prominent features in the Raman spectra of the biological samples are assigned to their specific pigments, also considered as biomolecular signatures of the extremophiles. The critical issue of specific advantages and limitations of each particular excitation source implies study for gaining scientific return from Raman spectroscopy for exobiological prospecting, for instance, the best trade between a single or dual excitation wavelength(s) for both biological and geological spectral data.Peer Reviewe

Raman spectra of the Markovka chondrite (H4)

Raman spectroscopy and scanning electron microscopy methods were used to study the fragment of the Markovka (H4 chondrite) meteorite. A characteristic set of silicate minerals (olivine and pyroxene), oxides and hydroxides (maghemite and goethite), troilite, and carbonates (aragonite) was determined. The structural features revealed by Raman spectroscopy allow us to draw important conclusions on thermal history of the parent body including both the temperature experienced by the rock on the parent body and their cooling rate as well as the constraints on the size of the parent body and the Mg composition of the assumed fluid

Biosignature stability in space enables their use for life detection on Mars

Two rover missions to Mars aim to detect biomolecules as a sign of extinct or extant life with, among other instruments, Raman spectrometers. However, there are many unknowns about the stability of Raman-detectable biomolecules in the martian environment, clouding the interpretation of the results. To quantify Raman-detectable biomolecule stability, we exposed seven biomolecules for 469 days to a simulated martian environment outside the International Space Station. Ultraviolet radiation (UVR) strongly changed the Raman spectra signals, but only minor change was observed when samples were shielded from UVR. These findings provide support for Mars mission operations searching for biosignatures in the subsurface. This experiment demonstrates the detectability of biomolecules by Raman spectroscopy in Mars regolith analogs after space exposure and lays the groundwork for a consolidated space-proven database of spectroscopy biosignatures in targeted environments

BIOLEX – The Biology and Lunar experiment and the LOGOS Cubes

BIOLEX is a concept designed for in situ science on the Moon or in its orbit. As heritage of the polar and space experiment BIOMEX (Biology and Mars Experiment) on the ISS it is a more developed concept. Measurement operations on an exposure platform as well as within a micro-greenhouse device are part of this concept. The goal is to investigate the use of lunar resources as well as to analyse the stability of biomolecules as potential biosignatures serving as reference for future space exploration missions to Mars and the icy ocean moons in the outer solar system. Astrobiological exploration of the solar system is a priority research area such as emphasized by the European Astrobiology Roadmap (AstRoMap). It is focusing on several research topics, such as "Habitability" and on "Biomarkers for the detection of life". Therefore, "space platforms and laboratories", such as the EXPOSE setup installed outside the ISS, are essential to gain more knowledge on space- and planetary environments, which might be an essential basis for improvement of the robotic and human interplanetary exploration (Moon, Mars, Encedalus, Titan and Europa). In reference to these exposure platforms a new generation of hardware is needed to be installed in the lunar orbit or directly on the Moon. The BIOLEX is representing by its LOGOS (Lunar Organisms, Geo-microbiology and Organics Space Experiment) cubes such a concept combining the life detection topics with topics relevant to autonomous life supporting systems. A combination of a sample exposure device and a microhabitat for plants and microorganisms could address a tremendous number of questions from astrobiology and life sciences. The main scientific objectives for the use of BIOLEX-LOGOS cubes are: (i) in situ measurements by spectroscopy methods (such as Raman, IR, UV/VISspectroscopy) for analysis of biosignatures and their stability what is relevant for support of future life detection missions on Mars and the icy moons in the outer solar system); (ii) in situ measurements of environmental conditions (radiation, pressure/vacuum, temperature, pH, humidity) in micro-modules or compartments in reference to planned micro-habitat experiments placed on the Moon or incorporated on an exposure facility in orbit; (iii) in situ measurements of microorganisms’ activity in micro-modules / compartments in reference to planned microhabitat experiments placed on the moon or incorporated in the exposure facility in orbit. In reference to these scientific ideas the Moon is an excellent platform to operate different space experiments which will be of relevance for astrobiology, life sciences and human space missions. BIOLEX tries to fulfil a large number of scientific investigations in reference to these disciplines. The lunar environment is much harsher compared to Mars; and tests on biomolecules in this environment could provide information on their stability and therefore on the value to be used as reference for future space missions to Mars or the icy ocean moons in the outer solar system. Resources of the Moon such as the regolith or the freely available radiation on the surface could be tested by using them in a micro-greenhouse. Within this greenhouse different filters could test the optimal spectra range of the radiation

Biosignature stability in space enables their use for life detection on Mars

Two rover missions to Mars aim to detect biomolecules as a sign of extinct or extant life with, among other instruments, Raman spectrometers. However, there are many unknowns about the stability of Raman-detectable biomolecules in the martian environment, clouding the interpretation of the results. To quantify Raman-detectable biomolecule stability, we exposed seven biomolecules for 469 days to a simulated martian environment outside the International Space Station. Ultraviolet radiation (UVR) strongly changed the Raman spectra signals, but only minor change was observed when samples were shielded from UVR. These findings provide support for Mars mission operations searching for biosignatures in the subsurface. This experiment demonstrates the detectability of biomolecules by Raman spectroscopy in Mars regolith analogs after space exposure and lays the groundwork for a consolidated space-proven database of spectroscopy biosignatures in targeted environments

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements

Evaluation of techniques for handling luminescence in Raman spectroscopy for space application in regard to the search for extraterrestrial life

Die Ramanspektroskopie (RS) ist eine analytische Technik, die in Folge einer optischen Anregung eines Stoffes materialspezifische Informationen über dessen molekulare Schwingungen und Kristallstruktur liefert. Da sowohl Minerale als auch biologische Materialien untersucht werden können, ist die RS in der Weltraumforschung von besonderem Interesse. So werden im Jahr 2020 gleich zwei Marsrover (ExoMars und Mars 2020) Ramanspektrometer mitführen, deren Aufgabe unter anderem die Detektion von Spuren von vergangenem oder gegenwärtigem extraterrestrischen Leben sein wird. Die Charakterisierung von stark lumineszierenden biologischen Proben und Mineralen stellt eine der größten Herausforderungen in der konventionellen RS dar. Daher beschäftigt sich diese Dissertation mit dem Problem der Lumineszenz in der RS. Dazu wird das Potenzial von fünf verschiedenen ramanspektroskopischen Techniken zur Handhabung der Lumineszenz evaluiert. Diese Techniken beinhalten (i) die Auswahl von verschiedenen Anregungswellenlängen (325 nm, 532 nm, 785 nm, 1064 nm), welche auf dem Konzept der spektralen Trennung des Lumineszenz- und Ramansignals basiert. (ii) Eine Alternative ist das Photobleichen, wobei die Lumineszenz durch eine lange Belichtungszeit unterdrückt wird. (iii) Eine weitere Methode für die spektrale Separation von Raman- und Lumineszenzphotonen ist die anti-Stokes RS. (iv) Bei der SERDS Technik werden zwei leicht verschobene Anregungswellenlängen verwendet. (v) Abschließend erfolgt die Untersuchung der Streu- und Emissionsstrahlung in der Zeitdomäne. Die Ergebnisse dieser Arbeit zeigen, dass es keine universelle Lösung gibt um das Problem der Lumineszenz in der RS zu überwinden. Allerdings weist die Verwendung unterschiedlicher Laserwellenlängen großes Potenzial für die erfolgreiche Handhabung der Lumineszenz in der RS auf. In Kombination mit SERDS und/oder Photobleichen steigt die Wahrscheinlichkeit verwertbare Spektren für die Probencharakterisierung zu erhalten.Raman spectroscopy (RS) is an analytical technique conveying material-specific information about a material’s molecular vibrations and crystal structure in succession of an optical excitation of the material. Due to the fact that mineralogical as well as biological material can be examined, RS is of special interest for space research. For instance, two Mars rovers (ExoMars and Mars 2020) will each carry along a Raman spectrometer in the year 2020, with the aim of detecting inter alia traces of extant or extinct extraterrestrial life. One of the biggest challenges in conventional RS is the characterization of strongly luminescent biological or mineralogical material; therefore, the dissertation at hand deals with the problem of luminescence in RS. For this purpose, the potential of five different Raman spectroscopic techniques for the handling of luminescence will be evaluated. These techniques include (i) the selection of different excitation wavelengths (325 nm, 532 nm, 785 nm and 1064 nm), which is based on the concept of the spectral separation of the luminescence signals as well as Raman signals. (ii) Photobleaching provides an alternative whereby the luminescence is suppressed by long exposure. (iii) A further method for the spectral separation of Raman photons as well as luminescence photons is provided by the anti-Stokes RS. (iv) The SERDS technique uses two slightly shifted excitation wavelengths. (v) Finally the examination of inelastic scattering and emission takes place in the time domain. The results of this dissertation show that there is no universal solution to overcome the problem of luminescence in RS. However, the usage of different excitation wavelengths offers great potential for handling luminescence in RS successfully. In combination with SERDS and/or photobleaching the probability to obtain exploitable spectra for sample characterization increase