Pascale Ehrenfreund

Pascale Ehrenfreund
Leiden University | LEI

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495
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Publications

Publications (495)
Article
Full-text available
The detection of biomolecules on Solar System bodies can help us to understand how life emerged on Earth and how life may be distributed in our Solar System. However, the detection of chemical signatures of life on planets or their moons is challenging. A variety of parameters must be considered, such as a suited landing site location, geological a...
Article
Full-text available
The identification of reliable biomarkers, such as amino acids, is key for the search of extraterrestrial life. A large number of microorganisms metabolize, synthesize, take up and excrete amino acids as part of the amino acid metabolism during aerobic and/or anaerobic respiration or in fermentation. In this work, we investigated whether the anaero...
Preprint
Full-text available
More than 500 diffuse interstellar bands (DIBs) have been observed in astronomical spectra, and their signatures and correlations in different environments have been studied over the past decades to reveal clues about the nature of the carriers. We compare the equivalent widths of the DIBs, normalized to the amount of reddening, E_B-V, to search fo...
Article
Full-text available
The signatures of element isotope fractionation can be used for the indirect identification of extant or extinct life on planetary surfaces or their moons. Element isotope fractionation signatures are very robust against the harsh environmental conditions, such as temperature or irradiation, which typically prevail on solar system bodies. Sulphur i...
Article
Full-text available
Background Extreme terrestrial, analogue environments are widely used models to study the limits of life and to infer habitability of extraterrestrial settings. In contrast to Earth’s ecosystems, potential extraterrestrial biotopes are usually characterized by a lack of oxygen. Methods In the MASE project (Mars Analogues for Space Exploration), we...
Article
The detection and identification of biosignatures on planetary bodies such as Mars in situ is extremely challenging. Current knowledge from space exploration missions suggests that a suite of complementary instruments is required in situ for a successful identification of past or present life. For future exploration missions, new and innovative ins...
Article
Full-text available
For the last four decades space exploration missions have searched for molecular life on planetary surfaces beyond Earth. Often pyrolysis gas chromatography mass spectrometry has been used as payload on such space exploration missions. These instruments have relatively low detection sensitivity and their measurements are often undermined by the pre...
Chapter
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Five bacterial (facultatively) anaerobic strains, namely Buttiauxella sp. MASE-IM-9, Clostridium sp. MASE-IM-4, Halanaerobium sp. MASE-BB-1, Trichococcus sp. MASE-IM-5, and Yersinia intermedia MASE-LG-1 isolated from different extreme natural environments were subjected to Mars relevant environmental stress factors in the laboratory under controlle...
Article
Full-text available
The detection of biosignatures on Mars is of outstanding interest in the current field of Astrobiology and drives various fields of research, ranging from new sample collection strategies to the development of more sensitive detection techniques. Detailed analysis of the organic content in Mars analog materials collected from extreme environments o...
Article
Five bacterial (facultatively) anaerobic strains, namely Buttiauxella sp. MASE-IM-9, Clostridium sp. MASE-IM-4, Halanaerobium sp. MASE-BB-1, Trichococcus sp. MASE-IM-5, and Yersinia intermedia MASE-LG-1 isolated from different extreme natural environments were subjected to Mars relevant environmental stress factors in the laboratory under controlle...
Article
Full-text available
In 2019 it was exactly 100 years ago that the first two DIBs, diffuse interstellar bands, were discovered by Mary Lea Heger. Today some 500 + DIBs are known. In numerous observational, modelling and laboratory studies, efforts have been made to identify the carriers of these absorption features that are observed in the light of reddened stars cross...
Article
Full-text available
One of the main objectives for astrobiology is to unravel and explore the habitability of environments beyond Earth, paying special attention to Mars. If the combined environmental stress factors on Mars are compatible with life or if they were less harsh in the past, to investigate the traces of past or present life is critical to understand its p...
Article
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Discovery of a remnant habitable environment by the Mars Science Laboratory in the sedimentary record of Gale Crater has reinvigorated the search for evidence of martian life. In this study, we used a simulated martian mudstone material, based on data from Gale Crater, that was inoculated and cultured over several months and then dried and pressed....
Preprint
The properties of the smallest subunits of cometary dust contain information on their origin and clues to the formation of planetesimals and planets. Compared to IDPs or particles collected during the Stardust mission, dust collected in the coma of comet 67P/Churyumov-Gerasimenko during the Rosetta mission provides a resource of minimally altered m...
Article
Context. The properties of the smallest subunits of cometary dust contain information on their origin and clues to the formation of planetesimals and planets. Compared to interplanetary dust particles or particles collected during the Stardust mission, dust collected in the coma of comet 67P/Churyumov-Gerasimenko (67P) during the Rosetta mission pr...
Article
Full-text available
Filamentous fungi have been associated with extreme habitats, including nuclear power plant accident sites and the International Space Station (ISS). Due to their immense adaptation and phenotypic plasticity capacities, fungi may thrive in what seems like uninhabitable niches. This study is the first report of fungal survival after exposure of mono...
Article
Full-text available
The Yilgarn Craton in Australia has a large number of naturally occurring shallow ephemeral lakes underlain by a dendritic system of paleodrainage channels. Processes like evaporation, flooding, erosion, as well as inflow of saline, often acidic and ion-rich groundwater contribute to the (dynamic) nature of the lakes and the composition of the sedi...
Preprint
Recent advances in laboratory spectroscopy lead to the claim of ionized Buckminsterfullerene (C60+) as the carrier of two diffuse interstellar bands (DIBs) in the near-infrared. However, irrefutable identification of interstellar C60+ requires a match between the wavelengths and the expected strengths of all absorption features detectable in the la...
Conference Paper
During the project “Mars Analogues for Space Exploration” (MASE) several microbial isolates were obtained from extreme terrestrial environments. Some of these strains were subjected to Mars relevant environmental stress factors in the laboratory under controlled conditions; e.g. radiation, low water activity, high salt concentrations, or oxidizing...
Article
Full-text available
Growth in sodium chloride (NaCl) is known to induce stress in non-halophilic microorganisms leading to effects on the microbial metabolism and cell structure. Microorganisms have evolved a number of adaptations, both structural and metabolic, to counteract osmotic stress. These strategies are well-understood for organisms in NaCl-rich brines such a...
Data
Principal Component Analysis (PCA) plot showing the multivariate variation among the three sample sets (control, NaCl stressed and MgSO4 stressed; n = 3) in terms of the obtained peaks.
Data
List of identified and putatively identified lipids. Metabolite levels for each experimental group are shown. Levels are expressed as mean peak intensity relative to the mean peak intensity of the control group. Numbers indicated in bold indicates statistically significance (p < 0.05).
Article
Full-text available
Gas phase spectroscopic laboratory experiments for the buckminsterfullerene cation C60⁺ have resulted in accurate rest wavelengths for five C60⁺ transitions that have been compared with diffuse interstellar bands (DIBs) in the near infra-red. Detecting these in astronomical spectra is difficult because of the strong contamination of ground-based sp...
Article
Full-text available
Four facultative anaerobic and two obligate anaerobic bacteria were isolated from extreme environments (deep subsurface halite mine, sulfidic anoxic spring, mineral-rich river) in the frame MASE (Mars Analogues for Space Exploration) project. The isolates were investigated under anoxic conditions for their survivability after desiccation up to six...
Article
Gas phase spectroscopic laboratory experiments for the buckminsterfullerene cation C60+ resulted in accurate rest wavelengths for five C60+ transitions that have been compared with diffuse interstellar bands (DIBs) in the near infra-red. Detecting these in astronomical spectra is difficult due to the strong contamination of ground-based spectra by...
Article
Full-text available
The limits of life of aerobic microorganisms are well understood, but the responses of anaero-bic microorganisms to individual and combined extreme stressors are less well known. Motivated by an interest in understanding the survivability of anaerobic microorganisms under Martian conditions, we investigated the responses of a new isolate, Yersinia...
Data
Results of the API R 20 A and Rapid ID 32 A tests. + Y. intermedia MASE-LG-1 metabolized the named substance; − Y. intermedia MASE-LG-1 did not metabolize the named substance. (DOCX)
Data
Dendrogram Y. intermedia MASE-LG-1. Neighbor-joining tree based on 16S rDNA sequences showing the phylogenetic position of Y. intermedia MASE-LG-1 related to 14 species of the genus Yersinia. DNA sequences were aligned using BioEdit. The dendrogram was constructed by using MEGA6. Bar: 0.01 substitutions per nucleotide position. (TIF)
Article
Full-text available
The carriers of the diffuse interstellar bands (DIBs) are largely unidentified molecules ubiquitously present in the interstellar medium (ISM). After decades of study, two strong and possibly three weak near-infrared DIBs have recently been attributed to the C+60 fullerene based on observational and laboratory measurements. There is great promise f...
Article
Full-text available
Scientists use the Earth as a tool for astrobiology by analyzing planetary field analogues (i.e. terrestrial samples and field sites that resemble planetary bodies in our Solar System). In addition, they expose the selected planetary field analogues in simulation chambers to conditions that mimic the ones of planets, moons and Low Earth Orbit (LEO)...
Article
Full-text available
The space environment is regularly used for experiments addressing astrobiology research goals. The specific conditions prevailing in Earth orbit and beyond, notably the radiative environment (photons and energetic particles) and the possibility to conduct long-duration measurements, have been the main motivations for developing experimental concep...
Article
Full-text available
The Rosetta lander Philae successfully landed on the nucleus of comet 67P/Churyumov-Gerasimenko on 12 November 2014. Philae is equipped with two gas analyzers: The Cometary Sampling and Composition experiment (COSAC) and the gas chromatograph and mass spectrometer Ptolemy. On 12 to 14 November 2014 both instruments measured the organic composition...
Article
Context. The Rosetta lander Philae successfully landed on the nucleus of comet 67P/Churyumov-Gerasimenko on 12 November 2014. Philae is equipped with two gas analysers: The Cometary Sampling and Composition experiment (COSAC) and the gas chromatograph and mass spectrometer Ptolemy. Aims. COSAC is designed for in situ analysis of organic molecules o...
Article
Full-text available
Este trabajo es un review interdisciplinar que recoge la historia de 60 años de investigación astrobiológica en el espacio (desde el comienzo de la “Exobiología”, Lederberg 1960), con el fín de obtener respuestas sobre la posibilidad de encontrar vida extraterrestre, los efectos del ambiente espacial sobre microorganismos (ref. protección planetari...
Conference Paper
During the project MASE (Mars Analogues for Space Exploration) several isolates were obtained and these strains were subjected to Mars relevant environmental stress factors in the laboratory under controlled conditions; e.g. radiation, low water activity, high salt concentrations, oxidizing compounds. First screening steps were always the microorga...
Conference Paper
The MASE (Mars Analogues for Space Exploration) [1] project is a four-year collaborative research project supported by the European Commission Seventh Framework Contract. The aim of the project is to understand how combined environmental stresses influence the habitability of a number of Mars analogue environments in Europe and beyond. Field sites...
Conference Paper
Is life out there? In order to assess the habitability of Mars, which is (or has been) the most Earth-like planet in our Solar System, the first step is to investigate microorganisms thriving in terrestrial biotops with Mars similar conditions (0.13% O₂ in the atmosphere, low nutrients, low temperatures, high salinity and oxidising compounds, acidi...
Article
Full-text available
Astrobiology is an interdisciplinary scientific field not only focused on the search of extraterrestrial life, but also on deciphering the key environmental parameters that have enabled the emergence of life on Earth. Understanding these physical and chemical parameters is fundamental knowledge necessary not only for discovering life or signs of li...
Research
Full-text available
The Philae Lander of ESA’s Rosetta Mission landed succcessfully on, but immediately rebounded from, the nucleus of comet 67P/Churyumov–Gerasimenko. Thereafter the COmetary SAmpling and Composition Experiment (COSAC), a pyrolysis Gas Chromatograph–Mass Spectrometer, on board Philae made, while in resumed flight, unique mass spectral measurements of...
Conference Paper
The Philae Lander of ESA’s Rosetta Mission landed succcessfully on, but immediately rebounded from, the nucleus of comet 67P/Churyumov-Gerasimenko. Thereafter the COmetary SAmpling and Composition Experiment (COSAC), a pyrolysis Gas Chromatograph-Mass Spectrometer, on board Philae made, while in resumed flight, made unique mass spectral measurement...
Article
MarcoPolo-R is a sample return mission to a primitive Near-Earth Asteroid (NEA) selected in February 2011 for the Assessment Study Phase at ESA in the framework of ESAfs Cosmic Vision 2 program. MarcoPolo-R is a European-led mission with a proposed NASA contribution. MarcoPolo-R takes advantage of three industrial studies completed as part of the p...
Article
Full-text available
A significant number of molecules that are used in contemporary biochemistry on Earth are found in interstellar and circumstellar regions as well as solar system environments. In particular small solar system bodies hold clues to processes that formed our solar system. Comets, asteroids, and meteorite delivered extraterrestrial material during the...
Article
Full-text available
Comets harbor the most pristine material in our solar system in the form of ice, dust, silicates, and refractory organic material with some interstellar heritage. The evolved gas analyzer Cometary Sampling and Composition (COSAC) experiment aboard Rosetta's Philae lander was designed for in situ analysis of organic molecules on comet 67P/Churyumov-...
Article
Comets harbor the most pristine material in our solar system in the form of ice, dust, silicates, and refractory organic material with some interstellar heritage. The evolved gas analyzer Cometary Sampling and Composition (COSAC) experiment aboard Rosetta’s Philae lander was designed for in situ analysis of organic molecules on comet 67P/ Churyumov...
Article
The detection of biomarkers plays a central role in our effort to establish whether there is, or was, life beyond Earth. In this review, we address the importance of considering mineralogy in relation to the selection of locations and biomarker detection methodologies with characteristics most promising for exploration. We review relevant mineral-b...
Conference Paper
In this paper data recorded by the Cometary Sampling and Composition experiment (COSAC), a pyrolysis - gas-chromatograph - mass-spectrometer (pyr GC-MS) aboard Philae are presented. After landing in a somewhat non-nominal way on the cometary nucleus of 67/P, Philae carried out its First Science Sequence. As part of these activities COSAC acquired s...
Article
The three main requirements for life as we know it are the presence of organic compounds, liquid water, and free energy. Several groups of organic compounds (e.g., amino acids, nucleobases, lipids) occur in all life forms on Earth and are used as diagnostic molecules, i.e., biomarkers, for the characterization of extant or extinct life. Due to thei...
Article
Full-text available
The pace of scientific exploration of our solar system provides ever-increasing insights into potentially habitable environments, and associated concerns for their contamination by Earth organisms. Biological and organic-chemical contamination has been extensively considered by the COSPAR Panel on Planetary Protection (PPP) and has resulted in the...
Article
Full-text available
This paper presents a spectral survey of diffuse interstellar bands (DIBs) in the NIR range, from 0.9 to 2.5 micron. The observations were designed to detect new DIBs, confirm previously proposed NIR DIBs, and characterise their behaviour with respect to known line-of-sight properties (including the optical DIBs present in our spectra). X-shooter a...
Conference Paper
Full-text available
PAHs are among the most commonly proposed and popular candidates for DIB carriers. We present a critical assessment of the PAH-DIB model in view of the progress and the advances that have recently been achieved through a series of complementary studies involving astronomical observations of DIBs, laboratory simulation of interstellar analogs for PA...
Article
Full-text available
We report results from the exposure of the metalloporphyrin iron tetraphenylporphyrin chloride (FeTPPCl) to the outer space environment, measured in situ aboard the Organism/Organic Exposure to Orbital Stresses nanosatellite. FeTPPCl was exposed for a period of 17 months (3700 h of direct solar exposure), which included broad-spectrum solar radiati...
Article
Full-text available
This technical note describes a novel solar simulation experiment designed to mimic the solar radiation experienced by the Organism/Organics Exposure to Orbital Stresses (O/OREOS) nanosatellite in low-Earth orbit. Thin films of organic compounds within hermetically sealed sample cells (identical to the films and cells of the spaceflight mission) we...