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-Gerasimenko. Twenty-five minutes after Philae's initial comet touchdown, the COSAC mass spectrometer took a spectrum in sniffing mode, which displayed a suite of 16 organic compounds, including many nitrogen-bearing species but no sulfur-bearing species, and four compounds—methyl isocyanate, acetone, propionaldehyde, and acetamide—that had not previously been reported in comets.

Amino acids are the essential molecular components of living organisms on Earth, but the proposed mechanisms for their spontaneous generation have been unable to account for their presence in Earth's early history. The delivery of extraterrestrial organic compounds has been proposed as an alternative to generation on Earth, and some amino acids have been found in several meteorites. Here we report the detection of amino acids in the room-temperature residue of an interstellar ice analogue that was ultraviolet-irradiated in a high vacuum at 12 K. We identified 16 amino acids; the chiral ones showed enantiomeric separation. Some of the identified amino acids are also found in meteorites. Our results demonstrate that the spontaneous generation of amino acids in the interstellar medium is possible, supporting the suggestion that prebiotic molecules could have been delivered to the early Earth by cometary dust, meteorites or interplanetary dust particles.

The second ExoMars mission will be launched in 2020 to target an ancient location interpreted to have strong potential for past habitability and for preserving physical and chemical biosignatures (as well as abiotic/prebiotic organics). The mission will deliver a lander with instruments for atmospheric and geophysical investigations and a rover tasked with searching for signs of extinct life. The ExoMars rover will be equipped with a drill to collect material from outcrops and at depth down to 2 m. This subsurface sampling capability will provide the best chance yet to gain access to chemical biosignatures. Using the powerful Pasteur payload instruments, the ExoMars science team will conduct a holistic search for traces of life and seek corroborating geological context information. Key Words: Biosignatures—ExoMars—Landing sites—Mars rover—Search for life. Astrobiology 17, 471–510.

Ribose is the central molecular subunit in RNA, but the prebiotic origin of ribose remains unknown. We observed the formation of substantial quantities of ribose and a diversity of structurally related sugar molecules such as arabinose, xylose, and lyxose in the room-temperature organic residues of photo-processed interstellar ice analogs initially composed of H2O, CH3OH, and NH3 Our results suggest that the generation of numerous sugar molecules, including the aldopentose ribose, may be possible from photochemical and thermal treatment of cosmic ices in the late stages of the solar nebula. Our detection of ribose provides plausible insights into the chemical processes that could lead to formation of biologically relevant molecules in suitable planetary environments.

The Mars Organic Molecule Analyzer (MOMA) instrument onboard the ESA/Roscosmos ExoMars rover (to launch in July, 2020) will analyze volatile and refractory organic compounds in martian surface and subsurface sediments. In this study, we describe the design, current status of development, and analytical capabilities of the instrument. Data acquired on preliminary MOMA flight-like hardware and experimental setups are also presented, illustrating their contribution to the overall science return of the mission. Key Words: Mars—Mass spectrometry—Life detection—Planetary instrumentation. Astrobiology 17, 655–685.

This series aims to report new developments in research and teaching in the interdisciplinary fields of astrobiology and biogeophysics. This encompasses all aspects of research into the origins of life -from the creation of matter to the emergence of complex life forms -and the study of both structure and evolution of planetary ecosystems under a given set of astro-and geophysical parameters. The methods considered can be of theoretical, computational, experimental and observational nature. Preference will be given to proposals where the manuscript puts particular emphasis on the overall readability in view of the broad spectrum of scientific backgrounds involved in astrobiology and biogeophysics. The type of material considered for publication includes: • Topical monographs • Lectures on a new field, or presenting a new angle on a classical field • Suitably edited research reports • Compilations of selected papers from meetings that are devoted to specific topicsThe timeliness of a manuscript is more important than its form which may be unfinished or tentative. Publication in this new series is thus intended as a service to the international scientific community in that the publisher, Springer-Verlag, offers global promotion and distribution of documents which otherwise have a restricted readership. Once published and copyrighted, they can be documented in the scientific literature.

The delivery of organic matter to the primitive Earth via comets and meteorites has long been hypothesized to be an important source for prebiotic compounds such as amino acids or their chemical precursors that contributed to the development of prebiotic chemistry leading, on Earth, to the emergence of life. Photochemistry of inter/ circumstellar ices around protostellar objects is a potential process leading to complex organic species, although difficult to establish from limited infrared observations only. Here we report the first abiotic cosmic ice simulation experiments that produce species with enantiomeric excesses (e.e.'s). Circularly polarized ultraviolet light (UV-CPL) from a synchrotron source induces asymmetric photochemistry on initially achiral inter/circumstellar ice analogs. Enantioselective multidimensional gas chromatography measurements show significant e.e.'s of up to 1.34% for (13 C)-alanine, for which the signs and absolute values are related to the helicity and number of CPL photons per deposited molecule. This result, directly comparable with some L excesses measured in meteorites, supports a scenario in which exogenous delivery of organics displaying a slight L excess, produced in an extraterrestrial environment by an asymmetric astrophysical process, is at the origin of biomolecular asymmetry on Earth. As a consequence, a fraction of the meteoritic organic material consisting of non-racemic compounds may well have been formed outside the solar system. Finally, following this hypothesis, we support the idea that the protosolar nebula has indeed been formed in a region of massive star formation, regions where UV-CPL of the same helicity is actually observed over large spatial areas.

C hondritic meteorites, in particular the CM-type carbonaceous chondrites, make up a unique subset of primitive meteorites, which are of particular interest in the context of origins of life because of their relatively high carbon content and because most of this carbon is present as organic matter. This material is a diverse mixture of compounds that in particular includes carboxylic acids, dicarboxylic acids, hydroxy acids, sulfonic acids, phosphonic acids, and amino acids in the form of monoamino alkanoic acids and monoamino alkandioic acids (1). Among these classes of compounds, a very small fraction of the meteoritic isomers is believed to support prebiotic evolutionary processes. We analyzed hydrolyzed hot-water extracts of a fresh sample of the Murchison CM-chondrite by GC-MS with a chiral column. With an efficient derivatization method and an improved detection technique we focused on compounds with more than two functional groups. MethodsA 1.19-g sample (MPI 320͞14) was taken from the interior of the Murchison meteorite by using a stone crusher. The sample provided fresh fracture surfaces. The sample was powdered for 2 ϫ 2 min at 600 rpm by a planetary micro mill (Pulverisette 7, Fritsch, Idar-Oberstein, Germany) in a positive-pressure ''class 100'' clean room. A 5-mg aliquot of the sample was imaged by a raster electron microscope (CS44, CamScan, Cranberry Township, PA), showing a homogeneous particle size distribution in the low micrometer range. A cold-water (water for organic trace analysis, Fluka) extraction was performed with a 130-mg aliquot that was subjected to diamino acid analysis. In parallel, 347 mg of the powdered sample was extracted with 700 l of water for 20 h at 100°C. After centrifugation (Eppendorf safe-lock tubes in Biopur-quality), the liquid phase was split. One hundred microliters was taken for direct derivatization by using the procedure described ref.2, leading to N,NЈ-diethoxycarbonyl diamino acid ethyl ester (ECEE) derivatives. Another aliquot of 100 l was hydrolyzed in 6 M HCl (hydrochloric acid for amino acid analysis, ampoule, Fluka) at 110°C for 24 h (3). After evaporation of the 6 M HCl, the residue was dissolved in 0.1 M HCl and derivatized by the above protocol. The ECEE derivatives obtained in this way were subjected to enantioselective GC-MS (Varian Chrompack Chirasil-L-Val capillary column; 12 m ϫ 0.25-mm inner diameter, 0.12-m film thickness, 250°C inlet temperature, pulsed splitless injection, 1.5 ml⅐min Ϫ1 constant f low of He carrier gas). The oven temperature program applied for the solvent trapping mode started at 50°C with 10°C⅐min Ϫ1 up to 90°C and then with 2°C⅐min Ϫ1 to 110°C, then was 10°C⅐min Ϫ1 to 180°C, where it was held constant for 39 min. The Agilent 6890͞5973 GC-MSD system was used. The identities of the diamino acid peaks obtained via enantioselective GC-MS were verified by comparing the retention times and the mass spectra with literature data (4) and external standards purchased from Fluka. A serpentine sample was taken as a blank (5). Results a...