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All sourcesNASA NTRSDOE OSTI
NASA NTRS2011

Organic Compounds in Stardust

The successful return of the STARDUST spacecraft provides a unique opportunity to investigate the nature and distribution of organic matter in cometary dust particles collected from Comet 81P/Wild-2. Analysis of individual cometary impact tracks in silica aerogel using the technique of two-step laser mass spectrometry (L2MS) demonstrates the presence of complex aromatic organic matter. While concerns remain as to the organic purity of the aerogel collection medium and the thermal effects associated with hypervelocity capture, the majority of the observed organic species appear indigenous to the impacting particles and are hence of cometary origin. While the aromatic fraction of the total organic matter present is believed to be small, it is notable in that it appears to be N-rich. Spectral analysis in combination with instrumental detection sensitivities suggest that N is incorporated predominantly in the form of aromatic nitriles (R-C N). While organic species in the STARDUST samples do share some similarities with those present in the matrices of carbonaceous chondrites, the closest match is found with stratospherically collected interplanetary dust particles. These findings are consistent with the notion that a fraction of interplanetary dust is of cometary origin. The presence of complex organic N-containing species in comets has astrobiological implications since comets are likely to have contributed to the prebiotic chemical inventory of both the Earth and Mars.

McKay, David S.↗
NASA NTRS2014

Interstellar Organics, the Solar Nebula, and Saturn's Satellite Phoebe

The diffuse interstellar medium inventory of organic material (Pendleton et al. 1994, Pe 2002) was likely incorporated into the molecular cloud in which the solar nebula condensed. This provided the feedstock for the fo planets, and the smaller icy bodies in the region outside Neptune's orbit (transneptunian objects, or TNOs). Saturn's satellites Phoeb open a window to the composition of one class of TNO as revealed by the near-infrared mapping spectrometer (VIMS) on the Cass Phoebe (mean diameter 213 km) is a former TNO now orbiting Saturn. VIMS spectral maps of Phoebe's surface reveal a complex consisting of prominent aromatic (CH) and aliphatic hydrocarbon (CH2, CH3) absorption bands (3.2-3.6 μm). Phoebe is the source encircling Saturn, and from which particles (~5-20 μm size) spiral inward toward Saturn. They encounter Iapetus and Hyperion wh blanket the native H2O ice of those two bodies. Quantitative analysis of the hydrocarbon bands on Iapetus demonstrates that aroma abundant as aliphatic CH2+CH3, significantly exceeding the strength of the aromatic signature in interplanetary dust particles, com carbonaceous meteorites (Cruikshank et al. 2013). A similar excess of aromatics over aliphatics is seen in the qualitative analysis o itself (Dalle Ore et al. 2012). The Iapetus aliphatic hydrocarbons show CH2/CH3 ~4, which is larger than the value found in the di as Phoebe is a primitive body that formed in the outer regions of the solar nebula and has preserved some of the original nebula inv understanding the content and degree of processing of that nebular material. There are other Phoebe-like TNOs that are presently b in the organic spectral region, but JWST will open that possibility for a number of objects. We now need to explore and understand organic-bearing Solar System material to the solar nebula and the inventory of ISM materials incorporated therein.

Interstellar↗
NASA NTRS2017

Analysis of Mixed Aryl/Alkyl Esters by Pyrolysis Gas Chromatography-Mass Spectrometry in the Presence of Perchlorate

Mars is an important target for Astrobiology. A key goal of the MSL mission was to determine whether Mars was habitable in the past, a que-tion that has now been definitely determined to be yes. Another key goal for Mars exploration is to understand the origin and distribution of organic material on Mars; this question is being addressed by the SAM instrument on MSL, and will also be informed by two upcoming Mars exploration missions, ExoMars and Mars 2020. These latter two missions have instrumentation capable of detecting and characterize organic molecules. Over the next decade, these missions will analyze organics in surface, near-surface and sub-surface samples. Each mission has the capability to analyze organics by different methods (pyrolysis gas chromatography-mass spectrometry [py-GC-MS]; laser desorption and thermal volatilization GC-MS; and Raman spectroscopy). Plausibly extraterrestrial organics were recently discovered by the Mars Science Laboratory (MSL), providing an important first step towards understanding the organic inventory on Mars [1]. The compounds detected were chlorobenzenes and chloroalkanes, but it was argued that chlorination of these compounds occurred during pyrolysis of samples containing unchlorinated organics in the presence of perchlorate. A recent report analyzed a suite of aromatic (benzene, toluene, benzoic acid, phthalic acid, and mellitic acid) and aliphatic (acetic acid, propane, propanol, and hexane) by pyrolysis under SAM-like conditions in the presence of perchlorate to attempt to constrain possible precursor molecules for the organic molecules detected on Mars. For aromatic compounds, the aromatic acids all readily produced SAM-relevant chlorobenzes, whereas benzene and toluene did not. This observation suggests that the chlorobenzene detected on Mars could have derived from compounds like mellitic acid, consistent with the previous hypothesis by Benner et al. [3]. Among the aliphatic molecules, it was shown that pyrolysis of alkanes and alcohols in the presence of perchlorates produced polychlorine containing chloro-alkanes similar to what was observed on Mars. Surpris-ingly, however, similar treatment of acetic acid pro-duced chloroketones, instead, and no chloroalkanes were reported. This suggests that the chloroalkanes detected in the Sheepbed mudstone were not derived from aliphatic carboxylic acids, but instead were from more reduced alcohols or even alkanes, or perhaps were degradation products of more complicated organic material. Because organics analyses on mars will rely heavily on py-GC-MS of perchlorate-containing samples over the next decade, it is important to understand the fate of organic molecules of biotic and abiotic origin under such conditions. In this work we begin a series of experiments to improve our understanding of products generated during py-GC-MS of increasingly complex organic molecules (esters, amides, peptides, nucleic acids, fatty acids) in the presence of perchlorate.

Burton, A. S.↗
NASA NTRS2017

Multi-Wavelength Laser Transmitter for the Two-Step Laser Time-of-Flight Mass Spectrometer

Missions to diverse Outer Solar System bodies will require investigations that can detect a wide range of organics in complex mixtures, determine the structure of selected molecules, and provide powerful insights into their origin and evolution. Previous studies from remote spectroscopy of the Outer Solar System showed a diverse population of macromolecular species that are likely to include aromatic and conjugated hydrocarbons with varying degrees of methylation and nitrile incorporation. In situ exploration of Titan's upper atmosphere via mass and plasma spectrometry has revealed a complex mixture of organics. Similar material is expected on the Ice Giants, their moons, and other Outer Solar System bodies, where it may subsequently be deposited onto surface ices. It is evident that the detection of organics on other planetary surfaces provides insight into the chemical and geological evolution of a Solar System body of interest and can inform our understanding of its potential habitability. We have developed a prototype two-step laser desorption/ionization time-of-flight mass spectrometer (L2MS) instrument by exploiting the resonance-enhanced desorption of analyte. We have successfully demonstrated the ability of the L2MS to detect hydrocarbons in organically-doped analog minerals, including cryogenic Ocean World-relevant ices and mixtures. The L2MS instrument operates by generating a neutral plume of desorbed analyte with an IR desorption laser pulse, followed at a delay by a ultraviolet (UV) laser pulse, ionizing the plume. Desorption of the analyte, including trace organic species, may be enhanced by selecting the wavelength of the IR desorption laser to coincide with IR absorption features associated with vibration transitions of minerals or organic functional groups. In this effort, a preliminary laser developed for the instrument uses a breadboard mid-infrared (MIR) desorption laser operating at a discrete 3.475 μm wavelength, and a breadboard UV ionization laser operating at a wavelength of 266 nm. The MIR wavelength was selected to overlap the C-H stretch vibrational transition of certain aromatic hydrocarbons, and the UV wavelength provides additional selectivity to aromatic species via UV resonance-enhanced multiphoton ionization effects. The use of distinct laser wavelengths allows efficient coupling to the vibrational and electronic spectra of the analyte in independent desorption and ionization steps, mitigating excess energy that can lead to fragmentation during the ionization process and leading to selectivity that can aid in data interpretation.

Yu, Anthony W.↗
NASA NTRS2017

Observations of VOC Emissions and Photochemical Products over US Oil- and Gas-Producing Regions Using High-Resolution H3O+ CIMS (PTR-ToF-MS)

VOCs (Volatile Organic Compounds) related to oil and gas extraction operations in the United States were measured by H3O (sup plus) chemical ionization time-of-flight mass spectrometry (H3O (sup plus) ToFCIMS/PTR-ToF-MS (Time of Flight Chemical Ionization Mass Spectrometry/Proton Transfer Reaction-Time of Flight-Mass Spectroscopy) from aircraft during the Shale Oil and Natural Gas Nexus (SONGNEX) campaign in March-April 2015. This work presents an overview of major VOC species measured in nine oil- and gas-producing regions, and a more detailed analysis of H3O (sup plus) ToF-CIMS measurements in the Permian Basin within Texas and New Mexico. Mass spectra are dominated by small photochemically produced oxygenates and compounds typically found in crude oil: aromatics, cyclic alkanes, and alkanes. Mixing ratios of aromatics were frequently as high as those measured downwind of large urban areas. In the Permian, the H3O (sup plus) ToF-CIMS measured a number of underexplored or previously unreported species, including aromatic and cycloalkane oxidation products, nitrogen heterocycles including pyrrole (C4H5N) and pyrroline (C4H7N), H2S, and a diamondoid (adamantane) or unusual monoterpene. We additionally assess the specificity of a number of ion masses resulting from H3O (sup plus) ion chemistry previously reported in the literature, including several new or alternate interpretations.

mass spectrometr↗
NASA NTRS2017

Method and Apparatus for Detecting and Quantifying Bacterial Spores on a Surface

A method and an apparatus for detecting and quantifying bacterial spores on a surface. In accordance with the method: a matrix including lanthanide ions is provided on the surface containing the bacterial spores; functionalized aromatic molecules are released from the bacterial spores on the surface; a complex of the lanthanide ion and the aromatic molecule is formed on the surface; the complex of the lanthanide ion and the aromatic molecule is excited to generate a characteristic luminescence of the complex on the surface; and the bacterial spores exhibiting the luminescence of the complex on the surface are detected and quantified.

Ponce, Adrian↗
NASA NTRS2019

Prebiotic Chemistry of Pluto

We present the case for the presence of complex organic molecules, such as amino acids and nucleobases, formed by abiotic processes on the surface and in near-subsurface regions of Pluto. Pluto's surface is tinted with a range of non-ice substances with colors ranging from light yellow to red to dark brown; the colors match those of laboratory organic residues called tholins. Tholins are broadly characterized as complex, macromolecular organic solids consisting of a network of aromatic structures connected by aliphatic bridging units (e.g., Imanaka et al.,2004; Materese et al.,2014, 2015). The synthesis of tholins in planetary atmospheres and in surface ices has been explored in numerous laboratory experiments, and both gas- and solid-phase varieties are found on Pluto. A third variety of tholins, exposed at a site of tectonic surface fracturing called Virgil Fossae, appears to have come from a reservoir in the subsurface. Eruptions of tholin-laden liquid H2O from a subsurface aqueous repository appear to have covered portions of Virgil Fossae and its surroundings with a uniquely colored deposit (D.P. Cruikshank, personal communication) that is geographically correlated with an exposure of H2O ice that includes spectroscopically detected NH3 (C.M. Dalle Ore, personal communication). The subsurface organic material could have been derived from presolar or solar nebula processes, or might have formed in situ. Photolysis and radiolysis of a mixture of ices relevant to Pluto's surface composition (N2, CH4, CO) have produced strongly colored, complex organics with a significant aromatic content having a high degree of nitrogen substitution similar to the aromatic heterocycles pyrimidine and purine (Materese et al.,2014, 2015; Cruikshank et al.,2016). Experiments with pyrimidines and purines frozen in H2O-NH3 ice resulted in the formation of numerous nucleobases, including the biologically relevant guanine, cytosine, adenine, uracil, and thymine (Materese et al.,2017). The red material associated with the H2O ice may contain nucleobases resulting from energetic processing on Pluto's surface or in the interior. Some other Kuiper Belt objects also exhibit red colors similar to those found on Pluto and may therefore carry similar inventories of complex organic materials. The widespread and ubiquitous nature of similarly complex organic materials observed in a variety of astronomical settings drives the need for additional laboratory and modeling efforts to explain the origin and evolution of organic molecules. Pluto observations reveal complex organics on a small body that remains close to its place of origin in the outermost regions of the Solar System.

Cruikshank, D. P.↗
NASA NTRS2020

First Detections of Dichlorobenzene Isomers and Trichloromethylpropane from Organic Matter Indigenous to Mars Mudstone in Gale Crater, Mars: Results from the Sample Analysis at Mars Instrument Onboard the Curiosity Rover

Chromatographic analysis of the Cumberland mudstone in Gale crater by the Sample Analysis at Mars (SAM) instrument revealed the detection of two to three isomers of dichlorobenzene. Their individual concentrations were estimated to be in the 0.5–17 ppbw range relative to the sample mass. We also report the first detection of trichloromethylpropane and the confirmation of the detection of chlorobenzene previously reported. Supporting laboratory experiments excluded the SAM internal background as the source of those compounds, thus confirming the organic carbon and chlorine of the newly detected chlorohydrocarbons are indigenous to the mudstone sample. Laboratory experiments also demonstrated that the chlorohydrocarbons were mainly produced from chemical reactions occurring in the SAM ovens between organic molecules and oxychlorines contained in the sample. The results we obtained show that meteoritic organics and tested chemical species (a polycyclic aromatic hydrocarbon, an amino acid, and a carboxylic acid) were plausible organic precursors of the chlorinated aromatic molecules detected with SAM, thus suggesting that they could be among the organic molecules present in the mudstone. Results from this study coupled with previously reported detections of chlorinated aromatics (<300 ppbw) indigenous to the same mudstone highlight that organics can be preserved from the harsh surface conditions even at shallow depth. The detection of new chlorohydrocarbons with SAM confirms that organic molecules should have been available in an environment favorable to life forms, strengthening the habitability aspect of Gale crater. Key Words: Mars—Chlorinated organic molecules—In situ measurements—Sample Analysis at Mars— Mudstone—Gale crater. Astrobiology 20, 292–306.

Szopa, Cyril↗
NASA NTRSDate not supplied

ELM: Europa Luminescence Microscope

The Europa Luminescence Microscope (ELM) is an automated fluorescence and bright-field microscope designed to meet key objectives defined in the 2016 NASA Europa Lander Study Report, including the identification and characterization of morphological biosignatures. ELM’s heritage stems from a 2U cubesat fluorescence microscope, the Fluorescence Analysis for In situ Research imager, designed and built at NASA Ames Research Center, for the autonomous study of microbial biology in low Earth orbit. For ELM implementation, a sample is autonomously manipulated with a microfluidic system using in-line 10, 1.0, and 0.2 μm pore-size filters to capture successively smaller particles for imaging. For bright-field imaging, ELM uses deep-ultraviolet, ultraviolet and visible light to image organic and inorganic structures with submicron resolution. The ability to detect biosignatures as small as 0.2 μm in size is achieved by imaging native fluorescence and using fluorescence microscopy stains to identify key structural and functional indicators of microbial life (proteins, lipids, nucleic acids). For fluorescence imaging, ELM uses 265, 370, 470, and 530 nm LEDs with five emission bands. The use of multiple excitation and emission wavelengths for native fluorescence imaging enables the detection of a wide range of molecular species and their rough classification. Excitation at 265 nm allows for the detection of smaller polycyclic aromatic hydrocarbons (PAH), aromatic amino acids, and proteins with little to no interference from mineral fluorescence, given proper emission band selection. 370 and 470 nm light excites increasingly larger PAH structures and larger aromatic biomolecules that may be present (e.g., protective pigments). Similarly, inorganic fluorescence can be characterized and separated from organic fluorescence, allowing the recognition and in some cases classification, of minerals and other abiotic particles. ELM is based upon work supported by the NASA COLDTech and ICEE-2 programs.

Richard C Quinn↗
NASA NTRSDate not supplied

Low-Temperature Formation of Carbonaceous Grains from PAHs

Astronomical observations have detected interstellar carbon in the form of polycyclic aromatic hydrocarbons(PAHs) as well as carbonaceous dust, confirming its presence in both gaseous and solid phases. The goal of this study is to experimentally investigate low-temperature chemical pathways between these two phases in order to better understand the evolution of cosmic carbon. Cosmic dust analogs are produced in the supersonic expansion of an argon jet seeded with aromatic molecules: benzene, naphthalene, anthracene, phenanthrene, and pyrene. These are prototype aromatic molecules of compact and non compact structure, and are used to evaluate the effect of precursor structure on the molecular complexity of the resulting grains. The seeded jet is exposed to an electrical discharge and the carbonaceous grains are collected and probed ex situ via laser desorption mass spectrometry. Mass spectra reveal a rich molecular diversity within the grains, including fragments of the parent molecule but also growth into larger complex organic molecules (COMs). In all experiments, the largest number of products is found in the m/z range 200-250, and C16H10 (attributed to pyrene and/or its isomers) is found to be a dominant product, pointing at the formation of this stable PAH as a preferential route in the growth to larger PAHs. Comparison to mass spectra from the Murchison meteorite reveals a similar dominance of compounds related toC16H10 at m/z = 202. Evidence of the methyl addition-cyclization mechanism in the anthracene experiment is reported. PAH structure is found to impact the dust production yield, as seen by the greater yield for the anthracene compared to the phenanthrene experiment. PAH growth at low temperatures via barrierless routes involving the addition of alkyl- and phenyl-type radicals is suggested as a viable pathway to COMs. These results suggest that PAH growth and dust formation from PAHs are feasible at low temperatures in photon-dominated regions and circumstellar envelopes.

L Gavilan↗
NASA NTRSDate not supplied

SHERLOC Investigations at the Máaz and Séítah formations within Jezero crater

Introduction: The Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals (SHERLOC) instrument combines microscopic imaging, native fluorescence and Raman spectroscopy to better understand the mineral and chemical makeup of rocks on the martian surface. Native fluorescence emissions from aromatic organic species allow for detection and classification of aromatic organic molecules, whereas Raman scattered photons from molecules allow identification of functional groups of organics, chemicals, and minerals. These signatures are obtained on a 100 micron spatial scale and collocated to images so textures, minerals and chemicals can all be compared [1]. Results: SHERLOC has been operating on Mars since February 18, 2021. As of this writing, we have analyzed 3 natural surfaces, and 5 abraded rock patches created during the Crater Floor Campaign within Jezero crater [2]. The Guillaumes target (from the Roubion outcrop, Roubion member of the Máaz Formation) is dominated by Ca-sulfate with patches of perchlorate. The Bellegarde target (from the Rochette outcrop, Rochette member of the Máaz Formation) exhibits Raman peaks that match hydrated Ca-sulfate, amorphous/microcrystalline silicate (AMS), carbonate, and phosphate phases. A fluorescence doublet at ~305 and ~325 nm was detected and is most likely due to indigenous organic material in the sample. The Garde target (from the Bastide outcrop, Bastide member of the Séítah Formation) is dominated by olivine and carbonate with AMS occurring across the material. The Dourbes target (from the Brac outcrop, Bastide member of the Séítah Formation) is dominated by olivine and shows minor amounts of carbonate, hydrated Ca-sulfate, and AMS. The Quartier target exhibits a large sulfate feature, as well as carbonate, perchlorate, olivine and a fluorescence doublet at 305 and 325 nm and is very similar to that observed at Bellegarde. In each of these samples we have identified fluorescence features that are likely aromatic organics native to the rock interiors. Acknowledgments: This work was carried out at the Jet Propulsion Laboratory, The California Institute of Technology under a contract from NASA.

L W Beegle↗
NASA NTRSDate not supplied

SHERLOC: Results of the first 350 sols of operations

On February 18th 2021, the Perseverance rover landed in Jezero crater, Mars. This site was chosen because orbiter data analysis provides evidence that the crater hosted a stream-fed lake during the Martian Noachian period. The Octavia Butler landing site is located ~1.9 km east of the remnants of a river delta. Deltaic and lacustrine sediments can preserve biosignatures, making Jezero crater a prime target for Mars sample return science. One of the seven instruments on Perseverance’s science payload is SHERLOC –Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals. SHERLOC combines fluorescence and Raman spectroscopy with microscopic imaging to analyze surface material to better understand the history of the aqueous environments recorded in the rocks of Jezero crater and to search for potential biosignatures. SHERLOC imaging obtains high spatial resolution images of geological targets to identify grain-scale structure and texture. SHERLOC spectroscopy enables high-sensitivity detection, characterization, and spatially resolved correlation of trace organic materials. Native fluorescence emissions from aromatic organic species allow for detection and classification of aromatic organic molecules, whereas Raman scattered photons from molecules allow identification of functional groups of organics, chemicals, and minerals. In the first 300 sols, SHERLOC has analyzed 3 natural surfaces, and 5 abraded rock patches created during the Crater Floor Campaign within Jezero crater. SHERLOC has been able to identify phosphates, amorphous/microcrystalline silicate (AMS), olivine, sulfates, and carbonates in abraded patches in the green zone campaign within Jezero Crater Máaz and Séítah formations. Within these detections we have begun to tell the story of what this crater was like when it was full of liquid water over 3 billion years ago. In each of these samples we have identified fluorescence features that are likely aromatic organics native to the rock interiors. We have identified multiple unique fluorescence signatures, within each of the abraded patches. The organic signatures have either been widely distributed over an extended area, which is probably due to planetary wide dust, or have spatially resolved locations that are collocated with different mineral signatures. Note: Additional information available on attachment.

L. W. Beegle↗
NASA NTRS2015

The Formation of N- and O-Heterocycles from the Irradiation of Benzene and Naphthalene in H2O/NH3- Containing Ices

Aromatic hydrocarbons are an important class of molecules for both astrochemistry and astrobiology (Fig. 1). Within this class of molecules, polycyclic aromatic hydrocarbons (PAHs) are known to be ubiquitous in many astrophysical environments, and are likely present in interstellar clouds and protostellar disks. In dense clouds, PAHs are expected to condense onto grains as part of mixed molecular ice mantles dominated by small molecules like H2O,CH3OH, NH3, CO, and CO2. These ices are exposed to ionizing radiation in the form of cosmic rays and ambient high-energy X-ray and UV photons.

Ice Irradiation↗
NASA NTRS1970

New hyperthermal thermosetting heterocyclic polymers

Polyimidazopyrrolone polymers, formed by the condensation of aromatic dianhydrides with aromatic tetraamines in various solvents, form moldings that resist degradation in air and retain great strength at 400 to 700 degrees F. The resins have good insulating properties, are easy to mold, and make good protective coatings.

Bilow, N.↗
NASA NTRS1972

Ultraviolet and thermally stable polymer compositions

Copolymers, produced from aromatic substituted aromatic azine-siloxane compositions, are thermally stable, solar ultraviolet light non-degradable by wavelengths shorter than those reaching earth surface.

Adamson, M. J.↗
NASA NTRS1972

Effects of surface contamination on the infrared emissivity and visible-light scattering of highly reflective surfaces at cryogenic temperatures

A technique is described for the simultaneous in situ measurement of film thickness, refractive index, total normal emissivity, visible-light scattering, and reflectance of contaminant films on a highly reflective liquid-nitrogen cooled, stainless steel substrate. Emissivities and scattering data are obtained for films of water, carbon dioxide, silicone oil, and a number of aromatic and aliphatic hydrocarbons as a function of film thickness between zero and 20 microns. Of the contaminants investigated, water has by far the greatest effect on emissivity, followed by silicone oil, aliphatic hydrocarbons, aromatic hydrocarbons, and carbon dioxide. The emissivity increases more rapidly with film thickness between zero and 2.5 microns than at thicknesses greater than 2.5 microns. Scattering of visible light changes very little below 2 microns thickness but increases rapidly with thickness beyond 2 to 3 microns. The effect of contaminant films on passive radiation coolers is discussed.

Viehmann, W.↗
NASA NTRS1972

Effects of surface contamination on the infrared emissivity and visible-light scattering of highly reflective surfaces at cryogenic temperatures

A technique is described for the simultaneous in situ measurement of film thickness, refractive index, total normal emissivity, visible light scattering, and reflectance of contaminant films on a highly reflective liquid nitrogen-cooled, stainless steel substrate. Emissivities and scattering data were obtained for films of water, carbon dioxide, silicone oil, and a number of aromatic and aliphatic hydrocarbons as a function of film thickness between zero and 20 microns. Water had the greatest effect on emissivity, followed by silicone oil, aliphatic hydrocarbons, aromatic hydrocarbons, and carbon dioxide. Emissivity increased more rapidly with film thickness between zero and 2.5 microns, than at thickness greater than 2.5 microns. Scattering of visible light changed little below 2-microns thickness but increased rapidly with thickness beyond 2 to 3 microns. The effect of contaminant films on passive radiation coolers is discussed.

Viehmann, W.↗
NASA NTRS1972

Origin of organic matter in early solar system. V - Further studies of meteoritic hydrocarbons and a discussion of their origin.

The Murchison meteorite contains aliphatic and aromatic hydrocarbons similar to those made in static Fischer-Tropsch-type syntheses. Principal compound classes above C8 are n-alkanes, mono- and dimethylalkanes, alkenes, alkylbenzenes and -naphthalenes. Below C8, n-alkanes are virtually absent; instead, benzene, toluene, branched alkanes dominate. The CH4/C2H6 ratio is greater than 30, possibly greater than 700. Isoprenoids from C17 to C20 occur in a surface rinse but not in subsequent extracts and appear to be terrestrial contaminants. Thiophenes, porphyrin-like pigments, and chlorobenzenes were also found; the latter appear to be contaminants. In the Allende meteorite, only methane, benzene, toluene and an aromatic polymer seem to be indigeneous. A comprehensive review of current evidence shows that Fischer-Tropsch-type reactions can account for most principal features of meteorite organic matter.

Studier, M. H.↗