Laboratory Spectra of CO2 Vibrational Modes in Planetary Ice Analogs

Laboratory spectra have shown that CO2 is a powerful diagnostic tool for analyzing infrared data from remote observations, as it has been detected on icy moons in the outer Solar System as well as dust grain surfaces in the interstellar medium (ISM). IR absorption band profiles of CO2 within ice mixtures containing H2O and CH3OH change with respect to temperature and mixture ratios. In this particular study, the CO2 asymmetric stretching mode near 4.3 m (2350 cm (exp-1)), overtone mode near 1.97 m (5080 cm (exp-1)), and the combination bands near 2.7 m (3700 cm (exp-1)), 2.8 m (3600 cm (exp-1)), and 2.02 m (4960 cm (exp -1)), are systematically observed in different mixtures with H2O and CH3OH in temperature ranges from 15K to 150 K. Additionally, some high-temperature deposits (T greater than 50 K) of H2O, CH3OH, and CO2 ice mixtures were performed. These data may then be used to interpret infrared observational data obtained from icy surfaces in the outer Solar System and beyond

Laboratory Studies of Solid Carbon Dioxide in Planetary and Interstellar Ices

Laboratory spectra have shown that CO2. is a powerful diagnostic tool for analyzing infrared data from remote observations, as it has been detected on icy moons in the outer solar system as well as dust grain surfaces in the interstellar medium. IR absorption profiles of CO2 wi thin ice mixtures containing H2O and CH30H change with respect to tem perature and mixture ratios. In this particular study, the CO2 stretch mode around 235O cm (exp -1) (4.3 rricrons) is systematically observ ed in different mixtures with H2O and CH30H in temperature ranges from 15K to 150 K, as well as vibrational modes in the near-IR such as th e combination bands near 3700 cm (exp -1) (2.7 microns) and 5080 (exp -1) (2.0 microns). Additionally, some high?temperature deposits (T > 50 K) of H2O, CH30H, and CO2 ice mixtures were performed to determine the maximum temperatures at which CO2 will deposit on the sample win dow. These data may then be used to interpret spectra obtained from remote IR observations. This research was sponsored by Oak Ridge Associ ated Universities (ORAU) through the NASA Postdoctoral Program (NPP) as well as Ames Research Center and the SETI institute who provided fa cilities and equipment

Ethane on Pluto and Triton

International audienceNew spectra of Pluto were obtained with the Gemini Near-Infrared Spectrometer (GNIRS) on the Gemini South 8-m telescope covering the region 1.9-2.5 µm. We have analyzed these data and two spectra of Triton with particular emphasis on a weak absorption feature detected at 2.405 μm. While this wavelength is coincident with a 13CO absorption band that is the isotopic variant of the 12CO band (2.35 μm) seen on both Pluto and Triton, our analysis, supported by new lab spectra of CO, shows that the strength of the 2.405-μm band is much too great to be attributed to any plausible abundance of 13CO. Instead, we identify this band as the 2.4045 μm absorption of pure ethane in solid form (Quirico & Schmitt Icarus 127, 354, 1997). Published models of the spectra of Triton (Quirico et al. Icarus 139, 159, 1999) and Pluto (Douté et al. Icarus 142, 421, 1999) show small variations from the data at 2.28 μm. The addition of absorption from the ethane band at 2.274 μm removes this small discrepancy. We do not see evidence for the 2.461 μm ethane band, although this is a somewhat noisy region of both spectra. Other investigators (Nakamura et al. P.A.S. Japan 52, 551, 2000) noted that Pluto's absorption bands at 2.28 and 2.32 μm are best fit with ethane, but their 2.405 μm region is discrepant with ethane. At longer wavelengths, Sasaki et al. (Ap.J. 618, L57, 2005) noted that models fit their Pluto data best when ethane was added, but they did not clearly identify ethane bands. Estimates of the abundances of ethane on Triton and Pluto suggest that this ice is deposited on relatively short time-scales by precipitation from the atmosphere, where it is produced by photochemistry (Krasnopolsky & Cruikshank JGR 100, 21271, 1995; JGR 104, 21979, 1999)

Composition of KBO (50000) Quaoar

International audienc

Composition of KBO (50000) Quaoar

International audienc

Composition of KBO (50000) Quaoar

International audienc

New Optical Constants of Titan and Pluto Aerosol Analogs from the Visible to the Infrared and Their Use to Analyze Cassini and New Horizons Observations

International audienceIn planetary atmospheres like those of Titan and Pluto, complex organic solid particles are produced from photolysis and radiolysis processes. These aerosols form haze layers, and also settle to the surface. Their presence can significantly impact the atmospheric and surface spectra obtained by remote-sensing instruments like the Visible Infrared Mapping Spectrometer and Composite Infrared Spectrometer on Cassini and the Ralph instrument on New Horizons. Numerous laboratory experiments have been developed to simulate and investigate the chemistry occurring in Titan's and more recently Pluto's atmosphere, resulting in the formation of these solid particles. Many different analytical diagnostics have been used to characterize laboratory-generated analogs (or tholins) of Titan and Pluto aerosols and provide insight on their formation pathways and physical, chemical, and spectral properties. In particular, the complex refractive indices (n + ik, or optical constants) of a variety of Titan and Pluto tholins have been measured over the years. These optical constants describe how the tholins interact with light (transmission, reflection, absorption, scattering), and are therefore fundamental input parameters to simulate haze particles in radiative transfer models used for the interpretation of observational data. These radiative transfer models can leverage the optical constants of different tholins to explore a wide range of compositions, allowing for improved fits and interpretations of observational data resulting in a better understanding of Titan's and Pluto's atmosphere and surface compositions. Here we present the results of several optical constants studies: 1. The measurements of optical constants of Titan tholins produced from plasma chemistry in N2:CH4-based gas mixtures in the NASA Ames COSmIC Facility from the Visible to the Near Infrared (0.4–1.6 µm) and their use in a new analysis of Cassini VIMS observations[1]. 2. The measurements of optical constants of Pluto tholins produced in N2:CH4:CO gas mixtures in COSmIC from 0.4 to 1.6 µm and their use in a new analysis of New Horizons Ralph observations[2,3]. 3. The preliminary results of a comparative analysis of two Titan tholin samples produced from plasma chemistry in N2:CH4 gas mixtures in two different experimental facilities: the LATMOS PAMPRE experiment and the NASA Ames COSmIC facility, and measured from 0.4 to 300 µ

New Optical Constants of Titan and Pluto Aerosol Analogs from the Visible to the Infrared and Their Use to Analyze Cassini and New Horizons Observations

International audienceIn planetary atmospheres like those of Titan and Pluto, complex organic solid particles are produced from photolysis and radiolysis processes. These aerosols form haze layers, and also settle to the surface. Their presence can significantly impact the atmospheric and surface spectra obtained by remote-sensing instruments like the Visible Infrared Mapping Spectrometer and Composite Infrared Spectrometer on Cassini and the Ralph instrument on New Horizons. Numerous laboratory experiments have been developed to simulate and investigate the chemistry occurring in Titan's and more recently Pluto's atmosphere, resulting in the formation of these solid particles. Many different analytical diagnostics have been used to characterize laboratory-generated analogs (or tholins) of Titan and Pluto aerosols and provide insight on their formation pathways and physical, chemical, and spectral properties. In particular, the complex refractive indices (n + ik, or optical constants) of a variety of Titan and Pluto tholins have been measured over the years. These optical constants describe how the tholins interact with light (transmission, reflection, absorption, scattering), and are therefore fundamental input parameters to simulate haze particles in radiative transfer models used for the interpretation of observational data. These radiative transfer models can leverage the optical constants of different tholins to explore a wide range of compositions, allowing for improved fits and interpretations of observational data resulting in a better understanding of Titan's and Pluto's atmosphere and surface compositions. Here we present the results of several optical constants studies: 1. The measurements of optical constants of Titan tholins produced from plasma chemistry in N2:CH4-based gas mixtures in the NASA Ames COSmIC Facility from the Visible to the Near Infrared (0.4–1.6 µm) and their use in a new analysis of Cassini VIMS observations[1]. 2. The measurements of optical constants of Pluto tholins produced in N2:CH4:CO gas mixtures in COSmIC from 0.4 to 1.6 µm and their use in a new analysis of New Horizons Ralph observations[2,3]. 3. The preliminary results of a comparative analysis of two Titan tholin samples produced from plasma chemistry in N2:CH4 gas mixtures in two different experimental facilities: the LATMOS PAMPRE experiment and the NASA Ames COSmIC facility, and measured from 0.4 to 300 µ