Search Publications
Sampling Plume Deposits on Enceladus' Surface to Explore Ocean Materials and Search for Traces of Life or Biosignatures
Malaska, Michael J.; Choukroun, Mathieu; Backes, Paul +14 more
Enceladus is unique as an astrobiology target in that it hosts an active plume sourced directly from its habitable subsurface ocean. Ice particles from the plume contain geochemical constituents that are diagnostic of the ocean conditions, and may hold traces of life and/or biosignatures, if they exist. Up to 93% of the plume particles fall back o…
Using VIRTIS on Venus Express to Constrain the Properties of the Giant Dark Cloud Observed in Images of Venus by IR2 on Akatsuki
Tsang, Constantine C. C.; Barstow, Joanna K.; McGouldrick, Kevin +1 more
A cloud opacity contrast feature that has been called a "long-lived sharp disruption" has been seen in the atmosphere of Venus in the near-infrared using Akatsuki's IR2 camera, most clearly at equatorial latitudes. This feature was found to have a consistent planet-circling period of 4.9 days, and subsequent searches of past imagery revealed that …
The Geographic Distribution of Dense-phase O2 on Ganymede
Brown, Michael E.; Trumbo, Samantha K.; Adams, Danica
Ground-based spectroscopy of Ganymede's surface has revealed the surprising presence of dense-phase molecular oxygen (O2) via weak absorptions at visible wavelengths. To date, the state and stability of this O2 at the temperatures and pressures of Ganymede's surface are not understood. Its spatial distribution in relation to …
Titan in Transit: Ultraviolet Stellar Occultation Observations Reveal a Complex Atmospheric Structure
Tribbett, Patrick D.; Robinson, Tyler D.; Koskinen, Tommi T.
Transit spectroscopy is a key tool for exoplanet atmospheric characterization. However, transit spectrum observations can be limited by aerosol extinction when gas opacities are weak. The ultraviolet wavelength range contains a variety of strong molecular and atomic features, potentially enabling gas species detection even when atmospheric hazes a…
Heavy Positive Ion Groups in Titan's Ionosphere from Cassini Plasma Spectrometer IBS Observations
Coates, Andrew J.; Lavvas, Panayotis; Waite, J. Hunter +4 more
Titan's ionosphere contains a plethora of hydrocarbons and nitrile cations and anions as measured by the Ion Neutral Mass Spectrometer and Cassini Plasma Spectrometer (CAPS) on board the Cassini spacecraft. Data from the CAPS Ion Beam Spectrometer (IBS) sensor have been examined for five close encounters of Titan during 2009. The high relative vel…
Volatile Composition and Outgassing in C/2018 Y1 (Iwamoto): Extending Limits for High-resolution Infrared Cometary Spectroscopy between 2.8 and 5.0 µm
Vervack, Ronald J., Jr.; Kawakita, Hideyo; DiSanti, Michael A. +7 more
We used the powerful high spectral resolution cross-dispersed facility spectrograph, iSHELL, at the NASA Infrared Telescope Facility (IRTF) to observe C/2018 Y1 (Iwamoto), a long-period comet from the Oort cloud. We report production rates for water and eight other parent molecules (native ices), C2H6, CO, CH4, H
Midsummer Atmospheric Changes in Saturn's Northern Hemisphere from the Hubble OPAL Program
Wong, Michael H.; Hueso, Ricardo; Sánchez-Lavega, Agustín +1 more
Using the Hubble Space Telescope, Saturn was observed in 2018, 2019, and 2020, just after the northern hemisphere summer solstice. Analysis of multispectral imaging data reveals three years of cloud changes associated with a 70° N storm that began in 2018. Additionally, there is an increase in equatorial brightness and perhaps haze optical depth a…
Constraining the Positive Ion Composition in Saturn's Lower Ionosphere with the Effective Recombination Coefficient
Vigren, Erik; Wahlund, Jan-Erik; Dreyer, Joshua +4 more
The present study combines Radio and Plasma Wave Science/Langmuir Probe and Ion and Neutral Mass Spectrometer data from Cassini's last four orbits into Saturn's lower ionosphere to constrain the effective recombination coefficient α300 from measured number densities and electron temperatures at a reference electron temperature of 300 K.…
A Case for a Small to Negligible Influence of Dust Charging on the Ionization Balance in the Coma of Comet 67P
Rubin, M.; Vigren, E.; Eriksson, A. I. +3 more
A recent work aided by Rosetta in situ measurements set constraints on the dust-to-gas mass emission ratio and the size distribution of dust escaping the nucleus of comet 67P/Churyumov-Gerasimenko near perihelion. Here we use this information along with other observables/parameters as input into an analytical model aimed at estimating the number d…
The Mars Orbiter for Resources, Ices, and Environments (MORIE) Science Goals and Instrument Trades in Radar, Imaging, and Spectroscopy
Murchie, Scott L.; Ehlmann, Bethany L.; Calvin, Wendy M. +9 more
The Mars Orbiter for Resources, Ices, and Environments (MORIE) was selected as one of NASA's 2019 Planetary Mission Concept Studies. The mission builds upon recent discoveries and current knowledge gaps linked to two primary scientific questions: (1) when did elements of the cryosphere form and how are ice deposits linked to current, recent, and a…