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Photolysis and Sublimation Chemistry of Ammonium Cyanide with Relevance to Cometary Environments
Gerakines, P. A.; Milam, S. N.; Yocum, K. M. +3 more
Bulk nitrogen is depleted in solar system objects, including the terrestrial planets, chondritic meteorites, and comets. Recently, it was suggested that cometary nitrogen may be locked up in ammonium salts—ionic solids comprising ammonia (NH3) and an acid such as hydrogen cyanide (HCN)—based on Rosetta/ROSINA data from comet 67P/Churyum…
Noble Gas Planetology and the Xenon Clouds of Uranus
Zahnle, Kevin
Noble gases provide tracers of cosmic provenance that are accessible to a future Uranus atmospheric probe. Argon and krypton are expected to be well mixed on Uranus with respect to H2 and He, although condensation at the winter pole may be possible. The Ar/H2 and Ar/Kr ratios address whether the materials accreted by Uranus r…
Parent Volatile Outgassing Associations in Cometary Nuclei: Synthesizing Rosetta Measurements and Ground-based Observations
Bodewits, Dennis; Luspay-Kuti, Adrienn; Bonev, Boncho P. +5 more
Comets, as remnants of the solar system's formation, vary in volatile-refractory content. In situ comet studies, such as the Rosetta mission to 67P/Churyumov–Gerasimenko, provide detailed volatile composition insights, while ground-based studies offer broader comet samples but in fewer species. Comparing 67P's volatile correlations during the 2 yr…
Dual Sources of S2 Observed in Comet 67P: Insights from Comparing ROSINA Measurements and Laboratory Simulations
Choukroun, Mathieu; Hodyss, Robert; Mahjoub, Ahmed +2 more
Hydrogen sulfide (H2S) is the fifth most abundant molecule observed in the coma of comet 67P/Churyumov–Gerasimenko (67P). Prior to its incorporation into cometary materials, H2S likely underwent ultraviolet (UV) radiation exposure, which is thought to initiate a complex sulfur chemistry. We present an investigation into the U…
The Evolution of Activity and Chemical Composition in Rosetta's Comet Targets across Multiple Apparitions: Complications for CS2 as the CS Parent in Comet Nuclei
Parker, Joel Wm.; Harris, Walter M.; Bodewits, Dennis +9 more
Jupiter-family comets are ephemeral small bodies injected into the inner solar system from the Kuiper Belt, doomed to either sublimate all their volatiles and become inert or violently shatter from the activity. We investigate two target candidates of the ESA Rosetta mission, comets 46P/Wirtanen and 67P/Churyumov-Gerasimenko, which had favorable a…
Pits on Jupiter-family Comets and the Age of Cometary Surfaces
Guilbert-Lepoutre, Aurélie; Besse, Sébastien; Benseguane, Selma +4 more
Large and deep depressions, also known as pits, are observed at the surface of all Jupiter-family comets (JFCs) imaged by spacecraft missions. They offer the opportunity to glimpse the subsurface characteristics of comet nuclei and study the complex interplay between surface structures and cometary activity. This work investigates the evolution of…
Topographically Influenced Evolution of Large-scale Changes in Comet 67P/Churyumov-Gerasimenko's Imhotep Region
Soderblom, Jason M.; Bodewits, Dennis; Vincent, Jean-Baptiste +5 more
Large portions of comet 67P/Churyumov-Gerasimenko's northern hemisphere are blanketed by fallback material consisting of centimeter-sized particles termed the smooth terrains. Observations from the Rosetta mission show that the most drastic transient changes during 67P's 2015 perihelion passage occurred within a subset of these deposits. However, …
The EXCITING Experiment Exploring the Behavior of Nitrogen and Noble Gases in Interstellar Ice Analogs
Bekaert, David V.; Broadley, Michael W.; Marty, Bernard +3 more
Comets represent some of the most pristine bodies in our solar system and can provide a unique insight into the chemical makeup of the early solar system. Due to their icy volatile-rich nature, they may have played an important role in delivering volatile elements and organic material to the early Earth. Understanding how comets form can therefore…
Near-infrared Spectroscopy of the Nucleus of Low-activity Comet P/2016 BA14 during Its 2016 Close Approach
Kareta, Theodore; Harris, Walter M.; Reddy, Vishnu +1 more
The near-Earth comet P/2016 BA14 (PanSTARRS) is a slow-rotating, nearly dormant object, a likely dynamical twin of 252P/LINEAR, and was recently shown to have a mid-infrared spectrum very dissimilar to other comets. Comet BA14 was also recently selected as one of the backup targets for the ESA's Comet Interceptor, so a cleare…
First Comet Observations with NIRSPEC-2 at Keck: Outgassing Sources of Parent Volatiles and Abundances Based on Alternative Taxonomic Compositional Baselines in 46P/Wirtanen
Villanueva, Geronimo L.; Cochran, Anita L.; Bodewits, Dennis +18 more
A major upgrade to the NIRSPEC instrument at the Keck II telescope was successfully completed in time for near-infrared spectroscopic observations of comet 46P/Wirtanen during its exceptionally close flyby of Earth in 2018 December. These studies determined the abundances of several volatiles, including C2H2, C2H