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Comparative Kbology: Using Surface Spectra of Triton, Pluto, and Charon to Investigate Atmospheric, Surface, and Interior Processes on Kuiper Belt Objects
This thesis presents analyses of the surface compositions of the icy outer Solar System objects Triton, Pluto, and Charon. Pluto and its satellite Charon are Kuiper Belt Objects (KBOs) while Triton, the largest of Neptune’s satellites, is a former member of the KBO population. Near-infrared spectra of Triton and Pluto were obtained over the previous 10+ years with the SpeX instrument at the IRTF and of Charon in Summer 2015 with the OSIRIS instrument at Keck. The Charon data were reduced by spectrophotometry using code that I wrote for this purpose. I present evidence of short-term volatile transport and the presence of the non-methane hydrocarbon ethane on Pluto and Triton, as well as uniform temperature and ammonia ice distributions on Charon. Based on previous laboratory work and the results of my analysis, I conclude that cryovolcanism is not necessary to explain the high percentage of crystalline water ice on Charon. The three “geologic” bodies, those previously visited by spacecraft, provide context for understanding the larger population of KBOs, the “astronomical” bodies that may never be visited by spacecraft. Observations of the geologic bodies can be used to better understand the atmospheric, surface, and interior processes on all KBOs through what I term “comparative KBOlogy.” Next-generation observatories, both in space and on the ground, will further contribute to our knowledge of the dominant processes that shape the surface evolution of KBOs
The Concreteness of The Invisible
The project commenced with the assumption that the manifested physical form of city (the one which we verify through common perception as objectivization of the idea of city) is a deception
Solar system science with the Wide-Field Infrared Survey Telescope
We present a community-led assessment of the solar system investigations achievable with NASA’s next-generation space telescope, the Wide Field Infrared Survey Telescope (WFIRST). WFIRST will provide imaging, spectroscopic, and coronagraphic capabilities from 0.43 to 2.0  μm and will be a potential contemporary and eventual successor to the James Webb Space Telescope (JWST). Surveys of irregular satellites and minor bodies are where WFIRST will excel with its 0.28  deg^2 field-of-view Wide Field Instrument. Potential ground-breaking discoveries from WFIRST could include detection of the first minor bodies orbiting in the inner Oort Cloud, identification of additional Earth Trojan asteroids, and the discovery and characterization of asteroid binary systems similar to Ida/Dactyl. Additional investigations into asteroids, giant planet satellites, Trojan asteroids, Centaurs, Kuiper belt objects, and comets are presented. Previous use of astrophysics assets for solar system science and synergies between WFIRST, Large Synoptic Survey Telescope, JWST, and the proposed Near-Earth Object Camera mission is discussed. We also present the case for implementation of moving target tracking, a feature that will benefit from the heritage of JWST and enable a broader range of solar system observations
Moderate D/H Ratios in Methane Ice on Eris and Makemake as Evidence of Hydrothermal or Metamorphic Processes in Their Interiors: Geochemical Analysis
Dwarf planets Eris and Makemake have surfaces bearing methane ice of unknown
origin. D/H ratios were recently determined from James Webb Space Telescope
(JWST) observations of Eris and Makemake (Grundy et al., submitted), giving us
new clues to decipher the origin of methane. Here, we develop geochemical
models to test if the origin of methane could be primordial, derived from
CO or CO ("abiotic"), or sourced by organics ("thermogenic"). We find that
primordial methane is inconsistent with the observational data, whereas both
abiotic and thermogenic methane can have D/H ratios that overlap the observed
ranges. This suggests that Eris and Makemake either never acquired a
significant amount of methane during their formation, or their original
inventories were removed and then replaced by a source of internally produced
methane. Because producing abiotic or thermogenic methane likely requires
temperatures in excess of ~150{\deg}C, we infer that Eris and Makemake have
rocky cores that underwent substantial radiogenic heating. Their cores may
still be warm/hot enough to produce methane. This heating could have driven
hydrothermal circulation at the bottom of an ice-covered ocean to generate
abiotic methane, and/or metamorphic reactions involving accreted organic matter
could have occurred in response to heating in the deeper interior, generating
thermogenic methane. Additional analyses of thermal evolution model results and
predictions from modeling of D-H exchange in the solar nebula support our
findings of elevated subsurface temperatures and a lack of primordial methane
on Eris and Makemake. It remains an open question whether their D/H ratios may
have evolved subsequent to methane outgassing. Recommendations are given for
future activities to further test proposed scenarios of abiotic and thermogenic
methane production on Eris and Makemake, and to explore these worlds up close.Comment: Submitted to Icarus, 29 pages, 5 figures, 1 tabl
Astro2020 Science White Paper: Triggered High-Priority Observations of Dynamic Solar System Phenomena
Unexpected dynamic phenomena have surprised solar system observers in the
past and have led to important discoveries about solar system workings.
Observations at the initial stages of these events provide crucial information
on the physical processes at work. We advocate for long-term/permanent programs
on ground-based and space-based telescopes of all sizes - including Extremely
Large Telescopes (ELTs) - to conduct observations of high-priority dynamic
phenomena, based on a predefined set of triggering conditions. These programs
will ensure that the best initial dataset of the triggering event are taken;
separate additional observing programs will be required to study the temporal
evolution of these phenomena. While not a comprehensive list, the following are
notional examples of phenomena that are rare, that cannot be anticipated, and
that provide high-impact advances to our understandings of planetary processes.
Examples include: new cryovolcanic eruptions or plumes on ocean worlds; impacts
on Jupiter, Saturn, Uranus, or Neptune; extreme eruptions on Io; convective
superstorms on Saturn, Uranus, or Neptune; collisions within the asteroid belt
or other small-body populations; discovery of an interstellar object passing
through our solar system (e.g. 'Oumuamua); and responses of planetary
atmospheres to major solar flares or coronal mass ejections.Comment: Astro2020 white pape
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