ALMA Thermal Observations of Europa

Trumbo, Samantha K.; Brown, Michael E.; Butler, B. J.

doi:10.3847/1538-3881/aada87

Cited by 24 publications

(46 citation statements)

References 36 publications

(71 reference statements)

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“…One-dimensional thermophysical modeling allows the simulation of daily surface temperature cycles based on the orbital characteristics and surface properties of an object, such as albedo, thermal inertia, emissivity, etc. (e.g., Spencer et al, 1999;Trumbo et al, 2017Trumbo et al, , 2018. This allows for the determination of simulated surface temperatures over a complete orbit, and therefore, a first-order approximation of the spatially-dependent average surface temperatures over long timescales.…”

Section: Integrated Band Area Ratiosmentioning

confidence: 99%

“…ICICLE employs an adaptation of a 1D numerical thermophysical model for airless bodies (Spencer et al, 1989) that has been adjusted to reflect orbital characteristics of Europa and environmental and surface conditions of its leading hemisphere. Spatially varying thermal inertia, emissivity, and albedo values employed are those presented in Figure 3 of Trumbo et al (2018). Their albedo values at a 0.5°latitude-longitude spatial resolution were extrapolated from albedo measurements made by Voyager, and their thermal inertia and emissivity values were derived via modeling at a 3°l atitude-longitude spatial resolution based on four 233 GHz (1.3 mm) observations acquired with the Atacama Large Millimeter Array (ALMA).…”

Section: Integrated Band Area Ratiosmentioning

confidence: 99%

“…We include uncertainties in thermal inertia, emissivity, and albedo of ±5%, ±5%, and ±0.03, respectively. We produce latitudinal averages at each longitude to latitudinally extend the thermal inertia and emissivity data beyond those presented in Trumbo et al (2018) in order to obtain approximate values for those higher latitude locations for which there were no observations. We also resampled the albedo data from a 0.5°spatial resolution to a 3°spatial resolution in order to match the spatial sampling of the thermal inertia and emissivity data.…”

Section: Integrated Band Area Ratiosmentioning

confidence: 99%

“…We computed a projection area-weighted average of the crystallinity at each model gridpoint to derive a full-disk crystallinity (case 1) of the leading hemisphere as viewed from Earth to compare with the full-disk crystallinities derived from ground-based spectroscopic observations and laboratory spectra, as discussed in §2. For extended thermal inertia and emissivity data that were computed from latitudinal averages of the data derived in Trumbo et al (2018), we Filled TI/e with T=T−3 K 83.0 ± 13.3 % 8…”

Section: Integrated Band Area Ratiosmentioning

confidence: 99%

“…One-dimensional thermophysical modeling allows the simulation of surface temperature cycles based on the orbital characteristics and surface properties of an object, such as albedo, thermal inertia, emissivity, etc. (e.g., Spencer et al, 1999;Rathbun et al, 2010;Trumbo et al, 2017Trumbo et al, , 2018. Baragiola et al (2013) Baragiola et al (2013).…”

Section: Introductionmentioning

confidence: 99%

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Europa’s surface water ice crystallinity: Discrepancy between observations and thermophysical and particle flux modeling

Berdis

Gudipati

Murphy

et al. 2020

Icarus

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Physical processing of Europan surface water ice by thermal relaxation, charged particle bombardment, and possible cryovolcanic activity can alter the percentage of the crystalline form of water ice compared to that of the amorphous form of water ice (the "crystallinity") on Europa's surface. The timescales over which amorphous water ice is thermally transformed to crystalline water ice at Europan surface temperatures (80-130 K) suggests that the water ice there should be primarily in the crystalline form, however, surface bombardment by charged particles induced by Jupiter's magnetic field, and vapor deposition of water ice from Europan plumes, can produce amorphous water ice surface deposits on short timescales.The purpose of this investigation is to determine whether the Europan surface water ice crystallinity derived from ground-based spectroscopic measurements is in agreement with the crystallinity expected based upon temperature and radiation modeling. Using a 1D thermophysical model of Europa's surface, we calculate an integrated full-disk crystallinity of Europa's leading hemisphere by incorporating the thermal relaxation of amorphous to crystalline water ice and the degradation of crystalline to amorphous water ice by irradiation. Concurrently, we derive the full-disk crystallinity of Europa's leading hemisphere using a comparison of near-infrared ground-based spectral observations from Grundy et al. (1999), Busarev et al. (2018), and the Apache Point Observatory in Sunspot, NM, with laboratory spectra from Mastrapa et al. (2008) and the Ice Spectroscopy Lab at the Jet PropulsionLaboratory. We calculate a modeled crystallinity significantly higher than crystallinities derived from ground-based observations and laboratory spectra. This discrepancy may be a result of geophysical processes, such as by vapor-deposited plume material, or it may arise 1 arXiv:2002.04132v1 [astro-ph.EP] 10 Feb 2020 from assumptions and uncertainties in the crystallinity calculations.

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Section: Integrated Band Area Ratiosmentioning

confidence: 99%

Section: Integrated Band Area Ratiosmentioning

confidence: 99%

Section: Integrated Band Area Ratiosmentioning

confidence: 99%

Section: Integrated Band Area Ratiosmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Europa’s surface water ice crystallinity: Discrepancy between observations and thermophysical and particle flux modeling

Berdis

Gudipati

Murphy

et al. 2020

Icarus

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The Origin and Fate of O 2 $\mbox{O}_{2}$ in Europa’s Ice: An Atmospheric Perspective

et al. 2019

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The early prediction and subsequent detection of an O 2 atmosphere on Europa, coupled with the discovery that Europa has an ocean under its ice mantle, has made this moon a prime astrobiologic target, soon to be visited by the JUICE and Europa Clipper spacecraft. In spite of the considerable number of observational, modeling, and laboratory efforts, understanding the physics leading to the observed morphology of Europa's nearsurface O 2 atmosphere has been problematic. This is the case as the observed emissions depend on the local incident plasma ion flux, the local temperature and composition of the regolith, as well as on the near-surface electron temperature and density. Here we rely heavily on earlier reviews briefly summarizing the observational, laboratory and simulation efforts. Although it is agreed that radiolysis of the surface ice by the incident Jovian plasma is the ultimate source of observed O 2 , a recent, simple model of thermal desorption from a regolith permeated with O 2 has changed the usual paradigm. In that model, the observed orbital dependence of the local source of the near-surface O 2 atmosphere is suggested to be due to the release of O 2 likely trapped on the ice grains at dangling bonds by the solar flux with a smaller contribution due to direct sputtering. This assumes that Europa's icy regolith is permeated with trapped O 2 , which could also affect our understanding of the suggestion that the radiolytic products in Europa's regolith might be a source of oxidants for its underground ocean.

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Planned Geological Investigations of the Europa Clipper Mission

Daubar,

Hayes,

Collins

et al. 2024

Space Sci Rev

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Geological investigations planned for the Europa Clipper mission will examine the formation, evolution, and expression of geomorphic structures found on the surface. Understanding geologic features, their formation, and any recent activity are key inputs in constraining Europa’s potential for habitability. In addition to providing information about the moon’s habitability, the geologic study of Europa is compelling in and of itself. Here we provide a high-level, cross-instrument, and cross-discipline overview of the geologic investigations planned within the Europa Clipper mission. Europa’s fascinating collection of ice-focused geology provides an unparalleled opportunity to investigate the dynamics of icy shells, ice-ocean exchange processes, and global-scale tectonic and tidal stresses. We present an overview of what is currently known about the geology of Europa, from global to local scales, highlighting outstanding issues and open questions, and detailing how the Europa Clipper mission will address them. We describe the mission’s strategy for searching for and characterizing current activity in the form of possible active plumes, thermal anomalies, evidence for surface changes, and extremely fresh surface exposures. The complementary and synergistic nature of the data sets from the various instruments and their integration will be key to significantly advancing our understanding of Europa’s geology.

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ALMA Thermal Observations of Europa

Cited by 24 publications

References 36 publications

Europa’s surface water ice crystallinity: Discrepancy between observations and thermophysical and particle flux modeling

Europa’s surface water ice crystallinity: Discrepancy between observations and thermophysical and particle flux modeling

The Origin and Fate of O 2 $\mbox{O}_{2}$ in Europa’s Ice: An Atmospheric Perspective

Planned Geological Investigations of the Europa Clipper Mission

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