J. R. Spencer
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View article: Prospects of a New <i>L</i> <sub>5</sub> Trojan Flyby Target for the Lucy Mission
Prospects of a New <i>L</i> <sub>5</sub> Trojan Flyby Target for the Lucy Mission Open
NASA’s Lucy spacecraft is en route to conduct the first close encounter with Jupiter’s Trojans. While most scheduled flybys lie in the L 4 cloud, the only L 5 target is the Patroclus–Menoetius binary. Since each flyby offers unique insight…
View article: Plume Activity on Europa: Current Knowledge and Search Strategy for Europa Clipper
Plume Activity on Europa: Current Knowledge and Search Strategy for Europa Clipper Open
The presence of cryovolcanic activity in the form of geyser-like plumes at Jupiter’s moon Europa is a much-debated topic. As an active plume could allow direct sampling by a passing spacecraft of a potentially habitable interior environmen…
View article: Pit Chains on Asteroid (52246) Donaldjohanson
Pit Chains on Asteroid (52246) Donaldjohanson Open
On April 20, 2025, NASA’s Lucy spacecraft [1] completed its closest approach with main-belt asteroid (52246) Donaldjohanson [2]. Donaldjohanson appears to be a contact binary and is about 8 km long with a greater than 2 to 1 axis ratio [3]…
View article: Shape Reconstruction and Rotation State of Asteroid (52246) Donaldjohanson from Lucy Imaging and Ground-Based Photometry
Shape Reconstruction and Rotation State of Asteroid (52246) Donaldjohanson from Lucy Imaging and Ground-Based Photometry Open
On April 20, 2025, while crossing the Main Asteroid Belt, the NASA Lucy mission—en route to the Jupiter Trojan regions—encountered its second cruise target, the C-type asteroid (52246) Donaldjohanson.During the fly-by, the L’LORRI instrume…
View article: Europa Thermal Emission Imaging System (E-THEMIS) cruise observations of Mars
Europa Thermal Emission Imaging System (E-THEMIS) cruise observations of Mars Open
The Europa Thermal Emission Imaging System (E-THEMIS) on the Europa Clipper spacecraft will investigate the temperature and physical properties of Europa using thermal infrared images in three wavelength bands at 7-14 µm, 14-28 µm and 28-7…
View article: Interior and gravity characterization of the C-type asteroid (52246) Donaldjohanson seen by NASA’s Lucy flyby
Interior and gravity characterization of the C-type asteroid (52246) Donaldjohanson seen by NASA’s Lucy flyby Open
NASA’s Lucy [1] successfully flew by the C-type asteroid (52246) Donaldjohanson [2] on April 20, 2025 [3]. The asteroid exhibited unique topographic and geological features [4-6]. While the imaged area was limited to the illuminated hemisp…
View article: The Lucy Encounter with asteroid (52246) Donaldjohanson - An Overview
The Lucy Encounter with asteroid (52246) Donaldjohanson - An Overview Open
On April 20, 2025 NASA's Lucy mission performed a flyby of the main belt asteroid (52246) Donaldjohanson, hereafter DJ. Lucy is a NASA Discovery-class mission to study primitive bodies near both the L4 and L5 Lagrange points with Jupiter -…
View article: Phyllosilicates on Donaldjohanson as seen from the Lucy Flyby
Phyllosilicates on Donaldjohanson as seen from the Lucy Flyby Open
NASA’s Lucy mission [1] successfully completed a flyby encounter with the main-belt asteroid (52246) Donaldjohanson on April 20, 2025, collecting data as part of a full-scale operational test for Lucy’s future Trojan encounters. Donaldjoha…
View article: Compositional analysis of (52246) Donaldjohanson from the Lucy flyby
Compositional analysis of (52246) Donaldjohanson from the Lucy flyby Open
The NASA Lucy mission was designed to provide the first reconnaissance of Jupiter Trojan asteroids. These primitive bodies hold important clues to the origin and evolution of the Solar System. The Lucy spacecraft is currently en route to i…
View article: Lightcurve of Asteroid (52246)Donaldjohanson from the Lucy Spacecraft’s Observations
Lightcurve of Asteroid (52246)Donaldjohanson from the Lucy Spacecraft’s Observations Open
The Lucy Mission is a NASA Discovery class mission to study the Trojan asteroids. Its targets are the asteroids Eurybates (Aug. 2027), Polymele (Sep. 2027), Leucus (Apr. 2028), Orus (Nov. 2028) and the Patroclus – Menoetius binary (Mar. 20…
View article: Albedo Features on (52246) Donaldjohanson, from Lucy L’LORRI Observations
Albedo Features on (52246) Donaldjohanson, from Lucy L’LORRI Observations Open
During its April 20th 2025 flyby of the approximately 8 km long C-type asteroid (52246) Donaldjohanson, the Lucy spacecraft obtained several hundred spatially resolved images of the target with the panchromatic Lucy Long Range Reconnaissan…
View article: NASA’S Lucy Mission to Trojan Asteroids: Unraveling the History of the Outer Solar System
NASA’S Lucy Mission to Trojan Asteroids: Unraveling the History of the Outer Solar System Open
Lucy is a NASA Discovery-class mission to send a highly capable and robust spacecraft to investigate primitive bodies near both the L4 and L5 Lagrange points with Jupiter; the Jupiter Trojan asteroids. This heretofore unexplored population…
View article: Thermal-IR Observations of (152830) Dinkinesh during the Lucy Mission Flyby
Thermal-IR Observations of (152830) Dinkinesh during the Lucy Mission Flyby Open
NASA’s Lucy spacecraft flew by the main-belt asteroid (152830) Dinkinesh on 2023 November 1, providing a test of its instruments and systems prior to its encounters with the Jupiter Trojans and enabling an opportunity for scientific invest…
View article: Lucy Mission Search Plans for Activity around Its Jovian Trojan Flyby Targets
Lucy Mission Search Plans for Activity around Its Jovian Trojan Flyby Targets Open
Activity in small bodies, defined here as the episodic or continuous release of material, was long thought to be exclusively a behavior of comets, but it has since been discovered in some centaurs, main-belt asteroids, and near-Earth aster…
View article: A Demonstration of Interstellar Navigation Using New Horizons
A Demonstration of Interstellar Navigation Using New Horizons Open
As NASA’s New Horizons spacecraft exits the solar system bound for interstellar space, it has traveled so far that the nearest stars have shifted markedly from their positions seen from Earth. We demonstrated this by imaging the Proxima Ce…
View article: A Demonstration of Interstellar Navigation Using New Horizons
A Demonstration of Interstellar Navigation Using New Horizons Open
As NASA's New Horizons spacecraft exits the Solar System bound for interstellar space, it has traveled so far that the nearest stars have shifted markedly from their positions seen from Earth. We demonstrated this by imaging the Proxima Ce…
View article: Beneath the Shell: Managing Ocular Surface Health of a No Light Perception Eye with a Prosthetic Shell
Beneath the Shell: Managing Ocular Surface Health of a No Light Perception Eye with a Prosthetic Shell Open
Patients with a non-seeing eye and an intact globe may experience secondary psychological trauma due to cosmetic concerns as well as potential social ramifications. A prosthetic scleral shell fit over the intact, scarred globe is an import…
View article: Comparing NASA Discovery and New Frontiers Class Mission Concepts for the Io Volcano Observer
Comparing NASA Discovery and New Frontiers Class Mission Concepts for the Io Volcano Observer Open
Jupiter’s moon Io is a highly compelling target for future exploration that offers critical insight into tidal dissipation processes and the geology of high heat flux worlds, including primitive planetary bodies, such as the early Earth, t…
View article: Thermal Infrared Spectra of the Moon: Results From the Lucy Thermal Emission Spectrometer Observations
Thermal Infrared Spectra of the Moon: Results From the Lucy Thermal Emission Spectrometer Observations Open
The Lucy Thermal Emission Spectrometer (L’TES) instrument acquired hyperspectral thermal infrared (TIR) observations of the Earth's Moon during Lucy's 2022 Earth gravity assist. L’TES covers the spectral range of 100–1,750 cm −1 (100–5.8 μ…
View article: The Ly<i>α</i> Sky as Observed by New Horizons at 57 au
The Ly<i>α</i> Sky as Observed by New Horizons at 57 au Open
During 2023 September the Alice ultraviolet spectrograph on the New Horizons (NH) spacecraft was used to map diffuse Lyα emission over most of the sky, at a range of ∼56.9 au from the Sun. At that distance, models predict that the interpla…
View article: Crater Dimensions on the Dwarf Planets
Crater Dimensions on the Dwarf Planets Open
The icy dwarf planets of Pluto, Charon, and Ceres provide important geologic comparisons for each other as they possess similar gravities and experience impacts of similar velocities compared to larger planets and moons. Differences in the…
View article: Lucy L′Ralph In-flight Calibration and Results at (152830) Dinkinesh
Lucy L′Ralph In-flight Calibration and Results at (152830) Dinkinesh Open
The L’Ralph instrument is a key component of NASA’s Lucy mission, intended to provide spectral image data of multiple Jupiter Trojans. The instrument operates from ∼0.35 to 4 μ m using two focal plane assemblies: a 350–950 nm multispectral…
View article: Observations of Uranus at High Phase Angle as Seen by New Horizons
Observations of Uranus at High Phase Angle as Seen by New Horizons Open
We present flux measurements of Uranus observed at phase angles of 43.°9, 44.°0, and 52.°4 by the Multispectral Visible Imaging Camera on the New Horizons spacecraft during 2023, 2010, and 2019, respectively. New Horizons imaged Uranus at …
View article: Novel pathways for headache via neurology same day emergency care: admission avoidance, prevention of lumbar punctures and reduced length of stay in hospital
Novel pathways for headache via neurology same day emergency care: admission avoidance, prevention of lumbar punctures and reduced length of stay in hospital Open
There are various models for acute neurology services in the UK, with considerable variation in practice. Patients are often admitted unnecessarily for neurology review, leading to delay in diagnosis and treatment. Alternative models, such…
View article: The New Horizons Extended Mission Target: Arrokoth Search and Discovery
The New Horizons Extended Mission Target: Arrokoth Search and Discovery Open
Following the Pluto flyby of the New Horizons spacecraft, the mission provided a unique opportunity to explore the Kuiper Belt in situ. The possibility existed to fly by a Kuiper Belt object (KBO), as well as to observe additional objects …
View article: New Synoptic Observations of the Cosmic Optical Background with New Horizons
New Synoptic Observations of the Cosmic Optical Background with New Horizons Open
We obtained New Horizons LORRI images to measure the cosmic optical background (COB) intensity integrated over 0.4 μ m ≲ λ ≲ 0.9 μ m. The survey comprises 16 high-Galactic-latitude fields selected to minimize scattered diffuse Galactic lig…
View article: Comparing NASA Discovery and New Frontiers Class Mission Concepts for the Io Volcano Observer (IVO)
Comparing NASA Discovery and New Frontiers Class Mission Concepts for the Io Volcano Observer (IVO) Open
Jupiter's moon Io is a highly compelling target for future exploration that offers critical insight into tidal dissipation processes and the geology of high heat flux worlds, including primitive planetary bodies, such as the early Earth, t…
View article: New Synoptic Observations of the Cosmic Optical Background with New Horizons
New Synoptic Observations of the Cosmic Optical Background with New Horizons Open
We obtained New Horizons LORRI images to measure the cosmic optical background (COB) intensity integrated over $0.4\lesssimλ\lesssim0.9{~\rmμm}.$ The survey comprises 16 high Galactic-latitude fields selected to minimize scattered diffuse …
View article: Constraining Enceladus' Endogenic Emission
Constraining Enceladus' Endogenic Emission Open
Introduction: Enceladus’ activity is concentrated across its south polar terrain (SPT). The activity is concentrated along four fractures dubbed tiger stripes. Constraining the magnitude of the endogenic emission from this region has…
View article: The Dynamical State of the Dinkinesh - Selam Binary
The Dynamical State of the Dinkinesh - Selam Binary Open
The Lucy spacecraft encountered the Main Belt asteroid (152830) Dinkinesh on 01 November 2023 revealing it to be a binary system with a first-of-its-kind contact binary secondary, now named Selam. However, despite the novelty of Selam̵…