J. E. Colwell
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View article: Opaque Expanses in Saturn’s B ring
Opaque Expanses in Saturn’s B ring Open
Stellar occultation measurements of Saturn’s rings from the Cassini Ultraviolet Imaging Spectrograph (UVIS) High Speed Photometer (HSP) reveal dozens of regions in the heart of the B ring that are opaque at the sensitivity level of the mea…
View article: A Comparison of Orbital Phase-Resolved Mesoscale Structure and Particle Sizes in the Narrow and Eccentric Rings of Saturn and Uranus
A Comparison of Orbital Phase-Resolved Mesoscale Structure and Particle Sizes in the Narrow and Eccentric Rings of Saturn and Uranus Open
We present a comparative occultation analysis of narrow, eccentric ringlets in the Saturnian and Uranian ring systems, focusing on how mesoscale structure and particle size distributions vary with orbital phase (true anomaly). Our study co…
View article: High-level environmental sustainability guidelines for large accelerator facilities
High-level environmental sustainability guidelines for large accelerator facilities Open
The proposed construction of new particle accelerator-based facilities in the coming decades -- and upgrades to existing facilities -- provides the unique opportunity to embed innovative environmental impact reduction techniques into their…
View article: How Predator-Prey Dynamics Creates ‘Straw’ in the Strongest Density Waves
How Predator-Prey Dynamics Creates ‘Straw’ in the Strongest Density Waves Open
<p>The Cassini cameras detected elongated structures in Saturn&#8217;s ring in highly perturbed regions near ring edges and within the strongest density waves. These &#8216;straw&#8217; features are likely triggered by th…
View article: Low-speed Impacts into Ice–Dust Granular Mixtures
Low-speed Impacts into Ice–Dust Granular Mixtures Open
We present the results of a series of laboratory low-speed impacts (< 4 m s −1 ) of centimeter-sized spherical projectiles into simulated dry and icy regolith samples. The target material was comprised of JSC-1 (Johnson Space Center) lunar…
View article: Shape and compression of self-gravity wakes in Saturn&#8217;s rings
Shape and compression of self-gravity wakes in Saturn’s rings Open
<p>The varying geometry of Cassini star occultations by Saturn&#8217;s rings constrains both the size and shape of structures that block starlight. Statistics of UVIS star occultations measure structures as small as meters, on ti…
View article: Stick-slip Dynamics in Penetration Experiments on Simulated Regolith
Stick-slip Dynamics in Penetration Experiments on Simulated Regolith Open
The surfaces of many planetary bodies, including asteroids and small moons, are covered with dust to pebble-sized regolith held weakly to the surface by gravity and contact forces. Understanding the reaction of regolith to an external pert…
View article: Characterizing self-gravity wake morphology in Saturn&#8217;s rings from Cassini UVIS stellar occultation statistics
Characterizing self-gravity wake morphology in Saturn’s rings from Cassini UVIS stellar occultation statistics Open
 Cassini’s Ultraviolet Imaging Spectrograph (UVIS) observed 276 stellar occultations of Saturn’s rings over the course of its mission. During these occultations, UVIS’ High-Speed Photometer (HSP) collected photon cou…
View article: Phantoms in the Dark: Mesoscale Openings in the Core of Saturn&#8217;s B Ring
Phantoms in the Dark: Mesoscale Openings in the Core of Saturn’s B Ring Open
The Cassini Ultraviolet Imaging Spectrograph (UVIS) High Speed Photometer (HSP) observed 15 occultation traces of the bright star Hadar (Beta Centauri) in 2008-2009 at an elevation above the ring plane of 66.7 degrees. The combination of t…
View article: Flattening of ring particles and self-gravity wakes in Saturn&#8217;s rings
Flattening of ring particles and self-gravity wakes in Saturn’s rings Open
The varying geometry of Cassini star occultations by Saturn’s rings constrains both the size and shape of structures that block starlight. Statistics of UVIS star occultations measure structures as small as meters, on times scales of…
View article: Friedrich Christoph Mayer and his theory of the aurora borealis
Friedrich Christoph Mayer and his theory of the aurora borealis Open
The eleventh volume in the series presents two articles on the aurora borealis by Friedrich Christoph Mayer (1697–1729), a mathematician at the Imperial Academy of Sciences in Saint Petersburg. The first paper, titled “De Luce Boreali” (On…
View article: Architectures and Technologies for a Space Telescope for Solar System Science
Architectures and Technologies for a Space Telescope for Solar System Science Open
We advocate for a mission concept study for a space telescope dedicated to solar system science in Earth orbit. Such a study was recommended by the Committee on Astrobiology and Planetary Science (CAPS) report "Getting Ready for the Next P…
View article: The science enabled by a dedicated solar system space telescope
The science enabled by a dedicated solar system space telescope Open
The National Academy Committee on Astrobiology and Planetary Science (CAPS) made a recommendation to study a large/medium-class dedicated space telescope for planetary science, going beyond the Discovery-class dedicated planetary space tel…
View article: Frontiers in Planetary Rings Science
Frontiers in Planetary Rings Science Open
We now know that the outer solar system is host to at least six diverse planetary ring systems, each of which is a scientifically compelling target with the potential to inform us about the evolution, history and even the internal structur…
View article: Flattening of ring particles and self-gravity wakes in Saturn&#8217;s rings
Flattening of ring particles and self-gravity wakes in Saturn’s rings Open
<p>The varying geometry of Cassini star occultations by Saturn&#8217;s rings constrains both the size and shape of structures that block starlight. Statistics of UVIS star occultations measure structures as small as meters, on ti…
View article: Probing regolith-covered surfaces in low gravity
Probing regolith-covered surfaces in low gravity Open
The surfaces of many planetary bodies, including asteroids, moons, and planets, are composed of rubble-like grains held together by varying levels of gravitational attraction and cohesive forces. Future instrumentation for operation on, an…
View article: The Adhesive Response of Regolith to Low-Energy Disturbances in Microgravity
The Adhesive Response of Regolith to Low-Energy Disturbances in Microgravity Open
Small, airless bodies are covered by a layer of regolith composed of particles ranging from μm-size dust to cm-size pebbles that evolve under conditions very different than those on Earth. Flight-based microgravity experiments investigatin…
View article: Frontiers in Planetary Rings ScienceA Science White Paper for the Planetary Science and Astrobiology Decadal Survey 2023-2032
Frontiers in Planetary Rings ScienceA Science White Paper for the Planetary Science and Astrobiology Decadal Survey 2023-2032 Open
A Science White Paper for the Planetary Science and Astrobiology Decadal Survey 2023-2032
View article: Probe-insertion exhibits gravity-dependent stick-slip dynamics in experiments on a model system for regolith surfaces
Probe-insertion exhibits gravity-dependent stick-slip dynamics in experiments on a model system for regolith surfaces Open
The surfaces of many planetary bodies, including asteroids and small moons, are covered with dust to pebble-sized grains held weakly to the surface by gravity and contact forces. The Hayabusa2 and OSIRIS-REx missions have both confirmed th…
View article: Gravity-dependent stick-slip dynamics in penetration experiments on simulated regolith
Gravity-dependent stick-slip dynamics in penetration experiments on simulated regolith Open
The surfaces of many planetary bodies, including asteroids and small moons, are covered with dust to pebble-sized regolith held weakly to the surface by gravity and contact forces. Understanding the reaction of regolith to an external pert…
View article: Stick-slip dynamics in penetration experiments on simulated regolith
Stick-slip dynamics in penetration experiments on simulated regolith Open
The surfaces of many planetary bodies, including asteroids and small moons, are covered with dust to pebble-sized regolith held weakly to the surface by gravity and contact forces. Understanding the reaction of regolith to an external pert…
View article: Identifying and Characterizing Local Gaps in Saturn&#8217;s Rings from Skewness of Cassini UVIS Stellar Occultation Data
Identifying and Characterizing Local Gaps in Saturn’s Rings from Skewness of Cassini UVIS Stellar Occultation Data Open
The Ultraviolet Imaging Spectrograph (UVIS) high-speed photometer (HSP) aboard the Cassini spacecraft collected stellar occultation data for stars of various brightness and viewing geometries as they were occulted by Saturn’s rings. …
View article: Sizes of Particles, Clumps, and Gaps Within the Strong Janus 2:1 and Mimas 5:3 Density Waves from Cassini UVIS Stellar Occultation Data Statistics
Sizes of Particles, Clumps, and Gaps Within the Strong Janus 2:1 and Mimas 5:3 Density Waves from Cassini UVIS Stellar Occultation Data Statistics Open
The high-speed photometer of Cassini’s Ultraviolet Imaging Spectrograph (UVIS) collected data from stellar occultations across Saturn’s rings at unprecedented high resolution over a wide range of viewing geometries. Because pho…