Joshua A. Kammer
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View article: In situ and remote observations of the ultraviolet footprint of the moon Callisto by the Juno spacecraft
In situ and remote observations of the ultraviolet footprint of the moon Callisto by the Juno spacecraft Open
View article: Space Telescope Imaging Spectrograph Observations of Europa’s Optical Aurora
Space Telescope Imaging Spectrograph Observations of Europa’s Optical Aurora Open
We analyzed Hubble Space Telescope observations of Europa’s optical aurora, yielding further insight into the composition of its tenuous atmosphere and its plasma-interaction variability. We obtained these observations of auroral emissions…
View article: Europa-UVS Commissioning and In-Flight Calibration Results and Plans Ahead with Europa Clipper
Europa-UVS Commissioning and In-Flight Calibration Results and Plans Ahead with Europa Clipper Open
The Europa Clipper mission launched on 14 October 2024, and includes the Europa Ultraviolet Spectrograph (Europa-UVS) instrument. Europa-UVS’s science goals are focused on Europa habitability goals, specifically: 1) Search for and characte…
View article: Investigating Europa’s Atmosphere: Hubble Space Telescope Analysis and Europa-UVS Stellar Occultation Preparations
Investigating Europa’s Atmosphere: Hubble Space Telescope Analysis and Europa-UVS Stellar Occultation Preparations Open
Europa’s tenuous atmosphere remains poorly constrained to this day. It is primarily composed of O2 with a concentration of H2O near the subsolar point when the trailing hemisphere is illuminated and surrounded by an extended neutral cloud …
View article: Ocean-sourced CO2 inflates radiolytic H2O2 at Europa’s Chaos
Ocean-sourced CO2 inflates radiolytic H2O2 at Europa’s Chaos Open
JWST observations of Europa's leading hemisphere show excess CO2 over chaos terrains [1, 2] where the subsurface ocean is likely to have breached the ice shell. Analysis of the 3.5-µm hydrogen peroxide (H2O2) absorption band reveals elevat…
View article: Jupiter's UV Auroral Response to a Magnetospheric Compression Event
Jupiter's UV Auroral Response to a Magnetospheric Compression Event Open
The highly elliptical polar orbit of the Juno mission provides a unique opportunity to simultaneously measure the compression state of Jupiter's magnetosphere and the total power emitted by the planet's ultraviolet aurora, using a single s…
View article: Jupiter's UV auroral response to a magnetospheric compression event
Jupiter's UV auroral response to a magnetospheric compression event Open
The highly elliptical polar orbit of the Juno mission provides a unique opportunity to simultaneously measure the compression state of Jupiter's magnetosphere and the total power emitted by the planet's ultraviolet aurora, using a single s…
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: Electron Densities in Jupiter's Upper Ionosphere Inferred From Juno Plasma Wave Observations
Electron Densities in Jupiter's Upper Ionosphere Inferred From Juno Plasma Wave Observations Open
Juno's highly eccentric polar orbit takes it to perijove distances of 1.06 on each orbit. For the first perijove, this occurred just north of the jovigraphic equator, but has precessed north by about a degree per orbit over the mission. Mi…
View article: Electron Densities in Jupiter's Upper Ionosphere Inferred from Juno Plasma Wave Observations
Electron Densities in Jupiter's Upper Ionosphere Inferred from Juno Plasma Wave Observations Open
View article: Europa Ultraviolet Spectrograph (Europa-UVS)
Europa Ultraviolet Spectrograph (Europa-UVS) Open
View article: Jupiter's Auroral Ionosphere: Juno Microwave Radiometer Observations of Energetic Electron Precipitation Events
Jupiter's Auroral Ionosphere: Juno Microwave Radiometer Observations of Energetic Electron Precipitation Events Open
View article: Europa-UVS at One Month Prior to Europa Clipper Launch
Europa-UVS at One Month Prior to Europa Clipper Launch Open
The Europa Clipper mission will launch in October 2024. The Europa Ultraviolet Spectrograph (Europa-UVS) instrument science goals are focused on Europa habitability goals, specifically: 1) Search for and characterize the vapor composition …
View article: Catalog of Ultraviolet Bright Stars: Strategies for UV Occultation Measurements, Planetary Illumination Modeling, and Sky Map Analyses Using Hybrid IUE-Kurucz Spectra
Catalog of Ultraviolet Bright Stars: Strategies for UV Occultation Measurements, Planetary Illumination Modeling, and Sky Map Analyses Using Hybrid IUE-Kurucz Spectra Open
Ultraviolet spectroscopy is a powerful method to study planetary surface composition through reflectance measurements, atmospheric composition through stellar/solar occultations, transits of other planetary bodies, and direct imaging of ai…
View article: Juno-UVS Observations of Io during the PJ58 Flyby
Juno-UVS Observations of Io during the PJ58 Flyby Open
Currently in its first extended mission, NASA’s Juno spacecraft has made several close approaches to Jupiter’s Galilean satellites. The final of these very close flybys will be of Io during the perijove (PJ) 58 orbit, sch…
View article: Investigating Europa’s Radiation Environment with the Europa Clipper Radiation Monitor
Investigating Europa’s Radiation Environment with the Europa Clipper Radiation Monitor Open
We present an overview of the radiation environment monitoring program planned for the Europa Clipper mission. The harsh radiation environment of Jupiter will be measured by a dedicated Radiation Monitor (RadMon) subsystem, yielding missio…
View article: The Io, Europa, and Ganymede Auroral Footprints at Jupiter in the Ultraviolet: Positions and Equatorial Lead Angles
The Io, Europa, and Ganymede Auroral Footprints at Jupiter in the Ultraviolet: Positions and Equatorial Lead Angles Open
Jupiter's satellite auroral footprints are a consequence of the interaction between the Jovian magnetic field with co‐rotating iogenic plasma and the Galilean moons. The disturbances created near the moons propagate as Alfvén waves along t…
View article: The Io, Europa and Ganymede auroral footprints at Jupiter in the ultraviolet: positions and equatorial lead angles
The Io, Europa and Ganymede auroral footprints at Jupiter in the ultraviolet: positions and equatorial lead angles Open
Jupiter's satellite auroral footprints are a consequence of the interaction between the Jovian magnetic field with co-rotating iogenic plasma and the Galilean moons. The disturbances created near the moons propagate as Alfvén waves along t…
View article: Enhanced C$_2$H$_2$ absorption within Jupiter's southern auroral oval from Juno UVS observations
Enhanced C$_2$H$_2$ absorption within Jupiter's southern auroral oval from Juno UVS observations Open
Reflected sunlight observations from the Ultraviolet Spectrograph (UVS) on the Juno spacecraft were used to study the distribution of acetylene (C$_2$H$_2$) at Jupiter's south pole. We find that the shape of the C$_2$H$_2$ absorption featu…
View article: Enhanced C<sub>2</sub>H<sub>2</sub> Absorption Within Jupiter's Southern Auroral Oval From Juno UVS Observations
Enhanced C<sub>2</sub>H<sub>2</sub> Absorption Within Jupiter's Southern Auroral Oval From Juno UVS Observations Open
Reflected sunlight observations from the Ultraviolet Spectrograph (UVS) on the Juno spacecraft were used to study the distribution of acetylene (C 2 H 2 ) at Jupiter's south pole. We find that the shape of the C 2 H 2 absorption feature va…
View article: Ganymede's UV Reflectance From Juno‐UVS Data
Ganymede's UV Reflectance From Juno‐UVS Data Open
During the Juno orbit 34 Ganymede encounter, the ultraviolet spectrograph mapped UV sunlight reflected by Ganymede from a closest approach altitude of 1,044 km, allowing us to study spatial variations in Ganymede's far ultraviolet reflecta…
View article: UVS Observations of Ganymede's Aurora During Juno Orbits 34 and 35
UVS Observations of Ganymede's Aurora During Juno Orbits 34 and 35 Open
On 7 June 2021, Juno‐UVS mapped Ganymede's auroral emissions near a closest approach altitude of 1,046 km. The high spatial resolution map exhibits bright, 200–1,000 R, oxygen emissions organized into northern and southern auroral ovals. T…
View article: Charon’s refractory factory
Charon’s refractory factory Open
We combine novel laboratory experiments and exospheric modeling to reveal that “dynamic” Ly-α photolysis of Plutonian methane generates a photolytic refractory distribution on Charon that increases with latitude, consistent with poleward d…
View article: Extreme Exospheric Dynamics at Charon: Implications for the Red Spot
Extreme Exospheric Dynamics at Charon: Implications for the Red Spot Open
Charon's exosphere may exhibit extreme seasonal dynamics, with centuries of quiescence punctuated by short lived (∼4 earth years) exospheric surges near the equinoxes, as spring sunrise bi‐annually drives frozen methane off the polar night…
View article: Extreme Exospheric Dynamics at Charon: Implications for the Red Spot
Extreme Exospheric Dynamics at Charon: Implications for the Red Spot Open
Folder "CharonCode": Charon model code in MATLAB script, used in "Extreme Exospheric Dynamics at Charon: Implications for the Red Spot", Geophysical Research Letters, 2022, by Ben Teolis, Ujjwal Raut, Joshua A. Kammer, Caleb J. Gimar, Carl…
View article: Extreme Exospheric Dynamics at Charon: Implications for the Red Spot
Extreme Exospheric Dynamics at Charon: Implications for the Red Spot Open
Folder "CharonCode": Charon model code in MATLAB script, used in "Extreme Exospheric Dynamics at Charon: Implications for the Red Spot", Geophysical Research Letters, 2022, by Ben Teolis, Ujjwal Raut, Joshua A. Kammer, Caleb J. Gimar, Carl…
View article: The two faces of the Jovian UV aurorae
The two faces of the Jovian UV aurorae Open
<p>Being mostly connected via closed magnetic field lines, the aurorae at the two poles display two broadly similar signatures of the same magnetospheric processes. However, differences are sometimes observed, indicative of asymmetri…
View article: A Comprehensive Set of Juno In Situ and Remote Sensing Observations of the Ganymede Auroral Footprint
A Comprehensive Set of Juno In Situ and Remote Sensing Observations of the Ganymede Auroral Footprint Open
Jupiter's satellite auroral footprints are a manifestation of the satellite‐magnetosphere interaction of the Galilean moons. Juno's polar elliptical orbit enables crossing the magnetic flux tubes connecting each Galilean moon with their as…
View article: Local Time Dependence of Jupiter's Polar Auroral Emissions Observed by Juno UVS
Local Time Dependence of Jupiter's Polar Auroral Emissions Observed by Juno UVS Open
Auroral brightness and color ratio imagery, captured using the Juno mission's Ultraviolet Spectrograph, display intense emissions poleward of Jupiter's northern main emission, and these are split into two distinctly different spectral or “…
View article: New Horizons Detection of the Local Galactic Lyman-α Background
New Horizons Detection of the Local Galactic Lyman-α Background Open
Since 2007 the Alice spectrograph on the New Horizons (NH) spacecraft has been used to periodically observe the Lyman- α (Ly α ) emissions of the interplanetary medium (IPM), which mostly result from resonant scattering of solar Ly α emiss…