Related papers: H$_2$O$_2$ within chaos terrain on Europa's leadin…
We present results from Keck II observations of Europa over four consecutive nights using the near-infrared spectrograph (NIRSPEC). Spectra were collected in the 3.14--4.0 micron range, allowing detection and monitoring of the 3.5 micron…
H$_2$O$_2$ is part of Europa's water-ice radiolytic cycle and a potential source of oxidants to Europa's subsurface ocean. However, factors controlling the concentration of this critical surface species remain unclear. Though laboratory…
Recent observations from the Hubble Space Telescope show a mid-UV absorption feature localized to leading hemisphere chaos regions on Europa. The same regions were previously found to have a visible absorption at 450 nm that was attributed…
Recent visible-wavelength observations of Europa's surface obtained with the Hubble Space Telescope revealed the presence of an absorption feature near 450 nm that appears spatially correlated with leading-hemisphere chaos terrain. This…
Observations of Europa's leading hemisphere reveal elevated H2O2 in the warmer, low latitude chaos terrains compared to the colder, polar regions. This distribution disagrees with prior laboratory radiolysis studies of pure water ice, which…
We present hemispherically resolved spectra of the surface of Europa from ~3.1--4.13 microns, which we obtained using the near infrared spectrometer NIRSPEC on the Keck II telescope. These include the first high-quality L-band spectra of…
The icy surface of Europa is continuously bombarded by ions and electrons from Jupiter's magnetosphere. The bombardment of the particles dissociates water molecules on the surface of Europa and introduces impurities to the icy surface. Such…
We report results of a Hubble Space Telescope (HST) campaign with the Advanced Camera for Surveys to observe Europa at eastern elongation, i.e. Europa's leading side, on 2008 June 29. With five consecutive HST orbits, we constrain Europa's…
Jupiter's moon Europa has a subsurface ocean, the chemistry of which is largely unknown. Carbon dioxide (CO$_2$) has previously been detected on the surface of Europa, but it was not possible to determine whether it originated from…
An image of Lyman-$\alpha$ (Ly$\alpha$) emission from Europa obtained with the Hubble Space Telescope Space Telescope Imaging Spectrograph (HST/STIS) has previously provided the first evidence of localized water vapor (H$_2$O) aurora,…
Recent infrared observations at 1.5-4.0 $\mu m$ using large ground-based telescopes have suggested that Cl-bearing salts are likely present on Europa's surface as non-ice materials. The chemical compositions of those Cl-bearing salts are…
A weak absorption feature at 2.07 \textmu m on Europa's trailing hemisphere has been suggested to arise from radiolytic processing of an endogenic salt, possibly sourced from the interior ocean. However, if the genesis of this feature…
The composition of Europa's trailing hemisphere reflects the combined influences of endogenous geologic resurfacing and exogenous sulfur radiolysis. Using spatially resolved visible-wavelength spectra of Europa obtained with the Hubble…
Competing processes shape Europa's surface: geological activity replenishes material through resurfacing, while bombardment by charged particles alters surface chemical composition. Each process leaves distinct spectral signatures. We…
Auroral emissions provide opportunities to study the tenuous atmospheres of Solar System satellites, revealing the presence and abundance of molecular and atomic species as well as their spatial and temporal variability. Far-UV aurorae have…
The presence of NH$_3$-bearing components on icy planetary bodies has important implications for their geology and potential habitability. Here, I report the detection of a characteristic NH$_3$ absorption feature at 2.20 $\pm$ 0.02 $\mu$m…
We constrain Europa's tenuous atmosphere on the subsolar hemisphere by combining two sets of observations: oxygen emissions at 1304 {\AA} and 1356 {\AA} from Hubble Space Telescope (HST) spectral images, and Galileo magnetic field…
The evolution of Europa's water-product exosphere over its 85-hour day, based on current models, has not been shown to exhibit any diurnal asymmetries. Here we simulate Europa's exosphere using a 3-D Monte Carlo routine including, for the…
Europa's surface composition and evidence for cryovolcanic activity can provide insight into the properties and composition of the subsurface ocean, allowing the evaluation of its potential habitability. One promising avenue for revealing…
The surface of Europa is geologically young and shows signs of current activity. Studying it from a photometric point of view gives us insight on its physical state. We used a collection of 57 images from Voyager's Imaging Science System…