Galileo SSI Team's research while affiliated with Arizona State University and other places

Publications (37)

Article
The Solid-State Imaging (SSI) instrument provided the first high- and medium-resolution views of Io as the Galileo spacecraft closed in on the volcanic body in late 1999 and early 2000. While each volcanic center has many unique features, the majority can be placed into one of two broad categories. The "Promethean" eruptions, typified by the volcan...
Conference Paper
Full-text available
GEM-era investigations of impact features on Europa have focused on: (1) the deposits of Mannann'an; (2) Tegid; (3) the topography of craters; (4) Pwyll secondaries; and (5) a survey and ordering of all primary impact features.
Article
Three close flybys of Io by the tenacious Galileo spacecraft have revealed a world unlike any other in the Solar System. Repeat imaging at moderate resolution (100-500 m/pixel) shows that the long-lived Prometheus and Amirani flow fields are being emplaced from many individual lava breakouts, similar to compound flows growing by inflation of pahoeh...
Article
Images obtained by the Galileo spacecraft's solid-state imaging (SSI) system represent the first survey of Jupiter's northern auroral emissions at visible wavelengths and on the nightside of the planet. These images captured the emissions with unprecedented spatial resolutions down to ~26 km pixel-1. Four classes of emission were observed: (1) a co...
Article
We present a geological map of central Agenor Linea. Previously thought to be recently or currently active, we show that the band probably formed in three episodes and is deformed and disrupted by later features, hence is older than expected.
Article
The abstract gives a summary of global color properties of Ganymede which are partly correlated to its magnetic field. Areas on the surface which are exposed to charged particles from the Jovian field are often redder than shielded terrain.
Article
Craters, palimpsests and multi-ring basins are important stratigraphic markers in establishing sequences of geologic events by stratigraphic relationships. In this paper, we present ages for craters on Ganymede and Callisto, based on two impact cratering chronologies.
Article
MicroChaos material in lenticulae is morphologically similar to the internal texture of chaos. We find chaos forms and grows by fracturing and incorporation of lenticulae, suggesting a possible origin of chaos by coalescence of diapiric lenticulae.
Article
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Tyre's morphology suggests that the impact occurred on a target with a brittle elastic lithosphere underlain by a liquid or highly ductile material. Infrared data show this region and the impact scar dominated by water ice with some features such as linea, some lenticulae, and a few portions of Tyre's concentric ring structure possessing a subtle a...
Article
Galileo images of Io during eclipse reveal diffuse atmospheric emissions which are sometimes distinct in character from those noted in ground-based and HST observations. The airglow has been imaged by the Solid State Imaging (SSI) system over the course of 14 eclipses in 10 orbits during the nominal and extended missions. The emissions can be divid...
Article
Full-text available
The Galileo Solid State Imager (SSI) detected lightning at six different latitudes between +/- 50(o) , each latitude corresponding either to a cyclonic shear zone or its poleward boundary - the center of a westward jet. In day side images the cyclonic shear zones are the most active regions on the planet, which suggests an association between visua...
Article
At Voyager resolution, dark terrain on Ganymede (which comprises approximately half of the satellite; the remainder is bright terrain) is a nearly primordial, impact-generated surface of dark plains material with morphological features which include impact structures and huge systems of concentric furrows. One of the outstanding questions from Voya...
Article
Full-text available
Voyager images of the surface of Europa revealed several circular features identified to various degrees of certainty as impact features. The arrival of the Galileo Orbiter in the Jupiter system has offered an opportunity to examine several impact features on Europa at considerably better resolution and greater spectral coverage than was possible b...
Article
Full-text available
Recent Earth-based and Galileo observations have shown that high- temperature hot spots are common on Io. The highest temperatures are well above 500 K, too hot for elemental sulfur alone, so Io's volcanism is probably driven by silicate eruptions. Two short-lived events observed from the ground (Veeder et al., 1994, JGR 99, 17,095; Spencer et al.,...
Article
We have used the Galileo G1, G2, G7, and G8 images to study the morpholo- gy and degradation of impact craters on Ganymede. Results from the G1 and G2 data showed three types of degradation states: pristine, partially degraded, and heavily degraded. With the more recent G7 and G8 images, there are now several other distinct crater morphologies that...
Article
The new Europa images currently being acquired by the Galileo spacecraft, in addition to the Voyager dataset, provide an excellent starting point for understanding the properties of Europa's icy surface. Classification of spectral units on the surface of Europa is important for relative age dating of surface features [1,2], but first we must normal...
Article
Full-text available
In May 1997, the Galileo SSI Team obtained observations of a small portion of Jupiter near 33deg S planetographic latitude, which contains the long-lived White Ovals: FA, DE and BC. Due to data transmission constraints, the observations were limited to a region centered on a cyclonic system between BC and DE. This Galileo data has been supplemented...
Article
Full-text available
Observations by the Galileo Solid State Imaging (SSI) experiment and by the HST have both yielded surprises with respect to airborne volcanic plumes on Io. As of late 1996 SSI has detected far fewer bright visible plumes than were seen by Voyager in 1979. Although the SSI data return is strongly limited by tape and downlink resources, we are now co...
Article
Full-text available
A portion of Europa's 'wedges' province, near the satellite's anti-Jovian point, was imaged by the Galileo SSI instrument on orbit C3. Dark wedges in the region show broad morphological similarities to grooved terrain on Ganymede as that terrain appears at Voyager resolution. The C3 Europa resolution of about 420 m/pxl is close to that of the best...
Article
Full-text available
Voyager images of the surface of Europa revealed many diverse features, including bright and dark linea, triple bands, gray bands, ridges, pits, and dark spots termed maculae. Seen at Voyager resolution, maculae are circular to irregularly shaped, low albedo patches with little additional morphologic character. Maculae occur in both bright and mott...
Article
Full-text available
Galileo images of the small satellites of Jupiter are discussed. For the first four Galileo orbits, images of Amalthea have provided new information of shape, local morpohology, albedo, and color. The first image of Thebe shows it to have a mean radius of about 48 km. The first Adrastea images suggest slight errors in the ephemeris, and a size abou...
Article
Full-text available
Triple bands (TB) are linear features discovered on the Galilean satellite, Europa, during the Voyager mission. TB consist of a central bright stripe averaging one to two km in width, flanked by two parallel low-albedo stripes, each several km or more across. Multispectral imaging data acquired by the Galileo spacecraft provide new insight into the...
Article
Full-text available
During its second close encounter with Ganymede, the Galileo SSI instrument imaged a region that is transitional from the dark terrain of northern Marius Regio to the bright grooved terrain of Nippur Sulcus. These 190-m/pixel images reveal a complex sequence of extensional and strike-slip structural deformation as furrowed dark terrain undergoes a...
Article
Full-text available
Dark, wedge-shaped bands on the surface of Europa, interpreted as 'pull-apart' zones that divide icy crustal plates which have rotated and moved relative to one another, were observed at 1.6 km/pixel during Galileo's first orbit. Galileo images show this style of tectonism extends WSW from the area viewed by Voyager to the western limit of Galileo...
Article
Full-text available
Progress in digital cartography and mosaicking of Galileo and Voyager images of Europa is reported, and plans for mapping endogenic units are described. The latest Europe mosaics, attempts at photometric and exogenic normalizations and classification of endogenic units, and a discussion of geologic interpretations are presented.
Article
Full-text available
The first two orbits of the Galileo spacecraft through the Jovian system saw two close encounters with Ganymede. Imaging of Ganymede's bright grooved terrain is a primary objective of the SSI instrument in order to elucidate the nature, origin, and evolution of grooved terrain and its constituent structures. Galileo images are in agreement with the...
Article
Full-text available
The first four orbits of the Galileo spacecraft around Jupiter have returned pictures of Europa ranging in resolution from 6.9-km/pixel global views to 26-m/pixel images of small areas, as well as new color data for representative terrains and surface features. The best Voyager (VGR) coverage was only 1.8 km/pixel in a very limited area. Average VG...

Citations

... horizontal resolution of the topography map which is different from the one of the base images) is around 350 m at best. Arbela Sulcus is a prominent SSW–NNE trending smooth, 20 km-wide band (Pappalardo et al., 1998 ). Most parts of the band are topographically lower than the near surroundings, primarily dark terrain. ...
... In the case of Tyre Macula the two teams planned observations at different times for an additional reason: the two sets of observations were coordinated to decrease the discrepancy in spatial resolution from x50 to x8 with the specific intent of allowing more effective coregistration of the two data sets and implementing this interdisciplinary study. The resulting NIMS-based compositional map [Granahan et al., 1997b[Granahan et al., , 1998], when superimposed upon the morphological features, shows the following: the non-H20 ice or salt component is very clearly and closely associated with the lineae (Plates 1 and 3). In the case of the crater itself is, the ring structure is associated with apparent deposits of the "non-H20 ice" component. ...
... Oval BC (at 33ºS) (Mitchell et al., 1981) and for a cyclone "barge" at 16ºN (Hatzes et al., 1981). Images obtained by the Galileo obiter allowed to measure the wind field of the GRS (Choi et al., 2007) and a few smaller vortices Simon et al., 1998). ...
... 4. Spots are low albedo concave features that do not have lineaments preserved within the feature (Fig. 1d). Spots are mostly 10-20 km across (Carr et al., 1998;Pappalardo et al., 1998;Spaun et al., 1999). 5. Finally, we introduce an intermediate category called "dome/chaos". ...
... Landforms described here are usually too small to provide reliable dating with crater counting (Wagner et al. 1999). Some of the landforms lack high-resolution coverage. ...
... Technology concepts proved in VALKYRIE will lead to surface lander mission concepts to Europa. The need for radar sounding of Europan sub-surface is motivated by the imaging results from the Galileo mission [1]. Radar sounding for Europa in the upcoming Europa fly-by mission has been discussed in [2]. ...
... Grooved terrains represent the deformation of Ganymede's light terrains: they exhibit two superposed scales of grooves with different structure, spacing and length (Patterson et al., 2010). The local scale allows the identification of structures spacing <5 km and length <50 km, while grooves identified at the regional scale are usually clustered in sets of grooves with length >100 km and average spacing of about 10 km, often displaying parallel ordered patterns (Bianchi et al., 1984;Casacchia and Strom, 1984;Collins et al., 2000Collins et al., , 2013Lucchitta, 1980;Pappalardo et al., 1998Pappalardo et al., , 2004Pappalardo and Greeley, 1995;Patterson et al., 2010). ...
... [1985], McEwen [1986b], and Leith and McKinnon [1996] Kraft and Greeley, 1997; Spaun et al., 1998b; Sullivan et al., 1999b], 1985; Greenberg et al., 1998a][Hoppa et al., 1999; Tuffs, 1996]. Hoppa and Tuffs [1999] [McEwen, 1986a; Domingue and Hapke, 1992; Phillips et al., 1997; Clark et al., 1998; Helfenstein et al., 1998][1982, 1983] (Figure 17 ). In addition to showing an off-limb feature that was interpreted as a volcanic event [Cook et al., 1982[Cook et al., , 1983 Verbiscer and Helfenstein, 1998]. ...
... The atomic hydrogen halo and the oxygen emissions are hence likely generated partly by surface sputtering and partly by thermal sublima- tion [Spencer, 1987]. This effect is consistent with the difference in the color ratios between the high-and lowlatitude regions [Hillier et al., 1996; Denk et al., 1999]. This suggests that the polar caps of Ganymede could be the result of plasma precipitation along the open field lines [Johnson, 1997]. ...