Showing papers by "Kenneth P. Klaasen published in 2000"
TL;DR: During late 1999/early 2000, the solid state imaging experiment on the Galileo spacecraft returned more than 100 high-resolution images of volcanically active Io, observing an active lava lake, an active curtain of lava, active lava flows, calderas, mountains, plateaus, and plains.
Abstract: During late 1999/early 2000, the solid state imaging experiment on the Galileo spacecraft returned more than 100 high-resolution (5 to 500 meters per pixel) images of volcanically active Io. We observed an active lava lake, an active curtain of lava, active lava flows, calderas, mountains, plateaus, and plains. Several of the sulfur dioxide–rich plumes are erupting from distal flows, rather than from the source of silicate lava (caldera or fissure, often with red pyroclastic deposits). Most of the active flows in equatorial regions are being emplaced slowly beneath insulated crust, but rapidly emplaced channelized flows are also found at all latitudes. There is no evidence for high-viscosity lava, but some bright flows may consist of sulfur rather than mafic silicates. The mountains, plateaus, and calderas are strongly influenced by tectonics and gravitational collapse. Sapping channels and scarps suggest that many portions of the upper ∼1 kilometer are rich in volatiles.
132 citations
TL;DR: The lack of observed plume activity on the surface of Jupiter's satellite Europa has been investigated in this article, where the authors estimate a maximum steady state surface alteration rate of 1 km2 y−1 in the regions analyzed, assuming alterations will cover contiguous areas of at least 4 km2.
Abstract: Observational evidence and theoretical arguments suggest that Jupiter's satellite Europa could be geologically active and possess an “ocean” of liquid water beneath its surface at the present time. We have searched for evidence of current geologic activity on Europa in the form of active plumes venting material above the surface and by comparison of Voyager and Galileo images to look for any changes on the surface. So far, we have observed no plumes and have detected no definitive changes. The lack of observed activity allows us to estimate a maximum steady state surface alteration rate of 1 km2 y−1 in the regions analyzed, assuming alterations will cover contiguous areas of at least 4 km2 over a period of 20 years. Assuming this as a constant, globally uniform resurfacing rate leads to a minimum average surface age of 30 million years. We also suggest that the lack of obvious circular albedo patterns on the surface due to plumes, coupled with the presence of bright-rayed craters such as Pwyll and the predicted sputtering erosion rate, implies that no large-scale plume activity has taken place over at least the last few thousand years. We thus conclude that if Europa's surface is currently active, any changes must be relatively small in spatial scale or episodic in nature rather than continuous. To detect potential small-scale surface changes, we need high-resolution comparisons between the Galileo data and future Europa Orbiter images.
64 citations
TL;DR: A brief synopsis of the nature of SSI data that was taken during the nominal Galileo mission can be found in this paper, where the authors present evidence for geologic activity on Europa that supports the hypothesis of liquid water under a thin ice shell, and demonstrate the ubiquitous presence of a thick crust and high temperature silicate volcanism on Io.
8 citations
01 Mar 2000
TL;DR: Galileo has returned new high-resolution images of Io as mentioned in this paper, and an overview of the encounters and science results can be found in this paper. But the results are limited.
Abstract: Galileo has returned new high-resolution images of Io. Here we provide an overview of the encounters and science results.
1 citations