Article,
The search for current geologic activity on Europa
Journal of Geophysical Research-Planets, 105 (E9): 22579--22597 (2000)
Abstract
Observational evidence and theoretical arguments suggest that Jupiter's
satellite Europa could be geologically active and possess an öcean"
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 km(2) y(-1) in the regions
analyzed, assuming alterations will cover contiguous areas of at
least 4 km(2) 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.
Tags
- calibration;
- features;
- galilean
- ice
- mixtures
- ocean;
- performance;
- satellites;
- shell;
- state;
- subsurface
- temperatures;
- volcanism;
