The final Galileo SSI observations of Io: orbits G28-I33
Icarus, 169 (1):
3--28 (2004)Abstract
We present the observations of to acquired by the Solid State Imaging
(SSI) experiment during the Galileo Millennium Mission (GMM) and
the strategy we used to plan the exploration of to. Despite Galileo's
tight restrictions on data volume and downlink capability and several
spacecraft and camera anomalies due to the intense radiation. close
to Jupiter, there were many successful SSI observations during GMM.
Four giant, high-latitude plumes, including the largest plume ever
observed on to, were documented over a period of eight months; only
faint evidence of such plumes had been seen since the Voyager 2 encounter,
despite monitoring by Galileo during the previous five years. Moreover,
the source of one of the plumes was Tvashtar Catena, demonstrating
that a single site can exhibit remarkably diverse eruption styles-from
a curtain of lava fountains, to extensive surface flows, and finally
a similar to 400 km high plume-over a relatively short period of
time (similar to 13 months between orbits 125 and G29). Despite this
substantial activity, no evidence of any truly new volcanic center
was seen during the six years of Galileo observations. The recent
observations also revealed details of mass wasting processes acting
on to. Slumping and landsliding dominate and occur in close proximity
to each other, demonstrating spatial variation in material properties
over distances of several kilometers. However, despite the ubiquitous
evidence for mass wasting, the rate of volcanic resurfacing seems
to dominate; the floors of paterae in proximity to mountains are
generally free of debris. Finally, the highest resolution observations
obtained during Galileo's final encounters with to provided further
evidence for a wide diversity of surface processes at work on to.
(C) 2003 Elsevier Inc. All rights reserved.