Chuck Wood
2010 Annual Research Report
As
a member of the Cassini Radar Team Wood helps plan mission activities and analyze
resulting images of Saturn’s moon Titan. His My main interests are craters, both
volcanic and impact, but there are very few of either. The paucity of impact
craters says that Titan has a youthful, dynamic surface with processes that
bury or remove the impact craters that must form. But we are not certain what
the processes are that remove the impacts. Evidence for volcanism is
controversial, but there certainly are not large volcanic cones and craters
such as we seen on Earth, Mars, Venus and Jupiter’s moon, Io. Some scientists
propose that Titan is dead, with no internal geologic processes such as
volcanism and tectonics, and that all the surface changes are due to the
atmosphere. There are dunes that undoubtedly do cover part of the surface.
Large and small lakes of methane also submerge parts of the landscape, and
clouds and apparent rainstorms have been detected, and we do see river valleys
that have carved into the surface. All of these processes are driven by the
atmosphere, so it is a reasonable hypothesis that the Titan’s interior does not
affect the surface. But Wood thinks it is probably wrong. There are hundreds of circular lakes that appear
to be contained in volcanic craters. That is an interpretation, not a fact.
Similarly, there are a few images of what may be volcanic lava flows, but could
be sedimentary flows. He can not prove these are volcanics, and the opponents
can’t prove they are not. The
problem with Titan is that it is completely different from all other worlds we
have explored. It is not a largely dead world, highly cratered by ancient and
continuing impacts. And it is not full of volcanics, as we see in the solar
system’s three worlds with youthful surfaces, Earth, Venus and Io. It may be a third type of world with odd
processes due to it water ice crust that is enveloped in a methane-rich
atmosphere. The clouds make it hard for spacecraft cameras to clearly image the
surface, and the ice crust absorbs some of the radar beams adding confusion to
the interpretation. We are left without a model for Titan’s geologic behavior
and thus without a compelling interpretation of its surface history.
Fortunately, there are still dozens of Titan passes by the Cassini spacecraft
and we can hope for some new data that will help us decide if Titan is dead or
alive. Papers: Wood,
Charles A.; Lorenz, Ralph; Kirk, Randy; Lopes, Rosaly; Mitchell, Karl; Stofan,
Ellen; Cassini RADAR Team (2010) Impact Craters on Titan. Icarus 206, p. 334-344. Jaumann,
Ralf; Kirk, Randolph L.; Lorenz, Ralph D.; Lopes, Rosaly M. C.; Stofan, Ellen;
Turtle, Elizabeth P.; Keller, Horst Uwe; Wood, Charles A.; Sotin, Christophe;
Soderblom, Lawrence A.; Tomasko, Marty (2010) Geology and Surface Processes on
Titan. Titan from Cassini-Huygens.
Edited by R. Brown, J.P. Lebreton, and H. Waite. Springer Netherlands,
p.75-140. Abstracts: Wood,
C. A.; Radebaugh, J. D.; Stofan, E. and Zebker, H. (2010)
Titan's Xanadu: Ancient and Young. 41st
Lunar and Planetary Science Conference. Wood,
C. A.; Reese, D. D.; Ruberg, L.; Harrison, A.; Lightfritz, C. and
Avatrian, Llc (2010) MoonWorld: Implementation of Virtual Lunar
Exploration. 41st Lunar and Planetary
Science Conference. Lopes,
R. M. C.; Stofan, E. R.; Peckyno, R.; Radebaugh, J.; Mitchell, K. L.; Mitri,
G.; Wood, C. A.; and 19 coauthors (2010) Distribution and interplay of
geologic processes on Titan from Cassini radar data. 41st Lunar and Planetary Science Conference. Reese,
D. D. and Wood, C. A. (2010) Learning Lunar Science Through the Selene
Videogame. 41st Lunar and Planetary
Science Conference.
