HOUSTON, Texas - A leading
planetary scientist said that Titan, one of Saturn's moons, should be targeted
for a new round of outer planet exploration.
Thanks
to new data streaming in from the Cassini mission, said Jonathan Lunine,
Professor of Planetary Sciences and of Physics at the University of Arizona in Tucson. Titan
deserves prime-time scrutiny, perhaps using an airship to reveal the moon as
never before.
"(However)
all plans for exploring the outer solar system, more or less, are in complete
ruins at the moment," Lunine said during a major lecture at the 37th Lunar and
Planetary Science Conference (LPSC), being held here throughout the week.
Lunine
said that the scientific community can start with a clean sheet of paper. "We
have no baggage or anything that's weighing us down in terms of thinking about
what we might do."
A state of mind
The
outer reaches of our solar system is not a destination, in the same sense that
the Moon and Mars might be, Lunine said. "It's not a place in the sense of a
planet...it's a region. Some people might say it's a state of mind...but it's
certainly an important element of our solar system," he said.
In
that immense expanse of space, most of the mass of our solar system is present
today, a region where most of the volume is located, Lunine pointed out. "And
it potentially has several places that are of interest in the search for life
elsewhere and for clues to the origin of life."
In
developing a new outer solar system exploration strategy, Lunine said there are
fundamental scientific questions that come to the forefront:
- How did our solar system arrive at the architecture
that it has today?
- How did the giant planets and their satellite systems
form?
- Are there habitable or interesting pre-biotic
environments in the outer solar system? Furthermore, how best to explore
them and access those interesting environments from the point of view of
life and astrobiology?
In
orchestrating a next round of outer solar system study, Lunine focused on both
Europa--a moon of Jupiter--and Saturn's Titan.
Europa: Questions and conflicting clues
Perhaps
the most "fundamental discovery" of the NASA Galileo mission that surveyed
Jupiter and several of its moons from 1995-2003, is that under Europa's icy face
is a liquid water layer - a layer that potentially is accessible, Lunine
suggested.
But
questions and conflicting clues remain about Europa: How thick is that ice
crust? Just how variable is that icy covering? Answering these questions can
literally plunge scientists into another realm--the prospective that the moon's
ocean environment is habitable.
Galileo
imagery suggests that the landscape of Europa is "very, very bizarre," Lunine
said. A landed vehicle there may or may not survive touching down on the "very
intricate and difficult landscape," he said.
More
studies are needed at Europa to tease out information about the thickness of
the moon's shell of ice, the nature of its surface, and how best to operate
landed vehicles on that moon, Lunine said. "Before one can land and drill down
into the ocean of Europa there's an awful lot of geophysics that has to be
done."
Titan: a subtle, complex place
In
his view, Lunine suggested, new data stemming from the ongoing Cassini mission
at Saturn--and the European Space Agency's Huygens lander on Titan--bolster the
case for returning to that celestial target. It offers astrobiological
potential too.
The
scientist said he has struggled over Titan compared to investigation of Europa,
adding that Jupiter's moon is a fascinating and important target to go to. "And
maybe it's the right target to go to first in the outer solar system. But we've
tried three times," Lunine said, noting a mission to Europa was most recently
deferred in NASA's new budget.
"Titan
is so mysterious...so hard to understand and so complex. But that's why it is
such a wonderful place," Lunine said. "It's not a world that has one newspaper
headline-type feature. It's just a subtle, complex place."
Lunine
painted a futuristic picture of airship or balloon exploration craft that pick
out landing sites "on the fly"--freely navigating in Titan's winds moving from
spot to spot.
Titan
is just waiting for us...Titan wants us," Lunine suggested. "There is no body in
the outer solar system that is better designed for exploration than Titan."
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