“All plans for exploring the outer solar system, more or less, are in complete ruins at the moment,” Jonathan Lunine, professor of planetary sciences and of physics at the University of Arizona in Tucson, said during a lecture at the 37th Lunar and Planetary Science Conference (LPSC), held here March 13-17. “We have no baggage or anything that’s weighing us down in terms of thinking about what we might do.”
The outer solar system — the vast region of space beyond the orbit of Mars — potentially has several places that are of interest in the search for life beyond Earth and for clues to the origin of life, he said. In developing a new outer solar system exploration strategy, Lunine noted, there are some fundamental scientific questions that should be addressed:
– 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?
His own priorities for that research would be exploration of Jupiter’s moon Europa and Saturn’s moon Titan.
Perhaps the most “fundamental discovery” of the NASA Galileo mission that surveyed Jupiter and several of its moons from 1995 to 2003 was Europa, an icy world that may contain a layer of liquid water that potentially is accessible, Lunine said.
But questions and conflicting clues remain about Europa, he said. How thick is that ice crust? Just how variable is that icy covering? Galileo imagery suggests that the landscape of Europa is “very, very bizarre,” Lunine said. A vehicle landed 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 there, 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.”
Also high on Lunine’s list for that clean sheet of paper is further exploration of Saturn’s moon Titan, the object of a great deal of recent attention from the Cassini spacecraft orbiting the Saturn system and the European Space Agency’s Huygens spacecraft, which landed on Titan in 2005.
Lunine said data from Cassini and Huygens bolster the case for returning there.
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; it is 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 said. “There is no body in the outer solar system that is better designed for exploration than Titan.”