Is Pluto Another Geyser World? "Shocking" Images Baffle Scientists
In addition to featureless plains, Pluto may even sport active geysers—with no recourse to tidal heating to power them.
Smooth plains with possible geysers, ice mountains rivaling the Rockies, and rapidly escaping atmosphere: these are some of the “shocking” signatures of youth revealed at today’s press conference about the New Horizons mission to Pluto. New images downloaded since Wednesday are also showing a sunken mountain on Charon that looks like a castle with a moat (NASA press release). Large areas devoid of craters are telling scientists they cannot be more than 100 million years old (1/45 the assumed age of Pluto), but that’s only an upper limit: the regions “may still be active today,” Space.com writes. The scientists are delighted but also baffled: “Who would have expected this kind of complexity?” principal scientist Alan Stern said. The reporters don’t quite know what to think.
- “New Horizons team baffled by discovery of icy plains on Pluto” (New Scientist). The smooth area called Sputnik Planum has no craters (see fly-over movie posted on the Space.com and BBC News coverage). “When I saw this image for the first time I decided I was going to call it ‘not easy to explain’ terrain,” said team geologist Jeff Moore in a press conference earlier today at today’s NASA press conference. “This could be only a week old, for all we know.”
- “This terrain is not easy to explain,” said Jeff Moore, leader of the New Horizons Geology, Geophysics and Imaging Team (GGI) at NASA’s Ames Research Center in Moffett Field, California. “The discovery of vast, craterless, very young plains on Pluto exceeds all pre-flyby expectations.” (NASA press release)
- “Complicated,” “fascinating,” and “astounding” are words used in National Geographic‘s coverage. “Already, these images are challenging views about how small, icy worlds work.” The land of icy mountains produced earlier “looks relatively young—so young, in fact, that it suggests the planet is still geologically active.” John Spencer called the smooth plains in the “heart” region (Tombaugh Regio) “absurdly featureless.” And for Charon as well, “the moon’s sparsely cratered face looks surprisingly young, suggesting that it might also be an active world.“
- “Potential geysers spotted on Pluto” (Eric Hand at Science Magazine). “Most tantalizing of all, the team has spotted streaks of material that may have blown downwind from dark spots. Although the team is not yet ready to declare that these spots are geysers shooting plumes above Pluto, scientists say the spots and streaks resemble actively spewing geysers on Neptune’s moon Triton that were discovered in 1989.” Charon is young, too: “The lack of craters—also seen on Charon, Pluto’s largest moon—is evidence for youthfulness, and geological activity that could pave over the surfaces in fresh icy materials. This was unexpected because many thought that the internal heat sources within Pluto and Charon, leftover from their formation in a giant impact billions of years ago, would have dissipated long ago.” Retired Voyager planetologist Larry Soderblom remembers the surprise at Triton. “But where that activity on Triton can be driven by the tidal pull of Neptune, scientists are scratching their heads over what could be driving it on Pluto. There are other differences between the worlds, Soderblom says: Triton lacks Pluto’s tall mountains and its rugged, ropey pits. ‘Everywhere we go, we’re surprised,’ he says. ‘We should know better by now.‘”
Another big surprise is the rate at which Pluto’s atmosphere is escaping. Some 68,000 miles from Pluto, nitrogen gas was measured that allowed estimates of the escape rate. Space.com says,
“What we think it is, based on models and a pretty good guess, is about 500 tons per hour of material that is escaping,” said Fran Bagenal of the University of Colorado Boulder, who leads New Horizons’ particles and plasma team.
For comparison, Mars is losing about 1 ton of its atmosphere per hour, Bagenal added.
That’s an astonishing escape rate for a body much smaller than Mars, with no known heat source. What could replenish that gas for 4.5 billion years?
This could represent a revolution in planetary science happening before our eyes. Everyone is saying these surfaces are “young” and all the experts are at a loss to keep them young-looking for billions of years. Unlike with Triton and Enceladus, there is not a large planet nearby to force heat into it. The traditional theory escape mechanisms (radioactivity and tidal heating) are not available on this dwarf planet and its tidally-locked moon, isolated from gravitational influences. Both are also too small to store vast amounts of radioactive heavy elements (especially Charon). Read the quotes: mysterious, baffling, shocking, astonishing. Creationists enjoy the show, but are not using those words. They expect things to be young. It’s only the old-age moyboys, accustomed to mythical billions of years, who are shocked. We’ll keep tabs on the latest developments as more data and images come down over the next 16 months.