Titan Continues to Surprise Saturn Scientists
Since reaching Saturn in 2004, the Cassini spacecraft has now made 68 flybys of Titan, the large smog-shrouded moon. Space.com highlighted a recent picture showing the rings appearing to bisect the moon. What are some of the latest findings of this alien world – the only moon in the solar system with a substantial atmosphere?
Space.com reported on work by scientists at the University of Louisiana to determine whether there is lightning in Titan’s atmosphere. Evidence was tantalizing but not certain from the Huygens probe in 2005. “So far, the only world where lightning is 100 percent confirmed is Earth,” said Andi Petculescu, professor of physics at the University of Louisiana at Lafayette.
Now that 22 percent of Titan’s surface has been mapped in radar, scientists at the Lunar and Planetary Laboratory at the University of Tucson in Arizona are trying to get a handle on Titan’s crater count, reported PhysOrg and Space.com. So far they have only identified 5 certain impact craters, and 44 probable candidate craters. That is surprising for such a large world. By end of mission (2017) scientists should have 50% of the surface mapped in radar.
Another story on Space.com reported that the interior of Titan appears to be slushy inside. Scientists infer from gravitational tugs on the spacecraft that Titan lacks a hard core. Inferring the nature of the interior required measuring changes in spacecraft speed on the order of five thousandths of a millimeter per second, the article said. Assuming the interior is as they believe, they think Titan must have built up “rather slowly for a moon, in perhaps around a million years or so, back soon after the formation of the solar system.” National Geographic also reported this story in March and printed a larger picture of the cutaway artwork of Titan’s interior. The finding was “really quite a surprise” according to one team member because it suggests that Titan had a very different history than Ganymede, a similar-size moon of Jupiter.
Some Utah scientists found similarities to their home state in Titan’s landscape. PhysOrg said last March that Cassini scientists found karst-like landscape in the radar images that “suggests there is a lot happening right now under the surface that we can’t see.” Liquid methane may take the place of water flowing under the surface. The article includes a short video flyover of some of Titan’s “canyon country” compared with similar terrain in Utah.
One of the most unusual findings announced recently is that Titan’s river channels may be studded with gems. JPL’s Cassini page announced a rock-n-roll feature this month: Titan may act as a “gem tumbler” Large ice boulders like the ones seen by the Huygens Probe may tumble down channels of liquid methane for hundreds of miles. Like pebbles on earth, which get rounded by the friction of a streambed, these ice boulders may end up as sparkling spheres of ice 1 to 8 inches in diameter. “The effect would be similar to bejeweling an area with light-catching rhinestones.” This may be the explanation for the brightness of the land of Xanadu on Titan – a mysterious region brighter than the rest of the moon.
Each month a Cassini scientist makes a detailed presentation on some aspect of the science returns of the mission in a series called CHARM: “Cassini-Huygens Analysis and Results of the Mission.” The April presentation by Christophe Sotin, Titan: the Moon that Would Be a Planet (PDF) included comparisons of Titan to Earth and Mars. Sotin reiterated the problem of maintaining Titan’s atmosphere for billions of years. Slide 9 says, “Without the greenhouse effect caused by methane, the surface temperature would be around 70 K.” Slide 13 states that the methane irreversibly transforms into ethane. “If there is no replenishment (from the interior or from meteorites), the methane would disappear, the greenhouse effect would vanish, the surface temperature would drop, and nitrogen would freeze,” Sotin said. “All this would happen in less than 100 Myrs (likely 30 Myrs).” What is the source of the methane? Can it be replenished from the interior? Slide 25 says that “No convincing evidence of active cryo-volcanoes has been found so far.” It also notes, “The number of impact craters is small. It suggests that Titan’s surface is young.” Young could mean anything from 100 Myr to 3 billion years, he quickly stated, but even the upper estimate falls far short of the estimated time of Titan’s formation according to standard theory. His last slide said the “Carbon cycle implies replenishment in methane,” but then said there’s no evidence for it: “Still lacking convincing evidence for cryovolcanic features.”
PhysOrg subtitled its article on crater counts with this line: “Impact craters found on Titan could help scientists determine the age of this Earth-like moon and its potential for life.” But in the body of the story, it said, “But it’s no secret that Saturn’s largest moon is a very unfriendly place for life” primarily because of its temperature, which makes liquid water impossible. The article later quoted the opinion of Charles Wood at LPL who said, “If it were warmer, you’d definitely think life existed there.” Even without life on Titan, “Understanding the chemical processes on Titan may help scientists understand how life began on Earth billions of years ago,” the article said, even though the evidence so far is inconclusive about the geological prospects for life.
William Bains of the Royal Astronomical Society didn’t need evidence to tell UK astronomers what he thinks of life on Titan. It stinks. Science Daily shared his opinions: “Hollywood would have problems with these aliens,” he said. “Beam one onto the Starship Enterprise and it would boil and then burst into flames, and the fumes would kill everyone in range. Even a tiny whiff of its breath would smell unbelievably horrible. But I think it is all the more interesting for that reason. Wouldn’t it be sad if the most alien things we found in the galaxy were just like us, but blue and with tails?”
Yes, it would be sad. Very sad. Very sad that scientists get their science from Star Trek and Avatar instead of empirical lab work, like they should.
The life angle is a distraction. Nobody really believes there is life on Titan. The L-word is the sexy girl standing next to the pickup truck that draws the public eye to an otherwise ugly, smoggy thing you would not give a second look. Titan is fascinating in its own way, from a distance, but you wouldn’t want to live there. Titan’s environment not unlike that of pre-biotic Earth? Who are they kidding? It’s vastly different. We have water here.
It’s also illogical to talk about “life emergence” from chemical constituents. Life is more than its parts. Why not talk about life on the sun? After all, the sun has protons and electrons – look: the building blocks of life! Oh yes, it’s a little hot there, but “understanding the chemical process on” the sun “may help scientists understand how life began on Earth billions of years ago.” Pick any planet, moon, or location in the universe and you can play their silly game.
The real story they have not addressed is the age question. Once again we have seen them admit that Titan’s atmosphere is undergoing irreversible processes. The methane keeps the nitrogen from freezing, but it is being depleted. It should have rained down as ethane and formed oceans on the surface, but the surface is largely dry. Try as they might, they cannot find clear evidence of outgassing to replenish the methane – and where are they going to dispose of the ethane, which should be a half mile thick over the whole moon? There are also few craters. None of this says Titan is very, very young, but it sure says Titan is likely not 4.5 billion years old. If not that old, then many questions spring up, if not a whole new paradigm.