NASA’s Cassini spacecraft is providing scientists with key clues about Saturn’s moon Titan, and in particular, its hydrocarbon lakes and seas.
Titan is one of the most Earth-like places in the solar system, and the only place other than our planet that has stable liquid on its surface.
Cassini’s recent close flybys are bringing into sharper focus a region in Titan’s northern hemisphere that sparkles with almost all of the moon’s seas and lakes. Scientists working with the spacecraft’s radar instrument have put together the most detailed multi-image mosaic of that region to date. The image includes all the seas and most of the major lakes. Some of the flybys tracked over areas that previously were seen at a different angle, so researchers have been able to create a flyover of the area around Titan’s largest and second largest seas, known as Kraken Mare and Ligeia Mare, respectively, and some of the nearby lakes.
“Learning about surface features like lakes and seas helps us to understand how Titan’s liquids, solids and gases interact to make it so Earth-like,” said Steve Wall, acting radar team lead at NASA’s Jet Propulsion Laboratory in Pasadena, Calif. “While these two worlds aren’t exactly the same, it shows us more and more Earth-like processes as we get new views.”
An analysis of gravity and topography data from Saturn’s largest moon, Titan, has revealed unexpected features of the moon’s outer ice shell. The best explanation for the findings, the authors said, is that Titan’s ice shell is rigid and that relatively small topographic features on the surface are associated with large roots extending into the underlying ocean. The study is published in the August 29 issue of the journal Nature.
Led by planetary scientists Douglas Hemingway and Francis Nimmo at the University of California, Santa Cruz, the study used new data from NASA’s Cassini spacecraft. The researchers were surprised to find a negative correlation between the gravity and topography signals on Titan.
“Normally, if you fly over a mountain, you expect to see an increase in gravity due to the extra mass of the mountain. On Titan, when you fly over a mountain the gravity gets lower. That’s a very odd observation,” said Nimmo, a professor of Earth and planetary sciences at UC Santa Cruz.
Full Story: http://news.ucsc.edu/2013/08/titan-ice-shell.html
Saturn’s moon Titan might be in for some wild weather as it heads into its spring and summer, if two new models are correct. Scientists think that as the seasons change in Titan’s northern hemisphere, waves could ripple across the moon’s hydrocarbon seas, and hurricanes could begin to swirl over these areas, too. The model predicting waves tries to explain data from the moon obtained so far by NASA’s Cassini spacecraft. Both models help mission team members plan when and where to look for unusual atmospheric disturbances as Titan summer approaches.
“If you think being a weather forecaster on Earth is difficult, it can be even more challenging at Titan,” said Scott Edgington, Cassini’s deputy project scientist at NASA’s Jet Propulsion Laboratory, Pasadena, Calif. “We know there are weather processes similar to Earth’s at work on this strange world, but differences arise due to the presence of unfamiliar liquids like methane. We can’t wait for Cassini to tell us whether our forecasts are right as it continues its tour through Titan spring into the start of northern summer.”
Scientists have created the first global topographic map of Saturn’s moon Titan, giving researchers a valuable tool for learning more about one of the most Earth-like and interesting worlds in the solar system. The map was just published as part of a paper in the journal Icarus.
Titan is Saturn’s largest moon – with a radius of about 1,600 miles (2,574 kilometers), it’s bigger than planet Mercury – and is the second-largest moon in the solar system. Scientists care about Titan because it’s the only moon in the solar system known to have clouds, surface liquids and a mysterious, thick atmosphere. The cold atmosphere is mostly nitrogen, like Earth’s, but the organic compound methane on Titan acts the way water vapor does on Earth, forming clouds and falling as rain and carving the surface with rivers. Organic chemicals, derived from methane, are present in Titan’s atmosphere, lakes and rivers and may offer clues about the origins of life.
“Titan has so much interesting activity – like flowing liquids and moving sand dunes – but to understand these processes it’s useful to know how the terrain slopes,” said Ralph Lorenz, a member of the Cassini radar team based at the Johns Hopkins University Applied Physics Laboratory, Laurel, Md., who led the map-design team. “It’s especially helpful to those studying hydrology and modeling Titan’s climate and weather, who need to know whether there is high ground or low ground driving their models.”
An ice cloud taking shape over Titan’s south pole is the latest sign that the change of seasons is setting off a cascade of radical changes in the atmosphere of Saturn’s largest moon. Made from an unknown ice, this type of cloud has long hung over Titan’s north pole, where it is now fading, according to observations made by the Composite Infrared Spectrometer (CIRS) on NASA’s Cassini spacecraft.
“We associate this particular kind of ice cloud with winter weather on Titan, and this is the first time we have detected it anywhere but the north pole,” said the study’s lead author, Donald E. Jennings, a CIRS Co-Investigator at NASA’s Goddard Space Flight Center in Greenbelt, Md.
The southern ice cloud, which shows up in the far infrared part of the light spectrum, is evidence that an important pattern of global air circulation on Titan has reversed direction. When Cassini first observed the circulation pattern, warm air from the southern hemisphere was rising high in the atmosphere and got transported to the cold north pole. There, the air cooled and sank down to lower layers of the atmosphere, where it formed ice clouds. A similar pattern, called a Hadley cell, carries warm, moist air from Earth’s tropics to the cooler middle latitudes.
Titan’s siblings must be jealous. While most of Saturn’s moons display their ancient faces pockmarked by thousands of craters, Titan – Saturn’s largest moon – may look much younger than it really is because its craters are getting erased. Dunes of exotic, hydrocarbon sand are slowly but steadily filling in its craters, according to new research using observations from NASA’s Cassini spacecraft.
“Most of the Saturnian satellites – Titan’s siblings – have thousands and thousands of craters on their surface. So far on Titan, of the 50 percent of the surface that we’ve seen in high resolution, we’ve only found about 60 craters,” said Catherine Neish, a Cassini radar team associate based at NASA’s Goddard Space Flight Center, Greenbelt, Md. “It’s possible that there are many more craters on Titan, but they are not visible from space because they are so eroded. We typically estimate the age of a planet’s surface by counting the number of craters on it (more craters means an older surface). But if processes like stream erosion or drifting sand dunes are filling them in, it’s possible that the surface is much older that it appears.
It’s not exactly icing on a cake, but it could be icing on a lake. A new paper by scientists on NASA’s Cassini mission finds that blocks of hydrocarbon ice might decorate the surface of existing lakes and seas of liquid hydrocarbon on Saturn’s moon Titan. The presence of ice floes might explain some of the mixed readings Cassini has seen in the reflectivity of the surfaces of lakes on Titan.
“One of the most intriguing questions about these lakes and seas is whether they might host an exotic form of life,” said Jonathan Lunine, a paper co-author and Cassini interdisciplinary Titan scientist at Cornell University, Ithaca, N.Y. “And the formation of floating hydrocarbon ice will provide an opportunity for interesting chemistry along the boundary between liquid and solid, a boundary that may have been important in the origin of terrestrial life.”
Titan is the only other body besides Earth in our solar system with stable bodies of liquid on its surface. But while our planet’s cycle of precipitation and evaporation involves water, Titan’s cycle involves hydrocarbons like ethane and methane. Ethane and methane are organic molecules, which scientists think can be building blocks for the more complex chemistry from which life arose. Cassini has seen a vast network of these hydrocarbon seas cover Titan’s northern hemisphere, while a more sporadic set of lakes bejewels the southern hemisphere.
The international Cassini mission has spotted what appears to be a miniature extraterrestrial version of the Nile River: a river valley on Saturn’s moon Titan that stretches more than 400 km from its ‘headwaters’ to a large sea. It is the first time images have revealed a river system this vast and in such high resolution anywhere beyond Earth.
Scientists deduce that the river is filled with liquid because it appears dark along its entire extent in the high-resolution radar image, indicating a smooth surface.
“Though there are some short, local meanders, the relative straightness of the river valley suggests it follows the trace of at least one fault, similar to other large rivers running into the southern margin of this same Titan sea,” says Jani Radebaugh, a Cassini radar team associate at Brigham Young University, USA. “Such faults – fractures in Titan’s bedrock – may not imply plate tectonics, like on Earth, but still lead to the opening of basins and perhaps to the formation of the giant seas themselves.”
Among the oddities of the outer solar system are the middle-sized moons of Saturn, a half-dozen icy bodies dwarfed by Saturn’s massive moon Titan. According to a new model for the origin of the Saturn system, these middle-sized moons were spawned during giant impacts in which several major satellites merged to form Titan.
“We think that the giant planets got their satellites kind of like the Sun got its planets, growing like miniature solar systems and ending with a stage of final collisions,” Asphaug (professor of Earth and planetary sciences at the University of California, Santa Cruz) said. “In our model for the Saturn system, we propose that Titan grew in a couple of giant impacts, each one combining the masses of the colliding bodies, while shedding a small family of middle-sized moons.”
Full Story: http://news.ucsc.edu/2012/10/saturn-moons.html
Radar images from NASA’s Cassini spacecraft reveal some new curiosities on the surface of Saturn’s mysterious moon Titan, including a nearly circular feature that resembles a giant hot cross bun and shorelines of ancient seas. The results were presented today (Oct. 16, 2012) at the American Astronomical Society’s Division of Planetary Sciences conference in Reno, Nev.
Steam from baking often causes the top of bread to lift and crack. Scientists think some similar process involving heat may be at play on Titan. The image showing the bun-like mound was obtained on May 22, 2012, by Cassini’s radar instrument. Scientists have seen similar terrain on Venus, where a dome-shaped region about 20 miles (30 kilometers) across has been seen at the summit of a large volcano called Kunapipi Mons. They theorize that the Titan cross, which is about 40 miles (70 kilometers) long, is also the result of fractures caused by uplift from below, possibly the result of rising magma.
“The ‘hot cross bun’ is a type of feature we have not seen before on Titan, showing that Titan keeps surprising us even after eight years of observations from Cassini,” said Rosaly Lopes, a Cassini radar team scientist based at NASA’s Jet Propulsion Laboratory, Pasadena, Calif. “The ‘bun’ may be the result of what is known on Earth as a laccolith, an intrusion formed by magma pushing up from below. The Henry Mountains of Utah are well-known examples of this geologic phenomenon.”