Image: Sotra Facula
NASA
Sotra Facula, the peak shown toward the center of this false-color image, is the best example found so far of an ice volcano on the Saturnian moon Titan.
By Contributor
Inside Science News Service
updated 12/14/2010 2:14:19 PM ET 2010-12-14T19:14:19

Astronomers have announced the discovery of a potential new ice volcano on Saturn's moon Titan.

Named Sotra, the volcano is more than 3,000 feet (1 kilometer) tall and has a 1-mile-deep (1.2-kilometer) pit alongside it. Surrounded by giant sand dunes, it is thought to be the largest in a string of several volcanoes that once spewed molten ice from deep beneath the moon's surface.

“We think we have found the strongest case yet for an ice volcano on Titan,” said Randy Kirk, a geophysicist with the U.S. Geological Survey in Flagstaff, Ariz. “What we see is not just a flow like we see in other places, it's like a volcanic field would be on Earth.”

  1. Space news from NBCNews.com
    1. KARE
      Teen's space mission fueled by social media

      Science editor Alan Boyle's blog: "Astronaut Abby" is at the controls of a social-media machine that is launching the 15-year-old from Minnesota to Kazakhstan this month for the liftoff of the International Space Station's next crew.

    2. Buzz Aldrin's vision for journey to Mars
    3. Giant black hole may be cooking up meals
    4. Watch a 'ring of fire' solar eclipse online

Titan is about the size of the planet Mercury but has an atmosphere thicker than Earth's. This makes it incredibly difficult for astronomers to know what's happening on the surface. Planetary scientists, including Kirk, are using NASA's Cassini spacecraft to map the moon, but so far only about half of Titan has been imaged.

Kirk and his team created a three-dimensional mapping technique that patches together multiple images of the same area, so they were lucky that Sotra was in one of the rare places imaged twice.

“The classical volcano everybody thinks of when you say the word is a mountain with a crater on it and lava flows coming out of it,” said Kirk. “That's what we've found on Titan.”

The team can't be certain if the chain is active, but described the find as the best evidence found so far for a cryovolcano — the scientific term for an ice volcano. Previously, bright spots seen in low-resolution satellite images have been interpreted as volcanic flows and craters. However, once those areas were mapped in 3-D, it became obvious they weren't volcanoes.

“We had noted Sotra Facula as a candidate cryovolcano before,” said Rosaly Lopes, a senior research scientist from NASA's Jet Propulsion Laboratory in Pasadena, Calif. “But it was only when Randy [Kirk] got the topography done that we realized, wow, this is it.”

Spewing slush and gas
Earth's interior is divided into distinct layers of rock and liquid magma. When this molten rock erupts through the planet's crust, it's known as volcanism. Titan's volcanism is more complicated because beneath the moon's surface lies a layer of ice. Even a small amount of internal heat could create molten ices. Because the liquid would be less dense, it would force its way to the surface. The result would be a massive eruption of slushy liquid and gases similar to what scientists have seen on other icy moons.

“Ice at outer solar system temperatures is very rigid,” Kirk said. “Ice at close to its melting point is soft. What would be a glacier on Earth would be a volcano on a body that's made of that same material. It's the difference between the cake and the frosting.”

Some have theorized that volcanoes on Titan are the best way to explain the strange abundance of methane gas in its atmosphere. This gas is constantly being stripped from Titan's upper atmosphere by the sun, shining a billion miles away. Without a source to replenish it, all of the methane would disappear in a few million years.

However, if an ice volcano like Sotra were to erupt, it would release volatiles such as methane and ethane from inside Titan. Kirk's team calculates that it would take a Sotra-sized volcanic eruption every 1,000 years to maintain the current level of methane in Titan's atmosphere.

Alternate hypotheses
Others are skeptical about ice volcano claims and have proposed alternative theories to explain the methane abundance.

  1. Most popular

“There's been this whole list of volcanoes (on Titan) that have been published and then subsequently shot down,” said planetary scientist Jeffrey Moore, with the NASA Ames Research Center in Moffett Field, Calif. “This new feature doesn't make me change my tune that no one has unambiguously found a volcano on Titan.”

Moore believes that unlike Earth's well-defined and separate layers, beneath Titan's surface is a huge layer of mixed rock and ice, or what's called a partially differentiated interior. If this is the case it would  be much more difficult to heat ice enough to cause an eruption onto the surface.

Moore and others believe that Titan was once an enormous ice cube. According to their theory, as the sun aged and warmed, it heated Titan's surface. This process could have put methane into the atmosphere and subsequently fueled a rain-cycle that erased all impact craters. Moore said this would also have given Titan the young appearance that many have attributed to volcanism.

“If you press forward in time, all the methane will be erased and (Titan) will have a blue sky and a nitrogen atmosphere with sand dunes of hydrocarbons,” Moore said.

This report was originally published as "Giant Ice Volcano Candidate Found on Saturn Moon" with an accompanying video on the InsideScience.org website.

Copyright 2010 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

Photos: Best of Cassini

loading photos...
  1. Starring Saturn

    This backlit view of Saturn was voted the favorite image to come from the Cassini orbiter - and it has been described as "perhaps the most stunning photograph ever taken." The image, captured on Sept. 15, 2006, shows two faint rings that were discovered by the Cassini team. And at the highest resolution, Earth itself appears as a pale blue dot just to the left of the brightest rings, at about the 10 o'clock position. (NASA / JPL / Space Science Institute) Back to slideshow navigation
  2. Dark rings

    An infrared image from the Cassini orbiter, acquired May 24, 2007, reveals clouds beneath the hazes in Saturn's atmosphere, as well as the unilluminated side of the giant planet's rings. The shadows of the rings fall upon the planet's cloud layer. This image shares the honors as the favorite black-and-white picture from Cassini. (NASA / JPL / Space Science Institute) Back to slideshow navigation
  3. Abstract art

    A Cassini image from May 10, 2006, shows the shaded edge of Saturn's disk, rounded by dark rings seen nearly edge-on. The crescent disk of Titan, Saturn's largest moon, can be seen in the background beyond the rings. This image shares the honors as the favorite black-and-white image from Cassini. (NASA / JPL / Space Science Institute) Back to slideshow navigation
  4. Pearly moons

    Two of Saturn's moons - Tethys and Enceladus - look like pearls backdropped by the planet's disk in this image, captured on July 24, 2007. The thin "string" connecting the pearls is actually the plane of the planet's rings, seen edge-on. The rings cast a dark shadow on Saturn's disk. Two other moons appear in this image, although they can barely be made out at the highest resolution: Hyperion is near the lower left corner of the image, and Epimetheus is the slightest of specks between Tethys and Enceladus. (NASA / JPL / Space Science Institute) Back to slideshow navigation
  5. Saturn from on high

    The Cassini spacecraft provides a high-contrast view of Saturn and its rings, as seen from above. This portrait is actually a mosaic of 36 images taken on Jan. 19, 2007, from about 40 degrees above the plane of the rings. (NASA / JPL / Space Science Institute) Back to slideshow navigation
  6. Shadows on clouds

    Saturn's darkened rings cast shadows on the planet's blue and gold cloud tops, while the moon Dione hangs like a dot in the black sky beyond. This image was taken by the Cassini spacecraft on Feb. 4, 2007, from a distance of about 800,000 miles. (NASA / JPL / Space Science Institute) Back to slideshow navigation
  7. View from below

    Cassini coasts beneath giant Saturn, staring upward at its gleaming crescent and icy rings. A great bull's-eye pattern is centered on the south pole, where a vast, hurricane-like storm spins. This view, obtained on Jan. 30, 2007, looks toward the lit side of the rings from about 26 degrees below the ring plane. (NASA / JPL / Space Science Institute) Back to slideshow navigation
  8. Pastel planet

    Dark and sharply defined ring shadows appear to constrict the flow of color from Saturn's warmly hued south to the bluish northern latitudes. Scientists studying Saturn are not yet sure about the precise cause of the color change from north to south. The different colors may be due to seasonal effects on the atmosphere. The images that went into this mosaic were obtained by the Cassini spacecraft on Feb. 4, 2007. (NASA / JPL / Space Science Institute) Back to slideshow navigation
  9. Ringing success

    This ultraviolet image from the Cassini spacecraft shows the detailed composition of Saturn's outer C and inner B rings from left to right, with the inner B ring beginning a little more than halfway across the image. The general pattern is from "dirty" red particles to the denser ice shown in turquoise as the ringlets spread outward. (University Of Colorado, LASP / AP) Back to slideshow navigation
  10. A is for amazing

    This ultraviolet image shows the A ring, beginning with a 'dirty' interior of red followed by a general pattern of more turquoise as it spreads away from the planet, indicating a denser material made up of ice. The red band roughly three-fourths of the way outward in the A ring is known as the Encke gap. (University Of Colorado, LASP - NASA / Reuters) Back to slideshow navigation
  11. Casting a shadow

    This image taken by Cassini shows the planet Saturn casting a shadow over its rings. (NASA - JPL - Caltech / Reuters) Back to slideshow navigation
  12. Titan revealed

    This is an infrared image of Titan, one of Saturn's moons, mapping the surface hidden beneath the moon's opaque atmosphere. Green areas represent water ice, while yellow areas have higher concentrations of hydrocarbons. The white spot is a methane cloud. (NASA) Back to slideshow navigation
  13. Ripples in the ring

    Scallops in the ring on the left side of this image were likely caused by a Saturnian moon rolling along the edge. One bright ringlet is visible within the gap, and at least one other faint ringlet can be made out. "This is textbook ring physics, right there, in one image," says Cassini imaging team leader Carolyn Porco. (NASA - SSI) Back to slideshow navigation
  14. Wisps in space

    A close-up of one of Saturn's rings shows a wispy pattern of ripples that may have been stirred up by a moonlet's orbit. Such unprecedented views of ring details are possible because of the Cassini camera's resolution. (NASA TV) Back to slideshow navigation
  1. Editor's note:
    This image contains graphic content that some viewers may find disturbing.

    Click to view the image, or use the buttons above to navigate away.

  2. Editor's note:
    This image contains graphic content that some viewers may find disturbing.

    Click to view the image, or use the buttons above to navigate away.

  3. Editor's note:
    This image contains graphic content that some viewers may find disturbing.

    Click to view the image, or use the buttons above to navigate away.

  4. Editor's note:
    This image contains graphic content that some viewers may find disturbing.

    Click to view the image, or use the buttons above to navigate away.

  1. NASA / JPL / Space Science Institute
    Above: Slideshow (14) Best of Cassini
  2. Image:
    Y. Beletsky / ESO
    Slideshow (12) Month in Space: January 2014

Video: First look at Titan

Discuss:

Discussion comments

,

Most active discussions

  1. votes comments
  2. votes comments
  3. votes comments
  4. votes comments