A Hawaiian-Style Volcano on Io
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New images from Galileo reveal unexpected details of
the Prometheus volcano on Io including a caldera and lava flowing through
fields of sulfur dioxide snow.
A volcanic crater several times larger
than one found at Hawaii's Kilauea volcano has been
photographed on Jupiter's moon Io during a close flyby
performed by NASA's Galileo spacecraft.
"It appears that the Prometheus volcano on Io has characteristics remarkably similar to those of the Kilauea volcano in Hawaii, although Prometheus is much larger," said Dr. Laszlo Keszthelyi (KEST-ay), a Galileo research associate at the University of Arizona, Tucson, AZ. "Both volcanoes are long- lived eruptions, with flows that apparently travel through lava tubes and produce plumes when they interact with cooler materials."
Right: This is a high-resolution image of part of Prometheus, an active volcano on Jupiter's volcanic moon Io. In earlier, lower resolution images, it appeared that all the dark material at Prometheus comprised a single, long lava flow. The new image shows for the first time that the northeastern end of this dark feature is actually a lava-filled caldera 28 kilometers (17 miles) long and 14 kilometers (9 mile s) wide. The underground source of the Prometheus lava is probably beneath this newly discovered caldera. Galileo scientists are intrigued also by the snowfield containing hummocks, seen to the east of the Prometheus caldera. [more information].
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The sharp images of Prometheus released today come from two of Galileo's onboard instruments -- the camera, and the near- infrared mapping spectrometer which observes in wavelengths not visible to the naked eye. The images were taken during the close flyby of Io by Galileo on October 10, 1999, and are part of a large batch of data currently being transmitted to Earth.
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Prometheus is the "Old Faithful" of Io's many volcanoes. It has been active during every observation over the past 20 years by NASA's Voyager and Galileo spacecraft and the Hubble Space Telescope. The new spectrometer images show two distinct hot spots at Prometheus -- a large one to the west and a fainter, cooler one to the east. The images reveal numerous lava flows near the western hot spot and enable scientists to identify a crater, or caldera, 28 kilometers (17 miles) long and 14 kilometers (9 miles) wide near the hot spot to the east.
Previously, it was thought that the 50 to 100 kilometer- (30 to 60 mile-) tall plume observed at Prometheus formed where the lava erupts onto the surface. Now, however, it now appears that the plume forms at the far end of the lava flows. The caldera and eastern hot spot are thought to be associated with the vent where the molten rock rises to the surface. It appears that after the lava reaches the surface, it is transported westward through lava tubes for about 100 kilometers (60 miles) before breaking out onto the surface again. Here, numerous lava flows wander across a plain covered with sulfur dioxide-rich snow. The plume is created by the interaction of the hot lava with the snow.
|Visit IoFlyBy.com for coverage of Galileo's close encounters with Io, including science news and the latest images of Jupiter's volcanic moon.|
Another Io flyby, this time at an altitude of 300 kilometers (186 miles), is planned for November 25 at 8:40 p.m. Pacific Time (11:40 p.m. Eastern Time). (Times given are in Earth-received time -- or the time when the signal of the event is received on Earth.) The Io flybys are challenging and risky, because Io lies in an area of intense radiation from Jupiter's radiation belts, and that radiation can harm spacecraft components. Because of the risk, the flybys were scheduled for the final portion of Galileo's extended mission.
Additional information about the Galileo mission is available
on the Galileo home page at a new web address of http://galileo.jpl.nasa.gov.
JPL manages the Galileo mission for NASA's Office of Space Science, Washington, D.C. JPL is operated for NASA by the California Institute of Technology, Pasadena, CA.
December 3: Mars Polar Lander nears touchdown
December 2: What next, Leonids?
November 30: Polar Lander Mission Overview
November 30: Learning how to make a clean sweep in space
- Sulfuric Acid Discovered on Europa -- September 30, 1999. Sulfur from Io's fiery volcanoes may be responsible for a battery acid chemical on Europa with implications for astrobiology.
- Io or Bust -- September 16, 1999. Galileo braves extreme radiation as it plunges toward a close encounter with Io's volcanoes.
- Divining Water on Europa -- September 9, 1999. As circumstantial evidence for an underground ocean mounts, JPL scientists try an ingenious experiment to look for hexagonal ice crystals on the surface of Europa.
- Taking the Scenic Route to Io -- June 30, 1999. What's happening to the small craters on Callisto? That's the mystery scientists were contemplating as Galileo zoomed past Jupiter's pockmarked moon this morning in an orbit-changing maneuver designed to bring the spacecraft closer to volcanic Io.
- Turn Left at Callisto -- May 5, 1999. Galileo heads for a daring encounter with Io's volcanoes.
- Galileo buzzes Europa -- Feb. 2, 1999. Galileo executes a close flyby of Europa for the last time during the current mission.
- The Frosty Plains of Europa -- Dec. 3, 1998. As Galileo returns new images of Europa, NASA scientists prepare to study samples from a potentially similar environment here on Earth.
- Callisto makes a big splash -- Oct. 22, 1998. Scientists may have discovered a salty ocean and a possible ingredient for life on Jupiter's moon.
- Galileo takes a close look at icy Europa -- Oct 2, 1998. The spacecraft flew within 2300 miles of the mysterious satellite last weekend.
- Clues to possible life on Europa may lie buried in Antarctic ice -- Mar. 5, 1998. Exotic microbial forms turn up in ice above Antarctica's Lake Vostok.
- Ice, Water and Fire the Galileo Europa Mission
- Galileo home page at JPL, with the latest on Europa, Callisto and Io
- Jet Propulsion Laboratory home page
- Io from the SEDS Nine Planets web site
- Callisto from the SEDS Nine Planets web site
- Jupiter from the SEDS Nine Planets web site
- Io: The Prometheus Plume Aug. 18, 1997 Astronomy Picture of the Day
- Close-up of an Io volcano Aug. 4, 1995 Astronomy Picture of the Day
- Sizzling Io July 6, 1998 Astronomy Picture of the Day
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