Io Date Gets Dumped

JOVIAN DREAMS

Io Date Gets Dumped

Calculations of Io's total heat flow suggest that virtually everywhere on Io, even the oldest surfaces were produced by fresh lava so recently that they are still cooling off. NASA/JPL Image

Pasadena - March 14, 2001
The amount of lava gushing from individual volcanoes on Jupiter's moon Io dwarfs earthly comparisons, and the pace at which lava is repainting Io's surface suggests a novel technique for determining the relative ages of surface regions there.

The latest research about Io, much of it based on data from NASA's Galileo spacecraft, was reported Wednesday at the Lunar and Planetary Science conference in Houston, Texas.

Knowing the relative ages of surface features on a planet or moon is crucial for understanding the processes shaping that world. The favorite age gauge of planetary scientists is counting impact craters. The more impacts still showing, the older the surface. However, volcanoes are resurfacing Io so fast, not a single impact crater has been found there.

"It appears that the same process that destroys the traditional way of dating surfaces is going to provide a new way to date surfaces," said Dr. Dennis Matson, a research scientist at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "On Io, surface temperature can give us an indication of surface age."

Calculations of Io's total heat flow suggest that virtually everywhere on Io, even the oldest surfaces were produced by fresh lava so recently that they are still cooling off, Matson said. With some allowances for differences in composition and thickness of the flows, colder surface areas should be older surface areas.

"If we get this technique worked out, we look forward to combining it with other types of information to read the history of Io's surface," he said. "We hope to be able to tell whether lava flows that are far apart on the surface happened at approximately the same time."

Some of the first calculations were reported Wednesday for how fast lava is being produced by individual volcanic features on Io. One thermally steady volcano that produces broad flow fields named Amirani and Maui churns out about 100 cubic meters (about 3,500 cubic feet) of lava every second, said Dr. Ashley Davies, a JPL volcanologist.

That's about 200 times as productive as the Kilauea volcano in Hawaii. It's fast enough to overflow two Olympic size swimming pools every minute or three Houston Astrodomes every day.

Ionian volcanoes Monan, Tupan, Prometheus, Culann and Zamama each produce one-third to one-half as much lava as Amirani-Maui does, Davies calculates.

Estimates of the volume rate of an eruption are important for understanding what is happening under the surface and at the surface of each volcano. "Flow rate is tied to the source of the magma and the conduits the magma follows to the surface," Davies said. "It strongly influences how the lava landscape forms and how heat is lost from the lava as time passes."

The volume-rate estimates also help crosscheck estimates of the thickness of flows where Galileo's repeat flybys have provided information about how rapidly the flows increase in area.

Davies used infrared spectral measurements from Galileo plus modeling of cooling rates to calculate surface coverage rates and eruption volumes. The calculations suggest typical lava-flow thicknesses on Io of one to two meters (three to six feet), he said.

JOVIAN DREAMS

Is Ganymede Jupiter's Slush Puppy

St. Louis - Feb. 28, 2001
Planetary scientists studying Jupiter's icy moon Ganymede have combined stereo images from the Galileo mission with Voyager images from the 1970s and found provocative features on the moon. They have mapped long swathes of bright flat terrain that they think is evidence of water or slush that emerged one billion years or so ago.

Thanks for being here; We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain. With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords. Our news coverage takes time and effort to publish 365 days a year. If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.
SpaceDaily Contributor $5 Billed Once credit card or paypal		SpaceDaily Monthly Supporter $5 Billed Monthly paypal only

The content herein, unless otherwise known to be public domain, are Copyright 1995-2016 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement All images and articles appearing on Space Media Network have been edited or digitally altered in some way. Any requests to remove copyright material will be acted upon in a timely and appropriate manner. Any attempt to extort money from Space Media Network will be ignored and reported to Australian Law Enforcement Agencies as a potential case of financial fraud involving the use of a telephonic carriage device or postal service.