February 12, 2014
Voyager, Galileo Spacecraft Images Used To Create Geological Map Of Jupiter’s Largest Moon
[ Watch the Video: Rotating Globe of Ganymede Geology ]
Lee Rannals for redOrbit.com - Your Universe Online
The map, now published by the USGS as a global map, combines images of Ganymede taken by NASA's Voyager 1 and 2 spacecraft and Galileo orbiter. It is the first global, geologic map of Jupiter’s seventh moon, providing the geologic character of Ganymede’s surface.
“This map illustrates the incredible variety of geological features on Ganymede and helps to make order from the apparent chaos of its complex surface,” Robert Pappalardo, of NASA’s Jet Propulsion Laboratory in Pasadena, California, said in a statement. “This map is helping planetary scientists to decipher the evolution of this icy world and will aid in upcoming spacecraft observations.”
Ganymede was first discovered by astronomer Galileo Galilei in January 1610; since then it has been the focus of many observations. Studies of Ganymede show it to be a complex, icy world with a surface that features striking contrast between two major terrain types.
The scientists who constructed the map said three major geological periods have been identified for Ganymede that involve the dominance of impact cratering, then tectonic upheaval, followed by a decline in geologic activity. The map allows scientists to decipher geological time periods for an object in the outer solar system for the first time.
“The highly detailed, colorful map confirmed a number of outstanding scientific hypotheses regarding Ganymede’s geologic history, and also disproved others,” Baerbel Lucchitta, scientist emeritus at the USGS in Flagstaff, Arizona, said in a statement. “For example, the more detailed Galileo images showed that cryovolcanism, or the creation of volcanoes that erupt water and ice, is very rare on Ganymede.”
Researchers will be able to use this map to compare the geological characteristics of other icy moons. Ganymede offers a great starting point when comparing to other icy moons because nearly any feature found on the other natural satellites have similar features seen on Ganymede.
“The surface of Ganymede is more than half as large as all the land area on Earth, so there is a wide diversity of locations to choose from,” Collins said. “Ganymede also shows features that are ancient alongside much more recently formed features, adding historical diversity in addition to geographic diversity.”