Ganymede, Largest Moon in the Solar System, Mapped in Detail for First Time

The first full-scale geological map of Ganymede, Jupiter's largest moon, was published Wednesday by the US Geological Survey.

The detailed map of the largest moon in the solar system was created using data from NASA's 1979 Voyager mission and the orbital Galileo mission in 1995.

Geoffrey Collins led the extraterrestrial cartography project while getting a Ph.D. at Brown University. Ganymede's varied terrain and possible subterranean oceans make it an interesting point of reference for astronomers searching for habitable environments in the solar system.

"It is very rewarding to see the results of all of our efforts here at Brown come together into this integrated global compilation that will now be used to plan the next phase of scientific exploration of the Galilean satellites," said Jim Head, one of the map's co-authors.

Collins, Head and their colleagues relied on NASA data to create the map of Ganymede. The Voyager images from 1979 revealed a complex lunar surface segmented and fractured into dark and light terrain. The Galileo mission nearly 20 years later surveyed some of those same regions, but collected information on them in much greater detail.

At the time, Head was a co-investigator on the Galileo's Solid State Imaging (SSI) experiment. That role required him to plan the image sequencing used by the spacecraft and identify high-priority targets.

"This was an amazing time," Head said. "The discoveries were daily and the adrenaline was surging as we rushed to collect our thoughts and plans, review them with the SSI Team, and get them uploaded to the spacecraft in time for the next encounter."

A detailed version of the map is available from the USGS.