A team from Johns Hopkins University’s Applied Physics Laboratory has used spacecraft surveys of Jupiter’s Ganymede to create a geologic map of the moon.
In the journal “Icarus”, a team led by G. Wesley Patterson combined data and images from past Voyager and Galileo missions to Jupiter. About a third of the frozen moon’s surface is covered in dark material while the rest is a mixture of brighter, newer features, says the study.
“The dichotomy between these two basic terrain types leads to a number of fundamental questions about the formation and evolution of the surface of Ganymede,” the study authors note.
Judging from crater counts, the dark material appears to have formed some 4.5 billion years ago, after the beginning of the solar system. The lighter material appears the result of “cryovolcanism,” water-ice eruptions on the surface of the frozen moon, resulting in a complicated pattern of grooves, calderas and fractured landscapes.
“The current best guess from crater statistics is that light materials formed at some time during the middle half of Solar System history, but obtaining an exact age is likely to remain elusive for a long time,” says the study.
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