Ganymede Shows Signs of Past Strike-Slip Tectonics

Ganymede Shows Signs of Past Strike-Slip Tectonics

A moon of Jupiter experienced complex periods of geologic activity similar to what we get at the San Andreas Fault in Earth.

Ganymede is the 9th largest object and the most massive moon in our solar system. It is the only moon which has a magnetic field of its own. This Galilean moon possesses the lowest moment of inertia factor among all the solid bodies of our solar system. It takes around 7 days for Ganymede to complete an orbit around Jupiter. Having a diameter of 5,268 kilometers, it the largest celestial object without an atmosphere in our solar system. Despite being the 3rd Galilean moon, it is the 7th satellite outward from Jupiter.

Ganymede has a metallic core comprising mainly of liquid iron. Most of it is composed of equal amounts of water ice and silicate rock. There are two basic terrains on this moon, Dark regions and Lighter regions. Extensive grooves and ridges characterize the latter of the two and cover two-thirds of the satellite. On the other hand, dark regions are saturated with impact craters and cover the remaining area of the moon. According to an estimate of astronomers, it may have an internal ocean which could contain more water than all of Earth’s oceans combined. Consequently, this satellite of Jupiter was observed closely as it could have suitable conditions for harboring life.

A recent study showed complex periods of geologic activity on this icy moon of Jupiter. This is the first study in the geological history of Ganymede which exhaustively considered the role of strike-slip tectonics. Marissa E. Cameron, a Doctoral Candidate at the Department of Earth Sciences in SOEST and the Lead Author of the study, explained their findings by saying,

The heavily fractured surface of Ganymede displays many distinctive regions of inferred strike-slip faulting that may be important to the structural development of its surface.”

Europa, another moon of Jupiter, is also believed to have a similar ocean underneath its icy surface and for this reason, both of these satellites are collectively known as ‘Ocean Worlds’. The team led by the researchers from the Manoa School of Ocean and Earth Science and Technology at the University of Hawaii found that Ganymede used to be tectonically active but it is no longer experiencing this phenomenon. As a result, the chances of Ganymede supporting life become pretty bleak. Contrary to that, Europa is considered the most suitable place in our solar system to find signs of life because the icy shell of the moon acts us as a protection from harmful radiations. In addition to that, Europa has tectonic processes similar to Earth which make it even more feasible for our habitability.

The urge to have an in-depth knowledge about the strike-slip tectonics urged the scientists to perform extensive, methodical mapping of 9 locations. They wanted to understand the role of this tectonics in shaping the complex icy surface of Ganymede. They primarily used the data gathered by the Galileo spacecraft, which orbited the gas giant from 1995 to 2003. Cameron told the world about their working and the results in the following words:

The unexpected finding was how commonplace strike-slip faulting was. Indicators of strike-slip were observed at all nine sites, representing various geographic locations on Ganymede. Additionally, the similarities between the sites may be indicative of a past, larger-scale process. Incorporating our observations with previous studies provides an improved representation of Ganymede’s tectonic history and allows us to learn more about its neighbor, Europa.”

This information holds the key to future missions that aim to explore these extraterrestrial bodies. The knowledge about the dynamic system of the ocean worlds of Jupiter is immensely important for scientists as they want to prepare for these missions. One of the most popular missions in this regard is called Clipper which is expected to launch anytime between 2022 and 2025. It will observe Europa pretty closely during its 45 close-by orbits of the moon.

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