Violent Impact May Have Caused Huge Ring-Like Structure on the Surface of Jupiter’s Moon Ganymede

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Jupiter's Moon Ganymede

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Credit: Tsunehiko Kato, 4D2U Project, NAOJ

Researchers from Kobe University and the National Institute of Technology, Oshima College have actually carried out a comprehensive reanalysis of image information from Voyager 1, 2 and Galileo spacecraft in order to examine the orientation and circulation of the ancient tectonic troughs discovered on Jupiter’s moon Ganymede. They found that these troughs are concentrically dispersed throughout practically the whole surface area of the satellite. This international circulation suggests that these troughs might be really part of one giant crater covering Ganymede.

Based on the outcomes of a computer system simulation carried out utilizing the “PC Cluster” computer systems at the National Astronomical Observatory of Japan (NAOJ), it is hypothesized that this huge crater might have arised from the effect of an asteroid with a radius of 150km. If so, the structure is the biggest effect structure recognized in the planetary system up until now.

The European Space Agency’s JUICE (Jupiter Icy Moon Explorer) objective, which will be introduced in 2022 and get here in Jupiter’s system in 2029, intends to increase our understanding relating to Jupiter’s satellites, consisting of Ganymede. It is hoped that this expedition will validate the outcomes of this research study and more advance our understanding of the development and advancement of Jupiter’s satellites.

The research study group included Kobe University Graduate School of Science’s Assistant Professor HIRATA Naoyuki and Professor OHTSUKI Keiji (both of the Department of Planetology), and Associate Professor SUETSUGU Ryo of National Institute of Technology, Oshima College. The paper for this research study was released online in Icarus on July 15.

Ganymede's Surface

Figure 1: Images of Ganymede’s surface area taken by Voyager 2 (left) and Galileo (right). The Dark Terrain and Bright Terrain locations can be acknowledged, with concurrent furrows present in these Dark Terrains. Credit: NASA

Main Points

  • Many furrows, or trough developments, have actually been formerly observed on the surface area of Ganymede, among Jupiter’s moons.
  • The research study group thoroughly reanalyzed image information of Ganymede’s surface area acquired by NASA’s Voyager 1, Voyager 2 and Galileo spacecraft.
  • The results exposed that practically all of these furrows on the surface area of Ganymede seem in concentric rings focused at a single point, showing that this international multiring structure might be the remains of a huge crater.
  • The radial level of the multiring determined along the satellite’s surface area is 7800km. Therefore, if it is really formed by an effect, it is the biggest vestigial effect crater found in the planetary system up until now.
  • The outcomes of the mathematical effect simulation suggested that an asteroid with a radius of 150km impacting Ganymede at a speed of 20km/s would discuss the observed structures on the satellite’s surface area.
Ganymede Azimuthal Equidistant Map

Figure 2.
Above: Azimuthal equidistant map focused at 20° south 180° west proving Ganymede’s Dark Terrain and furrows (suggested by yellow lines).
Below: Azimuthal equidistant map of Ganymede’s surface area focused at 20° north and 0° west. This reveals the opposite hemisphere of Ganymede to the leading image. The white locations show Bright Terrain. (Image credit: NASA)

Research Findings

Ganymede’s surface area is classified into locations of Dark Terrain and Bright Terrain. Dark Terrain is exceptionally old and has lots of staying craters, in addition to trough developments (Figure 1). Bright Terrain is relatively current, with barely any craters. These 2 kinds of surface are not coherently organized and are arbitrarily dispersed over Ganymede’s whole. Furrows are thought to be Ganymede’s earliest geological functions due to the fact that they are just discovered on Dark Terrain and lots of effect craters[1] have actually been formed on top of them in the future.

This research study reanalyzed the circulation of these trough developments over Ganymede’s whole surface area, exposing for the very first time that practically all of these furrows are concentrically lined up around a single point (Figure 2). The research study revealed that these furrows kind giant, concentric rings over the whole satellite. From this, it can be presumed that there was a huge multiring effect crater which covered the whole surface area of Ganymede prior to the development of the Bright Terrain locations. A comparable ring structure called the Valhalla Crater stays on the surface area of Callisto, another satellite of Jupiter. Until now, the Valhalla Crater has actually been the biggest recognized multiring crater[2] in the planetary system, with a radius of roughly 1900km. However, the multiring crater on Ganymede has a radial level of 7800 km determined along the satellite’s surface area.

The research study group carried out a simulation to approximate the scale of the effect that formed this huge crater. This was performed utilizing the “PC Cluster” at the National Astronomical Observatory of Japan (NAOJ). The results suggested that an asteroid with a radius of 150km impacting Ganymede at a speed of 20km/s would suffice to form the observed structures on the satellite’s surface area (Figure 3). It is thought that such an effect happened around 40 billion years earlier.

Asteroid Ganymede Impact Simulation

Asteroid Ganymede Impact Simulation

Figure 3: Impact simulation of an asteroid with a 150km radius clashing into Ganymede at 20km/s. It is hypothesized that this would lead to a violent effect. Note: The sharp vertical circulation of the product along the vertical axis that can be seen at a range of 0 km at 12000 seconds is likely a mathematical artifact triggered by the limit conditions in the simulation, however we verified that this does not impact the primary outcomes of this research study. Credit: Naoyuki Hirata

Further Developments

The discovery that the consequences of a big scale effect stays on Ganymede’s surface area is significantly considerable in regards to the satellite’s development procedure and advancement. For example, Jupiter’s satellite Callisto is around the exact same size as Ganymede, nevertheless, it is thought that it doesn’t have an internal structure made up of distinguished layers. On the other hand, Ganymede is believed to be made up of a separated layer structure including rock, iron, and ice. An massive quantity of heat is essential to form these distinguished layers. It is possible that the abovementioned big scale effect might have been the source of this heat.

This research study’s discovery will likewise have significant significance for the Ganymede expedition programs arranged in the coming years. The image information from both Voyager and Galileo objectives just offer partial views of the satellite’s surface area. It is hoped that future expeditions will have the ability to validate or check this research study’s outcomes by carrying out in-depth examinations into the multiring developments and whether there are any other remains of big scale effects. Hopefully, this will lead to a much deeper understanding of the origins and advancement of Ganymede in addition to Jupiter’s other moons.

Glossary

  1. Impact crater – A circular anxiety that happens as the outcome of an asteroid or comet crashing into the surface area.
  2. Multiring crater – These several ring structures form around the area of effect craters.

Reference: “A global system of furrows on Ganymede indicative of their creation in a single impact event” by Naoyuki Hirata, Ryo Suetsugu and Keiji Ohtsuki, 15 July 2020, Icarus.
DOI: 10.1016/j.icarus.2020.113941



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