Jupiter’s moon Ganymede is home to an ancient impact structure called the Groove System, the largest impact structure in the outer Solar System, whose impact would have had a major impact on Ganymede’s early history.
The distribution of grooves and the location of the center of the groove system are always shown on the hemisphere away from Jupiter (top) and on a cylindrical projection of Ganymede (bottom). Grey areas represent geologically new terrains that are devoid of grooves. Gutters (green lines) are only present in geologically older terrains (black areas). Image courtesy of Naoyuki Hirata, doi: 10.1038/s41598-024-69914-2.
Ganymede is the largest moon in the solar system and has many unique features, including tectonic valleys known as grooves.
The grooves are the oldest surface features identified on Ganymede, as they are crossed by impact craters over 10 km in diameter. The grooves provide clues to the moon’s early history.
The trench is thought to be a fragment of a multi-ring impact basin structure similar to the Valhalla basin on Callisto and the Asgard basin.
The largest trench system lies across the Galileo-Marius region, the so-called Galileo-Marius trench system, which is the remnant of an ancient giant impact that radiates in concentric circles from a single point on Ganymede.
“Jupiter’s moons Io, Europa, Ganymede, and Callisto each have interesting features, but what caught my attention were the grooves on Ganymede,” said planetary scientist from Kobe University. paper Published in the journal Scientific Reports.
“We know that this feature was created by an asteroid impact about 4 billion years ago, but we didn’t know how large that impact was or how it affected the Moon.”
First, Dr. Hirata noticed that the estimated location of the impact was almost exactly on the meridian farthest from Jupiter.
“Similarities with the Pluto impact that shifted the dwarf planet’s rotation axis, as seen through NASA’s New Horizons spacecraft, suggest that Ganymede underwent a similar reorientation,” he said.
The asteroid that struck Ganymede was probably about 300 kilometers (180 miles) in diameter, roughly 20 times larger than the Chicxulub asteroid that smashed into Earth 65 million years ago, ending the age of the dinosaurs, leaving a temporary crater 800 to 1,000 miles (1,400 to 1,600 kilometers) across, according to the study.
Only an impact of this magnitude would be likely to shift the Moon’s rotation axis to its current position due to the change in mass distribution, regardless of where on the surface the impact occurred.
“We want to understand the origin and evolution of Ganymede and other Jupiter moons,” Dr. Hirata said.
“The giant impact must have had a major impact on Ganymede’s early evolution, but the thermal and structural effects of the impact on Ganymede’s interior remain largely unexplored.”
“We think that further research into the application of the internal evolution of icy moons could be done next.”
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N. Hirata. 2024. Giant impact on early Ganymede and subsequent reorientation. Scientific Reports 14, 19982. doi: 10.1038/s41598-024-69914-2
Source: www.sci.news
