This mosaic of Saturn’s moon Mimas, showing its crater-like surface, was created from images captured by NASA’s Cassini spacecraft. Photo credit: NASA / JPL-Caltech / Space Science Institute
A new chronology for the moons of Saturn was developed by Samuel W. Bell, Associate Research Scientist at the Planetary Science Institute.
“Most studies date the moon or surfaces Mars Rely on counting how many impact craters have formed and knowing the crater rate, but we don’t know the crater rate on Saturn’s moons, ”said Bell, author of“ Relative Crater Scaling Between the Major Moons of Saturn: Implications for the Planetary Center “Crater Formation and the Surface Age of Titan” in the Journal of Geophysical Research: Planets. “Earlier chronologies of the Saturn system assumed that the craters on Saturn’s moons were virtually all from objects orbiting the sun.”
“If the influences came exclusively from objects that orbit the sun, the relative crater rate would be higher the closer the moons are to Saturn. However, the crater densities of the oldest surfaces of Mimas, Tethys, Dione, Rhea and Iapetus are all relatively similar, ”said Bell. “It would be too much of a coincidence that the ages of the oldest surfaces on each moon vary by the exact amounts required to produce largely similar crater densities. As a result, it seems much more likely that the impactors actually came from objects orbiting Saturn itself, moonlets that would be too small with current technology to detect.
“There are many important implications of this new chronology,” said Bell. “Assuming that all impactors orbit the sun, for example, the possibility that one of the moons is younger than 4 billion years is excluded. However, with impactors orbiting Saturn itself, the moons could be younger, as shown by astrometric observations of tidal orbital evolution.
“The assumption that impactors orbit the sun suggests that the surface of titanium is likely to be at least 4 billion years old, although titanium has clear evidence of active weathering,” said Bell. “With the new chronology, Titan could still be quite young, which is much more in line with observations of lakes, river beds, dunes and mountains.
“With the new chronology, we can quantify what we’re doing much more accurately and don’t know about the ages of the moons and the features on them,” Bell said. “The large-scale history of the Saturn system still hides many secrets, but it is starting to focus.”
Reference: “Relative crater scaling between the main moons of Saturn: Implications for planetocentric crater formation and the surface age of the Titan” by Samuel W. Bell, May 26, 2020, Journal of Geophysical Research: Planets.
DOI: 10.1029 / 2020JE006392
Bell conducted research at Brown University’s Center for Computation and Visualization and the Planetary Science Institute.
