Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2023 May 12;9(19):eadf8537.
doi: 10.1126/sciadv.adf8537. Epub 2023 May 12.

Micrometeoroid infall onto Saturn's rings constrains their age to no more than a few hundred million years

Sascha Kempf  1   2 , Nicolas Altobelli  3 , Jürgen Schmidt  4   5 , Jeffrey N Cuzzi  6 , Paul R Estrada  6 , Ralf Srama  7
Affiliations

Micrometeoroid infall onto Saturn's rings constrains their age to no more than a few hundred million years

Sascha Kempf et al. Sci Adv. .

Abstract

There is ongoing debate as to whether Saturn's main rings are relatively young or ancient- having been formed shortly after Saturn or during the Late Heavy Bombardment. The rings are mostly water-ice but are polluted by non-icy material with a volume fraction ranging from ∼0.1 to 2%. Continuous bombardment by micrometeoroids exogenic to the Saturnian system is a source of this non-icy material. Knowledge of the incoming mass flux of these pollutants allows estimation of the rings' exposure time, providing a limit on their age. Here we report the final measurements by Cassini's Cosmic Dust Analyzer of the micrometeoroid flux into the Saturnian system. Several populations are present, but the flux is dominated by low-relative velocity objects such as from the Kuiper belt. We find a mass flux between 6.9 · 10-17 and 2.7 · 10-16 kg m-2s-1 from which we infer a ring exposure time ≲100 to 400 million years in support of recent ring formation scenarios.

PubMed Disclaimer

Figures

Fig. 1.
Fig. 1.. QP detection of an IDP on 2008-260/13:21:22 UTC at a distance of 13.0 RS to Saturn.
(A) Its charge of Qd = 2.7 fC (relative to the negative baseline around −20 μs) corresponds to a grain radius of 4.8 μm. The inset shows the particle’s trajectory in the CDA reference frame reconstructed from its QP signature. (B) The trapezoidal feature in (A) with a central dip corresponds to two possible particle orbits, both are trajectories of interplanetary grains in prograde orbits (blue, a = 9.5 atronomical units (AU), e = 0.26, i = 13.1°; green, a = 13.6 AU, e = 0.39, i = 17.9°). Circles denote the orbital distances of Saturnian satellites as well as the ring system and the planet.
Fig. 2.
Fig. 2.. Speed distribution of the dust particles.
Left: Distribution of injection speeds computed at Saturn’s Hill radius for all particles with at least one exogenic solution. The fraction of detections for which all solutions are exogenic is shown in green. Right: Size distribution of grains with at least one exogenic solution (see also text S5).
See this image and copyright information in PMC

References

    1. Esposito L. W., O’callaghan M., West R. A., The structure of Saturn’s rings–Implications from the Voyager stellar occultation. Icarus 56, 439–452 (1983).
    1. Iess L., Militzer B., Kaspi Y., Nicholson P., Durante D., Racioppa P., Anabtawi A., Galanti E., Hubbard W., Mariani M. J., Tortora P., Wahl S., Zannoni M., Measurement and implications of Saturn’s gravity field and ring mass. Science 364, eaat2965 (2019). - PubMed
    1. Cuzzi J. N., Estrada P. R., Compositional evolution of saturn’s rings due to meteoroid bombardment. Icarus 132, 1–35 (1998).
    1. Durisen R. H., Bode P. W., Cuzzi J. N., Cederbloom S. E., Murphy B. W., Ballistic transport in planetary ring systems due to particle erosion mechanisms: II. Theoretical models for Saturn’s A- and B-ring inner edges. Icarus 100, 364–393 (1992).
    1. Auer S., Grün E., Srama R., Kempf S., Auer R., The charge and velocity detector of the cosmic dust analyzer on Cassini. Planet. Space Sci. 50, 773–779 (2002).