Clump Detections and Limits on Moons in Jupiter's Ring System
Mark R. Showalter,1*
Andrew F. Cheng,2,3
Harold A. Weaver,3
S. Alan Stern,2
John R. Spencer,4
Henry B. Throop,4
Emma M. Birath,4
Debi Rose,5
Jeffrey M. Moore6
The dusty jovian ring system must be replenished continuously
from embedded source bodies. The New Horizons spacecraft has
performed a comprehensive search for kilometer-sized moons within
the system, which might have revealed the larger members of
this population. No new moons were found, however, indicating
a sharp cutoff in the population of jovian bodies smaller than
8-kilometer-radius Adrastea. However, the search revealed two
families of clumps in the main ring: one close pair and one
cluster of three to five. All orbit within a brighter ringlet
just interior to Adrastea. Their properties are very different
from those of the few other clumpy rings known; the origin and
nonrandom distribution of these features remain unexplained,
but resonant confinement by Metis may play a role.
2 NASA Headquarters, Washington, DC 20546, USA.
3 Applied Physics Laboratory, Johns Hopkins University, 11100 Johns Hopkins Road, Laurel, MD 20723, USA.
4 Southwest Research Institute, 1050 Walnut Street, Suite 300, Boulder, CO 80302, USA.
5 Synthsys-D, 1200 South Riverbend Court, Superior, CO 80027, USA.
6 NASA Ames Research Center, Moffett Field, CA 94035, USA.
* To whom correspondence should be addressed. E-mail: mshowalter{at}seti.org
