Small Satellites and Dust in the Pluto System: Upper Limits and Implications
Abstract
To help ensure safe passage of the New Horizons (NH) spacecraft as it flew through the Pluto system, we took a series of deep images with the Long Range Reconnaissance Imager (LORRI) to search for previously undetected satellites or rings. We obtained a total of 1100 10-second exposures, spread over 20 epochs between May 11 and July 1 2015. HST observations had previously set an upper limit to the brightness of undetected moons of about half Styx's brightness (i.e., a diameter of ~5 km for an a Charon-like albedo of 0.38). The final NH observations in early July could have detected objects down to ~1.5 km in diameter in the Charon - Hydra region, and ~2 km between Charon's orbit and ~5000 km above Pluto's surface. Despite the sensitivity of the searches, no additional moons were found. The lower limit on the brightness ratio between Styx and any undiscovered fainter satellites, ~20, is comparable to the brightness ratio between Nix and Kerberos (~16), and a power-law satellite size distribution, analogous to that seen in the Saturn system, cannot be ruled out. Implications of the satellite size distribution for the origin of the satellite system will be discussed. The data also place an upper limit of ~1 x 10-7 on the I/F of any dust rings in the vicinity of the known small satellites, a factor of several improvement over previous HST limits. This work was supported by NASA’s New Horizons project.
- Publication:
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AAS/Division for Planetary Sciences Meeting Abstracts #47
- Pub Date:
- November 2015
- Bibcode:
- 2015DPS....4710105S