[meteorite-list] SwRi Research Reveals New Kuiper Belt Satellite Mystery

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu Apr 22 10:08:24 2004
Message-ID: <200209111528.IAA00090_at_zagami.jpl.nasa.gov>

http://www.swri.org/9what/releases/KBMystery.htm

Southwest Research Institute (SwRI) News

SwRI research reveals new Kuiper Belt satellite mystery

Boulder, Colorado -- September 10, 2002 -- The Kuiper Belt region of the
solar system, which stretches from just past Neptune to beyond the
farthest reaches of Pluto's orbit, was only discovered in 1992, but
continues to reveal new knowledge into the formation processes of the
planets. Now, in a paper to be published in the October issue of The
Astronomical Journal, a Southwest Research Institute (SwRI) scientist
reveals a new mystery about Kuiper Belt Objects (KBOs).

The study examined the formation of KBO satellites, which have been
observed only since 2001 and continue to be discovered around an
unexpectedly large number of the more than 500 known KBOs.

"In just over a year since the first satellite of a KBO was found,
scientists have discovered a total of seven KBO satellites. Surprisingly,
observations by both ground-based telescopes and the Hubble Space
Telescope have indicated that, in many cases, the KBO satellites are as
large or nearly as large as the KBOs around which they orbit," says Dr. S.
Alan Stern, director of the SwRI Space Studies Department. "That so many
binary or quasi-binary KBOs exist came as a real surprise to the research
community."

The focus of Stern's work was not observational in nature, but rather it
sought to understand how such large KBO-satellite pairs could form. The
standard model for large satellite formation is based on collisions
between an interloping body and the parent object around which the
satellite orbits. This model has successfully explained binary systems
around asteroids and the Pluto-Charon system, and also has direct
relevance to the formation of the Earth-moon system.

Stern's findings call into question the formation of KBO satellites by
standard collisional processes. Collisions of the magnitude required,
Stern found, appear to be energetically improbable, given the number and
masses of potential impactors in both the ancient (more massive) and
modern day (eroded) Kuiper Belts.

This likely implies one of two alternatives: Either KBO satellites were
not formed by collisions, as has been commonly assumed, or the surface
reflectivities (which help determine size) of KBOs with satellites, or the
reflectivity of the satellites themselves, have been significantly
underestimated.

"If the surfaces of KBOs with satellites, or the satellites themselves,
are more reflective than previously thought," says Stern, "These objects
would be smaller and less massive, and would therefore require smaller,
less energetic impacts to create the satellite systems we see."

NASA's new Space Infrared Telescope Facility (SIRTF), set for launch early
next year, will help resolve these two alternatives, Stern says, by
directly measuring the reflectivities and sizes of numerous KBOs,
including those with satellites.

In addition to this work, Stern serves as principal investigator of the
NASA New Horizons mission to Pluto and the Kuiper Belt. Expected to launch
in January 2006, this spacecraft will make the first ever flyby
reconnaissance of the Pluto-Charon system and then go on to explore KBOs
as it leaves the solar system. New Horizons is the only NASA mission
planned to study Kuiper Belt Objects at close range.

The NASA Origins of Solar Systems program provided funding for this
research.

EDITORS: An image to accompany this story is available from
www.swri.org/press/kbo.htm, or download a preprint of "Implications
Regarding the Energetics of the Collisional Formation of Kuiper Belt
Satellites" from xxx.lanl.gov/html/astro-ph/0206104.

RESOURCES:

The Astronomical Journal - www.astro.washington.edu/astroj

Kuiper Belt Objects - www.solarviews.com/eng/kuiper.htm

Space Infrared Telescope Facility (SIRTF) - sirtf.caltech.edu

New Horizons Pluto-Kuiper Belt mission - pluto.jhuapl.edu

SwRI Space Studies Department (Boulder) - www.boulder.swri.edu

For more information, contact Maria Martinez, Communications, Phone (210)
522-3305, Fax (210) 522-3547, PO Drawer 28510, San Antonio, Texas
78228-0510.
Received on Wed 11 Sep 2002 11:28:53 AM PDT