The shape and surface variation of 2 Pallas from the Hubble Space Telescope

B E Schmidt; P C Thomas; J M Bauer; J-Y Li; L A McFadden; M J Mutchler; S C Radcliffe; A S Rivkin; C T Russell; J Wm Parker; S A Stern

doi:10.1126/science.1177734

The shape and surface variation of 2 Pallas from the Hubble Space Telescope

Science. 2009 Oct 9;326(5950):275-8. doi: 10.1126/science.1177734.

Authors

B E Schmidt¹, P C Thomas, J M Bauer, J-Y Li, L A McFadden, M J Mutchler, S C Radcliffe, A S Rivkin, C T Russell, J Wm Parker, S A Stern

Affiliation

¹ Institute of Geophysics and Planetary Physics, University of California, Los Angeles, CA 90095, USA. britneys@ucla.edu

PMID: 19815773
DOI: 10.1126/science.1177734

Abstract

We obtained Hubble Space Telescope images of 2 Pallas in September 2007 that reveal distinct color and albedo variations across the surface of this large asteroid. Pallas's shape is an ellipsoid with radii of 291 (+/-9), 278 (+/-9), and 250 (+/-9) kilometers, implying a density of 2400 (+/-250) kilograms per cubic meter-a value consistent with a body that formed from water-rich material. Our observations are consistent with the presence of an impact feature, 240 (+/-25) kilometers in diameter, within Pallas's ultraviolet-dark terrain. Our observations imply that Pallas is an intact protoplanet that has undergone impact excavation and probable internal alteration.

Publication types

Research Support, U.S. Gov't, Non-P.H.S.