Spitzer Space Telescope - General Observer Proposal #30241


Rotationally-Resolved Surface Mineralogy of an Extinct Comet

Principal Investigator: Humberto Campins
           Institution: University of Central Florida

Co-Investigators: 
Yanga Fernandez, University of Central Florida                        
Joshua Emery, NASA/Ames Research Center                               
Javier Licandro, Instituto de Astrofisica de Canarias                 
Carey Lisse, JHU Applied Physics Laboratory                           

Science Category: asteroids 
 Observing Modes: IrsPeakupImage IrsStare 
  Hours Approved: 3.0 

Abstract:
Object 944 Hidalgo is one of the asteroids most likely to be an
extinct or dormant comet.  Hidalgo's Tisserand invariant (T=2.07)
suggests very strongly that this object originated either in the
Kuiper belt or in the Oort cloud (Weissman et al.  2002).  Our latest
ground based results show significant rotational variability in the
near-infrared spectrum of Hidalgo, but the ground based spectra are
not sufficient to identify the nature of these surface variations.
Spitzer observations of Hidalgo would be diagnostic of the surface
mineralogy, as has been demonstrated for a number of asteroids (e.g.,
Emery et al.  2006).  We propose to obtain 7.3 to 38 micron IRS
spectra of 944 Hidalgo at 8 different rotational phases to
characterize its surface composition and other properties such as
thermal inertia.