Spitzer Space Telescope - General Observer Proposal #20539


High Latitude Dust Bands in the Main Asteroid Belt:  Fingerprints of
Recent Breakup Events

Principal Investigator: William  Bottke
           Institution: Southwest Research Institute

Co-Investigators: 
David Nesvorny, SWRI                                                  
Daniel Durda, SWRI                                                    
Mark Sykes, Planetary Science Institute                               
David Lien, Planetary Science Institute                               
Sumita Jayaraman, Planetary Science Institute                         
Russell Walker, MIRA                                                  
John Stansberry, University of Arizona                                
William Reach, Spitzer Science Center                                 

Science Category: zodiacal dust 
 Observing Modes: MipsScan 
  Hours Approved: 100.2 

Abstract:
The present population of main belt asteroids is largely the result of
many past collisions.  Ideally, the fragments produced by each impact
event could help us understand the collisional processes that shaped
the planets during early epochs.  Most known asteroid fragment
families, however, are very old and thus have undergone significant
collisional and dynamical evolution since their formation.  This
evolution masks the properties of the original collisions.  To
overcome this problem, our team has used numerical methods and a large
database of asteroid orbits to identify several families produced by
recent disruption events (<< few tens of My).  Not only have these
young families undergone little collisional and dynamical evolution,
but several of them appear to be the source of dust bands observed by
IRAS (e.g., the Karin and Veritas families, both which are < 10  My
old;  Nesvorny et al.  2002;  2003).  Here we propose to use Spitzer
observations to investigate the structure of high latitude dust bands
in the main asteroid belt.  Our results indicate that 2 faint dust
bands identified by IRAS, the J/K band at proper inclination i = 12
deg and the M/N band at i = 15 deg, were produced by break up events
associated with asteroids (4652) Iannini and (1521) Seinajoki,
respectively.  Numerical integration work by our team suggests the
former family is < 5 My old, making it the youngest family yet
discovered in the main belt.  Taking advantage of the increased
sensitivity of Spitzer over IRAS, we will determine the dust
production rate and size distribution in the high latitude bands,
relate them to the Zodiacal Cloud, and use this data to constrain main
belt collisional processes.