GEOMORPHOLOGICAL/GEOLOGICAL MAP OF ASTEROID 951 GASPRA

this is an experimental geological map of asteroid 951 Gaspra, the first
asteroid visited by a spacecraft.  As with all maps, it is the carto-
grapher's interpretation.  Basic information about Gaspra 
appears in:

Stooke, P.J., 1997.  The Surface of Asteroid 951 Gaspra.  (Earth,
   Moon & Planets, 75:53-75)

Gaspra was observed by the Galileo spacecraft on 29 October 1991.
Images are described in:

Veverka, J., et al., 1994.  'Galileo's Encounter with 951 Gaspra: Overview'
   (Icarus, 107:2-17)

and:

Thomas, P.C. et al., 1994.  'The Shape of Gaspra'  (Icarus, 107:23-36)

I have been developing concepts for geological mapping of asteroids.
In this case, 'rough terrain' is covered with craters up to 3 km across 
and numerous long shallow valleys ('grooves'), probably the surface 
expressions of fractures in the solid interior.  Smooth terrain is a 
thick layer of 'soil' (regolith) which is blasted out of craters elsewhere 
on Gaspra and preferentially accumulates on surfaces that face forwards 
as the asteroid rotates.  It covers up the rough terrain in these areas.  
Intermediate terrain is a thinner layer of the same regolith deposit.

This version of the file, with labels intact, is in the public domain.

Philip Stooke,
Department of Geography,
University of Western Ontario,
London, Ontario, Canada N6A 5C2
stooke@sscl.uwo.ca