SHADED RELIEF MAP OF ASTEROID 951 GASPRA

Gaspra.gif is a shaded relief map of asteroid 951 Gaspra, the first
asteroid visited by a spacecraft.  As with all maps, it is the carto-
grapher's interpretation and not all features are necessarily certain 
given the limited data available - this interpretation stretches the data
as far as is feasible.  The full form of this map, with grid etc.,
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)

The latter paper includes a map of radius contours.  I digitized the
contours and interpolated to give a low resolution shape model, then
refined it by fitting it to limbs and terminators in the images.  The
shape model is a matrix of radii at regular increments of latitude and 
longitude.  Positions in the map are controlled by the digital shape 
model.  For this map, the three dimensional convex hull of the shape 
model was projected into the Morphographic Conformal Projection (the 
conventional Stereographic Projection modified for non-spherical worlds).
Longitudes are measured from the crater Charax, just north of the
equator at the more pointed end of Gaspra.

As with all conformal (true shape) projections, the scale in these maps
varies, increasing from the centre to the outer edge.  The map projection
is described in:

Stooke, P.J. and Keller, C.P., 1990.  "Map Projections for Non-Spherical
Worlds / the Variable-Radius Map Projections", CARTOGRAPHICA, V. 27, No.
2, pp. 82-100.

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