SIMPLE CYLINDRICAL MAP OF ASTEROID 951 GASPRA

Gaspra3.gif is a shaded relief map of asteroid 951 Gaspra, the first
asteroid visited by a spacecraft.  It is the same shaded relief drawing
as Gaspra.gif, reprojected to Simple Cylindrical projection.  As with 
all maps, it is the cartographer's interpretation and not all features 
are necessarily certain given the limited data available - this 
interpretation stretches the data as far as is feasible.  This map has 
not yet been published.

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 the original drawing, 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).  That drawing was reprojected to Simple Cylindrical projection.
Longitudes are measured from the crater Charax, just north of the equator
at the more pointed end of Gaspra.  The Prime Meridian (longitude zero)
is at the centre of this map.  Longitudes increase to the west (left).
North is at the top.

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