  LAGEOS is an accurately-tracked, dense spherical satellite covered with 426
retroreflectors. The tracking accuracy is such as to yield a medium term (years
to decades) inertial reference frame determined via relatively inexpensive
observations. This frame is used as an adjunct to the more difficult and data
intensive VLBI absolute frame measurements. There is a substantial secular
precession of the satellite's line of nodes consistent with the classical,
Newtonian precession due to the non-sphericity of the earth. Ciufolini has
suggested the launch of an identical satellite (LAGEOS-3) into an orbit
supplementary to that of LAGEOS-1: LAGEOS-3 would then experience an equal and
opposite classical precession to that of LAGEOS-1. Besides providing a more
accurate real-time measurement of the earth's length of day and polar wobble,
this paired-satellite experiment would provide the first direct measurement of
the general relativistic frame-dragging effect. Of the five dominant error
sources in this experiment, the largest one involves surface forces on the
satellite, and their consequent impact on the orbital nodal precession. The
surface forces are a function of the spin dynamics of the satellite.
Consequently, we undertake here a theoretical effort to model the spin
ndynamics of LAGEOS. In this paper we present our preliminary results.
