Very high-speed data links from fast-moving mobile terminals to satellites are attractive in many military applications. In order to provide such high-speed data rates we consider a multiple-input multiple-output (MIMO) free space optical (FSO) system for the earth-to-satellite link. In this case the signal is transmitted via closely-spaced multiple transmit apertures and the receiver consists of multiple apertures. Mobility of the transmit platform will introduce beam pointing errors which will degrade the system performance. In this paper we determine the capacity of this MIMO FSO system in the presence of beam pointing errors for a set of typical operating parameters.