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Williams, D. F.

Publications and source records attributed to Williams, D. F..

Users manual for the IMA program

The Impulsive Mission Analysis (IMA) computer program provides a user-friendly means of designing a complete Earth-orbital mission profile using an 80386-based microcomputer. The IMA program produces a trajectory summary, an output file for use by the new Simplex Computation of Optimum Orbital Trajectories (SCOOT) program, and several graphics, including ground tracks on a world map, altitude profiles, relative motion plots, and sunlight/communication timelines. The user can design missions using any combination of three basic types of mission segments: double co-eliptic rendezvous, payload delivery, and payload de-orbit/spacecraft recovery. Each mission segment is divided into one or more transfers, and each transfer is divided into one or more legs, each leg consisting of a coast arc followed by a burn arc.

Williams, D. F.

An evaluation of Landsat 3 RBV imagery for an area of complex terrain in Southern Italy

Return Beam Videcon imagery from Landsat 3 was obtained in August, 1978 for part of Southern Italy in the regions of Basilicata and Apulia. The resolution of this imagery for medium contrast objects is approximately 40 meters and is shown to provide significant information concerning land cover and fluvial morphometry. Because of the wide spectral band width which is sensed (0.505-0.750 microns) by the RBV cameras, discrimination is only possible for spectrally distinct cover types, especially oak woodland. Fluvial morphometry can be readily described using the imagery. Because of the intense dissection of the area, the lowest order streams cannot be consistently mapped, but the rank order of the measured values of properties such as drainage density and link frequency for different lithologies corresponds closely to the actual ranking.

Townshend, J. R. G.