A report describes the ACS Design Tool - a Macintosh- and PC-based computer program for evaluating conceptual designs of a spacecraft attitude-control system (ACS) within a computation time of about 15 minutes. Services provided by the program include computation of ACS performance and sizing of ACS equipment for 3-axis gravity-gradient- and spin-stabilized spacecraft; computation of pointing jitter; computation of star-acquisition probabilities; computations of inertial quantities; radiation-shielding computations; transformation of attitude coordinate frame; con- version of units of measure; estimation of cost of an ACS at either of two different levels of complexity and accuracy; information on project definitions and standards; and data bases on celestial bodies, thrusters, ACS equipment lists, and costs for JPL missions. Developed within the Microsoft Excel software environment, this program provides easy-to- use graphical user interfaces (GUIs), including pull-down menus, scroll/increment buttons, and general buttons. The program consists of six collections of subprograms, which are summarized in the report. The report includes examples of GUI displays for all of the subprograms.

This work was done by Kenneth Lau, Edward Swenka, G. Mark Brown, Edward Mettler, Tooraj Kia, Samuel Sirlin, David Bayard, Fred Hadaegh, Edward Wong, John Lai, and Brian Cox of Caltech for NASA's Jet Propulsion Laboratory. NPO-20298