The Microcomputer Spacecraft Thermal Analysis Routines (MSTAR) software package is being developed for NASA/Goddard Space Flight Center by Swales and Associates, Inc. (S&AI). MSTAR is intended to replace the currently used thermal analysis programs SSPTA1, VIEW2, and TRASYS3. These software packages contain solution algorithms developed as much as 25 years ago. Many of the algorithms used in these programs are based on software and hardware available at that time. In recent years, the computer industry has made tremendous technological advances in providing powerful yet inexpensive desktop computers capable of competing with small mainframe computers. In June 1993, SAI completed the Phase I effort on the Small Business Innovative Research (SBIR) contract awarded from NASA to develop MSTAR.