The Deep Space System Technology Program (X2000) is managed by JPL for NASA. The program is designed to provide advanced flight and ground systems for the exploration of the outer planets. The X2000 Integrated First Delivery Project under DSST will provide flight avionics for the first set of mission customers, Europa Orbiter, Pluto/Kuiper Express and Solar Probe. These missions provide a challenge in terms of extreme environmental requirements. The key driving requirements are the one mega-rad total ionizing dose and the fifteen-year life. The X2000 Power System Electronics must reduce its power, mass and volume envelope by incorporating new technology developed by industry partners. The combination of Multi-chip module (MCM) packaging, rad-hard mixed signal application-specific integrated circuits (ASICs) and next-generation-power devices increases the packaging density of the Power System Electronics.