This paper describes key features of the instrument, spacecraft, and mission design for the Precision Optical INTerferometer in Space (POINTS), which have evolved through studies at the Jet Propulsion Laboratory during the last few years. Design of the flight-system configuration has been driven by several considerations. Since the most ambitious science goals require access to a large portion of the sky most of the time, minimal systematic errors, and a 10-year mission life, a high Earth orbit (higher than 50,000 km) is preferred; the nominal has been taken to be a circular orbit of 100,000-km radius. In order to provide a very uniform thermal environment for the instrument, a solar shield supporting an array of solar cells is mounted on a boom and gimballed along two axes so as to remain pointed at the Sun and to provide constant shade for the entire spacecraft. Silicon cells covering about 85% of the roughly 4.8-m-diameter shield and operating at about 100 deg C could supply sufficient power for a 10-year mission life. A unibody design was selected in which the instrument and spacecraft bus are solidly attached to form a single rigid body. Full pointing freedom for the instrument is provided by articulation of the solar shield about two axes plus roll of the entire spacecraft around the Sun direction. With the high orbit and Sun-facing, geometrically simple spacecraft configuration, the effects of solar radiation pressure--the only significant external disturbance to spacecraft acceleration--can be modeled accurately enough to guarantee no compromise in the accurate velocity determination needed to correct astrometric measurements for stellar aberration.