The design of the Space Station Platforms incorporates and expands on the serviceability and modularity features of the Multi-mission Modular Spacecraft (MMS). This design is adaptable to a wide range of mission requirements through the use of distributed systems with sizing granularity applicable to both multi-use missions, such as earth observations, and large facility missions such as astrophysics observatories. The design permits on-orbit growth, repair, instrument change-out, and resupply of propulsion fuel and cryogen at the Space Station Servicing Facility or with the Shuttle and Orbital Maneuvering Vehicle (OMV). The Platform Program encompasses the design and development of the orbiting unmanned elements of the Space Station to conduct long-term, autonomous, commercial, scien-tific, and technology ventures and investigations. These unmanned elements fall into two general classes of platforms: the Co-Orbiting Platform (COP) and the Polar Orbiting Platform (POP). The COP for the initial operating phase will be developed to support solar and stellar viewing astrophysics missions. The POP will be developed to accommodate earth observation, oceanographic, atmospheric, and solar and plasma physics missions. Current Shuttle payload capability limitations at the Western Test Range (WTR) place a restriction on another objective of platform designs for polar applications, which is to accomplish meaningful science or payload operations after one launch. For this reason, the POP will also be designed to be launched using Expendable Launch Vehicles (ELV's). Features of the Space Station Co-Orbiting and Polar Platforms are described that will allow them to be con-figured optimally to meet mission requirements and to be assembled, serviced, and modified on-orbit.