The current fleet of medium/heavy expendable launch vehicles (ELVs) and upper stages are expensive, inflexible, and non‐responsive to the needs of the satellite designer/builder. These transportation systems confine satellite designers to a very narrow operational envelope. If a satellite exceeds its mass budget by even a few percent, mission planners must choose between eliminating instrumentation (reducing the spacecraft’s capabilities) or launching on a larger/more expensive ELV. Many people have suggested the development of a new, less expensive ELV to reduce launch costs. While such a system may eventually repay its development cost, current budgets do not make this approach practical. A new upper stage based on chemical technology is also likely to be expensive, with little performance improvement. In order to significantly improve the cost effectiveness of launch assets, alternate propulsion technologies must be developed. The approach to electrical power system design should also be modified. Currently, a new power system is designed for each new satellite. Each of these new power systems must be thoroughly developed, tested, and integrated into the satellite. While this process has produced extremely reliable power systems, the approach is very costly.An alternate approach, currently under investigation, is the use of a single power system with a standard interface to serve all satellites within a specified power range. This standard power system may also incorporate the stationkeeping functions of the satellite, an approach which has been referred to as the ‘‘common bus.’’ While cost reductions ae possible in both the propulsion and power systems, numerous studies have shown that the combination of power and propulsion into a single system, the Bi‐modal approach, may offer additional benefits as well. These Bi‐modal systems use a single nuclear or solar energy source to serve both the power and propulsion sub‐systems. This paper will provide a preliminary assemment of the application of a solar thermal Bi‐modal system for orbit transfer and on‐orbit management missions in terms of: dependability (reliability and graceful degradation), performance (capacity and quality), availability and responsiveness (orbit response times, flexibility, survivability and launch time), coverage (orbit implications), and resources (affordability, life cycle costs, and supportability). © 1995American Institue of Physics