The RBSP Spacecraft Power System Design and Development

The RBSP (Radiation Belt Storm Probes) twin spacecraft are set to launch in August 2012. The spacecraft will be inserted into the highly elliptical regions of high energy particles trapped by the magnetic field of the earth. These regions are often referred to as the Van Allen Belts. The twin spacecraft will operate entirely within the radiation belts throughout their mission. Because of the intense environment of operation and to reduce cost and risk, the approach taken in the power system electronics was to use quasi conventional design, materials, and fabrication techniques encased in a 350mil thick aluminum enclosure. The spacecraft are spin stabilized with an axial boom that creates a shadow across the solar arrays. The power system topology selected was a 28V unregulated direct energy transfer (DET) system using an eight cell Li-Ion battery with cell balance electronics. The solar arrays are electrostatically clean with each string layout for magnetic self-cancellation. The spacecraft instruments electrostatic and magnetic cleanliness requirements impacted the design of the solar array, battery, and power system electronic boxes. The paper will cover the design and development of the RBSP spacecraft Power System including the battery, solar arrays, and the power electronics.