Design, Fabrication, and Testing of the Radiation Belt Storm Probes Propulsion Systems

The Radiation Belt Storm Probes spacecraft , part of NASA\textquoterights Living with a Star program, are scheduled for launch into Earth orbit in August 2012. 1,2,3 The twin spacecraft possess identical blowdown monopropellant hydrazine propulsion systems to provide spinup/spindown, precession, Delt a\textendashV, and deorbit capability. Each spacecraft manifests eight Aerojet 0.2 lbf (0.9 N) MR\textendash103G thrust ers, three ARD\ E Inconel 718 propellant tanks, and other components required to control the fl ow of propellant and monitor system health and performance. The propulsion systems were fabricated and installed by Aerojet Redmond and subsequently tested at the Jo hns Hopkins University / Applied Physics Laboratory (APL) in Laurel, MD. The test se quence at APL included thermal balance; end\textendash to\textendashend phasing; leak and functional; mass properties; water load (as a propellant simulant); water\textendashloaded vibration and acoustic testing; water offload; and thermal vacuum operations. This paper will document the design of th e propulsion system, component selection challenges faced, and system\textendashl evel tests performed prior to propellant load and launch.