Low Cost ESPA Based Satellite Bus

Busek and MSI propose to develop an ESPA-based satellite bus with standard mechanical, electrical, and logical interfaces.  This bus will service up to five dependent payloads attached to the ESPA ring.  Power, electrical, logical, and communication needs will be provided by an Avionics Module (AM) also attached to the ring.  The AM will leverage hardware developed by MSI for the DSX mission.  Delta-V will be provided by a Propulsion Module (PM) fitting within the circumference of the ring.  The baseline PM will use COTS feed system components and Busek Hall thrusters.  The architecture is modular, and can be configured to optimize mass, cost, or performance based on mission needs.  The recurring cost target is $5M.  The dry mass target for the AM and PM is 200 kg.  Almost 1.2 km/s of delta-V will be available from a 1330 kg wet mass system including the ESPA sat and five 181 kg payloads. In Phase I, we will define a CONOPS, detail the architecture, and identify requirements and interfaces.  We will analyze and baseline subsystem components that result in rapid, low cost development.  Finally, we will develop a Phase II program plan that identifies critical design analysis, procurements, and development efforts.   BENEFIT: The proposed system will provide bus functions, including propulsion, for up to five ESPA-class payloads (up to 181 kg) attached to the ESPA ring.  These dependent payloads could be sourced from DoD, NASA, universities, or industry.  An electric prolusion module will enable the system to ferry the payloads between widely varying orbits. In the nominal EELV configuration, the Avionics Module will be attached to the outside of the ESPA ring.  With larger propellant tanks and additional thrusters, this system could provide enough delta V to ferry ESPA payloads to an asteroid, the moon, Venus, or Mars.  This would be of great interest to NASA.  A derived configuration where the avionics and propulsion modules are stacked on top of each other could be used on smaller launch vehicles such as Taurus.   The system could also be used as an upper stage for primary payloads (located above the ESPA ring in the stack).  A flight proven, low cost, electric upper stage could generate significant commercial business for Busek. The ESPA-sat development program will directly benefit AFRLs existing efforts to develop an ESPA Orbit Maneuvering System (OMS) that would deliver independent payloads to different orbits, where they would be detached and left behind.  Unlike the ESPA-sat, the OMS would not provide bus functions to its payloads.  However, the OMS concept also requires avionics and propulsion modules, both of which could be derived from the ESPA-sat.  The ESPA-sat and OMS programs would be highly synergistic.