Session
Technical Session XI: The Technology Frontier-- Advanced Technologies, Subsystems, and components for Small Satellites: Section II
Abstract
Potential civilian and government users have expressed a strong interest in CubeSat class satellites for military, scientific and commercial purposes. The U.S. Air Force Research Laboratories (AFRL), using DARPA funding, have contracted with The Aerospace Corporation in El Segundo, California to develop a CubeSat class spacecraft called the MEMS PicoSat Inspector (MEPSI). In turn, AFRL and Aerospace Corporation selected VACCO to provide a Micro-Propulsion System (MiPS) for MEPSI. This paper describes the resulting system design and its capabilities. Related micro-propulsion activities will also be reviewed including work with AeroAstro Inc. to develop an advanced MiPS using decomposing nitrous oxide as the propellant. The VACCO Micro-Propulsion System is an advanced subsystem based on our proprietary Chemically Etched Micro Systems (ChEMS) integrated fluidic circuit technology (patent #6,334,301). Extremely flexible and easily expanded, MiPS can be adapted to a wide range of small spacecraft. The current isobutane unit can deliver 34 Newton-seconds of total impulse with over 61,000 minimum impulse bit firings. MiPS brings true propulsion capabilities to micro-spacecraft for formation flying, attitude control and velocity change (delta-V). Reliability features such as all-welded titanium construction and redundant soft-seat microvalves compliment the simple selfpressurizing design. Instead of simply creating a miniature version of a conventional system, VACCO has taken a highly integrated system level approach that eliminates all tubing connections in favor of a single ChEMS manifold. When combined with our system-in-a-tank packaging design, the resulting propulsion system is a significant advancement over published alternatives. VACCO’s ChEMS Micro-Propulsion System is a titanium weldment about half the size of a VHS videocassette. Four ChEMS 55 mN Micro-Thrusters are located around the periphery of the module tilting 15o toward the mounting plane. A single axial 55 mN Micro-Thruster is located in the center of the XY plane. The axial Micro-Thruster nozzle doubles as a fill/vent port for the system. Two sets of connector pins protrude from the Tank through glass headers to retain pressure while making electrical connections to the host MEPSI spacecraft. One flight MiPS unit has been designed, built and tested at both VACCO and Aerospace Corporation. This paper will describe the MiPS in sufficient detail for potential users to perform a preliminary assessment against their requirements. Performance test data will be presented and conclusions drawn. Lessons learned and future development plans will also be delineated. VACCO will also outline a plan for making MiPS available for University CubeSat projects. The idea is to build a number of sets of MiPS parts less the core assembly. The core assembly controls all component interconnections and tangential thruster geometry. These critical features could be designed by the student team in order to customize MiPS for their purposes. By stocking the machined parts, lead times can be reduced to less than four months. In this way, students can gain valuable skills and experience while keeping the entire project to less than one-year in duration. In addition to providing a learning experience, students would benefit from the enhanced capability and flexibility propulsion would bring to their CubeSat design.
Presentation Slides
A Cold Gas Micro-Propulsion System for CubeSats
Potential civilian and government users have expressed a strong interest in CubeSat class satellites for military, scientific and commercial purposes. The U.S. Air Force Research Laboratories (AFRL), using DARPA funding, have contracted with The Aerospace Corporation in El Segundo, California to develop a CubeSat class spacecraft called the MEMS PicoSat Inspector (MEPSI). In turn, AFRL and Aerospace Corporation selected VACCO to provide a Micro-Propulsion System (MiPS) for MEPSI. This paper describes the resulting system design and its capabilities. Related micro-propulsion activities will also be reviewed including work with AeroAstro Inc. to develop an advanced MiPS using decomposing nitrous oxide as the propellant. The VACCO Micro-Propulsion System is an advanced subsystem based on our proprietary Chemically Etched Micro Systems (ChEMS) integrated fluidic circuit technology (patent #6,334,301). Extremely flexible and easily expanded, MiPS can be adapted to a wide range of small spacecraft. The current isobutane unit can deliver 34 Newton-seconds of total impulse with over 61,000 minimum impulse bit firings. MiPS brings true propulsion capabilities to micro-spacecraft for formation flying, attitude control and velocity change (delta-V). Reliability features such as all-welded titanium construction and redundant soft-seat microvalves compliment the simple selfpressurizing design. Instead of simply creating a miniature version of a conventional system, VACCO has taken a highly integrated system level approach that eliminates all tubing connections in favor of a single ChEMS manifold. When combined with our system-in-a-tank packaging design, the resulting propulsion system is a significant advancement over published alternatives. VACCO’s ChEMS Micro-Propulsion System is a titanium weldment about half the size of a VHS videocassette. Four ChEMS 55 mN Micro-Thrusters are located around the periphery of the module tilting 15o toward the mounting plane. A single axial 55 mN Micro-Thruster is located in the center of the XY plane. The axial Micro-Thruster nozzle doubles as a fill/vent port for the system. Two sets of connector pins protrude from the Tank through glass headers to retain pressure while making electrical connections to the host MEPSI spacecraft. One flight MiPS unit has been designed, built and tested at both VACCO and Aerospace Corporation. This paper will describe the MiPS in sufficient detail for potential users to perform a preliminary assessment against their requirements. Performance test data will be presented and conclusions drawn. Lessons learned and future development plans will also be delineated. VACCO will also outline a plan for making MiPS available for University CubeSat projects. The idea is to build a number of sets of MiPS parts less the core assembly. The core assembly controls all component interconnections and tangential thruster geometry. These critical features could be designed by the student team in order to customize MiPS for their purposes. By stocking the machined parts, lead times can be reduced to less than four months. In this way, students can gain valuable skills and experience while keeping the entire project to less than one-year in duration. In addition to providing a learning experience, students would benefit from the enhanced capability and flexibility propulsion would bring to their CubeSat design.
