Session
Technical Session V: New Mission Concepts
Abstract
One way to achieve faster and cheaper small satellite missions is to make maximum use of off-the-shelf (OTS) technology. OTS subsystems are found in many small satellite missions, typically configured within a customized mission-specific space frame. Theoretically, costs and time-scales can be cut further by extending the OTS approach to the entire spacecraft, including mechanics, software and operations. This has been the objective of many "modular satellite" programs, including the Surrey Satellite Technology (SSTL) modular microsatellite bus. Since 1990, the basic SSTL bus has been applied to 11 missions carrying a wide variety of payloads into LEO. Inevitably, however, each mission has payload unique requirements that prevent the use of a purely OTS approach. Customers are willing to pay for some "alterations" to their OTS microsatellite, as long as the alterations don't cause unacceptable increases in cost, schedule, and/or performance risk. The initial difficult task for the prime mission contractor, payload customers, and spacecraft supplier is to arrive at a set of modifications which maximize the mission return while minimizing the impact on the cost, schedule, and performance baseline. This process requires a mutual understanding by all parties of the spacecraft's true capabilities as well as the payloads' minimum requirements. It also requires the payload customer to separate "desirements" from "requirements" and be willing to trade-off the former to prevent intolerable increases in cost and schedule. In many cases, with imagination from all parties, this customization process is successful and the resulting mission is still nearly OTS. This paper describes the USAF PICOSat mission, in which the SSTL OTS modular micro satellite was tailored to accommodate four unique science payloads from the U.S. Air Force Space Test Program (STP). This mission was enabled by funding from the Department of Defense Foreign Comparative Test Program. PICOSat, which will be built, integrated, tested and operated by SSTL in England, will carry the Polymer Battery Experiment (PBeX), the Ionospheric Occultation Experiment (lOX), the Coherent Electromagnetic Radio Tomography (CERTO) experiment, and the Optical Precision Platform Experiment (OPPEX), making it one of the most complex microsatellite missions executed to date. The PICOSat mission will run just 18 months between contract signing and launch readiness, including all tailoring of the platform hardware and software to accommodate the payloads-several of which existed prior to the commencement of the program. The methods used to accommodate these payloads and reach a compromise on cost, risk and experimental return are of interest to any group undertaking a multiple-payload small satellite mission based on off-the-shelf technology.
Off-The-Shelf Micro-Satellites for Science and Technology Missions: The USAF PICOSat Mission using the SSTL Modular Microsatellite
One way to achieve faster and cheaper small satellite missions is to make maximum use of off-the-shelf (OTS) technology. OTS subsystems are found in many small satellite missions, typically configured within a customized mission-specific space frame. Theoretically, costs and time-scales can be cut further by extending the OTS approach to the entire spacecraft, including mechanics, software and operations. This has been the objective of many "modular satellite" programs, including the Surrey Satellite Technology (SSTL) modular microsatellite bus. Since 1990, the basic SSTL bus has been applied to 11 missions carrying a wide variety of payloads into LEO. Inevitably, however, each mission has payload unique requirements that prevent the use of a purely OTS approach. Customers are willing to pay for some "alterations" to their OTS microsatellite, as long as the alterations don't cause unacceptable increases in cost, schedule, and/or performance risk. The initial difficult task for the prime mission contractor, payload customers, and spacecraft supplier is to arrive at a set of modifications which maximize the mission return while minimizing the impact on the cost, schedule, and performance baseline. This process requires a mutual understanding by all parties of the spacecraft's true capabilities as well as the payloads' minimum requirements. It also requires the payload customer to separate "desirements" from "requirements" and be willing to trade-off the former to prevent intolerable increases in cost and schedule. In many cases, with imagination from all parties, this customization process is successful and the resulting mission is still nearly OTS. This paper describes the USAF PICOSat mission, in which the SSTL OTS modular micro satellite was tailored to accommodate four unique science payloads from the U.S. Air Force Space Test Program (STP). This mission was enabled by funding from the Department of Defense Foreign Comparative Test Program. PICOSat, which will be built, integrated, tested and operated by SSTL in England, will carry the Polymer Battery Experiment (PBeX), the Ionospheric Occultation Experiment (lOX), the Coherent Electromagnetic Radio Tomography (CERTO) experiment, and the Optical Precision Platform Experiment (OPPEX), making it one of the most complex microsatellite missions executed to date. The PICOSat mission will run just 18 months between contract signing and launch readiness, including all tailoring of the platform hardware and software to accommodate the payloads-several of which existed prior to the commencement of the program. The methods used to accommodate these payloads and reach a compromise on cost, risk and experimental return are of interest to any group undertaking a multiple-payload small satellite mission based on off-the-shelf technology.
