No abstract

Agile system engineering practices have matured for software projects while hardware system engineering continues to embrace classical development techniques. High technology projects require innovative solutions to meet the restrictions of cost and schedule and still deliver high performance critical systems. This paper addresses the application of the flexible style of agile systems engineering for dynamic, complex hardware and software projects. These projects can benefit from applying the principles of agile systems engineering as has been demonstrated in the software realm. Fundamental to the rapid development is understanding the role of innovation and momentum in agile project management and systems engineering. For post industrial age projects that require non proven concepts, large degrees of uncertainty and ambiguity and extensive non-recurring engineering, agile systems engineering allows for project development with continuous change while addressing risk.Agile systems engineering exploits the role of momentum to allow innovation in the development process while allowing risk interactions to be managed in a disciplined manner. Examples of how these concepts were used on the design and development of two small satellites at The Johns Hopkins University Applied Physics Laboratory (JHU/APL) in the Multi-Mission Bus Demonstrator (MMBD) project. This challenging satellite build did not use existing key technology (heritage hardware) and created a large paradigm shift from traditional satellite development. Rapid design and development, a "momentum play", was used to continuously allow change and assessment in a hardware adaptation of the SCRUM technique seen in Extreme Programming. The MMBD project demonstrates the adaptation of these agile concepts. By freezing late in the design cycle, the MMBD project was able to insert innovations throughout the program cycle. The ability to be innovative related to the speed with which the development progressed, including working quickly through all technology choices. This paper discusses agile systems engineering as applied to both software and hardware. Short of papers on embedded systems using agile systems engineering, there are too few projects demonstrating these adaptations of techniques to complex, innovative hardware projects. The Multi-Mission Bus Demonstrator is an excellent benchmark example of program management of rapid technology maturity in a high technology application. This paper demonstrates how agile systems engineering techniques can be adapted to a high technology development program and shows how project momentum was critical to separate the constant non-recurring technology challenges to be worked rapidly from the engineering risk liens requiring longer time frames to retire.

No abstract

Future space missions will include constellations of spacecraft, including nano-and picosatellites, where adaptive thermal control systems will be needed that fit the constraints of space applications with limited power and mass budgets. A microelectromechanical systems (MEMS) solution has been developed that will vary the emissivity on the surface of the small satellite radiator. The system is based on louver thermal controllers, where panels are mechanically positioned to modulate the effective radiator surface area. This system consists of MEMS arrays of gold-coated sliding shutters, fabricated with the Sandia ultraplanar, multilevel MEMS technology fabrication process, which utilizes multilayer polycrystalline silicon surface micromachining. The shutters can be operated independently to allow digital control of the effective emissivity. This first demonstrator technology is limited in the possible emittance range to a 40% change. Early prototypes of MEMS louvers that open away from the structure have shown the capability of a much wider dynamic range. The first generation of this active thermal management system will be demonstrated on NASA's New Millennium Program ST-5 spacecraft. With the opportunity to validate the MEMS thermal control technology in space on ST-5, lightweight, low-power MEMS radiators offer a possibility for flexible thermal control on future nanosatellites.

Abstract. The advent of very small satellites, such as nano and microsatellites, logically leads to a requirement for smaller thermal control subsystems. In addition, the thermal control needs of the smaller spacecraft/instrument may well be different from more traditional situations. For example, power for traditional heaters may be very limited or unavailable, mass allocations may be severely limited, •and fleets of nano/microsatellites will require a generic thermal design as the cost of unique designs will be prohibitive. Some applications may require significantly increased power levels while others may require extremely low heat loss for extended periods. Small spacecraft will have low thermal capacitance thus subjecting them to large temperature swings when either the heat generation rate changes or the thermal sink temperature changes. This situation, combined with the need for tighter temperature control, will present a challenging situation during transient operation. The use of "off-the-shelf' commercial spacecraft buses for science instruments will also present challenges. Older thermal technology, such as heaters, thermostats, and heat pipes, will almost certainly not be sufficient to meet the requirements of these new spacecraft/instruments. They are generally too heavy, not scalable to very small sizes, and may consume inordinate amounts of power. Hence there is a strong driver to develop new technology to meet these emerging needs. Variable emittance coatings offer an exciting alternative to traditional control methodologies and are one of the technologies that will be flown on Space Technology 5, a mission of three microsatellites designed to validate "enabling" technologies. Several studies have identified variable emittance coatings as applicable to a wide range of spacecraft, and to potentially offer substantial savings in mass and/or power over traditional approaches. This paper discusses the development of the variable emittance thermal suite for ST-5. More specifically, it provides a description of and the infusion and validation plans for the variable emittance coatings.

The Multi Mission Bus Demonstrator (MBD) is a successful demonstration of agile program management and system engineering in a high risk technology application where utilizing and implementing new, untraditional development strategies were necessary. MBD produced two fully functioning spacecraft for a military/DOD application in a record breaking time frame and at dramatically reduced costs. This paper discloses the adaptation and application of concepts developed in agile software engineering to hardware product and system development for critical military applications. This challenging spacecraft did not use existing key technology (heritage hardware) and created a large paradigm shift from traditional spacecraft development.The insertion of new technologies and methods in space hardware has long been a problem due to long build times, the desire to use heritage hardware, and lack of effective process. The role of momentum in the innovative process can be exploited to tackle ongoing technology disruptions and allowing risk interactions to be mitigated in a disciplined manner. Examples of how these concepts were used during the MBD program will be delineated. Maintaining project momentum was essential to assess the constant non recurring technological challenges which needed to be retired rapidly from the engineering risk liens. Development never slowed due to tactical assessment of the hardware with the adoption of the SCRUM technique. We adapted this concept as a representation of mitigation of technical risk while allowing for design freeze later in the program's development cycle. By using Agile Systems Engineering and Management techniques which enabled decisive action, the product development momentum effectively was used to produce two novel space vehicles in a fraction of time with dramatically reduced cost.

No abstract

No abstract