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Reflections To The Future
highlights the need for low cost Guidance, Navigation, and Control (GN&C)
systems, suitable for use on simple sounding rockets and vehicles up through
orbital insertion. Microcosm has designed and built such a low cost GN&C
system in support of the NASA-Marshall SR-S sounding rocket. The SR-S concept
is based on earlier Microcosm work toward low cost space programs. In
recognition that launch vehicle development costs plus operational costs far
exceed unit build costs, all costs, including the GN&C overall life-cycle
cost, were attacked. Design of a GN&C system that truly minimizes cost
required that development and operational aspects be part of the design cost.
This, in turn, required a clean-sheet approach, resulting in adoption and use
of Commercial-Off-The-Shelf (COTS) components, hardware and software
technology. The GN&C modularity concept calls for changes in configuration
from vehicle to vehicle to be cable/interconnected-enabled, and changes from
mission to mission to be software-enabled. This concept called for innovation,
with modular design that avoided expensive and complicated integration and
optimization. Several interesting technological approaches are described in
this paper: 1.) use of GPS technology, 2.) use of reusable Generic Guidance
Navigation and Control system, 3.) a special purpose Digital Flight Computer of
general capability, combining the Flight Computer with smart, distributed
Electronic Controllers, and 4.) a cost-conscious system design and development
strategy. The system design and development strategy involved choosing
components that, together, provide the lowest life-cycle cost with adequate
performance. Modularity and scaleability principles are described which promise
future reusability at system, equipment, module, and component levels,
including dual-string reliability for orbital launches. |
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