The Role of Small Satellites in NASA and NOAA Earth Observation Programs (2000) / Chapter Skim
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6 Small Satellites and Mission Architectures
6 Small Satellites and Mission Architectures
Pages 41-50
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From page 41... ...
They typically require shorter mission development times (24 to 36 months) and can thus employ more current technology and deliver faster "time to science." A complement of sensors on multiple small satellites can be launched sequentially as budgets and schedules permit; and, in the case of a failed sensor, a direct replacement satellite can be launched without having to deal with residual assets on a multisensor platform.]
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From page 42... ...
This is always desirable when the measurements are complementary and is in some cases essential if full value of the data is to be realized. While single-sensor platforms provide the greatest mission flexibility, multisensor platforms have a higher probability of delivering an equivalent number of sensors to orbit because they require fewer launches and use more reliable launch vehicles (e.g., Delta, Atlas)
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From page 43... ...
COST-EFFECTIVENESS OF SMALL SATELLITE ARCHITECTURES One of the key factors driving the strong current interest in small satellites is a desire to reduce mission costs, largely as a result of very severe budget pressures. When discussing small satellite mission costs, it is important to distinguish between small (low-cost)
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From page 44... ...
. Employing single-sensor satellites to replace failed sensors on multisensor platforms avoids creating residual assets but involves similar operational complexities and, if sustained as a strategy, ultimately leads to a complete single-sensor platform architecture.
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From page 45... ...
Each system has a cost and average availability determined by the reliability and design lives assumed for the sensors and spacecraft bus, 7This study did not include the ground segment in mission cost trade-offs. It is likely that ground segment costs increase with a larger number of satellites in orbit and that the trends in the study results, which show life cycle cost advantages for multisensor satellites, would be sustained and possibly amplified by including them.
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From page 46... ...
Earlier, it was demonstrated that the cost to deliver a given set of sensors to orbit favored the use of multisensor satellites. Here we see that the cost versus availability results again favor larger satellite architectures because of the sensor and satellite bus reliability assumptions and fewer anticipated launch failures.
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From page 47... ...
Figure 6.3 shows the relative mission costs, using the same element cost assumptions as the operational weather system (POES) , and again normalized to the single, Delta class satellite case.
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From page 48... ...
The probability of completing the 5-year mission with a specific number of failures is shown in Figure 6.5 for each architecture. If mission success requires that at least three of the four sensors be operational over the full 5 years, then the single Delta class satellite is the most effective architecture in terms of having the highest probability of success.
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From page 49... ...
Clusters or constellations of small satellites may require additional ground station elements or spacecraft data crosslinks, in addition to more challenging mission operations planning, to accommodate increased communication, command, and control requirements. Cost trade-offs for single- versus multisensor platforms and for single- versus multisatellite architectures are driven by the costs, reliabilities, and design lives of the system elements (sensors, spacecraft buses, launch vehicles, ground segments)
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From page 50... ...
The Johns Hopkins University Applied Physics Laboratory, American Institute of Aeronautics and Astronautics/Utah State University Conference on Small Satellites, Utah State University, Logan. Rasmussen, A., and R
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