Optimization of the New Horizons Spacecraft Power Demand for a Single Radioisotope Thermoelectric Generator
- Paper number
IAC-06-C3.4.-D3.4.05
- Author
Mr. Chris Hersman, The John Hopkins University Applied Physics Laboratory, United States
- Coauthor
Mr. David Y. Kusnierkiewicz, The John Hopkins University, United States
- Year
2006
- Abstract
On January 19, 2006, an Atlas V 551 launched NASA's New Horizons spacecraft from the Cape Canaveral Air Force Station on the first journey to the last planet in our solar system. After a 9.5-year journey, the spacecraft will reach Pluto and its moons on July 14, 2015. Following this primary mission, the spacecraft intends to continue exploring objects beyond Pluto in the expanse of the Kuiper Belt. On board the spacecraft, a suite of seven scientific instruments provide the capability to image surfaces, determine atmospheric composition, and measure energetic particles and plasma. These instruments and the spacecraft subsystems are powered by a single radioisotope thermoelectric generator (RTG) as the sole source of electrical power for the mission. By using innovative energy-efficient designs, diligent tracking of peak power dissipations, and a flexible mission operations concept, the system engineering team was able to optimize the power demand to the changing output of the RTG. Throughout the development, circumstances beyond the control of the New Horizons project caused the predicted power output of the RTG to fluctuate. Early in the conceptual phase of the project, the proposed F-5 power source was removed from consideration for this mission, which increased the power supply estimates from 180W to 226W after 10 years. Later, a delay in fuel production threatened to reduce the power output of the F-8 power source from the original 226W estimates. An unexpected facility closure further dashed hopes of processing additional fuel for New Horizons. Numerous power saving measures were considered and selected options were implemented to reduce the spacecraft demand below 180W. Finally, fuel from alternate sources along with already allocated fuel eventually increased the projections to 200W. This article presents details of the energy efficient designs on board the spacecraft and how flexibility in the mission operations plans enabled the optimization of the New Horizons spacecraft power demand to the changing power supply predictions. After the first 35 days of the mission, the operations team has completed its commissioning activities for the spacecraft and preliminary results match the power supply and demand predictions for this phase of the mission. All subsystems are performing so well that selected power savings options will likely be modified to utilize some of the additional power margin.
- Abstract document
- Manuscript document
IAC-06-C3.4.-D3.4.05.pdf (🔒 authorized access only).
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