作者：
Oh, David Y.CALTECH
Jet Prop Lab Astron & Explorat Concepts Grp Pasadena CA 91109 USA
A detailed study examines the potential benefits that advanced electric propulsion technologies offer to cost-capped missions in NASA's Discovery program. The study looks at potential cost and performance benefits...
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A detailed study examines the potential benefits that advanced electric propulsion technologies offer to cost-capped missions in NASA's Discovery program. The study looks at potential cost and performance benefits provided by three electric propulsion technologies that are currently in development: NASA's evolutionary xenon thruster, an enhanced NSTAR system, and a low-power Hall effect thruster. These systems are analyzed on three potential Discovery-class missions and their performance is compared with a state-of-the-art system using the NSTAR ion thruster. An electric propulsion subsystem cost model is used to conduct a cost-benefit analysis for each option. The results show that each proposed technology offers a different degree of performance and/or cost benefit for Discovery-class missions. However, lower subsystem costs (particularly, power processing and digitalcontrolinterface unit costs) are needed for ion thruster systems, to make them more competitive for cost-capped missions. It is observed that the best mass performance generally comes from electric propulsion systems that best use available solar array power during the mission. Finally, first-flight qualification costs are identified as a significant barrier to the implementation of new electric propulsion technologies on cost-capped missions.
The historical background and characteristics of the experimental Rights of ion propulsion systems and the major ground-based technology demonstrations are reviewed, The results of the first successful ion engine Righ...
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The historical background and characteristics of the experimental Rights of ion propulsion systems and the major ground-based technology demonstrations are reviewed, The results of the first successful ion engine Right in 1964, Space Electric Rocket Test (SERT) I, which demonstrated ion beam neutralization, are discussed along with the extended operation of SERT II starting in 1970, These results together with the technologies employed on the early cesium engine Rights, the applications technology satellite series, and the ground-test demonstrations, have provided the evolutionary path for the development of xenon ion thruster component technologies, control systems, and power circuit implementations. In the 1997-1999 period, the communication satellite Rights using ion engine systems and the Deep Space 1 flight confirmed that these auxiliary and primary propulsion systems have advanced to a high level of Right readiness.
Propulsion for the Deep Space One (DS1) spacecraft is provided by a xenon ion engine. Xenon is stored in a supercritical state and is delivered as a low-pressure gas to the thruster and two cathodes (called the main c...
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Propulsion for the Deep Space One (DS1) spacecraft is provided by a xenon ion engine. Xenon is stored in a supercritical state and is delivered as a low-pressure gas to the thruster and two cathodes (called the main cathode and neutralizer) by a xenon feed system (XFS). This mission requires tight constraints on thruster performance, which in turn requires separate and very accurate throttling of the thruster and cathode flows;the DS1 spacecraft is the first of its type to utilize a xenon ion engine that can be throttled. Flow is regulated separately to the thruster and cathodes to an accuracy of +/-3% using three calibrated flow control devices that are each fed by a dedicated plenum tank. Bang-bang regulators are used to control the set pressures in the plena. The resulting XFS control algorithms are quite complex. The XFS is controlled by a digitalcontrolinterface unit and the control algorithm for achieving steady-state xenon flow is presented. The worst-case error in flow is shown to be less than +/-3%, accounting for random and systematic errors. At the time of writing, the individual components are in excellent health and the performance of the XFS is as expected.
The 7.4 kW NEXT-C (NASA's Evolutionary Xenon Thruster - Commercial) gridded ion thruster system provides a combination of performance and spacecraft integration capabilities that make it uniquely suited for deep s...
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ISBN:
(数字)9781624106026
ISBN:
(纸本)9781624106026
The 7.4 kW NEXT-C (NASA's Evolutionary Xenon Thruster - Commercial) gridded ion thruster system provides a combination of performance and spacecraft integration capabilities that make it uniquely suited for deep space robotic missions. With modifications, the NEXT-C system can meet some high total impulse defense and commercial missions as well. The purpose of the NEXT-C flight hardware development program, jointly funded by NASA and Aerojet Rocketdyne, was to establish a commercial supply of the thruster and power processing unit (PPU) for future NASA missions. The program has completed all development and flight production testing and delivered the first shipset of flight hardware to NASA GRC in early 2020 for use on the Applied Physics Laboratory's DART (Double Asteroid Redirection Test) mission. The NEXT system was developed to a readiness approaching TRL 6 in the mid-2000s, followed by characterization and long duration testing at NASA Glenn Research Center. The original NEXT project effort culminated in a long duration life test of 50,000 hours on a NASA EM thruster using Aerojet Rocketdyne high fidelity optics. The thruster is throttleable across a thrust range of approximately 25 to 235mN. Thruster specific impulse ranges from 1400 to 4200sec, depending on the throttle condition. Each NEXT-C thruster is powered by a PPU with an input power of up to 7.4kW. The PPU converts spacecraft power, over an unregulated input voltage range from 80 to 160 volts, to the conditions required to operate the thruster, and also utilizes spacecraft 28 Volt power to operate the PPU's communication and control circuitry. On the NEXT-C program, the component designs have matured to include design updates to increase capability, address issues identified during the development program, and incorporate lessons learned. Aerojet Rocketdyne has completed all program phases of the project, including full protoflight and integration testing of the Engineering Model hardware, Critical De
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