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At least 19 records

Development Efforts Expanded in Ion Propulsion: Ion Thrusters Developed With Higher Power Levels

The NASA Glenn Research Center was the major contributor of 2-kW-class ion thruster technology to the Deep Space 1 mission, which was successfully completed in early 2002. Recently, NASA s Office of Space Science awarded approximately $21 million to Glenn to develop higher power xenon ion propulsion systems for large flagship missions such as outer planet explorers and sample return missions. The project, referred to as NASA's Evolutionary Xenon Thruster (NEXT), is a logical follow-on to the ion propulsion system demonstrated on Deep Space 1. The propulsion system power level for NEXT is expected to be as high as 25 kW, incorporating multiple ion thrusters, each capable of being throttled over a 1- to 6-kW power range. To date, engineering model thrusters have been developed, and performance and plume diagnostics are now being documented. The project team-Glenn, the Jet Propulsion Laboratory, General Dynamics, Boeing Electron Dynamic Devices, the Applied Physics Laboratory, the University of Michigan, and Colorado State University-is in the process of developing hardware for a ground demonstration of the NEXT propulsion system, which comprises a xenon feed system, controllers, multiple thrusters, and power processors. The development program also will include life assessments by tests and analyses, single-string tests of ion thrusters and power systems, and finally, multistring thruster system tests in calendar year 2005. In addition, NASA's Office of Space Science selected Glenn to lead the development of a 25-kW xenon thruster to enable NASA to conduct future missions to the outer planets of Jupiter and beyond, under the High Power Electric Propulsion (HiPEP) program. The development of a 100-kW-class ion propulsion system and power conversion systems are critical components to enable future nuclear-electric propulsion systems. In fiscal year 2003, a team composed of Glenn, the Boeing Company, General Dynamics, the Applied Physics Laboratory, the Naval Research Laboratory, the University of Wisconsin, the University of Michigan, and Colorado State University will perform a 6-month study that will result in the design of a 25-kW ion thruster, a propellant feed system, and a power processing architecture. The following 2 years will involve hardware development, wear tests, single-string tests of the thruster-power circuits and the xenon feed system, and subsystem service life analyses. The 2-kW-class ion propulsion technology developed for the Deep Space 1 mission will be used for NASA's discovery mission Dawn, which involves maneuvering a spacecraft to survey the asteroids Ceres and Vesta. The 6-kW-class ion thruster subsystem technology under NEXT is scheduled to be flight ready by calendar year 2006. The less mature 25- kW ion thruster system under HiPEP is expected to be ready for a flight advanced development program in calendar year 2006.

Patterson, Michael J.

Ion propulsion cost effectivity

Ion propulsion modules employing 8-cm thrusters and 30-cm thrusters were studied for Multimission Modular Spacecraft (MMS) applications. Recurring and nonrecurring cost elements were generated for these modules. As a result, ion propulsion cost drivers were identified to be Shuttle charges, solar array, power processing, and thruster costs. Cost effective design approaches included short length module configurations, array power sharing, operation at reduced thruster input power, simplified power processing units, and power processor output switching. The MMS mission model employed indicated that nonrecurring costs have to be shared with other programs unless the mission model grows. Extended performance missions exhibited the greatest benefits when compared with monopropellant hydrazine propulsion.

Zafran, S.

Ion propulsion cost effectivity

Ion propulsion modules employing 8 cm thrusters and 30 cm thrusters were studied for Multimission Modular Spacecraft (MMS) applications. Recurring and non-recurring cost elements were generated for these modules. As a result, ion propulsion cost drivers were identified to be Shuttle charges, solar array, power processing, and thruster costs. Cost effective design approaches included short length module configurations, array power sharing, operation at reduced thruster input power (reduced solar array size), simplified power processing units, and power processor output switching.

Zafran, S.

Implementation of the dawn ion propulsion system

The Dawn ion propulsion system (IPS) was intended to be simply a larger version of the ion propulsion system that flew on Deep Space 1 (DS1). Implementation of this system to meet the needs of the Dawn mission, however, required modification of some IPS components and completely new developments of others.

ion propulsion

Ion propulsion

An ion engine is a plasma thruster which produces thrust by extracting ions from the plasma and accelerating them to high velocity with an electrostatic field. The ions are then neutralized and leave the engine as high velocity neutral particles. The advantages of ion engines are high specific impulse and efficiency and their ability to operate over a wide range of input powers. In comparison with other electric thrusters, the ion engine has higher efficiency and specific impulse than thermal electric devices such as the arcjet, microwave, radiofrequency and laser heated thrusters and can operate at much lower current levels than the MPD thruster. However, the thrust level for an ion engine may be lower than a thermal electric thruster of the same operating power, consistent with its higher specific impulse, and therefore ion engines are best suited for missions which can tolerate longer duration propulsive phases. The critical issue for the ion engine is lifetime, since the prospective missions may require operation for several thousands of hours. The critical components of the ion engine, with respect to engine lifetime, are the screen and accelerating grid structures. Typically, these are large metal screens that must support a large voltage difference and maintain a small gap between them. Metallic whisker growth, distortion and vibration can lead to arcing, and over a long period of time ion sputtering will erode the grid structures and change their geometry. In order to study the effects of long time operation of the grid structure, we are developing computer codes based on the Particle-In-Cell (PIC) technique and Laser Induced Fluorescence (LIF) diagnostic techniques to study the physical processes which control the performance and lifetime of the grid structures.

Meserole, J. S.

Ion propulsion

An ion engine is a plasma thruster which produces thrust by extracting ions from the plasma and accelerating them to high velocity with an electrostatic field. The ions are then neutralized and leave the engine as high velocity neutral particles. The advantages of ion engines are high specific impulse and efficiency and their ability to operate over a wide range of input powers. In comparison with other electric thrusters, the ion engine has higher efficiency and specific impulse than thermal electric devices such as the arcjet, microwave, radio frequency, and laser heated thrusters and can operate at much lower current levels than the MPD thruster. However, the thrust level for an ion engine may be lower than a thermal electric thruster of the same operating power, consistent with its higher specific impulse, and therefore ion engines are best suited for missions which can tolerate longer duration propulsive phases. The critical issue for the ion engine is lifetime, since the prospective missions may require operation for several thousands of hours. The critical components of the ion engine, with respect to engine lifetime, are the screen and accelerating grid structures. Typically, these are large metal screens that must support a large voltage difference and maintain a small gap between them. Metallic whisker growth, distortion, and vibration can lead to arcing, and over a long period of time ion sputtering will erode the grid structures and change their geometry. In order to study the effects of long time operation of the grid structure, we are developing computer codes based on the particle-in-cell (PIC) technique and laser induced fluorescence (LIF) diagnostic techniques to study the physical processes which control the performance and lifetime of the grid structures.

Meserole, J. S.

Advanced ion propulsion for space exploration

Ion propulsion is one of the numerous technologies proposed for the Space Exploration Initiative. To operate at the megawatt power levels required for Martian cargo and/or piloted missions, ion propulsion must evolve from present technologies. The principles of operation and a brief historical review of this form of propulsion are described. Also presented are the performance of present 50-cm diameter inert gas ion thrusters at power levels and specific impulse values up to 19 kW and 9300 seconds, respectively. These thrusters are applicable to orbit transfer vehicles, planetary probes, and other precursor missions.

Rawlin, Vincent K.

Additional Mission Applications for NASA's 13.3-kW Ion Propulsion System

NASA's Space Technology Mission Directorate has been recently developing critical technologies for high-power solar electric propulsion (SEP), including large deployable solar array structures and high-power electric propulsion components. An ion propulsion system based on these developments has been considered for many SEP technology demonstration missions, including the Asteroid Redirect Robotic Mission (ARRM) concept. These studies and the highpower SEP technology developments have generated excitement within NASA about the use of the ARRM ion propulsion system design for other types of potential missions. One application of interest is for Mars missions, especially with the types of orbiters now under consideration for flights in the early 2020's to replace the aging Mars Reconnaissance Orbiter. High-power SEP can deliver large payloads to Mars with many additional capabilities, including large orbital plane changes and roundtrip missions, compared to chemically-propelled spacecraft. Another application for high-power SEP is for exo-planet observation missions, where a large starshade spacecraft would need to be repositioned with respect to its companion telescope relatively frequently and rapidly. SEP is an enabling technology for the ambitious science goals of these types of missions. This paper will discuss the benefits of high-power SEP for these concepts based on the STMD technologies now under development.

Space Technology Mission Directorate

On-orbit propulsion requirements and performance assessment of ion propulsion subsystems for future GEO large satellite missions

It is pointed out that a large class of future spacecraft, referred to as large space structures (LSS), will require advanced stationkeeping thrust subsystems. The present investigation is concerned with the performance requirements of such advanced stationkeeping thrust subsystems. An analytical model is employed to evaluate the sensitivity of the total stationkeeping thrust-system mass, for geosynchronous spacecraft, to variations in the mission parameters and thrust-system performance, taking into account ion propulsion thrust systems. The model is formulated for geosynchronous missions and considers only the N-S orbit perturbations due to sun-moon forces and the E-W orbit perturbations due to solar pressure, since these are the dominant orbit perturbations of LSS missions. The thrust system is scaled in relation to the performance capabilities of the existing 8- and 30-cm diameter ion-thruster technology and consists of separate N-S and E-W thrusters.

Wessel, F. J.

Ion propulsion for communications satellites

In a recent study of potential applications for electric propulsion, it was determined that ion propulsion can provide North-South stationkeeping (NSSK) for communication satellites in geosynchronous orbit with appreciably less mass than chemical propulsion. While this finding is not new, the margin of benefit over advanced chemical propulsion technology depends strongly on the ion propulsion system specifications. Full advantage must be taken of the under-utilized stored energy available from the communication satellite's batteries. This paper describes a methodology for evaluating the benefits obtained in using ion propulsion for NSSK, both in terms of the mass reduction and its economic value.

Poeschel, R. L.

Ion Propulsion Technology Programs at NASA Glenn Research Center

As lead center for the agency in electric and ion propulsion, the NASA Glenn Research Center (GRC) is pursuing technology development in ion propulsion for a range of mission applications. The program goal is to develop key technologies for advanced NSTAR-derivative high-power ion propulsion, lightweight low power high-performance ion propulsion, 'micro' ion propulsion, and engine and component technologies for high-power electric propulsion for very ambitious missions. Products include: (1) a 5 kW, 400 kg throughput ion thruster and power processing technology; (2) extremely-lightweight high-efficiency sub-kilowatt ion thruster and power processor; (3) a 1-25 W high-specific impulse ion engine; and (4) engine and component technologies for high-power (30 kW class) ion and Hall engines. Identified applications include outer planetary science missions such as Europa orbiter/lander, Comet Nucleus Sample Return mission, Titan Explorer, Neptune/Triton, Pluto-Kuiper Belt Objects Mission, various second generation interplanetary Micro spacecraft, and the Interstellar Probe Mission. Additional information is contained in the original extended abstract.

Patterson, M. J.

Nuclear powered Mars cargo transport mission utilizing advanced ion propulsion

Nuclear-powered ion propulsion technology was combined with detailed trajectory analysis to determine propulsion system and trajectory options for an unmanned cargo mission to Mars in support of manned Mars missions. A total of 96 mission scenarios were identified by combining two power levels, two propellants, four values of specific impulse per propellant, three starting altitudes, and two starting velocities. Sixty of these scenarios were selected for a detailed trajectory analysis; a complete propulsion system study was then conducted for 20 of these trajectories. Trip times ranged from 344 days for a xenon propulsion system operating at 300 kW total power and starting from lunar orbit with escape velocity, to 770 days for an argon propulsion system operating at 300 kW total power and starting from nuclear start orbit with circular velocity. Trip times for the 3 MW cases studied ranged from 356 to 413 days. Payload masses ranged from 5700 to 12,300 kg for the 300 kW power level, and from 72,200 to 81,500 kg for the 3 MW power level.

Galecki, Diane L.

Nuclear powered Mars cargo transport mission utilizing advanced ion propulsion

Nuclear-powered ion propulsion technology was combined with detailed trajectory analysis to determine propulsion system and trajectory options for an unmanned cargo mission to Mars in support of manned Mars missions. A total of 96 mission scenarios were identified by combining two power levels, two propellants, four values of specific impulse per propellant, three starting altitudes, and two starting velocities. Sixty of these scenarios were selected for a detailed trajectory analysis; a complete propulsion system study was then conducted for 20 of these trajectories. Trip times ranged from 344 days for a xenon propulsion system operating at 300 kW total power and starting from lunar orbit with escape velocity, to 770 days for an argon propulsion system operating at 300 kW total power and starting from nuclear start orbit with circualr velocity. Trip times for the 3 MW cases studied ranged from 356 kW to 413 days. Payload masses ranged from 5700 to 12,300 kg for the 300 kW power level, and from 72,200 to 81, 500 kg for the 3 MW power level.

Galecki, Diane L.

Explorations of Psyche and Callisto Enabled by Ion Propulsion

Recent developments in ion propulsion (specifically solar electric propulsion - SEP) have the potential for dramatically reducing the transportation cost of planetary missions. We examine two representative cases, where these new developments enable missions which, until recently, would have required resouces well beyond those allocated to the Discovery program. The two cases of interest address differentiation of asteroids and large icy satellites

planetary missions

Next-Generation Ion Propulsion Being Developed

The NASA Glenn Research Center ion-propulsion program addresses the need for high specific-impulse systems and technology across a broad range of mission applications and power levels. One activity is the development of the next-generation ion-propulsion system as a follow-on to the successful Deep Space 1 system. The system is envisioned to incorporate a lightweight ion engine that can operate over 1 to 10 kW, with a 550-kg propellant throughput capacity. The engine concept under development has a 40-cm beam diameter, twice the effective area of the Deep Space 1 engine. It incorporates mechanical features and operating conditions to maximize the design heritage established by the Deep Space 1 engine, while incorporating new technology where warranted to extend the power and throughput capability. Prototype versions of the engine have been fabricated and are under test at NASA, with an engineering model version in manufacturing. Preliminary performance data for the prototype engine have been documented over 1.1- to 7.3-kW input power. At 7.3 kW, the engine efficiency is 0.68, at 3615-sec specific impulse. Critical component temperatures, including those of the discharge cathode assembly and magnets, have been documented and are within established limits, with significant margins relative to the Deep Space 1 engine. The 1- to 10-kW ion thruster approach described here was found to provide the needed power and performance improvement to enable important NASA missions. The Integrated In-Space Transportation Planning (IISTP) studies compared many potential technologies for various NASA, Government, and commercial missions. These studies indicated that a high-power ion propulsion system is the most important technology for development because of its outstanding performance versus perceived development and recurring costs for interplanetary solar electric propulsion missions. One of the best applications of a highpower electric propulsion system was as an integral part of a solar electric propulsion (SEP) stage to send a payload to outer planet targets. The IISTP studies showed that either trip time or launch vehicle class could be significantly reduced when compared with state-of-the-art systems.

Patterson, Michael J.

NASA's Evolutionary Xenon Thruster: The NEXT Ion Propulsion System for Solar System Exploration

This viewgraph presentation reviews NASA s Evolutionary Xenon Thruster (NEXT) Ion Propulsion system. The NEXT project is developing a solar electric ion propulsion system. The NEXT project is advancing the capability of ion propulsion to meet NASA robotic science mission needs. The NEXT system is planned to significantly improve performance over the state of the art electric propulsion systems, such as NASA Solar Electric Propulsion Technology Application Readiness (NSTAR). The status of NEXT development is reviewed, including information on the NEXT Thruster, the power processing unit, the propellant management system (PMS), the digital control interface unit, and the gimbal. Block diagrams NEXT system are presented. Also a review of the lessons learned from the Dawn and NSTAR systems is provided. In summary the NEXT project activities through 2007 have brought next-generation ion propulsion technology to a sufficient maturity level.

Pencil, Eric J.

Xenon ion propulsion for orbit transfer

For more than 30 years, NASA has conducted an ion propulsion program which has resulted in several experimental space flight demonstrations and the development of many supporting technologies. Technologies appropriate for geosynchronous stationkeeping, earth-orbit transfer missions, and interplanetary missions are defined and evaluated. The status of critical ion propulsion system elements is reviewed. Electron bombardment ion thrusters for primary propulsion have evolved to operate on xenon in the 5 to 10 kW power range. Thruster efficiencies of 0.7 and specific impulse values of 4000 s were documented. The baseline thruster currently under development by NASA LeRC includes ring-cusp magnetic field plasma containment and dished two-grid ion optics. Based on past experience and demonstrated simplifications, power processors for these thrusters should have approximately 500 parts, a mass of 40 kg, and an efficiency near 0.94. Thrust vector control, via individual thruster gimbals, is a mature technology. High pressure, gaseous xenon propellant storage and control schemes, using flight qualified hardware, result in propellant tankage fractions between 0.1 and 0.2. In-space and ground integration testing has demonstrated that ion propulsion systems can be successfully integrated with their host spacecraft. Ion propulsion system technologies are mature and can significantly enhance and/or enable a variety of missions in the nation's space propulsion program.

Rawlin, V. K.