摘要:

Although high temperature, liquid metal heat pipe radiators have become a standard component design for many high power space systems, no experimental data on the operation of these kinds of heat pipes in a micro‐gravity environment exists. Issues such as which wick structures or fluids work best in these conditions are unknown. In addition, the freeze/thaw behaviour of liquid metals in zero‐g is not well understood. The purpose of the Liquid Metal Thermal Experiment, known as LMTE, is to fill this gap in our knowledge of liquid metal heat pipes by flying three potassium heat pipes on board the Space Shuttle in 1995. © 1995American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.47224

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The current fleet of medium/heavy expendable launch vehicles (ELVs) and upper stages are expensive, inflexible, and non‐responsive to the needs of the satellite designer/builder. These transportation systems confine satellite designers to a very narrow operational envelope. If a satellite exceeds its mass budget by even a few percent, mission planners must choose between eliminating instrumentation (reducing the spacecraft’s capabilities) or launching on a larger/more expensive ELV. Many people have suggested the development of a new, less expensive ELV to reduce launch costs. While such a system may eventually repay its development cost, current budgets do not make this approach practical. A new upper stage based on chemical technology is also likely to be expensive, with little performance improvement. In order to significantly improve the cost effectiveness of launch assets, alternate propulsion technologies must be developed. The approach to electrical power system design should also be modified. Currently, a new power system is designed for each new satellite. Each of these new power systems must be thoroughly developed, tested, and integrated into the satellite. While this process has produced extremely reliable power systems, the approach is very costly.An alternate approach, currently under investigation, is the use of a single power system with a standard interface to serve all satellites within a specified power range. This standard power system may also incorporate the stationkeeping functions of the satellite, an approach which has been referred to as the ‘‘common bus.’’ While cost reductions ae possible in both the propulsion and power systems, numerous studies have shown that the combination of power and propulsion into a single system, the Bi‐modal approach, may offer additional benefits as well. These Bi‐modal systems use a single nuclear or solar energy source to serve both the power and propulsion sub‐systems. This paper will provide a preliminary assemment of the application of a solar thermal Bi‐modal system for orbit transfer and on‐orbit management missions in terms of: dependability (reliability and graceful degradation), performance (capacity and quality), availability and responsiveness (orbit response times, flexibility, survivability and launch time), coverage (orbit implications), and resources (affordability, life cycle costs, and supportability). © 1995American Institue of Physics

ISSN:0094-243X    

DOI:10.1063/1.47232

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

With the downsizing or outright elimination of nuclear power capability in space in progress, it is important to understand what this means to science in therms of capability cost. This paper is a survey of the scientific possibilities inherent in the potential availability of between 15 to 30 kW through electrical nuclear power in space. The approach taken has been to interview scientists involved in space‐research, especially those whose results are dependent or proportional to power availability and to survey previous work in high‐power spacecraft and space‐based science instruments. In addition high level studies were done to gather metrics about what kind and quantity of science could be achieved throughout the entire solar system assuming the availability in the power amounts quoted above. It is concluded that: (1) Sustained high power using a 10–30 kW reactor would allow the capture of an unprecedented amount of data on planetary objects through the entire solar system. (2) High power science means high qualtiy data through higher resolution of radars, optics and the sensitivity of many types of instruments. (3) In general, high power in the range of 10–30 kW provides for an order‐of‐magnitude increase of resolution of synthetic aperture radars over other planetary radars. (4) High power makes possible the use of particle accelerators to probe the atomic structure of planetary surface, particularly in the dim, outer regions of the solar system. (5) High power means active cooling is possible for devices that must operate at low temperature under adverse conditions. (6) High power with electric propulsion provides the mission flexibility to vary observational viewpoints and select targets of opportunity. © 1995American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.47244

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The paper describes a Pluto/Charon orbiter utilizing a bi‐modal nuclear propulsion and power system based on the Particle Bed Reactor. The orbiter is sized for launch to Nuclear‐Safe orbit atop a Titan IV or equivalent launch veicle. The bi‐modal system provides thermal propulsion for Earth orbital departure and Pluto orbital capture, and 10 kWe of electric power for payload functions and for in‐system maneuvering with ion thrusters. Ion thrusters are used to perform inclination changes about Pluto, a transfer from low Pluto orbit to low Charon orbit, and inclination changes about charon. A nominal payload can be deliverd in as little as 15 years, 1000 kg in 17 years, and close to 2000 kg in 20 years. Scientific return is enormously aided by the availability of up to 10 kWe, due to greater data transfer rates and more/better instruments. The bi‐modal system can provide power at Pluto/Charon for 10 or more years, enabling an extremely robust, scientifically rewarding, and cost‐effective exploration mission. © 1995American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.47226

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

In the past, most studies dealing with the benefits of space nuclear electric power systems for solar system exploration have focused on the potential of nuclear electric propulsion (NEP) to enhance missions by increasing delivered payload, decreasing LEO mass, or reducing trip time. While important, such mission enhancements have failed to go to the heart of the concerns of the scientific community supporting interplanetary exploration. To put the matter succintly, scientists don’t buy delivered payload—they buy data returned. With nuclear power we can increase both the quantity of data returned, by enormously increasing data communication rates, and the quality of data by enabling a host of active sensing techniques otherwise impossible. These non‐propulsive mission enhancement capabilities of space nuclear power have been known in principle for many years, but they have not been adequately documented. As a result, support for the development of space nuclear power by the interplanetary exploration community has been much less forceful than it might otherwise be.In this paper we shall present mission designs that take full advantage of the potential mission enhancements offered by space nuclear power systems in the 15 to 30 kWe range, not just for propulsion, but to radically improve, enrich, and expand the science return itself. Missions considered include orbiter missions to each of the outer planets. It will be shown that by using hybrid trajectories combining chemical propulsion with NEP and (in certain cases) gravity assists, that it is possible, using Proton, Tatan III or Titan IV‐Centaur launch vehicles, for high‐powered spacecraft to be placed in orbit around each of the outer planets with electric propulsion burn times of less than 4 years. Such hybrid trajectories therefore make the outer solar‐system available to near‐term nuclear electric power systems. Once in orbit, the spacecraft will utilize multi‐kilowatt communication systems, similar to those now employed by the U.S. military, to increse data return far beyond that possible utilizing the 40 W rf traveling wave tube antennas that are the current NASA stadard. This higher data rate will make possible very high resolution multi‐space imaging (with high resolutions both spatially and spectrally), a form of science hitherto impossible in the outer solar system. Larger numbers of such images could be returned, allowing the creation of motion pictures of atmospheric phenomenon on a small scale and greatly increasing the probability of capturing transient phenomena such as lighting or volcanic activity.The multi‐kilowatt power sources on the spaecraft also enables active sensing, including radar, which could be used to do topographic and subsurface studies of clouded bodies such as Titan, ground pentrating sounding of Pluto, the major planet’s moons, and planetoids, and topside sounding of the electrically conductive atmospheres of Jupiter, Saturn, Uranus and Neptune to produce profiles of fluid density, conductivity, and horizontal and vertical velocity as a function of depth and global location. Radio science investigations of planetary atmospheres and ring systems would be greatly enhanced by increased transmitter power. The scientific benefits of utilizing such techniques are discussed, and a comparison is made with the quantity and quality of science that a low‐powered spacecraft employing RTGs could return. It is concluded that the non‐propulsive benefits of nuclear power for spacecraft exploring the outer solar system are enormous, and taken together with the well documented mission enhancements enabled by electric propulsion fully justify the expanditures needed to bring a space qualified nuclear electric power source into being. © 1995American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.47227

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The most significant impediment to the initiation of new space nuclear systems programs is that space policy and missions are in the process of taking new directions that have not yet been defined. For instance, the DoD is evaluating such issues as the relative merits of launch on schedule versus launch on demand and of the amount of repositioning needed for satellites. Budgets are decreasing and new approaches are needed to keep development costs down. The budget cycle is such that requiring substantial funding for new programs takes on the order of three years. Finally, the definite bias against nuclear systems makes it much more difficult to obtain the necessary long term commitments. Approaches to resolving these issues are addressed. They include (1) identifying missions that are enable in the current environment and (2) ways to develop and test future space nuclear systems more efficiently. © 1995American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.47228

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

As part of the TOPAZ International Program, the performance of single cell thermionic fuel elements (TFE) was evaluated durng unfueled ground testing of individual TEF’s and TOPAZ II space nuclear power systems. Experiments are coordinated between the TFE test rig and the TOPAZ II system tests to correlate TFE performance. The experiments conducted to date include optimum power data, low power operations in the ‘‘station keeping’’ mode and high output power performance. In addition, the data from these experiments are currently being evaluated by the U.S. Naval Post‐graduate School for computer thermal modeling of the heat transfer characteristics of a thermionic power system (Benke and Venable 1995). This testing is being conducted at the New Mexico Engineering Research Institute (NMERI) by the Air Force Phillips Laboratory (PL) for the Ballistic Missile Defense Organization (BMDO). © 1995American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.47229

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The Thermionic Fuel Element (TEF) Test Rig is designed for non‐nuclear testing of single‐cell TFEs, utilizing electric heaters as part of the Thermionic System Evaluation Test (TSET) Facility (Woldet al.1994). Certification of the American specialists as well as testing the TOPAZ‐II TFEs at high power levels has resulted in a significant step forward in the technology transfer process. This paper will discuss high power operations that were performed in Russia as compared to high power operations recently conducted at the TSET Facility. This paper will also discuss modifications made to the system to support the SC‐320 (40‐kW single‐cell TFE) test. © 1995American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.47163

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The Thermionic System Evaluation Test (TSET) facility, part of the TOPAZ International Program, in Albuquerque, New Mexico is currently testing Russian TOPAZ II space power systems (Wold 1993). The TOPAZ International Program has received six TOPAZ II Space Nuclear power Reactors. Two of these reactors (Eh‐43 and Eh‐44) are considered ‘‘flight quality.’’ A considerable transfer of technology has occurred during the preparations for acceptance testing of the Eh‐43 and Eh‐44 TOPAZ II reactors. The Eh‐43 and Eh‐44 are new systems that have not undergone any testing and require the coolant loop and gas cavities to be filled. The new systems will undergo an acceptance process that ranges from receipt inspection to thermal vacuum testing. The knowledge we gain from these tests will help determine the use of this technology in future applications. © 1995American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.47166

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The successful transportation and handling of a space nuclear power system is a very significant aspect in completing its mission. The factors to be considerd include environmental controls, shock and vibration, and fuel loading. The specific system to be examined here was created by the Russians for the TOPAZ II space nuclear power system (Ogloblin, 1992). © 1995American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.47167

出版商:AIP    

年代:1995

数据来源: AIP