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At least 73 records · Page 4

Preliminary comparison of laser and solar space power systems

Four laser receiver systems are compared to onboard solar photovoltaic power generation for spacecraft electrical requirements. The laser photovoltaic and laser MHD receivers were found to be lighter than a comparable planar solar photovoltaic system. The laser receiver also shows less drag at lower altitudes. Panel area is also reduced for the laser receiver allowing fewer Shuttle trips for construction. Finally, it is shown that a 1 megawatt laser and receiver system might be constructed with less weight than a comparable planar solar photovoltaic system.

Deyoung, R. J.

Advanced Electric Propulsion for Space Solar Power Satellites

The sun tower concept of collecting solar energy in space and beaming it down for commercial use will require very affordable in-space as well as earth-to-orbit transportation. Advanced electric propulsion using a 200 kW power and propulsion system added to the sun tower nodes can provide a factor of two reduction in the required number of launch vehicles when compared to in-space cryogenic chemical systems. In addition, the total time required to launch and deliver the complete sun tower system is of the same order of magnitude using high power electric propulsion or cryogenic chemical propulsion: around one year. Advanced electric propulsion can also be used to minimize the stationkeeping propulsion system mass for this unique space platform. 50 to 100 kW class Hall, ion, magnetoplasmadynamic, and pulsed inductive thrusters are compared. High power Hall thruster technology provides the best mix of launches saved and shortest ground to Geosynchronous Earth Orbital Environment (GEO) delivery time of all the systems, including chemical. More detailed studies comparing launch vehicle costs, transfer operations costs, and propulsion system costs and complexities must be made to down-select a technology. The concept of adding electric propulsion to the sun tower nodes was compared to a concept using re-useable electric propulsion tugs for Low Earth Orbital Environment (LEO) to GEO transfer. While the tug concept would reduce the total number of required propulsion systems, more launchers and notably longer LEO to GEO and complete sun tower ground to GEO times would be required. The tugs would also need more complex, longer life propulsion systems and the ability to dock with sun tower nodes.

Oleson, Steve

Space solar power - An available energy source

The development of satellite solar power stations is described with attention given to station design and assembly in space. Problems associated with conversion of solar energy into microwaves and with getting the station into orbit are considered. The use of a solar propulsion system for pushing the station to high orbit is discussed along with questions of station lifetime (estimated to be about thirty years). The paper is copiously illustrated with drawings projecting various aspects of station design and utilization.

Ferdman, S.

The Abacus/Reflector and Integrated Symmetrical Concentrator: Concepts for Space Solar Power Collection and Transmission

New energy sources are vital for the development of emerging nations, and the growth of industry in developed economies. Also vital is the need for these energy sources to be clean and renewable. For the past several years, NASA has been taking a new look at collecting solar energy in space and transmitting it to Earth, to planetary surfaces, and to orbiting spacecraft. Several innovative concepts are being studied for the space segment component of solar power beaming. One is the Abacus/Reflector, a large sun-oriented array structure fixed to the transmitter, and a rotating RF reflector that tracks a receiving rectenna on Earth. This concept eliminates the need for power-conducting slip rings in rotating joints between the solar collectors and the transmitter. Another concept is the Integrated Symmetrical Concentrator (ISC), composed of two very large segmented reflectors which rotate to collect and reflect the incident sunlight onto two centrally-located photovoltaic arrays. Adjacent to the PV arrays is the RF transmitter, which as a unit track the receiving rectenna, again eliminating power-conducting joints, and in addition reducing the cable lengths between the arrays and transmitter. The metering structure to maintain the position of the reflectors is a long mast, oriented perpendicular to the equatorial orbit plane. This paper presents a status of ongoing systems studies and configurations for the Abacus/Reflector and the ISC concepts, and a top-level study of packaging for launch and assembly.

Carrington, Connie

NASDA activities in space solar power system research, development and applications

NASDA activities in solar cell research, development, and applications are described. First, current technologies for space solar cells such as Si, GaAs, and InP are reviewed. Second, future space solar cell technologies intended to be used on satellites of 21st century are discussed. Next, the flight data of solar cell monitor on ETS-V is shown. Finally, establishing the universal space solar cell calibration system is proposed.

Matsuda, Sumio

Space Solar Power Concepts: Demonstrations to Pilot Plants

The availability of abundant, affordable power where needed is a key to the future exploration and development of space as well as future sources of clean terrestrial power. One innovative approach to providing such power is the use of wireless power transmission (WPT). There are at least two possible WPT methods that appear feasible; microwave and laser. Microwave concepts have been generated, analyzed and demonstrated. Technologies required to provide an end-to-end system have been identified and roadmaps generated to guide technology development requirements. Recently, laser W T approaches have gained an increased interest. These approaches appear to be very promising and will possibly solve some of the major challenges that exist with the microwave option. Therefore, emphasis is currently being placed on the laser WPT activity. This paper will discuss the technology requirements, technology roadmaps and technology flight experiments demonstrations required to lead toward a pilot plant demonstration. Concepts will be discussed along with the modeling techniques that are used in developing them. Feasibility will be addressed along with the technology needs, issues and capabilities for particular concepts. Flight experiments and demonstrations will be identified that will pave the road from demonstrations to pilot plants and beyond.

Carrington, Connie K.

Initial technical environmental, and economic evaluation of space solar power concepts. Volume 2: Detailed report

The SPS concepts which appear to be technically feasible are discussed in terms of the economic viability and competitive costs with other energy sources. The concepts discussed include: power station, microwave reception and conversion, space construction and maintenance, space transportation, and program costs and analysis. The conclusions presented include: (1) The maximum output of an individual microwave transmission link to earth is about 5 GW. (2) The mass of 10 GW SPS is between 47,000,000 and 124,000,00 kg. (3) The silicon solar cell arrays make up well over half the weight and cost of the satellite. (4) The SPS in equatorial orbit will be eclipsed by the earth and by other satellites.

Source record

Research plans for solar power in space.

The developments in space solar power technology are reviewed, with the emphasis on solar power output improvement as the goal of further efforts. It is contended that the biggest pay-off should be expected not from cost cutting in solar cell fabrication but from versatile improvement of solar cell designs to a feasible maximum.

Cohn, E. M.

The Solar Umbrella: A Low-cost Demonstration of Scalable Space Based Solar Power

Within the past decade, the Space Solar Power (SSP) community has seen an influx of stakeholders willing to entertain the SSP prospect of potentially boundless, base-load solar energy. Interested parties affiliated with the Department of Defense (DoD), the private sector, and various international entities have all agreed that while the benefits of SSP are tremendous and potentially profitable, the risk associated with developing an efficient end to end SSP harvesting system is still very high. In an effort to reduce the implementation risk for future SSP architectures, this study proposes a system level design that is both low-cost and seeks to demonstrate the furthest transmission of wireless power to date. The overall concept is presented and each subsystem is explained in detail with best estimates of current implementable technologies. Basic cost models were constructed based on input from JPL subject matter experts and assume that the technology demonstration would be carried out by a federally funded entity. The main thrust of the architecture is to demonstrate that a usable amount of solar power can be safely and reliably transmitted from space to the Earth's surface; however, maximum power scalability limits and their cost implications are discussed.

climate change

Advanced space solar dynamic power systems beyond IOC Space Station

Three different solar dynamic power cycle systems were evaluated for application to missions projected beyond the IOC Space Station. All three systems were found to be superior to two photovoltaic systems (a planar silicon array and a GaAs concentrator array), with both lower weight and area. The alkali-metal Rankine cycle was eliminated from consideration due to low performance, and the Stirling cycle was found to be superior to the closed Brayton cycle in both weight and area. LiF salt, which establishes peak cycle temperatures for both of the considered cycles at about 1090 K, was shown to be the most suitable material for Thermal Energy Storage.

Wallin, Wayne E.

Space-based solar power conversion and delivery systems study. Volume 3: Economic analysis of space-based solar power systems

A variety of economic and programmatic issues are discussed concerning the development and deployment of a fleet of space-based solar power satellites (SSPS). The costs, uncertainties and risks associated with the current photovoltaic SSPS configuration, and with issues affecting the development of an economically viable SSPS development program are analyzed. The desirability of a low earth orbit (LEO) demonstration satellite and a geosynchronous (GEO) pilot satellite is examined and critical technology areas are identified. In addition, a preliminary examination of utility interface issues is reported. The main focus of the effort reported is the development of SSPS unit production, and operation and maintenance cost models suitable for incorporation into a risk assessment (Monte Carlo) model (RAM). It is shown that the key technology area deals with the productivity of man in space, not, as might be expected, with some hardware component technology.

Hazelrigg, G. A., Jr.

Space transportation alternatives for large space programs: The International Space University Summer Session, 1992

In 1992, the International Space University (ISU) held its Summer Session in Kitakyushu, Japan. This paper summarizes and expands upon some aspects of space solar power and space transportation that were considered during that session. The issues discussed in this paper are the result of a 10-week study by the Space Solar Power Program design project members and the Space Transportation Group to investigate new paradigms in space propulsion and how those paradigms might reduce the costs for large space programs. The program plan was to place a series of power satellites in Earth orbit. Several designs were studied where many kW, MW, or GW of power would be transmitted to Earth or to other spacecraft in orbit. During the summer session, a space solar power system was also detailed and analyzed. A high-cost space transportation program is potentially the most crippling barrier to such a space power program. At ISU, the focus of the study was to foster and develop some of the new paradigms that may eliminate the barriers to low cost for space exploration and exploitation. Many international and technical aspects of a large multinational program were studied. Environmental safety, space construction and maintenance, legal and policy issues of frequency allocation, technology transfer and control and many other areas were addressed. Over 120 students from 29 countries participated in this summer session. The results discussed in this paper, therefore, represent the efforts of many nations.

Palaszewski, Bryan A.

Solar Pumped High Power Solid State Laser for Space Applications

Highly coherent laser light provides a nearly optimal means of transmitting power in space. The simplest most direct means of converting sunlight to coherent laser light is a solar pumped laser oscillator. A key need for broadly useful space solar power is a robust solid state laser oscillator capable of operating efficiently in near Earth space at output powers in the multi hundred kilowatt range. The principal challenges in realizing such solar pumped laser oscillators are: (1) the need to remove heat from the solid state laser material without introducing unacceptable thermal shock, thermal lensing, or thermal stress induced birefringence to a degree that improves on current removal rates by several orders of magnitude and (2) to introduce sunlight at an effective concentration (kW/sq cm of laser cross sectional area) that is several orders of magnitude higher than currently available while tolerating a pointing error of the spacecraft of several degrees. We discuss strategies for addressing these challenges. The need to remove the high densities of heat, e.g., 30 kW/cu cm, while keeping the thermal shock, thermal lensing and thermal stress induced birefringence loss sufficiently low is addressed in terms of a novel use of diamond integrated with the laser material, such as Ti:sapphire in a manner such that the waste heat is removed from the laser medium in an axial direction and in the diamond in a radial direction. We discuss means for concentrating sunlight to an effective areal density of the order of 30 kW/sq cm. The method integrates conventional imaging optics, non-imaging optics and nonlinear optics. In effect we use a method that combines some of the methods of optical pumping solid state materials and optical fiber, but also address laser media having areas sufficiently large, e.g., 1 cm diameter to handle the multi-hundred kilowatt level powers needed for space solar power.

Fork, Richard L.