Earth-to-orbit transportation for solar power satellites

The cargo transport capability and the cost of space transportation operations for transportation of solar power satellites (SPS) to space are addressed. The history of SPS launch vehicle evolution is shown. Alternative vehicle designs developed include: (1) a parallel burn, crossfeed configuration; (2) single stage to orbit airbreathing/rocket runway takeoff vehicle concept; and (3) a smaller HLLV concept. The smaller HLLV was analyzed to compare the nonrecurring cost benefits of a less challenging development with the recurring cost increases expected due to losses in efficiency associated with smaller vehicle size. The vehicle payload bay size was selected to be adequate to accommodate the SPS transmitter subarrays fully assembled. The resulting vehicle design is compared with the shuttle, the Saturn V, and the reference SPS HLLV. A nonrecurring savings of at least five billion dollars was obtained with a recurring cost penalty of 3% per SPS. The environmental benefits of the small vehicle were deemed more important than the slight increase in upper atmosphere propellant deposition. It is recommended that the small HLLV be adopted as the SPS reference launch system

Solar Power Satellite Microwave Power Transmission System Description Executive Summary

The history of the concept of microwave power beaming to Earth is reviewed with emphasis on transmission frequency selection. Constraints on the system power level results from (1) required rejection of waste heat resulting from inefficiencies in the cover conversion of dc electric power to microwave power; (2) the rf power intensity in the ionosphere; and (3) the effect of sidelobe level on aperture illumination factors. Transmitter arrangement, the power distribution system, attitude control, subarrays, waveguides, and alignment are discussed

Emerging SPS Concepts

Four technologies were evaluated to determine their effect on Satellite Power System concepts. Two of these technologies, solid-state power amplifiers and magnetrons, are replacements for the Klystrons used for dc to RF conversion on the satellite. A third technology, laser power transmission, transmits the energy at laser frequencies rather than microwave frequencies. The fourth technology, multibandgap solar cells, has the promise of significantly increased solar to dc conversion efficienty as compared to the reference-concept silicon and gallium arsenide solar cells. The design characteristics of concepts resulting from application of these technologies are summarized

High voltage systems (tube-type microwave)/low voltage system (solid-state microwave) power distribution

SPS satellite power distribution systems are described. The reference Satellite Power System (SPS) concept utilizes high-voltage klystrons to convert the onboard satellite power from dc to RF for transmission to the ground receiving station. The solar array generates this required high voltage and the power is delivered to the klystrons through a power distribution subsystem. An array switching of solar cell submodules is used to maintain bus voltage regulation. Individual klystron dc voltage conversion is performed by centralized converters. The on-board data processing system performs the necessary switching of submodules to maintain voltage regulation. Electrical power output from the solar panels is fed via switch gears into feeder buses and then into main distribution buses to the antenna. Power also is distributed to batteries so that critical functions can be provided through solar eclipses

A Comparison of State-Based Modelling Tools for Model Validation

In model-based testing, one of the biggest decisions taken before modelling is the modelling language and the model analysis tool to be used to model the system under investigation. UML, Alloy and Z are examples of popular state-based modelling languages. In the literature, there has been research about the similarities and the differences between modelling languages. However, we believe that, in addition to recognising the expressive power of modelling languages, it is crucial to detect the capabilities and the weaknesses of analysis tools that parse and analyse models written in these languages. In order to explore this area, we have chosen four model analysis tools: USE, Alloy Analyzer, ZLive and ProZ and observed how modelling and validation stages of MBT are handled by these tools for the same system. Through this experiment, we not only concretise the tasks that form the modelling and validation stages of MBT process, but also reveal how efficiently these tasks are carried out in different tools

Rectenna System Design

The fundamental processes involved in the operation of the rectenna system designed for the solar power satellite system are described. The basic design choices are presented based on the desired microwave rf field concentration prior to rectification and based on the ground clearance requirements for the rectenna structure. A nonconcentrating inclined planar panel with a 2 meter minimum clearance configuration is selected as a representative of the typical rectenna

Modified Reference SPS with Solid State Transmitting Antenna

The development of solid state microwave power amplifiers for a solar power satellite transmitting antenna is discussed. State-of-the-art power-added efficiency, gain, and single device power of various microwave solid state devices are compared. The GaAs field effect transistors and the Si-bipolar transistors appear potentially feasible for solar power satellite use. The integration of solid state devices into antenna array elements is examined and issues concerning antenna integration and consequent satellite configurations are examined

Annoyance due to railway vibration at different times of the day

The time of day when vibration occurs is considered as a factor influencing the human response to vibration. The aim of the present paper is to identify the times of day during which railway vibration causes the greatest annoyance, to measure the differences between annoyance responses for different time periods and to obtain estimates of the time of day penalties. This was achieved using data from case studies comprised of face-to-face interviews and internal vibration measurements (N=755). Results indicate that vibration annoyance differs with time of day and that separate time of day weights can be applied when considering exposure–response relationships from railway vibration in residential environments

Putting formal specifications under the magnifying glass: Model-based testing for validation

A software development process is effectively an abstract form of model transformation, starting from an end-user model of requirements, through to a system model for which code can be automatically generated. The success (or failure) of such a transformation depends substantially on obtaining a correct, well-formed initial model that captures user concerns. Model-based testing automates black box testing based on the model of the system under analysis. This paper proposes and evaluates a novel model-based testing technique that aims to reveal specification/requirement-related errors by generating test cases from a test model and exercising them on the design model. The case study outlined in the paper shows that a separate test model not only increases the level of objectivity of the requirements, but also supports the validation of the system under test through test case generation. The results obtained from the case study support the hypothesis that there may be discrepancies between the formal specification of the system modeled at developer end and the problem to be solved, and using solely formal verification methods may not be sufficient to reveal these. The approach presented in this paper aims at providing means to obtain greater confidence in the design model that is used as the basis for code generation