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A parametric analysis was performed to compare the costs of silicon and gallium arsenide arrays for Earth orbital missions. The missions included electric power in low Earth orbit (LEO), electric power in geosynchronous Earth orbit (GEO), and power for electric propulsion of a LEO to GEO orbit transfer mission. Inputs to the analysis for all missions included launch and purchase costs of the array. For the orbit transfer mission, the launch and purchase costs of the electric propulsion system were added. Radiation flux as a function of altitude and rediation tolerance as a function of cell type were used to determine power degradation for each mission. Curves were generated that show the sensitivity of launch-array cost and total mission cost to a variety of input parameters for each mission. These parameters included mission duration, cover glass thickness, array specific cost, array specific mass, and solar cell efficiency. Solar concentration was considered and the sensitivities of cost to concentration ratio, concentrator costs, and concentrator mass were also evaluated. Results indicate that solar cell development should give a high priority to reducing array costs and that the development of low cost, lightweight, solar concentrators should be pursued.

NAS 1.60:1811 Digitized from IA1177308-07-0040 .

1After London, or Wild England

By Richard Jefferies

Jefferies' novel can be seen as an early example of "post-apocalyptic fiction." After some sudden and unspecified catastrophe has depopulated England, the countryside reverts to nature, and the few survivors to a quasi-medieval way of life.<br /><br />The first part of the book, "The Relapse into Barbarism", is the account by some later historian of the fall of civilisation and its consequences, with a loving description of nature reclaiming England. The second part, "Wild England", is an adventure set many years later in the wild landscape and society.<br /><br />The book is not without its flaws (notably the abrupt and unsatisfying ending) but is redeemed by the quality of the writing, particularly the unnervingly prophetic descriptions of the post-apocalyptic city and countryside. (Summary by Ruth Golding and Wikipedia)

Richard Jefferies (1848 – 1887) was born and spent his childhood on a farm at Coate,Wiltshire. He joined the ‘Wiltshire and Gloucestershire Standard’ in 1868 and also started to write articles and pamphlets on various agricultural issues and local history topics. He is best known for his depiction of English rural life in essays, books of natural history, and novels. This classic of English nature writing gives an idea of the life of a gamekeeper in southern England in the second half of the nineteenth century. (Summary by AJM)

3Round About a Great Estate

By Richard Jefferies

John Richard Jefferies (1848-1887) wrote of country life, natural history, and agricultural practice at a time when the industrial revolution was bringing great change to long-settled patterns of English life. In this book, a work of fiction, he aims to tell us something of "the former state of things before it passes away entirely.” This is a gentle book with a keen eye for the beauty of the countryside, the uncultivated bonuses of plants and flowers; the antics of the birds and wild animals; and the agricultural practices, superstitions, and great generosity of the simple country folk who live on or about the Great Estate of the title. - Summary by Steven Seitel