16,735 research outputs found

    Lunar optical telescopes: An historical perspective

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    There is a long history of thought and discussion on the possibilities of astronomical observatories on the Moon. Numerous ideas have been suggested and a variety of concepts have resulted for lunar optical telescopes. This paper reviews some of the ideas and efforts of individuals and working groups including Hershel, Clarke, Malina, Herbig, and Hess; working groups of the 1960s; and recent initiatives of Burke, Burns, and others. The enhanced technologies of the 1980s and 1990s can make past dreams of lunar observatories come to reality in the 21st century

    Design of lunar base observatories

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    Several recently suggested concepts for conducting astronomy from a lunar base are cited. Then, the process and sequence of events that will be required to design an observatory to be emplaced on the Moon are examined

    Demographic Trends in National Forest, Recreational, Retirement, and Amenity Areas

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    Those who live near national forests are both potential forest visitors and neighbors who feel the impact of many forest management decisions. This paper provides some insights about those proximate populations. It does so by measuring the proportion of national forest land within each county and then combining that with an analysis of the patterns of demographic change over the past several decades. Because there is considerable overlap between counties that contain national forests and those designated as recreational, high amenity, and retirement destination counties, demographic trends in such counties are compared. A total of 757 of the 3,141 U.S. counties contain national forest land. More than 66.1 million people resided in these counties in 2000, some 24% of the U.S. total. The population in national forest counties grew by 19% between 1990 and 2000 compared to 13% for the nation as a whole. Most of the population gain in national forest areas resulted from net in-migration. Population gains in national forest counties were slightly smaller than those in recreational and natural amenity counties and significantly less than those in retirement destination counties; however, the gains were considerably larger than those in other counties. National forest counties that are metropolitan have significantly more Hispanics than other metropolitan counties but fewer Blacks and Whites. Nonmetropolitan national forest counties contain a much larger proportion of non-Hispanic Whites than their metropolitan counterparts, a finding consistent with that for nonmetropolitan counties in general. Knowledge about the changing size and demographic structure of the population in national forest counties has particular relevance to Forest Service planners and policymakers

    Balancing Leisure and Work: Evidence from the Seasonal Home

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    Seasonal homes are used during leisure time for many recreational activities, yet recent technological innovations have diminished the separation between the work place and the seasonal home. In a survey of Walworth County seasonal home owners, most who work full time report they seldom work during vacations and weekends from their seasonal home. Yet there is a distinct subgroup who do mix work into weekends and vacations for a variety of reasons. The most frequent reasons given by these people for working from the seasonal home were related to the expectations of coworkers and clients. Understanding more about the habits and motivations of those who frequently work during weekends and on vacations could provide a new perspective on the obstacles everyone faces in balancing work and leisure

    Assessment of the Lunar Surface Layer and in Situ Materials to Sustain Construction-related Applications

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    Present and future technologies to facilitate lunar composition and resource assessment with applications to lunar surface construction are presented. We are particularly interested in the construction activity associated with lunar-based astronomy. We address, as an example, the use of ground-probing radar to help assess subsurface conditions at sites for observatories and other facilities

    Required technologies for a lunar optical UV-IR synthesis array

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    A Lunar Optical UV-IR Synthesis Array (LOUISA) proposed to take advantage of the characteristics of the lunar environment requires appropriate advances in technology. These technologies are in the areas of contamination/interference control, test and evaluation, manufacturing, construction, autonomous operations and maintenance, power and heating/cooling, stable precision structures, optics, parabolic antennas, and communications/control. LOUISA needs to be engineered to operate for long periods with minimal intervention by humans or robots. What is essential for LOUISA operation is enforcement of a systems engineering approach that makes compatible all lunar operations associated with habitation, resource development, and science

    Engineering, construction, and operations in space

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    The century-old Mond process for carbonyl extraction of metals from ore shows great promise as an efficient low energy scheme for producing high-purity Fe, Ni, Cr, Mn, and Co from lunar or asteroidal feedstocks. Scenarios for winning oxygen from the lunar regolith can be enhanced by carbonyl processing of the metallic alloy by-products of such operations. The native metal content of asteroidal regoliths is even more suitable to carbonyl processing. High-purity, corrosion resistant Fe and Ni can be extracted from asteroidial feedstocks along with a Co-rich residue containing 0.5 percent platinum-group metals. The resulting gaseous metal carbonyl can produce a variety of end products using efficient vapor forming techniques

    Characterization of lunar surface materials for use in construction

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    The Workshop on the Concept of a Common Lunar Lander, which was held at the NASA Johnson Space Center on July 1 and 2, 1991, discussed potential payloads to be placed on the Moon by a common, generic, unmanned, vehicle beginning late in this decade. At this workshop, a variety of payloads were identified including a class of one-meter (and larger) optical telescopes to operate on the lunar surface. These telescopes for lunar-based astronomy are presented in an earlier section of this report. The purpose of this section is to suggest that these and other payloads for the Common Lunar Lander be used to facilitate technology development for the proposed 16-meter Aperture UV/Visible/IR Large Lunar Telescope (LLT) and a large optical aperture-synthesis instrument analogous to the Very Large Array of the National Radio Astronomy Observatory
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