1,480 research outputs found
Comments on the commercialization of expendable launch vehicles
The President's national space policy encourages private sector investment and involvement in civil space activities. Last November, the President designated the Department of Transportation as lead agency for the commercialization of expendable launch vehicles. This presents a substantial challenge to the United States Government, since the guidelines and requirements that are set now will have great influence on whether American firms can become a viable competitive industry in the world launch market. There is a dual need to protect public safety and free the private sector launch industry from needless regulatory barriers so that it can grow and prosper
Space-Based Thermal Infrared Studies of Asteroids
Large-area surveys operating at mid-infrared wavelengths have proven to be a
valuable means of discovering and characterizing minor planets. Through the use
of radiometric models, it is possible to derive physical properties such as
diameters, albedos, and thermal inertia for large numbers of objects. Modern
detector array technology has resulted in a significant improvement in spatial
resolution and sensitivity compared with previous generations of space-based
infrared telescopes, giving rise to a commensurate increase in the number of
objects that have been observed at these wavelengths. Space-based infrared
surveys of asteroids therefore offer an effective means of rapidly gathering
information about small body populations' orbital and physical properties. The
AKARI, WISE/NEOWISE, Spitzer, and Herschel missions have significantly
increased the number of minor planets with well-determined diameters and
albedos.Comment: Chapter for Asteroids IV book (accepted for publication
Political relevance in the eye of the beholder: Determining the substantiveness of TV shows and political debates with Twitter data
A permanent campaign? Tweeting differences among members of Congress between campaign and routine periods
The criminal is always the foreigner?! A case study of minority signification in German crime reporting
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