Beispiele für den einsatz von Radar in der satelliten-fernerkundung

(Examples of the application of radar to remote sensing via satellite) Europe, the United States of America, Canada and Japan are planning future space missions which will carry Synthetic Aperture Radar (SAR) systems as key sensors for remote sensing purposes. These systems are dedicated to application areas which cover nearly all Earth sciences from oceanography to agriculture.This paper introduces the measurement principles. The main emphasis is put on the usefulness and limitations of these techniques. Examples from airborne measurements as well as space-borne missions much as SEASAT and SIR A (Shuttle Imaging Radar) are presented.     

On the stability of the track of the space elevator

A string moving with geostationary angular velocity in its radial relative equilibrium configuration around the Earth, reaching from the surface of the Earth far beyond the geostationary height, could be used as track for an Earth to space elevator. This is an old dream of mankind, originating about 100 years ago in Russia. Besides the question of feasibility from a technological point of view also the question concerning the stability of such a configuration has not yet been completely solved. Under the assumption that a proper material (carbon nanotubes) is available, making the connection possible technologically, we address the question of existence and stability of the radial relative equilibrium of a tapered string on a circular geosynchronous trajectory around the Earth, reaching from the surface of the Earth far beyond the geostationary height.