Spaceborne submm-wave interferometry
The primary advantage of a geostationary Earth orbit (GEO) for remote sensing, compared with a low-Earth orbit (LEO), is that continuous monitoring is possible over a large area of the Earth's surface and atmosphere. The main technical challenges are the very large antenna aperture required for achieving the required spatial resolution (40 folds increase in the distance to the Earth as compared to the LEO) and the necessity for imaging of two-dimensional scanning due to the absence of a relative spacecraft-Earth movement. The requirements derived from this application includes an effective aperture diameter of more than 8 m, which can not be fulfilled by a classical reflector-based instrument. Hence, an interferometric concept has been studied. In this paper a theoretical derivation of the minimum number of receivers that is required is presented along with a discussion on the implementation of such a system in space within a 10-year time frame