GNSS Reflectometry and Passive Radar at DLR

Abstract

The presentation mainly summarises a planned GNSS reflectometry satellite mission that has been proposed by the Microwaves and Radar Institute to the DLR programme board in close cooperation with the GFZ Potsdam. The proposal was driven by the possible opportunity to use the DLR TET-1/-2 (Technologie Erprobungs Träger, very similar to the BIRD satellite bus) platform for a mission based on GNSS technology. The main instruments comprise Javad GNSS receivers (1- and multi-frequency), GNSS antennas plus a phased array beam-steerable reflectometer antenna (passive radar), an SLR retro reflector and a VLBI. The goals of the mission are • GNSS-based remote sensing for atmosphere, ionosphere, oceans, ice, soil (moisture), etc. using radio occultation and reflectometry • Precise orbit determination (POD) and co-location of geodetic methods from space (reference systems, gravity field, etc.) • Development of technologies and know-how for future micro satellite constellations (formation flights) using GNSS • Passive radar for altimetry and scatterometry using a beam-steerable antenna • Antenna development for passive radar, including space qualification A number of possible applications and experiments have been identified, particularly in the oceanographic field, i.e. sea level estimation (altimetry), determination of ocean wave spectra (2D), sea roughness and swells (scatterometry), retrieval of wind speeds, sea ice parameters and the estimation of ocean wave orbital velocities. Finally also the possibility of using a large constellation of such satellites for Tsunami detection is taken into account. Additional applications could be soil moisture extraction, ionospheric and atmospheric effects and land mapping (clutter). It is not yet decided whether the mission concept will be considered for TET-2 or not. However, it should be clearly pointed out that such an instrument would be the first complete demonstration of ESAs PARIS concept [Martin-Neira et al. 1993] from space and could thus serve the scientific community with very valuable information for future developments in this area.