Soil moisture and ocean salinity mapping by Earth observation satellites has contributed significantly towards a better understanding of the Earth system, such as its hydrosphere or climate. Nevertheless, an increased spatial resolution below 10 km with a radiometric resolution in the range of 2-3 Kelvin of microwave radiometer data could yield a more complete picture of global hydrological processes and climate change. Operational radiometers, such as SMOS, have already approached prohibitive sizes for spacecraft due to the required large antenna apertures. Therefore, radiometer concepts based on a large number of satellites flying in close proximity (swarms) have been proposed as a possible solution. This thesis investigates the feasibility of placing a satellite swarm-based aperture synthesis radiometer in low Earth orbit for Earth observation applications. The aperture synthesis antenna array is formed by a large number of individual antennas on autonomously controlled nanosatellites (deputies) and a correlator antenna in Y-configuration, carried by a chief satellite. The proposed design methodology is based on the optimization of satellite positions within a plane and the subsequent translation of coordinates into initial conditions for General Circular Orbits (GCO). This enables a more computationally efficient orbit optimization and ensures the time-invariance of the antenna array response. Based on this methodology, simulations have been performed with swarms consisting of up to 96 satellites. Simulations show the spatial resolution of an aperture synthesis radiometer can be increased to 7,5 km, for applications where the requirements on radiometric sensitivity are more relaxed (ΔT ~3 Kelvin).    «

Soil moisture and ocean salinity mapping by Earth observation satellites has contributed significantly towards a better understanding of the Earth system, such as its hydrosphere or climate. Nevertheless, an increased spatial resolution below 10 km with a radiometric resolution in the range of 2-3 Kelvin of microwave radiometer data could yield a more complete picture of global hydrological processes and climate change. Operational radiometers, such as SMOS, have already approached prohibitive s...    »