Synthetic observation alignment, and design implications for instruments on small satellites

Spaceborne Earth-Observation requires multi-spectral views of identical physical scenes, so that geophysical parameters can be derived from synergistic scene differences or combinations. This is traditionally achieved by mounting many instruments on a large platform, and constraining their beamshape relation and alignment — an approach inapplicable to SmallSats. However, an adequate density of image samples reports the entire ‘alias-free’ information-content of the spatially-continuous image-scene. Under these conditions sample-alignment is irrelevant; beamshape matching and alignment can be accurately synthesised by signal-processing manipulations of reported data — allowing instruments or channels to be mounted on separate platforms, without physical alignment. Current meteorological instruments vary in their image alias, but for many these limitations could be eliminated by small design changes; or a more radical change could give smaller and cheaper instruments with improved spatial resolution.