Mapping the World's Topography Using Radar Interferometry: the TOPSAT Mission
Document Type
Article
Publication Date
12-1994
Digital Object Identifier (DOI)
https://doi.org/10.1109/5.338070
Abstract
Global-scale topographic data are of fundamental importance to many Earth science studies, and obtaining these data is a priority for the Earth science community. Several groups have considered the requirements for such a data set, and a consensus assessment is that many critical studies would be enabled by the availability of a digital global topographic model with accuracies of 2 and 30 m in the vertical and horizontal directions, respectively. Radar interferometric techniques have been used to produce digital elevation models at these accuracies and are technologically feasible as the centerpiece of a spaceborne satellite mission designed to map the world's land masses, which we denote TOPSAT. A radar interferometer is formed by combining the radar echoes received at a pair of antennas displaced across-track, and specialized data processing results in the elevation data. Two alternative implementations, one using a 2 cm-/spl lambda/ radar, and one using a 24 cm-/spl lambda/ radar, are technologically feasible. The former requires an interferometer baseline length of about 15 m to achieve the required accuracy, and this could be built on a single spacecraft with a long extendible boom. The latter necessitates a kilometers long baseline, and would thus be best implemented using two spacecraft flying in formation. Measurement errors are dominated by phase noise, due largely to signal-to-noise ratio considerations, and attitude errors in determining the baseline orientation. For the 2-m accuracy required by TOPSAT, the orientation must be known to 1 arc-second. For the single-spacecraft approach, where attitude would be determined by star tracking systems, this performance is just beyond the several arc-second range of existing instruments. For the dual-spacecraft systems, though, differential global positioning satellite measurements possess sufficient accuracy. Studies indicate that similar performance can be realized with either system.
Was this content written or created while at USF?
No
Citation / Publisher Attribution
Proceedings of the IEEE, v. 82, issue 12, p. 1774-1786
Scholar Commons Citation
Zebker, H. A.; Farr, T. G.; Salazar, R. P.; and Dixon, Timothy H., "Mapping the World's Topography Using Radar Interferometry: the TOPSAT Mission" (1994). School of Geosciences Faculty and Staff Publications. 498.
https://digitalcommons.usf.edu/geo_facpub/498
