By Topic

Mapping the world's topography using radar interferometry: the TOPSAT mission

Sign In

Cookies must be enabled to login.After enabling cookies , please use refresh or reload or ctrl+f5 on the browser for the login options.

Formats Non-Member Member
$31 $13
Learn how you can qualify for the best price for this item!
Become an IEEE Member or Subscribe to
IEEE Xplore for exclusive pricing!
close button

puzzle piece

IEEE membership options for an individual and IEEE Xplore subscriptions for an organization offer the most affordable access to essential journal articles, conference papers, standards, eBooks, and eLearning courses.

Learn more about:

IEEE membership

IEEE Xplore subscriptions

4 Author(s)
Zebker, H.A. ; Jet Propulsion Lab., California Inst. of Technol., Pasadena, CA, USA ; Farr, T.G. ; Salazar, R.P. ; Dixon, T.H.

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-λ radar, and one using a 24 cm-λ 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

Published in:

Proceedings of the IEEE  (Volume:82 ,  Issue: 12 )