The TanDEM-X Mission


TanDEM-X opens a new era in space borne radar remote sensing. The first bistatic SAR mission, is formed by adding a second, almost identical spacecraft, to TerraSAR-X and flying the two satellites in a closely controlled formation with typical distances between 250 and 500 m. Primary mission objective is the generation of a consistent global digital elevation model with an unprecedented accuracy according to the HRTI-3 specifications. Beyond that, TanDEM-X provides a highly reconfigurable platform for the demonstration of new SAR techniques and applications. This paper gives an overview of the TanDEM-X mission concept, summarizes the capabilities of the system, illustrates the achievable performance, and provides some examples for new imaging modes and applications. The mission has been approved for full implementation by the German Space Agency with a planned launch in spring 2009.

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Available from: Gerhard Krieger, Oct 09, 2015
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    ABSTRACT: Synthetic aperture radar interferometry is a powerful technique for deriving highly accurate digital elevation models on a global scale. To keep costs low, receive only satellites have been proposed to fly in close formation with an illuminating radar satellite. A new formation, called Trinodal Pendulum, is introduced and described in detail. Results of a performance estimation, flight dynamics analysis, and safety investigation are presented adopting this formation to the planned TerraSAR-L satellite. It is shown, that a global Digital Elevation Model (DEM) according to the High Resolution Terrain Information (HRTI) level 3 standard can be derived within less than 1½ years.
    18th International Symposium on Space Flight Dynamics, Munich, 11-15 October; 01/2004
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    ABSTRACT: This paper presents theory, algorithm, and results of a maximum-likelihood algorithm that is capable to fuse a number of heterogeneous synthetic aperture radar interferograms into a single digital elevation model (DEM) without the need for the critical phase-unwrapping step. The fusion process takes place in the object space, i.e., the map geometry, and considers the periodic likelihood function of each individual interferometric phase sample. The interferograms may vary regarding their radar wavelength, their baseline, their heading angle (ascending or descending), and their incidence angle. Geometric baseline error estimates and a priori knowledge from other estimates like existing DEMs are incorporated seamlessly into the estimation process. The presented approach significantly differs from the standard DEM generation method where each interferogram is first phase-unwrapped individually, then geocoded into a common map geometry, and finally averaged with DEMs generated from other interferograms. By avoiding the phase-unwrapping step, the proposed algorithm does not depend on gradients between samples and is therefore capable to reconstruct the arbitrary height of each single scatterer. Because the height of each DEM sample is determined individually, spatial propagation of phase-unwrapping errors is avoided. The algorithm is targeted to fuse an ensemble of interferometric multiangle or multibaseline observations in areas of rugged terrain or highly ambiguous data where algorithms based on phase unwrapping may fail. The algorithm is explained, and examples with real data from the Shuttle Radar Topography Mission are given. Conditions of future missions are simulated, and optimization criteria for the viewing geometry are discussed.
    IEEE Transactions on Geoscience and Remote Sensing 02/2005; 43(1-43):24 - 36. DOI:10.1109/TGRS.2004.838389 · 3.51 Impact Factor
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    ABSTRACT: A novel SAR system architecture is presented. It allows to combine a high azimuth resolution with a wide imaged swath width. The architecture and the required on board signal processing is described. Finally two examples systems and their image performance are presented
    Geoscience and Remote Sensing Symposium, 2001. IGARSS '01. IEEE 2001 International; 02/2001