The TerraSAR-X Mission and System Design

This paper describes the TerraSAR-X Mission Concept within the context of a public-private-partnership (PPP) agreement between the German Aerospace Center DLR and industry. It briefly describes the PPP-concept as well as the overall project organization. The paper then gives an overview of the satellite design, the corresponding Ground Segment as well as the main mission parameters. After a short introduction to the scientific and commercial exploitation scheme, the paper finally focuses on the mission accomplishments achieved so far during the ongoing mission

The Tandem-L Mission Proposal: Monitoring Earth’s Dynamics with High Resolution SAR Interferometry

Tandem-L is a proposal for an innovative interferometric and polarimetric radar mission that enables the systematic monitoring of dynamic processes on the Earth surface. Important mission objectives are global forest height and biomass inventories, large scale measurements of millimetric displacements due to tectonic shifts, and systematic observations of glacier movements. The innovative mission concept and the high data acquisition capacity of Tandem-L provide a unique data source to observe, analyze and quantify the dynamics of a wide range of mutually interacting processes in the bio-, litho-, hydro- and cryosphere. By this, Tandem-L will be an essential step to advance our understanding of the Earth system and its intricate dynamics. This paper provides an overview of the Tandem-L mission concept and its main application areas. Performance predictions show the great potential of Tandem-L to acquire a wide range of bio- and geophysical parameters with high accuracy on a global scale. Innovative aspects like the employment of advanced digital beamforming techniques to improve performance and coverage are discussed in detail

TerraSAR-X Mission Status

TerraSAR-X is Germany's first national remote sensing satellite being implemented in a public-private partnership between the German Aerospace Centre (DLR) and EADS Astrium GmbH, with a significant financial contribution from the industrial partner. This radar satellite, launched at June 15th 2007 will supply high-quality radar data for purposes of scientific observation of the Earth for a period of at least five years. At the same time it is designed to satisfy the steadily growing demand of the private sector for remote sensing data in the commercial market. The TerraSAR-X features an advanced high-resolution X-Band Synthetic Aperture Radar based on the active phased array technology which allows the operation in Spotlight-, Stripmap- and ScanSAR Mode with various polarizations. It combines the ability to acquire high resolution images for detailed analysis as well as wide swath images for overview applications. In addition, experimental modes like the Dual Receive Antenna Mode allow for full-polarimetric imaging as well as along track interferometry, i.e. moving target identification

The TerraSAR-X Ground Segment

The Ground Segment of the TerraSAR-X mission provides the infrastructure required to command and control the satellite and the instrument, to receive user requests, to process and archive the acquired data and to deliver the image products. The TerraSAR-X Ground Segment is composed of three major elements designed and operated by DLR, - the Mission Operations Segment (MOS) provided by the German Space Operation Center (GSOC), - the Instrument Operation and Calibration Segment (IOCS) provided by the Microwaves and Radar Institute, and - the Payload Ground Segment (PGS) provided by the German Remote Sensing Data Center and the Remote Sensing Technology Institute Thus, the Ground Segment represents an interface between the satellite and both the scientific and commercial user services and the users

The German Satellite Mission TerraSAR-X

TerraSAR-X is Germany's first national remote sensing satellite being implemented in a public-private partnership between the German Aerospace Centre (DLR) and EADS Astrium GmbH, with a significant financial contribution from the industrial partner. This radar satellite, launched at June 15th 2007 will supply high-quality radar data for purposes of scientific observation of the Earth for a period of at least five years. At the same time it is designed to satisfy the steadily growing demand of the private sector for remote sensing data in the commercial market. The TerraSAR-X features an advanced high-resolution X-Band Synthetic Aperture Radar based on the active phased array technology which allows the operation in Spotlight-, Stripmap- and ScanSAR Mode with various polarizations. It combines the ability to acquire high resolution images for detailed analysis as well as wide swath images for overview applications. In addition, experimental modes like the Dual Receive Antenna Mode allow for full-polarimetric imaging as well as along track interferometry, i.e. moving target identification

THE SRTM PROJECT: INTERNATIONAL COOPERATION AND TECHNICAL COORDINATION. A GERMAN PERSPECTIVE

The Shuttle Radar Topography Mission (SRTM) project is a cooperative effort based on international agreements between the participating agencies. Memoranda of Understanding (MOUs) were signed between the National Aeronautics and Space Administration (NASA) and the US National Imagery and Mapping Agency (NIMA) as well as NASA and the German Aerospace Center (DLR). DLR and the Italian Space Agency (ASI) on the other hand signed a Letter Agreement (LA) controlling the respective responsibilities for Germany and Italy. To generate the near global DEM, the Earth was mapped with two different radar systems operating closely together to collect interferometric radar data for generation of a near global Digital Elevation Model (DEM), covering the Earth's surface in between –56 deg and +60 deg latitude. The payload consisted of C-radar subsystems, X-SAR subsystems and jointly used subsystems. Each system was operated individually but in close cooperation from a DLR and a JPL mission operations team at the NASA control center in Houston. The mission was a complete success. The first digital elevation model could be processed and presented only two hours after the first playback was received

TerraSAR-X / TanDEM-X Mission Status

TerraSAR-X is a new German radar satellite that was launched in June 15, 2007. It carries a high frequency Xband SAR sensor that can be operated in three different modes and various polarizations. The Spotlight-, Stripmap- and ScanSAR-modes provide high resolution images for detailed analysis as well as wide swath data whenever a larger coverage is required. These high geometric and radiometric resolutions together with the single, dual and quad-polarization capability are innovative and unique features with respect to space borne systems. Additionally several incidence angle combinations will be possible and double side access can be realized by satellite roll maneuvers. The satellite will be positioned in a sun-synchronous 11 days repeat orbit. TanDEM-X (TerraSAR-X add-on for Digital Elevation Measurement) opens a new era in spaceborne radar remote sensing. A single-pass SAR interferometer with adjustable baselines in across- and in along-track directions is formed by adding a second (TDX), almost identical spacecraft to TerraSAR-X (TSX) and flying the two satellites in a closely controlled formation. With typical across-track baselines of 200-400m a global Digital Elevation Model (DEM) with 2m relative height accuracy at a 12 m posting will be generated. The TDX satellite is a rebuild of TSX with only minor modifications. This offers the possibility for a flexible share of operational functions for both the TerraSAR-X and TanDEM-X missions among the two satellites. The TDX satellite is designed for a nominal lifetime of 5 years. Predictions for TSX based the current status of system resources indicate at least one extra year (until the end of 2013) of lifetime, providing the required 3 years of joint operation. The missions TerraSAR-X and TanDEM-X jointly share the same space segment consisting of the TSX and TDX satellites orbiting in close formation and are operated using a common ground segment, that was originally developed for TerraSAR-X and that has been extended for the TanDEM-X mission. A key issue in operating both missions jointly is the different acquisition scenarios: whereas TerraSAR-X requests are typically single scenes for individual scientific and commercial customers, the global DEM requires a global mapping strategy. The two satellites will downlink their data to a global network of ground stations: Kiruna in Sweden, Inuvik in Canada, O'Higgins in the Antarctic, and Chetumal in Mexico. The entire processing chain is a new TanDEM-X specific development. However, it consists of individual modules which strongly benefit from the TerraSAR-X and the Shuttle Radar Topography Mission (SRTM) heritage. Major design drivers result from the acquisition strategy which requires the combination of several (global) coverages and application of multi-baseline processing techniques based on supporting intermediate products. The TDX satellite was launched on 21st of June 2010. The first three month of the commissioning phase were dedicated to calibration and performance verification and revealed calibration accuracies and overall performance of the TDX SAR system and its products as good as for TSX. Comprehensive testing of the various safety measures has been performed in parallel to check-out activities on the new ground segment elements. In a Formation Flight Review early October “green light” was given for entering the close formation, which was achieved on October 14th. Bistatic DEMs are being acquired since then. The bistatic commissioning phase of the TanDEM-X mission concentrated on checking out the complete bistatic chains from acquisition planning to bistatic and interferometric processing and generation of so-called raw DEMs. Key features of the mission like the synchronization system and the determination and calibration of the baselines had to be verified for operational bistatic imaging and fully automated elevation model generation. Global DEM acquisitions have started after successful completion of an extensive test and verification program in December 2010

The German SAR-Satellite TerraSAR-X

TerraSAR-X is a high-resolution, next generation X-Band radar satellite which will be launched in 2005. The mission goal is the provision of remote sensing data and products for scientific applications as well as the commercial exploitation within a public private partnership between DLR and Astrium/Infoterra. An operational acquisition of multiple polarimetric data will be carried out in Stripmap, ScanSAR and Sliding Spotlight mode. In the following a brief description of the TerraSAR-X space- and ground segment will be presented