TanDEM-X

A New High Resolution Interferometric SAR Mission

TanDEM-X

The objective of the TanDEM-X mission (TerraSAR-X add-on for Digital Elevation Measurement) is to produce a highly accurate, three-dimensional image of our Earth with uniform quality and unprecedented accuracy. For this purpose, two almost identical satellites orbit the earth at an altitude of around 500 kilometres and scan the surface with radar equipment. The first of the two satellites, TerraSAR-X, has been operating successfully in space since 2007. Since 2010, it has been followed by the almost identical satellite TanDEM-X. Both fly only a few hundred metres apart in close formation, thus enabling the simultaneous imaging of the terrain from different angles. From this, precise elevation information is derived in a 12-metre grid and with a vertical accuracy of better than two metres.

A new high-resolution interferometric SAR mission

TanDEM-X

TanDEM-X (TerraSAR-X add-on for Digital Elevation Measurement) 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.

Misson Goal

The main goal of the TanDEM-X mission is the generation of world-wide, consistent, timely, high-precision Digital Elevation Models (DEM, <12 m posting and <2 m height accuracy) as the basis for a wide range of scientific research, as well as for operational DEM production.

Scientific Justification

Exact information about the Earth’s surface is of fundamental importance in all geoscience areas. For example, ecology investigates the dependencies between all life forms and their environment such as soil, water, climate and landscape – all are influenced by topography.

Scientific Areas

TanDEM-X was designed to provide high quality data for commercial and scientific applications. As for the scientific applications and the corresponding geophysical products, they were confirmed by a questionnaire distributed to a large number of scientists. Many of the scientists are end users and have many years of experience with the analysis of SRTM, SIR-C/X-SAR and ERS-1/2 data. The scientific applications can be summarized in three groups:

Technical Concept

With TanDEM-X a novel interferometric instrument is introduced, consisting of two companion SAR satellites flying in close formation with the main goal to provide operational, bi-static single pass interferometry products of new quality with tunable interferometric baselines.