TERRASAR-X AND TANDEM-X: 
REVOLUTION IN SPACEBORNE RADAR 
Ralf Dueling 
Infoterra GmbH 
Claude-Domier-Strasse, 88090 Immenstaad, Germany 
E-mail: ralf.duering@infotera-global.com 
www. info terra-global .com 
Commission VI, WG VIM 
KEY WORDS: TanDEM-X, spacebome radar satellite, X-band, high-resolution imagery, single pass SAR interferometry, digital 
elevation model 
ABSTRACT 
Commercially available imagery is and will remain indispensable to civilian and military organizations gathering various types of 
geo-spatial information. Whether fulfilling international agreements, providing military contingents in international peacekeeping or 
humanitarian missions, or conducting joint technical exercises with other countries - a reliable access to timely, high resolution 
remote sensing data is an essential basis for well-informed decision making, particularly in time-critical situations. Today, 
organizations with those needs customarily resort to high resolution data acquired by optical sensors - often a lengthy operation. The 
radar satellite TerraSAR-X, and at a later stage together with TanDEM-X with it’s complementary near-real time data acquisition 
capabilities, offer a whole new approach to the use of space-borne datasets for mapping purposes in timecritical situations. 
1. INTRODUCTION 
Due for launch in June 2007, EADS Astrium’s new radar 
satellite TerraS AR-X will provide Earth observation data of 
unprecedented quality, with a resolution of up to one metre, 
for increasingly diversified commercial as well as for scientific 
applications. Its scheduled lifetime will be 5 years. However, 
the whole SAR programme will last more than 10 years. 
Commercial users require detailed data adapted to their 
individual requirements, available quickly and reliably, 
independent of daylight and weather conditions. The design 
and performance of TerraS AR-X will exactly meet these 
requirements. The Synthetic Aperture Radar (SAR) 
instruments of the spacecraft supply extremely detailed radar 
images, day and night, under all weather conditions. The 
acquired data is the basis for a wide variety of products and 
services, such as highly sophisticated client-specific image 
interpretation, topographic maps up to a scale of 1:10,000, 
geo-spatial databases and terrain analysis much in demand for 
a wide scope of applications. Other application sectors include 
environmental planning, land cover and natural resource 
exploration, regional and urban development, catastrophe 
response and relief, insurance and risk assessment as well as 
applications in border control, security and defence. 
New-quality data records, as provided by TerraS AR-X, 
will also offer a vast number of new research incentives, 
for instance in forestry, ecology, geology, hydrology and 
oceanography. The smallest movements of the Earth's 
surface due to plate tectonics, volcanism, earthquakes, 
and land slides are further challenging fields of 
application of TerraS AR-X interferometry. 
The space mission TerraSAR-X is the first German space 
project implemented under a Public Private Partnership (PPP). 
Cooperation partners are the German Aerospace Centre (DLR) 
and EADS Astrium. Under this construct DLR will be 
responsible for the scientific use of the TerraSAR-X data, 
whereas commercial marketing will be undertaken 
exclusively by Infoterra GmbH, a wholly-owned EADS 
Astrium subsidiary specialising in the collection, processing, 
and distribution of air- and spacebome imagery and value- 
added products. 
2. DEMAND FOR HIGH RESOLUTION DATA 
Commercially available imagery is and will remain 
indispensable to organizations gathering intelligence 
information. Whether fulfilling international agreements, 
providing contingents in international peacekeeping or 
humanitarian missions, or conducting joint exercises with 
other countries - a reliable access to timely, high resolution 
remote sensing data is an essential basis for well-informed 
decision making, particularly in time-critical situations. 
Today, organizations with those needs customarily resort to 
high resolution data acquired by optical sensors with which 
huge area coverage can only be accomplished with large 
temporal offsets. TerraSAR-X, with it’s complementary near- 
real time data acquisition capabilities, offers a whole new