Space | 02. August 2010

TanDEM-X ground segment kicks off!

Höhendatensatz: Vulkan Longonot in Kenia
Höhendatensatz: Vulkan Longonot in Kenia

The successful setup of the 'wide' flight formation between the TerraSAR-X and TanDEM-X satellites marked the beginning of the 'TerraSAR-X Add-On for Digital Elevation Measurements' mission in its literal sense: Now, with both satellites flying as a team – three seconds apart – and seeing the same region of the Earth's surface, tricky instrument commanding is no longer needed to acquire interferometric data sets. Ordering, planning and commanding of the synchronous acquisitions, as well as reception and, in particular, processing of the data sets from both satellites are performed completely automatically.

Already, the first interferograms and raw DEMs, generated last week, demonstrated very impressively that the radar technique is functioning as expected. Also the setup and maintenance of the flight formation have not caused any difficulties up to now. As planned, we were able to go ahead with the activation of the combined TerraSAR-X / TanDEM-X ground segment on Thursday, 22 July 2010.


The system engineers Raph Kahle (flight dynamics), Ulrich Steinbrecher (radar instrument), Thomas Fritz (data processing) and Robert Metzig (TanDEM ground-station network) examine the first raw DEM data sets generated completely automatically by the ground segment. Credit: DLR.

Over 200 joint acquisitions were pre-planned for the first 11 days and are scheduled and commanded day-by-day for execution on both satellites. The raw radar data are received at the ground stations in Neustrelitz and Kiruna and transferred online to Oberpfaffenhofen, where they are accepted immediately by the automated processing chain and transformed into SAR images and raw DEM data sets. For this workflow, many ground segment gearwheels have to mesh together. A multitude of systems developed by various teams and institutes from DLR already interact very smoothly in fulfilling their tasks.

After only one week, we already have over 120 common TerraSAR-X / TanDEM-X acquisitions in our archive, from which we have generated over 250 raw DEM data sets. New ones are being added on a daily basis. The small image shows the top of Mount Longonot, a dormant volcano in Kenya.

Now the engineers are able to begin a detailed analysis of the data acquired in this first interferometric phase, before the setup of the 'close' formation starts in two months time and the data reach a still-higher quality level.
Tien Shan, China

Extract of a raw DEM data set from Tien Shan in China. Credit: DLR.