Tandem-L is a highly innovative SAR satellite mission for the global observation of dynamic processes on the Earth's surface with hitherto unknown quality and resolution. Thanks to its novel imaging techniques and its unprecedented acquisition capacity, Tandem-L will deliver urgently needed information for the solution of pressing scientific questions in the areas of the biosphere, geosphere, cryosphere and hydrosphere. The feasibility of Tandem-L has been analyzed and confirmed in the scope of a phase A study, which has been conducted in close cooperation between the German Aerospace Center (DLR) and the German space industry. This paper provides an overview of the Tandem-L mission concept and summarizes the actual development status.

The German Tandem-L mission is devoted to provide an overall observation of the dynamic processes within the Eart system at different spatial and temporal scales. Among the mission objectives, the measurement of the 3-D fores structure by means of multi-pass coherence SAR tomography (TomoSAR) has particular relevance. Up to now, th potential of TomoSAR for the characterization of the forest volume has been proved with airborne data, but Tandem-will allow for the first time to map the vertical forest structure and monitor seasonal and annual variations globall with a high spatial resolution. Recently, a performance model for the characterization of the structure information o multibaseline (MB) data stacks has been presented, and the primarily objective of this paper is to examine in dept such model for global performance analysis and investigate the required acquisition trade-offs in the framework of th Tandem-L mission design and acquisition plan.