Tandem-L is a proposal for a highly innovative satellite mission for the global observation of dynamic processes on the Earth’s surface with hitherto unknown quality and resolution. Thanks to the novel imaging techniques and the vast recording capacity, Tandem-L will provide urgently needed information for solving pressing scientific questions in the areas of the biosphere, geosphere, cryosphere, and hydrosphere. Tandem-L will make a vital contribution towards a better understanding of the Earth system and its dynamics.
Important mission goals are:
- the global measurement of forest biomass and its variation in time for a better understanding of the carbon cycle,
- the systematic recording of deformations of the earth’s surface with millimetre accuracy for earthquake research and risk analysis,
- the high resolution measurement of variations in soil moisture close to the surface,
- the large scale observation of ocean currents and sea ice drift as well as
- the quantification of glacier movements and melting processes in the polar regions.
The Tandem-L mission concept builds upon the success of TanDEM-X and utilises two radar satellites at L-band. The use of the special technique of synthetic aperture radar (SAR) enables the high-resolution imaging of Earth’s surface independent of weather and daylight and constitutes an ideal basis for the continuous monitoring of dynamic processes on Earth’s surface. Furthermore, the wavelength of Tandem-L (23.6 cm) optimally fulfills the requirements for tomographically imaging the three-dimensional structure of vegetation and ice bodies, as well as the wide-area measurement of deformations with millimetre precision. The goal of Tandem-L is to interferometrically image the entire landmass of Earth up to twice per week. Beyond the primary mission objectives, the data set recorded with Tandem-L represents a tremendous opportunity for the development of novel scientific applications and commercial services.
Beside the scientific component, Tandem-L is distinguished by the high degree of innovation with respect to the methodology and technology. Examples are the polarimetric SAR interferometry for measuring forest height, multi-pass coherence tomography for determining the vertical structure of vegetation and ice, the utilisation of the latest digital beam forming techniques for increasing the swath width and imaging resolution, as well as the close formation flying of two cooperative radar satellites with variable adjustable spacing.
With the implementation of Tandem-L, a globally unique Earth observatory will be created, which will surpass the performance of existing systems by at least one order of magnitude. According to current plans, the Tandem-L satellites could be launched in the year 2022 and be operated over a timespan of at least ten years. The utilisation phase of Tandem-L will greatly exceed this operational timespan, as the data obtained can still be used intensively for science and research after the end of the mission.