TandDEM-X Calibration Assessment after Redundancy Switch

After more than nine years of successful radar operations in space, a first major contingency passivated the TanDEM-X satellite's SAR instrument in July 2019. Subsequent investigations led to the decision to switch to the redundant instrument chain, i.e. using the redundant radio-frequency electronics for future radar operations. Here, we report results of the necessary re-assessment of the calibration of the instrument. The redundancy switch did not have a significant impact on the performance of the radar instrument. In particular, the radiometric accuracy remains excellent. The calibration factor differs by -0.9 dB in comparison to the previously operated nominal instrument chain