Entry: TSX-1
URI: https://terra-vocabulary.org/ncl/FAIR-Incubator/earthsciencesensors/c_0109745c
Synthetic Aperture Radar (SAR) The primary payload is a Synthetic Aperture Radar (SAR) with an active antenna that allows for the utilization of different imaging modes and can be used in a very flexible manner. With radar instruments various frequency ranges of the radar spectrum can be observed, the so-called bands. TerraSAR-X is operated in the X-band, which is lying at a frequency around 9.65 GHz, corresponding to a wavelength of about 3 centimeters. The technology of the active, phase-con-trolled antenna enables a high flexibility and mission efficiency. While in case of passive systems the whole radar antenna or even the satellite must be rotated in order to align the antenna onto the tar-get area, the active antenna of TerraSAR-X can steer its radar pulses in a certain direction. The antenna is 4.80 meters long and80 centimeters wide. The satellite is designed in a way that it can be installed, together with its antenna at its full size, on the launch vehicle. In this way a complex unfolding mechanism can be avoided. The TerraSAR-X radar can operate in two polarizations, H (horizontal) and V (vertical)and consists of 12 antenna panels, each equipped with 32 slotted waveguide radiators. Each of these waveguides is fitted with a transmit/receive module (TRM), so that the whole antenna consists of 384 TRMs. This allows the control of the radar beam by 0.75° in the flight direction and 20° perpendicular to the flight direction. The data received are stored in a mass storage system with a 256 Gbit capacity before they are transmitted via a 300 Mbit per second X-band system to the ground station. The active antenna enables different imaging methods to be used with very fast switching between them: - In the Spotlight Mode the radar image records an area of 5 to 10 by 10 kilo-meters size. In this manner a maximum resolution of up to one meter is achieved. - In the Stripmap Mode the satellite images a strip of 30 kilometers width and a maximum length of 1,500 kilo-meters. The resolution is 3 meters. - In the ScanSAR mode a strip of 100 kilometers width and 1,500 kilometers maximum length is scanned with a resolution of 18 meters. The elements of the SAR instrument are designed fully redundant, which means that two fully functional sets of electronic boxes exist. This allows to utilize a new concept that envisages the simultaneous activation of both chains. This experimental operating scenario is called “Dual Receive Antenna“ (DRA) mode, in which the antenna is electrically separated into two halves, and the data received are independently recorded and evaluated. In this way it is possible to apply interesting new techniques such as Along Track Interferometry, fully polarimetric data recording, or an increase in geometric resolution. Along Track Interferometry allows, amongst other things, the detection of moving objects such as, for example, cars or ships. This application is of particular interest both for traffic re-search, and also for the investigation of ocean currents, for example.