Smos Concept Demonstration and Product Validation

Hell Really Exists

Hell Really Exists

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The launch of a scientific instrument on board a satellite has often, if not always, been accompanied by the parallel development of a representative airborne version. Such a demonstrator is used to understand better the operational, performance and technological limitations of the instrument and its measurement technique in a realistic environment. Very importantly the airborne demonstrator also plays a crucial roll in the development of calibration techniques and retrieval algorithms for the geophysical parameters, the ultimate objective of the satellite mission, before launch (Martin-Neira et al. in press).

The complexity of MIRAS and of the SMOS mission called for an airborne demonstrator to be ready well before launch. AMIRAS, or Airborne MIRAS, is one such demonstrator. It consists of a 13-element two-dimensional Y-shaped aperture synthesis radiometer operating at 1400-1427 MHz with dual- and full-polarisation measurement capability. It is functionally and technologically equivalent to SMOS. It has been specifically designed mechanically and thermally to fly on-board a Short SC-7 Skyvan aircraft of the Helsinki University of Technology. The spacing between elements is the same as in SMOS, i.e. 0.875X. A photograph of the aircraft-mounted instrument is presented in Fig. 15.

The maiden flight of AMIRAS took place in June 2006 in the vicinity of Helsinki with the objective to acquire dual-polarisation images of coast lines and islands. An example of the acquired images is presented in Fig. 16. The image processing has focused on Lake Lohja and shows different snapshots (of 1.2 s integration time) of the alias-free field of view as the aircraft enters the lake from the South over a place where there is an island. The range of incidence angles along track varies from 5° to 35°. The coastlines are clearly imaged and geometry is well preserved. The

Fig. 15 AMIRAS installed on the Skyvan aircraft with its antenna radome (Martin-Neira et al. 2008)

Fig. 15 AMIRAS installed on the Skyvan aircraft with its antenna radome (Martin-Neira et al. 2008)

20-Jun-2006 21:03:42

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