FLORAD # 1

In the frame of the 'Small Mission' programme, launched by ASI at the beginning of 2008, The University of Rome La Sapienza was awarded a contract for the Study of a constellation of three minisatellites in Flower orbits carrying a multiband MMW radiometers to support narrowcasting in the Mediterranean area, and long term climate change forecasts at global level.

The Prime contractor was the University La Sapienza  leading a mixed scientific-industrial team including Thales Alenia Space, Telespazio, ELV, ELITAL, and the Research Center CETEMPS of l'Aquila.

ELITAL, on its turn, subcontracted to SpaceSys all tasks under her reponsibility which included:

- the choice and initial design of the multiband antenna, a vital part of the payload;

- the identification of suppliers and technologies for the MMW payload;

- the definition of the minisatellite that had to host  the payload 

-  the definition of its components and technologies;

- supporting the choice of a product assurance  plan meeting the severe programme cost limitations; 

The antenna study was by far the most interesting part of our study, which did consider several alternatives. The results were in favour of a rotating paraboloid illuminated by a fixed multiband conical horn operating in orthogonal polarization at the  three baseline frequencies  (86, 118 and 183 GHz)

The antenna geometry ( which was borrowed partly from that adopted in the SIRIO-1  satellite ) produced a linearly swept beam at 90° with respect to the feed axis which is parallel to the spacecraft velocity vector. Through 120° out of the 360° of its continuous rotation, the antenna beam mapped the space underneath the satellite, receiving information about the athmospheric conditions via the radiometric temperature measurements at the three frequencies. Two time intervals , during the antenna rotation, are devoted to the calibration, respectively when the beam looks laterally at the black sky,  and when the beam points at 180° from nadir, since it will then face an hot load constituted by a temperature controlled absorbing mat rigidly supported by an auxiliary structure external, but fixed,  to the  payload  baseplate.

.