LAGRANGE RO: A GNSS Receiver for Radio Occultation

A GPS Radio Occultation occurs when a transmitting GPS satellite, setting or rising behind the Earth limb, is viewed by a LEO satellite that carries on board a space-qualified GPS receiver. In this way, it is provided a vertical sounding of the atmosphere exploiting the relative motion between the GPS and the LEO satellites. The technique proved to be particularly precise in retrieving temperature profiles with an high vertical resolution (≤1 Km) and accuracy (≤1 K) . The Italian Space Agency (ASI) is very active in the field since several years. Currently, ASI is funding the development and the realization of the Proto Flight Model of a GNSS Receiver for Radio Occultation : Lagrange RO; after having cofunded the development and the manufacturing of a PFM of the first GNSS Receiver : Lagrange, installed on the Argentinian satellite SAC-C satellite. In same time ASI is sponsoring scientific activities in the field. The payload will be delivered to ASI for the first half of the 2004. The paper describes the main performances of the Lagrange RO and the status of the program. Finally an innovative approach for retrieving the atmosphere profiles is described in detail.