The JANUS experiment on ISS

In the frame of ASI supported programmes focused on the definition of utilization of the International Space Station (ISS), a university and industry consortium, lead by Space Engineering, proposed a mission, named JANUS (Joint Access to the Network for the Users of the Space Station) to define and realize an experimental technological payload to support the data transfer of other experiments on board the ISS to ground. Scope of the JANUS payload is the demonstration of the connection of the on-board ISS network, accessed by the ISS experiments, to an experiment ground facility, to create a direct link to ground in W band, directly controlled by the experimenters. JANUS has been conceived as a modular mission, in which the technological and scientific development can be stretched in flexible way and will realize two different experiments: 1) the data communication experiment, aiming at the interactive data transfer between the ISS and an Earth terminal. 2) The propagation experiment, which has been conceived by adding the TX section at W band, thus allowing characterizing the V and W band transmission channel, today largely unknown. The paper describes the conceived system architecture and the architecture solutions implemented on-board and on-ground to take advantage of parallel industry development contracts undertaken or in progress by means of ASI founds. Other interesting aspects are: 1) use of an oscillator architecture based on a common reference source, 2) use of a solid state phase locked local oscillator at a frequency of 89.2 GHz, 3) utilization of a common high quality phase noise characteristics first local oscillator (PLDRO) operated at 6.3 GHz for two TX plus RX chains 4) use, as second local oscillators, of two different dielectric resonator oscillators (PLDRO) at 24.3 GHz for the 37.9 GHz transmitter chain and 36.4 GHz for the 50 GHz receiving chain and 4) realization of a solid state 83.9 GHz power amplifier based on the use of a metamorphic InP based MMIC modules.