MACSIM: a cloud profiling radar for studying the Earth radiation processes and budget

Within the post-2000 time frame of the ESA Earth Observation Programme, an Earth Radiation mission has been selected together with three other candidate Earth Explorer missions for phase A studies. If selected for the phase B after the phase A study, the Earth Radiation mission could be flown as early as 2003 to 2005, for a mission duration of 4 years. The Earth Radiation mission would include in its payload a cloud profiling radar (Millimeterwave Active Cloud Structure Imaging Mission), which provides vertical active soundings of cloud-layer structures down to the Earth's surface. The radar foresees a sensing frequency located in the band 94-95 GHz in order to maximise its sensitivity for cloud measurements. This instrument represents a technological challenge, since no radar has yet been flown in space at such a high frequency and with high power. The limit of performance is imposed by the feasibility of the required technologies within the above specified time frame.