CIMR: THE DEVELOPMENT CHALLENGES

M. Grilli¹, P. G. Arpesi¹, S. Varchetta², G. Oronzo²

¹OHB Italia, ²Thales Alenia Space Italy

The Copernicus programme is an evolution of the previous Global Monitoring for Environment and Security (GMES) Programme. The Copernicus Imaging Microwave Radiometer Mission, namely CIMR mission, will provide improved monitoring of the Polar Regions in terms of measurement bands, spatial resolution, temporal resolution and geophysical accuracy as well as European operational continuity of L-band and enhanced AMSR type measurement capabilities.

The CIMR mission space segment consists in a conical scan microwave imaging multi-frequency (L, C, X, K and Ka) radiometer, with the capability to uniquely observe a wide range of floating sea ice and related ocean parameters, in particular sea ice concentration and sea surface temperature, and to serve operational systems in non-precipitating atmosphere conditions, day and night. For the high performances that will provide in terms of resolution, sensitivity and accuracy it is often considered a game changer, in particular for operational monitoring of sea-ice. The requirements drove the definition of a multi-beam instrument with 25 channels at 1.4135, 6.925, 10.65, 18.7 and 36.5 GHz, all of them working with both polarizations, managed through dual band, dual polarization feed chains for C/X bands (4 feed chains) and K/Ka bands (8 feed chains), and a single feed array for L-band. A key feature of CIMR is its very large antenna, based on an unfurlable mesh reflector, first of its kind developed in Europe and largest in the world working in ka-band. Other world premieres for a conical scan spaceborne radiometer working at those frequencies are the active calibration approach, based on internal active cold loads and passive matched hot loads instead of the traditional cold sky view and on-board hot calibration blackbody, and the extensive state-of-the-art on-board data processing for radio-frequency interference (RFI) detection and mitigation.

The technological challenges of CIMR will be presented, as well as a justification of the architecture driven by the mission requirement leading to the need of overcome such challenges. In addition to the new developments required for the RF design of the instrument, non-negligible challenges are the mechanical balance of such a large structure to allow for safe rotation for the duration of the mission, the capability to dissipate the high power required for the complex on-board electronics and the capability to pack all the instrument elements in the volume and mass available for compatibility with the launcher.

DISCLAIMER: Views and opinion expressed are those of the author(s) only and the European Commission and/or ESA cannot be held responsible for any use which may be made of the information contained therein.