The CIMR satellite
At 14 metres high – as high as a four-floor building – the Imaging Microwave Radiometer (CIMR) satellite is large. The reflector alone is eight metres wide, and when it unfolds after launch, it is equal to a size of a 50 square metre apartment. The whole satellite weighs 2000 kg.
It features a particular platform that carries, powers and manages the rotating microwave radiometer that is at the top and which transfers the scientific data to Earth. It is equipped with a scanner that allows the 700 kg instrument to rotate at 7.8 rpm.
This rotating part generates an angular momentum around the axis that needs to be counterbalanced otherwise the entire satellite would start to spin. To keep the satellite stable and to keep the solar panels pointing towards the Sun, a 100 kg momentum wheel is used to compensate for the 1000 Newton-metre-second angular momentum generated by the rotating instrument. This wheel was designed specifically for CIMR.
During the lunch, the CIMR instrument and large deployable reflector are securely held in place using dedicated launch locking devices assembly. These locking devices fasten the instrument to the satellite and protect it from the harsh vibrations encountered during liftoff.
Once the satellite is in orbit the locking devises release the reflector, which deploys in stages. First, the supporting boom, which is eight metres-long and in three sections, opens out. Once deployed and locked in place, the reflector unfurls from a stowed bundle that is just 40 cm in diameter to its full operational diameter of eight metres.
The final part then involves the whole instrument on top of the satellite starting to spin until it reaches 7.8 rpm for measurements to begin.
A dedicated rotating joint was developed for CIMR, building on heritage from the MetOp-SG microwave radiometer.
CIMR along with two of the other Copernicus Sentinel Expansion missions, ROSE-L and CHIME, projects, adopts satellite architecture based on the Thales Alenia Space Common Platform, which includes the Thales Alenia Space Multi-Mission Platform product line (MILA).
In order to comply with clean space policy, a controlled reentry will be performed as soon as CIMR’s life comes to an end. To ensure that any remnants that do not burn up in the atmosphere end up in the largest unpopulated area of ocean on Earth, CIMR carries a dedicated set of propulsion components and propellant.
CIMR is to be placed in a Sun synchronous dawn-dusk orbit, crossing the equator at 06:00 equator (descending node). It will orbit ahead of MetOp-SG-1B; 10 mins ahead over the Arctic.
The prime contractor for the CIMR satellite is Thales Alenia Space in Italy. The prime contractor for the CIMR microwave radiometer is OHB in Italy. The prime contractor for the reflector system is High Performance Space Structure Systems and Large Space Structures in Germany.
