ESA’s EarthCARE satellite successfully launched from Vandenberg Space Force Base in the early hours of this morning.
ESR Space was responsible for the design and build of the Mechanisms Assembly (MA) for the Broadband Radiometer, one of four instruments on the spacecraft.
The MA consists of two nested bearing assemblies; the inner one is the Chopper Drive Mechanism (CDM) which is a constantly rotating drum which controls the passage of light into the three instrument detectors. The outer Calibration Target Mechanism (CTM) positions the viewing baffles and calibration sources which are intermittently brought into view to calibrate the instrument. Both mechanisms are an essential part of the instrument operation.
This challenging mechanism combined bearing assemblies, motors and optical encoders for both mechanisms into a compact single unit. The lifetime requirements for both mechanisms was very high, with over 1 million revolutions required on the calibration target mechanism and over 400 million revolutions required on the chopper drive mechanism.
During mechanism testing ESR Space implemented novel techniques for monitoring bearing health; this included high precision accelerometers to measure changes in the micro-vibrations from the bearing assembly. Due to the long lifetime it was necessary to accelerate the lifetest, which even at accelerated speeds latest over 6 months. This lifetest, and the need to precisely monitor bearing health over long periods of time led to the development of ESTLs Advanced Bearing Test Rig – a dedicated facility for measuring bearing torque, preload, electrical conductivity, lubricant film thickness over a wide range of temperatures which is still in use today.
ESR Space delivered the BBR Mechanism Assembly to Thales-Alenia Space UK (formerly SEA) in 2015.
Further details on the BBR mechanism assembly design can be found here: https://esmats.eu/esmatspapers/pastpapers/pdfs/2011/munro.pdf
For any further information or enquires, email us at info@esrtechnology.com.
BBR installed on EarthCARE spacecraft. Image credit: ESA
BBR Mechanism Assembly