Louvers are thermal-control elements that have been used in different forms on numerous spacecrafts. They are devices which mask a high-emissivity radiator with a low-emissivity surface. As the temperature of the panel changes, blades angles also changes, changing the radiative flux exchanged between panel and deep space. The actuators are calibrated to cause the associated blades to be fully open and fully closed at specified temperatures.
In the frame of Rosetta project (space probe launched in 2004) a total of 15 louvers assemblies were designed and manufactured by SENER. These louvers were tri-metallic, spring-actuated, rectangular-blade louvers.
In 2019, SENER was requested to adapt this technology to a new mission. The design concept remains the same but temperature operational ranges and sizes need to be updated. The number of operation cycles along the mission is also different, new mission requires 2000 life test cycles while in Rosetta mission only 200 cycles were applied.
In order to reduce the associated risk to this long life operation, Rosetta hardware, stored at SENER premises since 2004, has been submitted to a life test at the very early stage of the project.
This presentation includes a description of the Rosetta louvers design and performances. Then, modifications implemented to adapt the louvers design to the new mission are also explained. Encountered design problems and test plan implications derived from modifications are also included. Finally, comparison between Rosetta louver performances observed in 2004 with results obtained in 2019 before and after the 2000 cycles life test are presented and discussed.