PEASSS Thermal Simulation

The CubeSat platform has been chosen due to its relatively low-cost simplicity, usage of COTS, standardized parts. For typical CubeSats missions, the space qualified parts or qualification campaigns for space applications are not affordable due to budget issues resulting in increased risks. Therefore design rules similar to those for “bigger” space projects have been applied, as qualification/acceptance test campaigns, trade-offs, mission scenarios analysis, thermal vacuum campaigns, including thermal modelling and simulation.

The thermal control subsystem, as one of the basic spacecraft subsystems, is responsible for providing appropriate thermal conditions within the satellite for the components to operate. These conditions are defined by the requirements of each component, e.g. typical electronics boards are able to operate between -20 and +70 °C. From a thermal point of view, the most demanding elements of PEASSS mission are the payload components, as these elements are mostly designed for on-ground applications and using COTS, without previous space heritage.

 

Payload    Components    Temperature  [°C]
    Min op Max op
Piezo-bench TNO Fine Sun Sensors -40.0 70.0
  Bimorphs 0.0 60.0
Power Generator PG assembly 0.0 60.0
FBG
Interrogator
Electronics -25.0 70.0
  Light-source 15.0 25.0

 


Within the project development, multiple attitude modes for the satellite have been taken into account, evaluating advantages and drawbacks, mainly in terms of complexity of the algorithms to be implemented for the control, hardware necessary, impact on the scientific objectives of the mission. Since a full stabilized satellite would require too much resources for the S/C attitude control, the finally selected attitude for PEASSS is a tumbling one. The rotation of the satellite among its axis is only partially controlled and limited below certain maximum values using the on-board magneto torquers.

Tumbling S/C
         

In order to fulfil the temperature requirements, the thermal study has been developed through the following steps: thermal model design of the S/C, implementation of more detailed analysis of some components (the most critical ones), thermal functional testing of the Interrogator and model correlation. PEASSS thermal model has been developed in ESATAN-TMS including a simplified model of the S/C structure and detailed models of the payload components; the most important components of the model are shown below.

Thermal model of the PEASSS Nano-Satellite