Engineering

Challenging requirements have to be met in the design of spacecraft with regard to their mass, stability and strength.
Spacecraft structures in general are allowed a mass of less than 10% of the whole spacecraft mass, whilst being required
to withstand mechanical loads equivalent to 50 to 100 times their weight during launch. The initial design constitutes the
basis for a numerical finite element model, which serves to predict the static and dynamic behavior of the final product.
The results gained by numeric simulation then provide the input for the detailed design. A continuous evolution in the
design processes at SAB Aerospace as well as the choice of materials assures the fulfilment of the most challenging
requirements of space programs.

To verify compliance with rigidity, strength and stability requirements SAB uses specific software packages: MsC
NASTRAN, HyperMesh, Optistruct.

All design activities are based on 3D computer aided design software packages such as Unigraphics NX.

Simulation of thermal/mechanic distortion as a result of changing temperature fields in orbit and definition of measures
to limit these effects.

As general skills related to the SAB capabilities in terms of design the partnership established in 2010 with OHB AG
allowed SAB people to participate to the mechanical development of the most important OHB projects such as: EDRS-C,
Galileo FOC, Exomars 2016. Thus a strong experience has been achieved in both full aluminum and CFRP platforms.

In addition to that, the company involvement in optical payloads programs such as OPSIS Satellite (Optical System for
Imagery and Surveillance) and METIS (Solar Orbiter Instrument), SAB has been able to gain substantial experience to solve
all the aspects connected to the accommodation of optical payloads in general.

Spacecraft are exposed simultaneously to the extreme cold of space and to the intense heat flux from the Sun. In addition, the spacecraft′s subsystems generate power, which produces additional heat flows. Finally, during the flight through the atmosphere at several times the speed of sound, the payload fairings experience aerodynamic heating thereby significantly increasing the fairings′ temperature.

These topics are the subject of thermal analysis, which aims at modelling the heat sources and heat sinks as well as the convective heat exchange processes over the materials and the radiative processes. The models have to take into account the design of the system and its materials and surface properties as well as the heat dissipated by the equipment on board the spacecraft. By means of advanced software tools (SINDA/Fluint, Thermal Desktop/RADCAD and ESATAN TMS), the heat exchange is simulated and the design may be adapted if necessary in order to ensure that the final product meets the thermal requirements.

The services offered by SAB Aerospace begin with the detailed analysis of the thermal fluxes and end up with the design and verification of the complete thermal subsystem.

SAB heritage on thermal design activities can be summarized in the following topics:

• TMM and GMM model generation
  • both in ESATAN TMS and Sinda/Fluint-Thermal Desktop
  • both for equipment (up to junction temperature), support structures, mechanisms and subsystems
• Reduced TMM and GMM model generation and correlation
• TMM and GMM translation between ESATAN TMS and Sinda/Fluint-Thermal Desktop
• Thermal Analyses: transient and steady state, from preliminary models up to CDR one (up to acceptance verification of derated component/junction-case temperature according to ECSS-Q60-11A)
• Thermal model correlation with TVTC test results
• Sensitivity analyses
• Generation of input for thermo-elastic analyses for optical P/L (input to FEM)
• Generation and handling of thermal IF data for equipment and subsystems (MERAT data)
• Thermal report and document issue