SpaceTech Sensors

SpaceTech Coarse Earth Sun Sensor CESS: While in safe-mode, preservation of a spacecraft is the number one priority. Essential AOCS input needs to be provided by high reliable sensors. For that purpose, SpaceTech developed a thermo-optical Coarse Earth and Sun Sensor (CESS).

The CESS is a passive sensor that provides spacecraft orientation at any time, crucial for SC deployment, de-spin and survival in safe mode.

A set of 6 orthogonal accommodated CESS heads is used to determine the relative earth and sun vector: 

  • Perform a continuous measurement of the temperatures of all black and mirror reference surfaces
  • Extrapolate temperatures to steady-state
  • Estimate the irradiated infra-red and solar flux, for both black and mirror OSR via their respective values for α and ε
  • Deduce IR (solar) flux imbalance for opposing CESS heads and construct earth (solar) vector

  • Altitude information during de-spin and earth-oriented safe-mode
  • Robust, lightweight, easy to accommodate
  • Zero power consumption
  • Excessive flight heritage

CESS deliverables

Standard HW:

  • 6 FM + 2 spare CESS heads incl. protective caps
  • Flight S/W algorithm


  • Customer specific acceptance testing
  • Mission specific mechanical interfaces
  • AIT support
  • Performance/thermal in-orbit simulator

The SpaceTech CESS has been used in numerous successful LEO space missions e.g., CHAMP, GRACE FO, TerraSAR-X, TanDEM-X, Paz, Cryosat, SWARM, Sentinel-6.

SpaceTech CESS .step model

Download the CESS .step model >

Find more details in our CESS brochure:

Download the STI CESS brochure


Contact Us

Electronics & Sensors

Joachim Krieger