SpaceTech Sensors

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).

Thermistors, especially highly stable platinum thermistors, are used in almost every spacecraft. SpaceTech designs industry standard PT1000 thermistors, screened to satisfy the strong requirements of space flight missions.

SpaceTech Coarse Earth 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

SpaceTech Thermistors

  • The thermistors are coming with a cable assembly to connect the thermistor easily to the spacecraft harness
  • PT1000 thermistor based on Heraeus M222
  • Class A and Class B types available
  • Different enclosures available   
  • Crimped Cable assembly
  • More than 500 pcs. already delivered and in space  
  • Enclosure of the sensor element: Kapton (large/small), RTV
  • Cable: TP AWG28 ETFE insulated acc. to ESCC 3901/12, Length: 0,1..1 m and other cable types and length upon request

Contact Us

Electronics & Sensors

Joachim Krieger