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.
- Altitude information during de-spin and earth-oriented safe-mode
- Robust, lightweight, easy to accommodate
- Zero power consumption
- Excessive flight heritage
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
- 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, TerraSAR-X, TanDEM-X, Paz, Cryosat, SWARM.