Protection
Since the space environment is very harsh compared to the environment on the earth, with rapid changes in temperature, high levels of radiation etc., it is required to take proper protection measures for the electrical components and boards. Some protection and prevention measures are listed below:
- Use tested components (components with space heritage) for the satellite
- Use ROM for storing data
- For power MOSFETs, use radiation hardened parts or keep generous margins
- Run microcontroller at less than rated frequency
- Ensure that system can reboot autonomously (watchdog)
- Get components list reviewed by radiation expert (e.g. BARC, TIFR, ISRO scientists)
- Simulate for effects of radiation on the satellite can be carried out using softwares like SPENVIS, the Space Environment Information System by ESA to model the space environment and its effects.
- Cover the boards with conformal coating.
In spite of these measures, some components might fail. Hence, for critical components, redundancy is provided. As far as possible, the components should be in series, so that the failure of one doesn't affect the others. Dissimilar redundancy should be used, i.e. two processors of different make and grade should be used so that they don't get affected by radiation equally.
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