According to sources cosmic rays that enter the atmosphere and scatter as they hit the air can cause a ‘bit flip’. A bit flip is where a transistor can change its state from 1 to 0 or 0 to 1 unexpectedly. As many computer control systems use a transistor array this phenomenon can affect systems in various random ways. Many modern aircraft are designed to cope with this situation. Some of the space rockets actually had four computers and at least three of them had to provide the same signal in order for calculations to be accepted.
This has made me think about the micro-controllers and how susceptible these could be to random error from ‘bit flip’. Now that’s hard to debug! This also shows how important checksums can be, as a checksum could stop corrupt data from being used.