> I've noted, unscientifically, space flight problems are now largely about software bugs. Looking at the recent years, I don't really think this is the case.

> I've noted, unscientifically, space flight problems are now largely about software bugs. Looking at the recent years, I don't really think this is the case. System design and process issues are the most frequent ones. Lack of testing, system logic errors, spec mismatches, rushing, bureaucracy, all that stuff. Mission-critical software has a relatively low footprint and has to follow the spec strictly; the payload can sometimes be made more complex but in this case it's also much less important. Most of the complexity in the spaceflight is in the specs and systems design, and in the testing. Critical software is relatively tiny in comparison, so the failures that can be unambiguously attributed to software bugs are relatively rare. > Rarely is the hardware the root cause Hardware and software is typically the immediate cause, not the root cause.