Systems thinking
Systems engineering ensures that thousands of components built by different teams work together. It manages requirements, interfaces, budgets, risks and trades across the whole mission lifecycle.
Verification and validation
Every requirement must be verified by test, analysis, inspection or demonstration. Spacecraft are shaken to simulate launch, cooked and frozen in thermal-vacuum chambers, and checked for electromagnetic compatibility. 'Test as you fly' catches problems that analysis misses.
Learning from failure
Mars Climate Orbiter was lost in 1999 because one team used imperial units and another metric in navigation software — an interface failure. Hubble's flawed mirror shape in 1990 traced back to a mis-assembled test instrument. Both shaped modern verification practice.