Tests Types of tests - vibration - thermal - vacuum - cryogenic Test but don't certify Centaur with Titan. No formal qualification. Cryogenic - test at cryogenic conditions LH2 (-420) is dangerous - risk of combustion or detonation always exists Use LN2 instead (-280) for safety. The idea is to give "cold shock" to the components. The use of LN2 is not precise but close and safer. Costs - cryogenic testing is expensive. H2 testing is very expensive. N2 is less expensive and therefore used.