Test to failure can provide important information. When designing something, possible failures must be considered so that a failure can occur in a safe way. “Safe” in quotes, because a failure can be catastrophic. In the case of Orbital Reef, it would be nice if a bursting Life module didn’t throw shrapnel into the other modules. In an airliner, it would be best if failing fan, compressor, or turbine blades didn’t fly into the fuselage, so a containment ring is designed into the engine to try to stop a blade from going in that direction. In the case of a manned launch vehicle, it would be best if a propellant tank burst sideways and not forward into the manned spacecraft on top. You may remember that SLS was tested to failure, and it split a seam along the length of the tank, not forward toward the upper stage. It may seem counterintuitive to design-in a weak point, but it is merely that the rest of the design is stronger.

Sierra Space’s Life module is made in a new and largely untested method with materials used in new ways. Their two most recent tests have had panels built into the side of their module so that they can find how the construction behaves with windows put into the assembly. They are learning things that will enable them to build their modules in ways that are currently hypothetical.

Starship uses a new steel alloy. Their tests to failure gave them similar information on their new material and their welding methods as used in practical application. It is one thing to test a sample in the lab, but it is something more important to test the designed assembly.

I noticed that SpaceX didn’t announce in advance that a few tests were tests to failure, at least not in the early years. This may have been why so many in the media would announce the test as a failure. My experience is that it is important to announce in advance that a test would be to failure, otherwise bosses and customers get excited in a bad way.

Failures during development testing tell the engineers much about their design. They give knowledge about weaknesses and suggest ways to improve the design. Little was learned from the Apollo 4 test launch, which worked almost perfectly, but many lessons were learned from the Apollo 6 test launch, which was full of problems. The designers and the flight controllers learned more than they expected.

Qualification testing and acceptance testing should not have failures or other problems. By this time, the design must be well understood, otherwise you get problems like we saw with Starliner. Acceptance testing should find assembly problems, such as the one with the recent RUD of a Falcon upper stage engine. Why was the insufficiently tight clamp not found during the engine’s ground testing? Perhaps the vibrations on the test stand are different than those experienced during flight.