The shuttle was never going to have a all titanium heat shield. The plan was always to have some sort of ablative or heat shedding ceramic heat shield.
It's just that the underlying structure would be stronger, stiffer, and much more heat tolerant.
We probably would have seen an effect akin to that of the WTC on 9/11. The titanium would have softened causing the wing structure to collapse.
Turbine blades in jet engines are titanium, not aluminum, for a reason. The stress levels and temperatures experienced during reentry aren't all that much different than those experienced by millions of turbine blades every day.
But, the assumption that a titanium structure would have survived long enough to make an intact touchdown is a false one.
Maybe. Maybe not. We'll never know the answer to that one. We do know an aluminum structure didn't
Back to the subject of the foam insulation...
We didn't have a foam shedding problem until political not engineering or scientific reasons forced the substitution of turpene based cleaners for the residue free Freon cleaners used during the pre-foam cleaning.
Columbia died because of a perfect storm of bad engineering decisions made by people willfully ignorant of the consequences of their decisions. One was the decision to eliminate Freon in the name of saving the ozone layer. Waivers were available for processes that had no acceptable substitute, NASA chose to make a symbolic gesture to inspire the rest of us to eliminate Freons (and curry funding favor with congress). Another was a decision to substitute a cheap, marginally usable material for a more expensive robust material, a decision made by a president with superb technical training courtesy of the US Navy's Nuclear program.
It didn't even save all that much money. Most of the cost wasn't materials, it was design and manufacturing.
The standard ET had a coat of paint that held the foam together better.
On the first launch only. Painting was skipped on all later flights, due to the weight of the paint. Did I mention that a titanium shuttle would have been both lighter and stronger?
Columbia, well foam shedding was a known issue, but nobody cared enough to try to mitigate it as it wasn’t seen as a large issue.
Yeah. No one put it together. Being hit by a pillow isn't much of a problem.
Unless that pillow is moving rilly fast, and is saturated and frozen because the paint that kept it dry was eliminated...
Originally some of the designs included an all-metal (titanium) heat shield. That’s what I was referring to.
There are lots of design compromises in the shuttle, more than there probably should be, but that’s why it’s about to be retired.