The following is strictly my opinion as a non-scientist.
Spray on insulation foam currently used in the space shuttle design inevitably dries up over time, and therefore the thermal effectiveness of the foam diminishes as well, which leads to chunks of the foam falling off and leading to a "hit or miss" chance of disaster.
The Space Shuttles were made to be reused over and over and the thermal insulation necessary for safe travel should have a matching philosophy.
My theory is that the foam needs to be designed in the same manner that a tire is made, with mutltiple treads and layers to help prevent the tire from suddenly separating down to the inner core.
Instead of using insulation material that inevitably dries up over time and becomes vulnerable to shrinkage and cracking, a layered approach should allow for more timely maintenance.
I'd rather there be 4-7 layers instead of just one or two foam layers. The outside layer would be designed to last for several flights, when it is worn, the layer below it can be inspected for wear and either recovered up by a new outside layer or it too can be repaired as well.
After a few more launches and the wearing out of the outside layer, the layer underneath is inspected again.
Eventually, the top two layers are replaced, and farther down the line, the top three layers are replaced, and so on.
It may cost more upfront, but if it negates an actual Shuttle disaster, the system pays for itself.
So what is the downside to my idea. It most likely is weight. The foam is probably an
incredible way to save on weight.
Maybe when the foam is created it could have "mix-ins" added that would incorporate the layered concept but keep the weight down.
Any opinions?
