Unfortunately, there is another safety problem that has no easy remedy. The problems with the insulating tiles are well known, and the potential for disaster if a tile is lost over a critical area of the shuttle reentry is obvious. What is not so well known is that such a disaster has almost occurred. One shuttle on the reentry came within seconds of burning through a main wing support due to loss of tiles. The failure of this support would have caused the shuttle to crash, killing all on board.They call for privitizing space launch. Sane.
Given the size of the shuttle, it is not feasible to return to the proven heat-resistant alloys used on previous manned space vehicles. Given the problems with keeping the tiles attached during launch and reentry, it is inevitable that despite NASA's best efforts a critical tile will someday fall off and another shuttle crew will go up in flames with their shuttle.
Shuttle Warning from 1986: "This letter was run in its entirety in the November 1986 edition of Physics Today, the general interest magazine of the American Physical Society.":