Freon-insulated ET Tanks and Foam-less ET Tanks

[dreada5]

LOL, ok seriously what about a protective shell for the underside of the orbiter as I described at the end of page2?

 

[henryhallam]

Probably a lot heavier than 500kg, difficult to attach and install, new ascent profile needed => expensive. Easier and cheaper to stop the major chunks of foam falling off, and keep doing the scans so that if any damage does occur then the crew can be rescued.