I looked into this in a lot of detail years back when I was writing the newsletter "The Commercial Space Report." Suffice it to say that any useful ejection system capable of operating through most of the flight regime pretty much would require rebuilding the orbiters almost from the ground up.

In any case, this does not address the core problem, which is that we are not building orbiters any more, and like the Saturn 5, have probably pretty much lost the capacity to build new ones. Even if the crew is saved, which is great, the Shuttle fleet is already small, and would be getting smaller.

If the Space Plane turns out to be another expensive boondoggle like the X-33, we could easily find ourselves out of the manned space business if we get another failure or two.