NASA's cancelled Ares V is based upon the shuttle's external tank, but is a top-mounted launcher instead of a side-mounted launcher. So, what if NASA builds the shuttle in the 70s WITHOUT engines in the orbiter, instead putting the engines at the bottom of what in OTL would become the exterThis has at least two benefits I can think of: no risk of falling debris from the external tank hitting the shuttle and cuasing a Columbia-like disaster on reentry; and in-line proposulsion. Could this be done?