As far as I know this isn't just speculation, it's fact. The US DoD required a 1500-mile crossrange capability on the Shuttle because they wanted to launch fro

As far as I know this isn't just speculation, it's fact. The US DoD required a 1500-mile crossrange capability on the Shuttle because they wanted to launch from Vandenberg into a polar orbit, immediately drop a satellite into orbit over the north pole, then land back at Vandenberg at the end of the same orbit, before the Soviets could track the shuttle's orbit by radar. (The earth would have turned ~1500 miles under the orbiter by that point, so it would have to be aerodynamic enough to fly those 1500 miles as a plane.) This crossrange requirement was what required the Shuttle to use the unusual delta-wing configuration. The Vandenberg-polar-orbit flight profile has never been attempted.