Aunc.1392
net.columbia
utzoo!decvax!duke!unc!smb
Fri Nov 13 00:33:38 1981
5th orbiter
There were originally to be 5 orbiters, but the 5th (actually the first,
Enterprise), was never completed as a functioning spacecraft.  I believe
that the reasons were budgetary, with the additional reasoning thrown
in that there wouldn't be enough demand for flights to need all 5;
thus, the leftover funds could be used for NASA's science stuff, and
there'd be less fixed overhead to absorb in the rest of the launches.