>>12219948The basic concept of using expendable rockets and capsules to run a space station program is realistic. Marshall Spaceflight Center came up with a plan to end moon missions after Apollo 15 and use the remaining Saturn Vs to launch interim space stations serviced by either 3- or 4-man Apollo capsules (a fourth seat could be added with almost no modifications). The launch vehicle they wanted was a cluster of three UA1207 solids + s-ivb, which would have been able to send up a larger payload than a Saturn IB at a lower cost. George Low seemed to favor this approach at one point before they worked out a shuttle design that could fit NASA's budget.
Big Gemini on Titan IIIM with a more long-term space station also a serious possibility and was preferred by the number-crunchers at the Office of Management and Budget. The station would have either been launched by a Saturn V or 2 Titan IIILs.
6-man refurbishable Apollo capsules were also studied but they were never seriously considered.
Where is ETS *not* realistic then? The Saturn IC was never studied or even brought up as a possibility that I can tell. The Saturn IB was much more expensive than a Titan IIIM and they weren't about to add an even more expensive F1 engine onto it. There were some low-cost IB replacements given serious study such as replacing the first stage with solids or a pressure-fed booster.
ETS is also not realistic in thinking that NASA would give up on the Shuttle just because they couldn't get it approved in 1972. Any ETS-style station program they had would be treated as an interim to give them something to do while they waited to finally develop the shuttle. If Nixon had said no, they would have tried under Reagan, who almost certainly would have said yes.
