Here’s a fun little thought experiment for the space enthusiast: suppose for a moment that NASA and the US had followed what the Soviets and later Roscosmos did with Soyuz: kept improving the existing system incrementally and kept the system flying while they did.

Instead of building a new booster stack for every new program – STS, now ISS, and later whatever we do with SLS when it finishes, we had kept the Saturn IB / Apollo CSM system in service and had iteratively improved it as technology improved? At least on the surface, the answer seems be a “yes.”

While it was hardly sexy, “Cluster’s Last Stand” had a great track record. Save for Apollo 13 (caused by human error) the same can be said for the CSM. I think the H-1 (later RS-27) engine would have evolved to something similar to the Merlin in performance terms (both are gas-generator engines) and the J2 engine on the S-IVB Saturn IB second stage had plenty of go (1,033.1 kN).

On the top, literally, an Apollo capsule with even the second generation Shuttle avionics much less CST-100 or Orion avionics would have been something to behold, plus whatever improvements to another 40 years of development and manufacturing would have brought. Would the Apollo CSM have evolved to something reusable? Maybe.

Did we quit flying every time we built a new kind of airplane? No. But that’s what the US has effectively done with its space program: nothing launched from US soil during the development of the next program. This happened in the 1970’s between Apollo and the Space Shuttle and it has been since 2011 and the end of the Shuttle program that US astronauts have gone to space on an American rocket. It seems illogical, but that’s what has happened.

Ironically, the US and NASA depend on the venerable Soyuz workhorse to ferry astronauts to ISS. Soyuz has been in service since 1967, and its replacement is only now in advanced development in Russia.

One thing is certain: the US would have never had the launch gap in the 1970’s between ASTP and STS, nor would we have one now. The Russians have never had a flight gap since Soyuz entered service in the late 1960’s, save for the short periods following incident investigations. And even today, they can continue to use the venerable Soyuz while RKK Energia works through the issues with their new Federation spacecraft (its maiden launch is expected to slip from 2022 to 2024.)

Meanwhile, our *three* human spaceflight programs all have their own issues. At the time of this writing in May, 2019, SpaceX is piecing together the data and the remains of its first Crew Dragon capsule after it exploded during a test, Boeing is working through its own issues with its onboard launch escape system engines on the CST-100 and SLS continues to plod through development and testing (and is years behind schedule.)

Perhaps we should have kept the old uprated Saturn I system. It would be interesting to have seen what we could have done in space had we kept the old bird flying.