Why does NASA not replicate existing manned launch systems?

Question

Since the retirement of the Space Shuttle, NASA has depended on contracts with Russia to launch manned vehicles to the International Space Station.

The specifics for other manned spacecraft must be well understood by engineers at NASA. Why do they not "simply" build their own Soyuz, or other similar rocket?

Is it due to some form of copyright on the craft, efficiency/economy of scale, or ease of logistics? Does NASA simply not have the research and understanding to make a similar craft at this time without lengthy R&D?

I should clarify; I'm talking "medium" payload boosters. Not super lifters like the Saturn V/STS/SLS, but specifically existing boosters like the Soyuz-2

Answer 1

The US chose to rely on the commercial sector for manned launch to LEO instead of developing its own launch vehicle. Sure, it's taking a few years but several companies are getting close now.

As an alternative, NASA could have...

• restarted production of the Titan variant used for Gemini or the Saturn 1B used for Apollo. Both are 50 year-old designs that would cost a lot of money to redevelop (see 1337joe's answer).
• designed a new rocket. This is politically difficult and takes a long time. Since the demise of the Shuttle, we've seen 3 different heavy-lift architectures, one of which included a lightweight variant for LEO crew access (Ares I). Their history (Constellation, Ares, SLS) shows the pitfalls of NASA developing anything.

Answer 2

We can't even directly rebuild a Saturn V at this point (without tons of new R&D) because the tools and manufacturing processes no longer exist and we've lost the institutional knowledge of the people who built it that have since retired: Why not build Saturn V's again?

Copying a design that we've never built is way more complex than trying to rebuild something we actually have all the plans for.

As to why we don't "simply" build a similar rocket we pretty much are (Orion/SLS, Commercial Crew Program), but to build spacecraft we have to:

• develop and build the tools/manufacturing line
• certify everything as man-rated because we don't currently have a launch system that is man-rated and the vehicle will be new (requirements are here)
• test everything extensively to make sure we don't kill any astronauts (because space is an amazingly unfriendly place if anything goes wrong)

All of that takes lots of funding and time. Throwing more money at it could speed things up to some degree, but there's not enough political interest for that to happen.

Answer 3

I should clarify; I'm talking "medium" payload boosters. Not super lifters like the Saturn V/STS/SLS, but specifically existing boosters like the Soyuz-2

Delta IV, Atlas V, and Falcon 9 each have more LEO payload capacity than Soyuz-2. Man-rating any of those launchers would be vastly cheaper than developing the capability to build a copy of the Soyuz launcher.

That would still leave us without a spacecraft comparable to the manned Soyuz craft, to rendezvous and dock with ISS, of course, but getting Dragon V2 into service is again more likely than making copies of a 50-year-old Russian design.

Answer 4

Anytime a complex machine is produced for a long time, there exists a problem where some of the parts no longer are manufactured after a period of time. This can happen for a variety of reasons, and is most common with electronics. For instance, buying a VME chassis today is difficult, and much more expensive than standard computer electronics today. Standards change over time to ones that are better, cheaper, faster, etc. The old goods become increasingly difficult to maintain.

I've worked in the aerospace industry for some time. Sometimes certain key parts suddenly are no longer available. There is a couple of different ways of addressing these issues, but they basically come down to some kind of a re-design. The objects that I have seen were more mass produced than the Saturn 5, and were about 15 years old, and some of them were no longer available.

Re-building the Saturn 5 would require tremendous work, almost as much as building a new similar rocket would be today. Modern techniques could make it lighter, stronger, more reliable, and cheaper than simply rebuilding the existing design would be. The Apollo spacecraft would be even more difficult, as it relied heavily on very dated technology.

The bottom line is, a re-design of the electronics is required to make it work, it'd be a vast improvement. The general physics, however, remain the same, and so there are some principals from the existing designs which are still applicable today. Saturn 5 lead to the Space Shuttle, and it is leading to SLS. And those technologies are inspiring the rockets we have today.

Answer 5

It is not useful to rebuild a Saturn the same way as decades ago. All electronics require a new development using today available parts. The rocket engines can not be build the same way today. The combustion chamber and the nozzle were built by welding a lot of thin tubes together. Nowadays the cooling of the walls is done with channels machined into copper and closed by galvanic deposition of nickel. The art of welding thin tubes is to difficult and expensive today when we have a cheaper, easier and more reliant method now. Therefore a completely new design of rocket engines is necessary. The new design requires a new series of tests.