In the context of the Russian space system, I asked the question What is different from the R-7 that launched Sputnik, to the Soyuz launcher used for Soyuz/Progress launches?

Thus we see that much of the current Soyuz booster has strong legacy ties back to the R-7 booster from the 1950's.

On the US side, what is the oldest legacy launcher in service?

Delta-4 uses a new engine and looses pretty much all of its Delta heritage.

Atlas-V uses almost nothing in common with the earlier Atlas versions. (Unless you count the Atlas 3, which also loses much of its commonality with the earlier Atlases, but is a stepping stone to Atlas-V).

The Space Shuttle would have been 30+ years old. We might say SLS using Shuttle components would continue the Space Shuttle longer if we stretch the definition.

To stretch the idea even further (to its own detriment) you could consider that the Merlin engine design is based on the Lunar Module Ascent engine design. But that seems like a two level stretch, a bridge too far in this context.

Capsule design, which of course has Apollo heritage, since how could SpaceX/Boeing ignore the tons of research papers NASA produced, but are not legacy in the sense meant here.


The Centaur upper stage is the one that springs instantly to mind. Its first successful flight was in 1965, and it is still being used by ULA as an upper stage for its Atlas V.

  • $\begingroup$ I used the RL-10 (The Centaur stages engine in my example) but excellent point. In fact, the interim upper stage for SLS might be Centaur based as well, prolonging it another generation. $\endgroup$
    – geoffc
    May 8 '14 at 15:50
  • 1
    $\begingroup$ By 'launcher' I assumed you meant (at least) the entire stage. $\endgroup$ May 8 '14 at 16:05
  • $\begingroup$ A fair assumption. I do not mean to differ, but engines, stages, launchers are sort of the major units to discuss. So all is fair. $\endgroup$
    – geoffc
    May 8 '14 at 16:41

The RL-10 engine, used in the upper stages of the Delta-4 and Atlas-V might count as a large heritage component. It dates back to 1962 for a first flight.

I see on the launch calendar that a Delta-2 is about to launch but that is a step away from the orginal Delta design as well.

Castor solid rocket engines have been in use since 1960's and the upper stage of an Antares is using one even today. (Of course Antares is a hodge podge of technology. Engines built in the 1970's and kept in storage till now. First stage structure from the people who build Zenits, Castor upper stages, etc).


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