"Rapid Unintentional Disassembly" is a tradition (baptism of fire?) of all agencies and companies that have embarked in this business known as "rocket science". NASA and the Soviets had a long series of catastrophic failures, and even the meticulous europeans once uploaded the wrong software to a rocket that was perfectly fine (Arianne 4 parameters into Arianne 5, IIRC); and everyone learns from those mistakes. Even Von Braun with the Nazis had a lot of failures with the V2, there was this hilarious comment of a general about its usefulness as a short range artillery weapon (when failing and blowing spectacularly at/near the launch site.
But then, after so many failures they did it:
With a historic landing, SpaceX launches new age of spaceflight
And this is their merit, one of many, and I expect them to keep delivering and return us to an age were we can dream again.
It is nice that brilliant people planned and hoped to realize this within NASA or other State agencies, but what is the value if it remains buried behind eternal bureaucracy and budget cuts? Yes, Orion could have performed this decades ago, but they didn't do it. In fact there is a lot of trouble just to send anything "nuclear", even a small passive generator for deep space missions, let alone using directly the energy from controlled nuclear blasts.
At least these people are opening a path, and i hope they can make it sustainable. I'm sure if an idea doesn't seem feasible, they will change it to one that could. From my fuzzy memory i think Elon was once asked about the ferry loop idea, IIRC he said something along the lines of: "that is not ruled out". I might be mistaken, but if it makes more sense from their point of view, they will reach to it one way or another, just like you see them using concepts and ideas others proposed decades ago.
Be careful, there are two things named Orion. First is the conceptual nuclear rocket, which was never built. Second is the current generation Orion deep space vehicle. This thing is a genuine class act and very impressive. (SIDE NOTE: Trump was pushing NASA to send 2 men on a cis lunar orbit in 2019, but NASA said they need more time, and that 2020 was possible. I have to laugh....let the democrats try to beat Trump as he takes us "Back to the Moon" right in the election cycle...)
https://en.wikipedia.org/wiki/Orion_(spacecraft)
What I was trying to impress is a very simple fact, that math and physics RULES, not what Musk says. With an understanding of some not-difficult level it's rather easy to think these things out.
As for nuclear, nuclear power is used routinely in spacecraft, "nuclear batteries." Apollo left polonium generators on the surface powering instrumentation, the Russians used plutonium batteries (and we do also). You would not have robotic spacecraft going to Saturn or Pluto without these.
Nuclear power plants such as NIRVA are totally practical for long distance travel such as to Mars and beyond. Again, physics rules. Mission profile is compared to possible power methods, then one is picked.
just like you see them using concepts and ideas others proposed decades ago.
More correctly, math and physics of spaceflight have not changed.