[michaelt]

> There is an incredible gap between the tech demo you're speaking about,

Didn't Apollo 11 land on the moon using a rocket, then take off from the moon again, back in the 1960s?

Not exactly a tech demo. And the Apollo missions had the additional challenges of being crewed, and targeting an atmosphere and gravity they couldn't reproduce on earth for test purposes.

The SpaceX stuff is neat though, compared to the defence industry clowns they're competing with.

[throw5959]

Apollo 11 had a three stage rocket and every stage was discarded. SpaceX is obviously not the first company to land something - but landing a rocket booster that just performed an orbital lift is the interesting and extremely hard thing to do. The payload can be entirely designed to land - but the booster has many other constraints (payload weight and its desired velocity and trajectory being some of them).

To do what Apollo 11 did without discarding the boosters you also need orbital refueling and probably rapid turnaround (or a huge inventory of boosters), which SpaceX plans to develop next. Awesome stuff.

[michaelt]

I'm talking about the Apollo Lunar Module.

You know, this bit https://en.wikipedia.org/wiki/Apollo_Lunar_Module that descended to the moon, landed, some guys walked out and grabbed some moon rocks, then they took off again and made it back to earth.

That's a rocket-propelled space vehicle gently landing tail first, and ready for immediately reuse.

Given that it clearly had been done, I doubt anyone who knew what they were talking about was telling Musk it couldn't be done.

[throw5959]

I don't know how to put this if you don't see the difference yourself by now, but that's not an orbital rocket that could lift anything from Earth nor land back there. One huge problem is hypersonic aerodynamics, something you absolutely don't care about on the Moon. The payload weight can be much greater due to tiny gravity. Google "tyranny of the rocket equation".

[gus_massa]

It's not reused. Only the top half goes up. The bottom half with the legs and descending engine is still in the Moon.

[AnimalMuppet]

Apollo 11 was crewed, though.