On the subject of radiation, it's far easier to shield one or few directions such as on a tube submarine with a reactor. Same thing with a spaceship with an exotic powerplant such as something involving nuclear and radiation, you can simply put a barrier in between because the radiation isn't coming from "all directions". For cosmic radiation...that tends to be the issue more, that radiation is from "all directions", possibly necessitating shielding in "every direction", which works out to a lot more weight no matter what is used.

I agree the challenges are there for the challenge and not insurmountable, but it's also many times harder to address cosmic radiation as opposed to radiation from a power source that can be much more easily shielded.

Anything that provides artificial gravity will also be far more complex and again, heavier. That weight thing works against every aspect, because you have to start at the "end" in terms of the payload delivered to the surface and then work backwards to figure out what kind of ship, payload, fuel, etc. is required.

There is an idea that interstellar exploration may be best achieved with extremely lightweight sensors such as a microchip on a solar sail, that can be accelerated to a significant % of the speed of light, vs. probes or manned ships, since the latter two require orders of magnitude more fuel and ability to accelerate due to the weight.

 

I didn't mention party of politics. That certainly doesn't help his case.

Musk's superpower is that he's rich, which compensates for a lot, and in the short term, apparently puts him above the law, the government, and beyond reach. That's not forever.