Comment by bell-cot
15 hours ago
A spacecraft with a 4m diameter spherical living space and 4m of water shielding around it will weigh about 1,000 tons. The propellant tanks needed to move it around the solar system will be similarly titanic.
How many orders of magnitude were you figuring for your "dramatically cheaper"?
Also you should be able to ISRU[0] water from Moon/Mars/asteroids.
[0] https://en.wikipedia.org/wiki/In_situ_resource_utilization
That's 5 Starship block 4 launches, seems fine? Propellant, presumably for long duration voyages we're not relying entirely on chemical combustion. If we're using cyclers, once they're up to speed, you need barely any fuel for corrections, just to taxi to/from the cycler.
Maybe when its actually demonstrated that it can actually launch with that payload. The largest payload they'd lifted so far is ~45 tons, and the claims I see on Wikipedia say its estimated 200 tons for LEO, not even for geosynchronous orbit much less a lunar trajectory.
20 launches would also be doable, though, if there's a reasonable launch cadence? And yeah, I don't expect they'd assemble for a Mars mission or other long range mission where they need a radiation shielded craft in geo or lunar.
And just for comparison on that number, the entire Apollo spacecraft (command+service+lunar modules) was about 50 tons to lunar orbit. And that took a gigantic Saturn V to launch.
SpaceX is planning on launching the significantly more gigantic Starship daily. It's not there yet, but they're steadily grinding toward regular launches, and they supposedly are retiring Falcon 9 from commercial launches within the next couple of years.
And "From a technology standpoint, Tesla will have a car that can do full autonomy in about three years, maybe a bit sooner.". Uttered by Musk in 2015. So ... yeeeeaaah.
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