Earth's gravity is too strong and human energy exploitation isn't large enough to allow for such reusable rockets. The rockets we humans fly look massive and shame to discard, but they're more like liquid fueled balloons than proper spaceships for their scales.
e.g., the Al-Li metal layer of Shuttle ET was 0.1" thick at thinnest points yet those ET were 150ft+ tall. iPhone back covers are thicker than that. Rocketry gears are infuriatingly flimsy relative to their size, but they have to be because that's what it currently takes to fly to space.
If we could build ships on the Moon from Lunar rocks out of a grinder, or if we could build an all-fusion spaceships, we can (relatively)easily have 2m thick radiation shielding, or 8km wide hulls, or anything we want.
But we're not doing it, but are stuck with lox-fuel chemical propulsion, so we can only make them so durable.
> The common soda can, a marvel of mass production, is 94% soda and 6% can by mass. Compare that to the external tank for the Space Shuttle at 96% propellant and thus, 4% structure. The external tank, big enough inside to hold a barn dance, contains cryogenic fluids at 20 degrees above absolute zero (0 Kelvin), pressurized to 60 pounds per square inch, (for a tank this size, such pressure represents a huge amount of stored energy) and can withstand 3gs while pumping out propellant at 1.5 metric tons per second. The level of engineering knowledge behind such a device in our time is every bit as amazing and cutting-edge as the construction of the pyramids was for their time.
The (early) Atlas ICBM was even less substantial than a soda can. There used to be one parked on the front lawn of our local science museum. It had to be kept inflated with pressurized air. When the time came to retire it and they let the air out...
e.g., the Al-Li metal layer of Shuttle ET was 0.1" thick at thinnest points yet those ET were 150ft+ tall. iPhone back covers are thicker than that. Rocketry gears are infuriatingly flimsy relative to their size, but they have to be because that's what it currently takes to fly to space.
If we could build ships on the Moon from Lunar rocks out of a grinder, or if we could build an all-fusion spaceships, we can (relatively)easily have 2m thick radiation shielding, or 8km wide hulls, or anything we want.
But we're not doing it, but are stuck with lox-fuel chemical propulsion, so we can only make them so durable.