[shiroiuma]

I haven't seen this show yet, but I know a little about why the STS was developed and why it was really a bad idea (basically the military wanted the ability to launch and recover spy satellites intact without anyone seeing, and this drove the requirements).

However, if you have a big settlement on the Moon, wouldn't a "space truck" actually make a lot of sense, for carrying large cargo loads both to and from the Moon? What am I missing?

[thedrbrian]

>what am I missing?

The wings, wheeled landing gear, all that aerodynamic streamlining,etc. everything that makes it useful to fly in the atmosphere is dead weight on its way to the moon. Best off sending the supplies up in a simple capsule and using something like a space tug to take the capsule to the moon

https://projectrho.com/public_html/rocket/spacetug.php

[shiroiuma]

Interesting. But is that mass really that significant compared to the rest of the craft and cargo?

If it is, would it make sense to use the Shuttle (or something like it) to ferry cargo to and from orbit, and then use a "space tug" to transport it to the Moon without the extra mass of the Shuttle?

From what I read, the main problem with the Shuttle was the requirement of bringing cargo back to Earth, intact: this prevented using small, simple capsules, with disposable rocket stages like on Saturn V (or now with SpaceX, a reusable lower stage). This required a big Shuttle craft that was horrifically expensive to both build and to maintain, and we no longer use the Shuttle because they finally figured that out. However, in an alternate timeline with significant facilities on the Moon, they'll probably want to, for instance, manufacture stuff there with the low-g environment and ship it back to Earth, which would require some way of transporting such cargo safely through re-entry. Just sticking it in a disposable capsule might not be sufficient.

[JKCalhoun]

I think that's the idea — space tug for the Earth/Moon trip. Even the movie 2001: A Space Odyssey got that right with the Earth-orbiting space station being the transfer point from streamlined Orion Space Clipper to spherical, leggy Aries Moon Lander.

[jessriedel]

ChatGPT + wikipedia suggests that payload to LEO, dry mass for ascent (engines, fuel tanks, etc), and dry mass for return (wings, landing gear, etc) were all in the roughly 30 tons.