cjh@CCA-UNIX@sri-unix (09/21/82)
Many authors have protrayed people badly crushed during space construction because they didn't allow for the fact that what they were handling had the same momentum as it had on the ground. Presumably this would be less of a problem with girders assembled in space out of flat stock (among other things, they wouldn't have to resist being crushed during launch), but would you really be able to build lightweight structures if you want to spin them for artificial gravity? Most of the descriptions of space colonies I've seen talk about spinning to produce [artificial gravity] greater than lunar-surface. Seems like you'd have to stress them two ways, since they'd have to support whatever G you select and resist the forces necessary to start up and balance the spin. Also, I don't think your 29,000-foot figure is a limit; that's simply as far ahead of erosion as the collision of the Indian and Asian plates has pushed the Himalayas. On Mars, still with twice the lunar G, a cinder cone (Olympus Mons) has gotten up to 80,000 feet.
REM@MIT-MC@sri-unix (09/22/82)
From: Robert Elton Maas <REM at MIT-MC> When planning for the stresses on a structure while fully built, you have only one configuration to check, the final structure. When you build something that will be spun up to make artificial gravity, you have two, during spin-up, and in stable spinning. But when you build something on Earth or in any other gravity field, you have all those intermediate states during construction. Most collapsing structures that kill people occur either during construction or during Earthquakes. Hardly any people are killed by structures that just colapse suddenly during normal operation. Thus construction in space will be much safer than construction on Earth, assuming nobody is dumb enough to spin up a structure while it's still being built. Actual operation will be about the same as on Earth, which is adequate. (You don't have to plan for Earthquakes or hurricanes or tornadoes or blizzards or heavy rain causing ground liquification in space either, so in that respect space habitat will be safer than on Earth.) In space your only unpredictable hazards are collisions with objects such as meteors spacecraft and mis-tossed industrial materials.