[Spaceships] Homebrew: Alternate Spin Tethers

[DaltonS]

FWIW: Slowly Spinning to Mars

One of the protocols of the Mars Direct scenario involves tethering a Transhab module to its nearly expended booster and rotating the assembly at one RPM to provide the habitat with 0.38 Gs artificial gravity. Using the formula

r = 975.723 × a × ω²

where

a = acceleration in Gs (Earth standard gravities)
ω = angular velocity in RPM (rotations per minute)
r = radius of rotation in yards

the spin radius of the module would be 370.77 yards. Given that as an upper stage the module would be one SM smaller than its booster, the booster's spin radius would be dependant on how many fuel tanks were expended.

Example: An SM+6 upper stage would use an SM+7 booster. Fully fuelled, the 14 remaining systems of the booster would mass 210 tons. At least one system must be the reaction engine. If 12 tanks were emptied, the mass would be 30 tons compared to the 100 tons of the upper stage. The booster's spin radius where therefore be 370.77×100/30=1,235.9 yards, making the total tether length 1,606.7 yards. Note that this would be true for any upper stage with an even SM number; for those with an odd SM number, the total tether length would be 4×370.77=1,483.08 yards.

Dalton “for my next physics lecture, I'll need an apple tree and a hard hat” Spence