Comfort chart
Drag your design on the chart to change its radius and spin rate together. Colored bands show the historical comfort guidelines; diagonal lines show constant gravity.
- ≤ 2 rpm: comfortable
- 2–4 rpm: most adapt
- 4–6 rpm: needs adaptation
- > 6 rpm: beyond guidelines
How it's calculated
The habitat is modelled as one or more thin-walled tori. R is the rim radius where people stand, g is the rim gravity, and a is half the tube diameter.
- Spin rate: ω = √(g / R). Apparent gravity is centripetal acceleration, ω²R.
- Rim speed: V = ωR.
- Gravity inside the tube falls linearly toward the axis, so the top deck feels g · (R − 2a) / R, and the head-to-foot difference is height / R.
- Coriolis while walking at speed v along the rim, relative to gravity: 2ωv / ω²R = 2v / V.
- Moment of inertia of a thin-walled torus: I = m (Rc² + 3/2 a²), with centerline radius Rc = R − a.
- Spin-up: thrusters fire tangentially at the rim, so torque τ = nFR, spin-up time t = Iω / τ, and propellant = nFt / (Isp g₀).
- Passive shielding: areal density × hull area, with hull area 4π² Rc a per ring.
- Deck area is approximated as rings × decks × 2πR × tube diameter.
Sources
- Hall, T. W. (2016). Artificial Gravity in Theory and Practice. ICES-2016-194. Composite of the Hill & Schnitzer (1962), Gilruth (1969), Gordon & Gervais (1969), Stone (1973), and Cramer (1985) comfort guidelines.
- Johnson, R. D. & Holbrow, C. (Eds.) (1977). Space Settlements: A Design Study. NASA SP-413. Stanford Torus geometry and 4.5 t/m² shielding.
- Patel, M., Jafar, M. R., Li, L., et al. (2026). Project Saoirse. NSS Space Settlement Contest Grand Prize.
This is a first-order design tool. It ignores structural stress, the mass of the spokes and spine, and non-rotating components.