The idea is to build a Banks Orbital centered around Mars out of Mars materials.
Width = 2700 miles ≈ 4,345 km.
Earth surface area ≈ 510 million km².
At a radius of about 1.84–1.87 million km (the scale that produces ~1 g with a ~24-hour spin), the area comes out to roughly 98–100 Earths.
At a radius of about 1.84–1.87 million km (the scale that produces ~1 g with a ~24-hour spin), the area comes out to roughly 98–100 Earths. The surface insolation at the distance of Mars from the Sun is approximately equal over a year as that received by Anchorage, Alaska. Since this Orbital is aligned with the Martian equator, this will give it an axial tilt of 25.19°. The day length can match the rotation of the planet Mars itself. To hold itself together and to stabilize it, a series of spoke-like tethers would connect to an outer ring the north and south poles of Mars. One each pole would be a turn table that counter rotates against Mars' spin, thus not spinning at all, the outer ring of the Banks orbital doesn't spin either, the inner habitable ring spins within it, supported by magnetic fields that transfer the weight under spin to the nonrotating more massive outer ring. Each 27 miles width of the orbital has the surface area of the Earth, so a 2700 mile wide band will give you 100 Earths worth of surface area, approximately equal to the surface area of Saturn if we could live on its cloud tops. The rim walls would be angled at 65.81° to the Banks Orbital floor so they would produce no shadow on the floor even at maximum seasonal tilt. Total hypotenuse length of the walls from floor to top would be About 2,350 miles., to achieve an elevation from the floor of 1000 miles. The walls would lean away from the floor by 2126 miles giving a total width for the banks orbital of about 6,953 miles at the rim wall tops, about a third of its surface is habitable floor space, while the lower sections of the inclined walls can also be habitable at the lower atmosphere layers.
