Orbital ring
In the traditional space elevator, a large station is placed in geostationary orbit (GEO) so that it remains in a single location above the equator of Earth.
[a] It also does not have to be a complete ring; depending on the desired lifting power the total mass of objects might be much smaller than even the thinnest cable circling Earth.
The main disadvantage is that the process of momentum exchange randomizes their velocity so some other system is required to shepherd the objects back into the correct orbits.
[3][4][5] In 1982, Soviet inventor Anatoly Yunitskiy also proposed an electromagnetic track encircling the equator, which he called "to space by a wheel"[6] (later, "String Transportation System").
Andrew Meulenberg and his students, from 2008 to 2011, presented and published a number of papers based on types and applications of low-Earth-orbital rings as humanity's "stepping-stones-to-space".
The "sling-on-a-ring" would involve rotating slings (made of colossal carbon tube) attached to the orbital ring that dip down into the atmosphere.
[7] Paul Birch published a series of three articles in the Journal of the British Interplanetary Society in 1982 that laid out the mathematical basis of ring systems.
Also, a whole network of orbital rings can be built, which, by crossing over the poles, could cover the whole planet and be capable of taking over most freight and passenger transport.
By an array of elevators and several geostationary ring stations, asteroid or Moon material can be received and gently put down where land fills are needed.
The electric energy generated in the process would pay for the system expansion and ultimately could pave the way for a solar-system-wide terraforming and astroengineering activity on a sound economical basis.
The system's cost-per-kilogram to accelerate payloads to low Earth orbit velocity would be around $0.05 in 1975 USD, assuming an energy requirement of 9 kWh/kg (roughly accurate) and an aspirational cost of electricity, provided by space-based solar power, of 0.005 US dollars per kWh.
[9] In the close of Arthur C. Clarke's Fountains of Paradise (1979), a reference is made to an orbital ring that is attached in the distant future to the space elevator that is the basis of the novel.
Arthur C. Clarke's 3001: The Final Odyssey (1997) features an orbital ring held aloft by four enormous inhabitable towers (assumed successors to space elevators) at the Equator.
The Star Trek novel Ring Around the Sky features a decrepit ringworld in orbit above the planet, Kharzh'ulla, connected by a series of space elevators with the surface.
The second iteration of the anime series Tekkaman features a complete ring, though abandoned and in disrepair due to war, and without surface tethers.
The anime Mobile Suit Gundam 00 also prominently features an orbital ring, which consists primarily of linked solar panels.
In Star Wars: Legends, Dac, the homeworld of the Calamari and the Quarrens has a massive orbital shipyard that encircles their oceanic planet.
