Shoot to the Stars: 15 Facts About the Fascinating Space Elevator Concept

Inspired by the Eiffel Tower in Paris, Tsiolkovsky dreamed up the notion of a spindle-shaped cable with a "celestial castle" at the end, held in a geosynchronous orbit at an altitude of 35,786 kilometers.

2. A space elevator would use the Earth's rotation to propel objects into geostationary orbit

Tsiolkovsky's hypothesis for a space elevator stated that objects would only need enough energy to go up the elevator. Earth's rotation, essentially, would provide free horizontal acceleration to the object traveling up the tower.

Once released at the top of the tower, the payload, or craft, would have enough horizontal velocity to remain in geostationary orbit without falling back to Earth. Though Tsiolkovsky's design was a compression structure, with its weight supported from below, most other concepts have focused on tensile structures, with the weight held up from above.

3. In theory, it could make space travel a lot cheaper by reducing our reliance on rocket fuel 

One thing that many people don't take into account when it comes to rockets is how much fuel they burn, both on launch and while in orbit. This is because they need to pick up enough horizontal velocity to outpace the speed at which they are dropping, so they can stay in geostationary orbit.

This is a large part of what makes space travel so prohibitively expensive — despite SpaceX's incredible work. Though a space elevator would cost billions to build, in theory, it would make this back in savings after transporting only a few payloads.

Transporting payloads using conventional rockets costs around $25,000 per kilogram ($11,000 per pound) for transfer to geostationary orbit — with a large percentage of this going towards rocket fuel. Some space elevator proposals envision prices as low as $220 per kilogram ($100 per pound).

4. A space elevator would have four main components

A space elevator would have four main parts: tether (or cable), counterweight, climber, and anchor. 

One idea for the counterweight was thought up by Russian engineer Yuri N. Artsutanov in 1959. Artsutanov suggested using a geostationary satellite as an orbital base from which to deploy the elevator structure. The counterweight would be extended away from Earth, allowing the top of the structure to always remain in the same location above Earth.

5. Space tethers have been used on real space missions

A number of space tethers, albeit of limited length, have been used in real missions, demonstrating that this part of the space elevator concept, at least, is feasible.

One example is the Tethered Satellite System-1 (TSS-1) which was deployed by NASA and the Italian Space Agency (ASI) in 1992 to verify the tether concept of gravity gradient stabilization.

6. Early concept research showed that no known materials are strong enough to withstand the required structural pressure

Although the space elevator idea is fascinating in theory, there are, of course, many problems and technological hurdles to overcome.

In 1966, four American engineers named Isaacs, Vine, Bradner, and Bachus, reinvented the concept, calling it the "Sky-Hook". In trying to determine what type of material would be required to build a space elevator — with the assumption it would be made using a straight cable with no variations in its cross-section area — they found that the strength required would be twice that of any then-existing material.

The materials the four engineers assessed included graphite, quartz, and diamond. 

7. Carbon nanotubes have been suggested as a material strong enough for a space elevator

After the development of carbon nanotubes in the 1990s, NASA engineer David Smitherman thought the immense strength of the material might make space elevators feasible.

He put together a workshop at the Marshall Space Flight Center, where he invited scientists and engineers to discuss ideas and work towards making the concept a reality.

8. American scientist Bradley C. Edwards greatly expanded on the concept in 2000

In 2000, American scientist, Bradley C. Edwards suggested creating a 100,000 km (62,000 miles) long paper-thin ribbon, using a carbon nanotube composite material. This, he argued, would be more resistant against potential asteroid impacts.

Supported by the NASA Institute for Advanced Concepts, Edwards also devised ideas for space elevator deployment, climber designs, an anchor system, and orbital debris avoidance. He also suggested that the space elevator's anchor station should be placed in the western equatorial Pacific to avoid hurricanes and lightning.

9. The Japan Space Elevator Association estimated that a space elevator could be built for $8 billion

In 2008, Shuichi Ono, chairman of the Japan Space Elevator Association, unveiled a space-elevator plan in which he estimated a cost of around one trillion yen ($8 billion) to build a space elevator. Many observers said that this was an extremely low estimate.

10. One organization estimated that we will have the technology required for a space elevator within 20 years

In 2013, the International Academy of Astronautics concluded a four-year study and published its findings on the technological feasibility of space elevators.

The organization concluded that the critical capability improvement needed was to the tether material. The study projected that human technological advances would see us achieve the necessary specific material strength within 20 years.

11. Japan's Shizuoka University launched a mini space elevator experiment into space in 2018

In 2018, researchers at Japan's Shizuoka University launched the STARS-Me space elevator experiment, in which they launched two CubeSats,  connected by a tether, into space. 

As part of the experiment, one of the CubeSats had a mini-elevator onboard that traveled from one CubeSat to the other via the tether. The experiment was designed as a test to provide information for developing a larger structure.

12. A study called 'Road to the Space Elevator Era' was published last year

In 2019, the International Academy of Astronautics published Road to the Space Elevator Era, a study compiled with the help of a large group of space professionals. The study came to the conclusion that space elevators appeared to be feasible.

Not only this, but the experts also concluded that space elevator development might be a lot closer than we'd think, largely due to potential developments in the manufacturing of macro-scale, single-crystal graphene — a material with higher strength than most nanotubes.

13. Alternatives include a maglev train concept and an elevator connected to the Moon

There are two alternatives to the space elevator which are essentially variations on the original concept. One of these is StarTram, a concept (image below) for a space elevator that would shoot rockets into orbit via a high-speed maglev rail track.

The other alternative, which was proposed only last year by astrophysicists Zephyr Penoyre, from the University of Cambridge in the UK, and Emily Sandford from Columbia University in New York, would see a tether dangled down from the Moon, which would allow objects to be slingshot into space.

14. It would be easier to build a space elevator on Mars

Though it rotates around its axis in about the same time as Earth, Mars' surface gravity is just 38% of Earth's. Due to this, the Red Planet's stationary orbit is much closer to its surface than Earth's. Therefore, a space elevator on a future Mars colony could be much shorter. Existing materials are already strong enough to make such an elevator.

15. Space elevators could also help to propel humans into deep space

An object attached to a space elevator at a radius of roughly 53,100 km would already be at escape velocity when released from its tether. In other words, it would have enough speed to escape the Earth's gravity. A gravitational slingshot around Jupiter could then allow a craft to pick up enough speed to travel further into space. So, a space elevator could conceivably allow us to explore the cosmos like never before.

In the book, Leaving the Planet by Space Elevator, co-author Philip Ragan states that, "the first country to deploy a space elevator will have a 95% cost advantage and could potentially control all space activities." 

As crazy as it seems, we might one day be using such gigantic structures to slingshot payloads and spacecraft into orbit and perhaps even into deep space, and this might just happen sooner than we think.