- Researchers revisit the concept of a space elevator with a minor modification.
- Instead of anchoring the cable on Earth, anchor it on the moon and dangle it toward Earth.
- This would make lunar and terrestrial gravitational pull cancel each other out.
- In this way, the space elevator could be built using today’s strongest materials, such as Zylon.
One of the reasons why fictional worlds like those in Avengers or Star Trek are famous is because they show us a reality where hope is possible everywhere.
In order to explore what’s beyond our planet, space activities steadily grew throughout the 1970s and 1980s. So far, space programs have proved extremely beneficial: they have generated numerous software and hardware that have made their way into a wide range of applications.
The astonishingly high cost of space exploration is one of the biggest problem scientists haven’t been able to solve. Today, it costs nearly $10,000 to put one pound of payload in Earth’s orbit, although SpaceX has been able to bring down this price to $1,800. Reaching beyond the Earth’s orbit costs even more.
Researchers are looking for cheaper ways to put satellites into space. One solution is to build a planet-to-space transportation system called a space elevator. It would consist of a cable anchored to the Earth’s surface and extending into space.
This concept was first proposed by a Russian rocket scientist Konstantin Tsiolkovsky. Its design would allow vehicles to travel along the cable from the planetary surface directly into orbit or space, without using large rockets. This would drastically reduce the cost of putting things into space.
Building such a giant elevator would require an incredibly strong cable. One of the potential materials is carbon nanotube, if it could ever be made long enough. Compared to steel, kevlar, and other strong materials, carbon nanotubes have very high tensile strength (130,000 MPa)
Recently, researchers at the University of Cambridge and Columbia University reevaluated the idea with a minor modification: instead of anchoring the cable on Earth, anchor it on the moon and dangle it toward Earth.
In this way, the space elevator — researchers have named it spaceline — could be developed with today’s technology.
How Is It Possible?
As per the basic idea, a conventional space elevator would contain a 42,000 km long cable anchored to the Earth’s surface and stretching beyond geosynchronous orbit. The massive mass of such an elevator would be supported by centrifugal forces, and it would rotate in line with Earth’s rotation.
The spaceline, on the other hand, would be anchored to the moon, which is why it would rotate slowly (orbit only once a month) with lower associated forces.
Reference: arXiv:1908.09339
Since spaceline would extend from the moon to Earth, it would pass through a space region (called Lagrange point) where lunar and terrestrial gravitational pull cancel each other out.
Below this region, Earth’s gravity pulls the cable toward it. And above this region, the cable is pulled toward the surface of the moon.
A sketch of spaceline drawn to scale. R=radius of Earth; r=radius of Moon; Rgeo=height of geostationary orbit; D=distance between Earth and Moon.
Researchers showed today’s strongest materials, such as Zylon, have enough strength to support the cable extending from the moon to Earth’s geosynchronous orbit.
Obviously, building this structure would a huge engineering challenge. Even in its most economical form, a cable as thick as pencil lead would cost billions, and it is difficult to anticipate what extra cost such a project could incur.
However, if built, spaceline would cut down the cost of sending people to the moon by 70 percent. The project would be incredibly difficult, but by no means impossible for modern space missions.
It would also enable scientists to explore Lagrange points where the gravitational forces of a two-body system like the Earth and moon generate enhanced regions of attraction and repulsion.
Since the gravity at this location is very weak and it contains less debris, it would be a much safer and stable location for construction projects.
Researchers believe that the Lagrange point base camp would be a crucial aspect for the early use of this space elevator. It would enable the manufacturing of next-generation astronomical machines (such as telescopes, gravitational wave detectors, and other satellite instruments) in space. It could also be used as a launch point for interplanetary missions.
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With concerted effort and investment, this may become a reality in decades. Researchers hope their findings inspire others to question, discuss, and evaluate the possibilities of the space elevator.
