“Space Elevator” is Looking More and More Like a RealityMay 14, 2019
Researchers from Japan’s Shizuoka University are taking the next step towards building the first space elevator by launching their Space Tethered Autonomous Robotic Satellite-Mini elevator, or STARS-Me from the International Space Station (ISS). “It’s going to be the world’s first experiment to test elevator movement in space,” said a spokesperson from the university in an interview with Agence France-Presse.
An elevator to the stars
The idea of a space elevator is not new. It was first proposed by Russian scientist Konstantin Tsiolkovsky in 1895 as a tower reaching up from the Earth. In the current plan, however, the elevator consists of a cable, or tether, extending from a station on the Earth’s surface and attached to a counter weight beyond geostationary orbit. The force of gravity on the Earth’s surface and the centrifugal force from rotation keep the tether tense. To get a picture of how this would work, imagine turning in circles while holding a rope with a ball attached to the end.
Chambers carrying cargo or people would travel up and down the tether between the Earth and a geostationary Space Station. Although the elevator would be slower than a rocket, the ride in the elevator would cost considerably less. In fact, it is estimated that a space elevator could cut the cost of sending cargo into space from more than $10,000 – $40,000 per pound required today to around $100 per pound.
The Obayashi Corporation, a Japanese construction company, has announced plans to construct the space elevator by 2050. The design they proposed has an Earth Port floating on the Pacific Ocean connected to a 96,000-km tether and a 12,500-ton counter-weight. Climbers travel along the tether between the Earth and several stations, including a Geostationary Earth Orbit Station at 36,000 km.
On September 27, an H-IIB rocket carrying the STARS-Me setup arrived at the ISS. The setup consists of two tiny cube-shaped satellites. Each mini satellite measures 10 x 10 x 22.7 cm, and they joined by a 10 m-long steel cable. A motor will move a small container between the two satellites, just like a miniature elevator. Cameras attached to each of the satellites will capture pictures of the setup. According to the latest news, the STARS-Me was released from the ISS on October 6.
This experiment will be the first ever to move a container between two objects connected by a cable in space. It is one small step forward in the road towards a real-world space elevator. But there are still many hurdles to overcome. The biggest of these is the lack of an appropriate material for the tether, which must be strong enough to resist the forces acting upon it. Yet, it must also be light enough not to collapse under its own weight. Currently, no material fits these requirements.
Many, including the Obayashi Corp., think that carbon nanotubes are the way to go. These structures are made of folded sheets of graphene, which is an extraordinary material that is only an atom thick but is 200 times stronger than steel. However, current technology doesn’t allow for the production of carbon nanotubes large enough for the tether. Additionally, some skeptics argue that not even carbon nanotubes would be capable of resisting the forces the tether would be subject to. This—said Keith Henson, cofounder of the National Space Society, in an interview with Gizmodo—is because the hexagonal bonds between the carbon atoms in a carbon nanotube become unstable when exposed to extreme loads.
Other issues facing the construction of a space elevator include the danger of space debris and the effect of extreme weather such as hurricanes.
However, if these can be fixed, the perspective of having a device taking us up and down to space in a couple of decades is pretty exciting.
Credit photos: NASA, Kenn Brown, Hackaday