Organizations like NASA and SpaceX have pledged to send humans to Mars in the near future, and each has its own unique technology in development to enable such a journey. One thing they all seem to have in common, however, is the proposed method of transportation.
Right now, the only way to reach space is via a large chemical rocket, the same way we have been since the 1960s. But what if there were a way to get there that was more fuel efficient and less costly?
Enter the space elevator.
Space elevator concepts generally consist of the same basic parts. A platform firmly planted on Earth would be the base, and elevator cars would travel up and down a long tether. The tether would end at a counter weight 99,779 kilometers (62,000 miles) above the Earth.
Such an elevator would drastically lower the cost of sending materials into space, from $20,000 per kilogram to perhaps as low as $200. If that's the case, the cost of building such an elevator would be recouped after having sent 1 million tons of cargo.
So what's preventing the construction of these elevators? As of now, we don't have material strong enough to serve as the tether. Some studies have said carbon nanotubes aren't strong enough, and current hopes are pinned on diamond nanothreads. Estimates suggest that the material needed for a tether will be developed by 2030.
Construction could also be derailed if an alternative technology is developed that makes space elevators unnecessary. SpaceX and other companies are trying to create reusable rockets, which are also expected to lower costs. If they are successful, the space elevator may be permanently relegated to its current place in sci-fi.