A space elevator on Earth or the moon could make space travel and cargo transport easier, cheaper, and more sustainable.

Companies in China and Japan hope to build such elevators by 2045 and 2050, respectively. Japanese researchers have even tested miniature prototypes in space.

Experts say a space elevator could be possible with current technology, especially if we were to build it on the moon. A lunar elevator would not have to contend with the Earth's gravitational force or space debris.

There are still many details to iron out, though, including how to build such a monumental structure.

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A growing number of scientists and space-technology enthusiasts are looking into ways to construct a huge elevator, either on Earth or the moon, that could transport cargo to and from space.

In a study published in September, which has not been peer-reviewed, two graduate students proposed a version of a space elevator that would stretch from the moon to Earth's satellite-level orbit. They said the structure could be built with current technology.

"They're right, and we were right first, that the lunar elevator is feasible technology," Michael Laine, the president of the space-elevator-development company LiftPort Group, told Business Insider.

Other advocates of space elevators have argued for years that building such a structure is feasible with current technology and could open up new frontiers of space exploration.

Here's how a space elevator would work.