Partial space elevators work without an Earth anchor

Credit: Tony Holmsten

Today, putting just one single kilogram of stuff into geosynchronous orbit will run you about $25,000. That's a huge cost that's long-term unsustainable for space exploration, which is why reusable rockets and spaceplanes are in the works, but another technology could make putting people and satellites into deep space cheaper still. Space elevators could someday whisk us up from Earth's atmosphere and straight into space, but until we can build one that goes the entire distance, it might make sense to start with a smaller version that only goes partway.

While most space elevator concepts call for an anchor point on Earth, there's a second idea floating around that sounds almost too wacky to be true: an elevator with no ground floor. Known as partial space elevators, these still-massive structures would be less than half the length of their Earth-anchored counterparts. Hanging in geosynchronous orbit, these elevators would only dip as low as 99 miles overhead — the very edge of low-Earth orbit.

Spaceplanes or plane or ballon-launched rockets could easily reach this height on a regular basis for a relatively low cost, delivering cargo and passengers to the base of the elevator in orbit. From the elevator's floating base, you would then travel by space-faring funicular along a tether of carbon nanotubes until you yourself reached geosynchronous orbit at a height of 26,200 miles. A counterweight would extend as far as 60,000 miles into space, just to make sure the whole structure didn't come crashing down on top of our heads.

All this can sound wildly unfeasible and massively expensive, but when all is said and done, a partial space elevator could cut the cost of traveling to geosynchronous orbit by 40 percent or more. And those savings could be just the beginning. A partial space elevator could also be seen as a (massive) first step toward building an Earth-connected elevator, which would do away with rockets entirely. Someday, you might even ride the space elevator on your way to visit your relatives living on the Moon.

Acta Astronautica, via National Geographic

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