Humanity’s quest to explore — and, perhaps eventually, colonize — outer space has prompted a great many ideas about how precisely to go about it.
While conventional wisdom suggests that space launch via rockets is the best way to send human beings into orbit, other “non-rocket” methods have been proposed, including a futuristic “space elevator.”
The concept of a space elevator — essentially a sky-high cable that would let humans climb into space — has been championed by some industry experts as a way to overcome the astronomical costs associated with sending people and cargo into space by rocket, says Alberto de la Torre, assistant professor of physics at Northeastern.
“Current launch systems are predominantly single-use and typically exceed $10,000 per kilogram of payload, totaling around $60 million per launch,” de la Torre says. “Here’s where space elevators are appealing.”
First imagined by Russian rocket scientist Konstantin Tsiolkovsky in the late 19th century, the space elevator would extend from the ground through the atmosphere, then past “geostationary orbit,” an altitude where objects in space — pulled in by the Earth’s gravity — orbit more or less in tandem with its rotation. Geostationary orbit is roughly 22,236 miles above the Earth’s surface.
Effectively, a cable would descend from a satellite structure anchored in geostationary orbit that would act as a “counterweight” down to Earth.
Theoretically, a satellite positioned beyond geostationary orbit would act to stabilize the cable through a combination of forces: the Earth’s gravitational pull, which would exert a downward force on it from the ground, and the centrifugal force of its rotation, which would exert an upward force on the cable from space. The interaction of forces would create an ideal tension — a tautness — necessary to sustain a cable of such length, de la Torre says.
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