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Humanity’s fascination with exploring and potentially settling in outer space has sparked numerous ideas about how to achieve this goal.
While the common belief is that rocket launches are the best method for sending humans into orbit, there have been other “non-rocket” proposals, such as the concept of a “space elevator.”
The idea of a space elevator, essentially a super-tall cable allowing humans to ascend into space, has been promoted by some industry experts as a way to overcome the high costs of sending people and cargo into space via rockets, according to Alberto de la Torre, assistant professor of physics at Northeastern University.
“Current launch systems are primarily single-use and typically cost over $10,000 per kilogram of payload, totaling around $60 million per launch,” de la Torre explains. “This is where space elevators come into play.”
The space elevator was first envisioned by Russian rocket scientist Konstantin Tsiolkovsky in the late 19th century. It would extend from the ground through the atmosphere and beyond “geostationary orbit,” an altitude where objects in space are in synchronized rotation with the Earth. Geostationary orbit is located approximately 22,236 miles above the Earth’s surface.
Essentially, a cable would descend from a satellite structure anchored in geostationary orbit, serving 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, exerting a downward force on it from the ground, and the centrifugal force of its rotation, exerting an upward force on the cable from space. The interaction of these forces would create the ideal tension required to sustain such a long cable, de la Torre says.
“The cable is the crucial element of a space elevator, positioned at the Earth’s equator and synchronized with the Earth’s rotation,” de la Torre explains.
There is currently no proof of concept for a space elevator. Despite various attempts at architectural designs, including an award-winning design by a British architect that recently received a six-figure prize, numerous technical challenges have prevented the realization of a space elevator for decades.
“A cable of such length [more than 22,236 miles above the Earth] is not feasible with conventional materials,” de la Torre points out. “If made of steel, the maximum tension it faces at geostationary orbit exceeds its tensile strength rating by over 60 times.”
For an Earth-based space elevator, strategies to reduce tensile forces, or the ability of a material to withstand tension, are crucial, he explains.
However, there are some promising materials. Boron nitride nanotubes, diamond nano threads, and graphene—all materials with “low density and high tensile strengths”—could be viable, de la Torre suggests.
“Carbon nanotubes are considered an ideal material due to their high tensile strength,” he says. “Recent research has raised concerns about the feasibility of scaling their nano-scale properties to megastructures.”
In the long run, the potential of space elevators lies in their ability to significantly reduce the cost of trips to outer space. “The cost of placing a payload beyond a geostationary orbit could be lowered to just a few hundred dollars per kilogram,” de la Torre states.
“While the initial investment in a space elevator may be substantial—similar to the expense of developing and launching the James Webb Space Telescope into orbit—the costs could be recovered after successfully launching just a few tons of payload,” he notes.
“With the continuous advancements in materials science, space technology, and engineering, the idea of space elevators should not be disregarded in the near future,” de la Torre remarks.
Until these breakthroughs in materials science occur, the space elevator may remain a topic primarily explored in science fiction.
“Space elevators fundamentally hold the potential to transform humanity into a spacefaring civilization,” de la Torre concludes. “They could offer a safe, cost-effective means to transport the heavy payloads necessary for hypothetical space stations, asteroid mining, or the development of extraterrestrial habitats.”
