How a ‘space elevator’ could work on Earth or the moon – Business Insider
In 1895, Russian rocket scientist Konstantin Tsiolkovsky gazed at the Eiffel Tower and imagined it stretching into space.
His daydream became the first pitch for a space elevator.
He imagined a tower like that could carry cargo to geostationary orbit — the height at which satellites can sync their orbit with Earth’s rotation — 35,786 kilometers (22,236 miles) above sea level. As objects ascended the tower, they would gain horizontal velocity from the Earth’s rotation and could use that speed to launch into orbit.
Relative to rockets, space elevators would be a cheaper, faster way to get cargo and people off of Earth. That’s because liftoff is one of the most expensive and difficult parts of space travel.
“The high cost of space transportation coupled with unreliability is a virtual padlock on the final frontier,” reads a 2008 NASA fact sheet. “Our dreams of everyday life in space and its promise for a better life on Earth are hostage to the high cost of space transportation.”
That hasn’t changed. On average, getting material from Earth’s surface into space costs about $20,000 per kilogram, or roughly $10,000 per pound. Since NASA’s space shuttle program ended in 2011, private companies have been launching supplies to the International Space Station.
“The space elevator would essentially be an economic game-changer for the space industry,” Tyler Harris, an engineer at the Pacific Northwest National Laboratory, told Business Insider.
By some estimates, a well designed elevator would cut the cost of cargo transportation to as low as $100 per kilogram. Even at $1,000 per kilogram, that would be just 5% of the current cost.
Experts say this type of structure could be built with current technology. Cost estimates range considerably, from $1 billion to nearly $90 billion.
Harris recently conducted an assessment of three different space-elevator designs and found that they would all be “environmentally sustainable and economically viable.”
The $90 billion cost estimate comes from the Obayashi Corporation, which is based in Japan. The company wants to build a space elevator by 2050.
The China Academy of Launch Vehicle Technology, a subdivision of the nation’s main space-program contractor, wants to build a space elevator by 2045, though company has not released any details about those plans.
NASA has funded research on space elevators, too, but has never committed to building one.
Obayashi expects it to take 20 years to construct the cable from a 400-meter base that floats in water.
The company envisions the final product carrying 100-ton climbers off of Earth.
The Japan Aerospace Exploration Agency (JAXA) launched a miniature version of a space elevator in September 2018 to see how it reacted to the space environment.
The device, called Space Tethered Autonomous Robotic Satellite – Miniature Elevator (STARS-Me), was designed by researchers at Shizuoka University. It involved two CubeSat satellites, each of which could communicate with the ground, with a 14-meter (46-foot) tether between them.
The goal: crawl a Bluetooth-enabled climber up the tether from one CubeSat to the other.
The launch was successful, according to a February report, but the researchers had difficulty communicating with one of the CubeSats. They have yet to verify whether the climber successfully traveled up and down the tether.
The trickiest part of developing a space elevator is finding the right material for the tether.
The tether would have to withstand the weather in Earth’s atmosphere, radiation from the sun, and impacts from meteorites and other debris.
Another hurdle keeping space elevators in the realm of science fiction: space debris.
The European Space Agency estimates that 128 million objects smaller than 1 centimeter are orbiting Earth, along with another 900,000 objects that measure 1 to 10 centimeters.
Any space elevator would be subject to collisions with these objects, so it would have to be capable of withstanding or out-maneuvering them.
One analysis calculated that a lunar elevator could pay for itself after 53 uses, since it could cut at least two-thirds of the cost of landing on the moon and reduce the cost of sample-return missions at least nine-fold.
You can read that full cost analysis here.
“There are a lot of advantages with a lunar space elevator,” Pearson said. “And with this new NASA program to return to the moon, there may be additional interest.”
For now, though, any space elevator remains theoretical. “The big idea is still subject to a lot of details that we don’t have the answers to,” Laine said.
He added that the LiftPort team still needs to research the effects of rapid temperature changes that cargo would undergo as it ascended the space elevator. Work is also needed to determine how to protect cargo from solar radiation and how potential tether materials handle atmospheric changes. Then, of course, there are the complicated logistics of building such an elevator in the first place.
Ironing out those details is a slow process in these early stages. For now, it involves a lot of paperwork, complicated simulations, and financing efforts, Laine said.
“It’s the boring, mundane task of building the biggest thing ever,” he added.
But if a space elevator eventually becomes a reality, it could also help us access resources in space.
“Not only does it enable new space exploration and opportunities in space, but the way I look at it is using those resources to improve sustainability on Earth,” Harris said.
Asteroids can be literal treasure troves, since they contain valuable elements like gold, platinum, and iron. Mining materials on an asteroid could mean that we’re not extracting those resources from the Earth.
