21 December 2008

Orbital express: here comes the space elevator

Cosmos Magazine
Forget rockets - advances in nanotechnology may soon make a trip into space as easy as riding an elevator.
Orbital express

Up, up and away: The first climber, designed to carry 20 tonnes of cargo. Eventually larger climbers would carry 200 tonnes. Credit: Photolibrary

THREE DECADES AGO, fledgling scientists and teenage technophiles began losing themselves in a novel by the late great science fiction icon Arthur C. Clarke. When they finally put the book down, they were dazzled by a vision of ordinary people rising into space. Many of them still think longingly of Clarke’s book when they peer at the stars.

The Fountains of Paradise is the story of a maverick 22nd-century engineer who proposes building a ‘space elevator’ that would ascend more than 32,000 km. The ground floor of this elevator would be at the top of an equatorial mountain in the mythical country of Taprobane. The engineer has to battle a host of sceptics as well as wage a philosophical war with the monks who own the mountain.

Funnily enough, the first person to develop a detailed plan for a space elevator hadn’t read Clarke’s book. Nine years ago, Brad Edwards, a physicist at the Los Alamos National Laboratory in New Mexico, USA, was a little bored with the limitations of working at a huge government bureaucracy.

One day he read an article that declared it would be 300 years – if ever – before anyone had the materials or the capability to build a space elevator. Edwards had a bit of a track record for proving naysayers wrong, so this piqued his interest.

“My first thought was, ‘Why can’t it be built?'” says Edwards, now president of a Seattle, Washington, start-up company called Black Line Ascension, which conducts space elevator research and development. “I looked into it and threw out some of the concepts, like capturing an asteroid, that we don’t have the technology to do. After that, I never found a good reason why it couldn’t be done.”

Edwards put together some calculations. Finally, he took a rough proposal for a space elevator to the NASA Institute for Advanced Concepts (NIAC), a division that encouraged people outside the U.S. space agency to explore bizarre yet scientifically sound concepts that might be useful decades in the future. In 1999 NIAC awarded Edwards a phase-one grant of US$75,000 (A$80,017) over six months.

Impressed with the paper from his phase-one study in 2000, NIAC then gave him a two year grant of US$500,000 to continue working on the project. Edwards quit his job and devoted himself to the space elevator full time. He polished off his phase-two term with a co-authored book, The Space Elevator: A Revolutionary Earth-to-Space Transportation System. It was a less poetic title than Clarke’s, but it still caught the attention of the world’s technology community.

Soon organisations such as the International Astronautical Congress and the American Society of Civil Engineers were holding sessions to discuss Edwards’ plan. Space elevator conferences began attracting serious scientists.

The Spaceward Foundation was formed in 2004 to popularise the space elevator concept and accelerate research in its core technologies. A year later, a NASA program called Centennial Challenges offered large cash awards for the Space Elevator Games, in which competing teams build prototypes of space elevator components.

“The space elevator was viewed as science fiction until Brad’s work,” says Robert Cassanova, former director of NIAC, which closed due to budget cuts in 2007. “There are still lots of details to work out, but there are no major problems with the physics behind the idea. The physics tells us that if you can put this thing out there, it will work.”

Now, hundreds of scientists around the world – from established researchers to students in graduate school – devote at least some of their time to working on the major components of Edwards’ plan. They hope for construction to begin in 2010 and have their fingers crossed that by then all the technical, financial, political, regulatory, legal and other issues should be worked out. If all goes as smoothly as they envision, the first of many space elevators will be completed by 2020 at a cost of around US$10 billion.

Most people without a science or technology background are startled by the idea. They can’t imagine what a space elevator would look like or why anyone would want to build one. Don’t we already have rockets? How can there be an elevator to space when most of it is empty? Unless the plan is to attach this thing to the Moon, what will hold it in space?

Here’s the concept, from the bottom up: Edwards’ plan is to build the space elevator over a floating platform, similar to an oil-drilling rig, in the ocean about 4,000 km south of California. Specifically, the platform would be located in the belt of warm air and low surface winds along the equator known as the doldrums. The lack of wind there makes sailors fret, but the relative calm would cause the least meteorological distress to the space elevator once it is in operation.

From the platform, a flat, narrow tether would extend 100,000 km into space, where it would connect with a counterweight weighing approximately 600 tonnes (more than twice the current weight of the International Space Station). Earth’s rotation would swing the tether and counterweight through space, and the tension in the tether would provide the centripetal force to keep the counterweight moving in a circle. The elevator would always extend in a straight line over the same point near the equator.

The elevator car, or ‘climber’, would hang below a mechanism that grips the tether between rollers. Powered by a laser beam on Earth, the car would move up and down at a speed of about 190 km/h. In one artist’s renditions, the elevator car looks like a large, slightly flattened yellow bus. The first space elevator would carry 20 tonnes of cargo; it’s envisaged that larger models would eventually be able to carry 200 tonnes and move faster, so that people could travel more comfortably.

OVER THE DECADES as scientists attempted to figure out how to make a working space elevator, it was the tether that stymied them. No one knew of a material that was strong and durable enough to withstand the pressure of stretching that far into space with such heavy loads.

“We had to talk about using a material that no-one had, what we called ‘unobtanium’,” says Jerome Pearson, an aerospace engineer and former branch chief for the U.S. Air Force Research Laboratory, who was the first to publish a concept for a space elevator in an international paper in the journal Acta Astronautica in 1975. Clarke consulted Pearson during the writing of The Fountains of Paradise.

The solution came in 1991, when physicist Sumio Iijima of the NEC Corporation in Tsukuba, Japan, discovered a new type of material called single-walled carbon nanotubes. (Russian scientists had observed multi-walled carbon nanotubes more than 40 years earlier). Carbon nanotubes are created when carbon atoms form very strong cylindrical bonds; the result is a material that is 10 times lighter than steel, but 50 times stronger. A strand of carbon nanotubes the size of a human hair is theoretically strong enough to support the weight of a car.

Edwards’ design calls for a paper-thin tether made of many strands of carbon nanotubes. The tubes would be bound together in a flat ribbon, 30 cm-wide at the ground and 90 cm-wide and twice as thick when it disappears from sight into Earth’s atmosphere. Viewed from the ground, the tether would look dark and shiny. Higher up, the tether would appear silvery because of a coating designed to protect it from the ravages of lone oxygen atoms floating around in low Earth orbit.

The problem with carbon nanotubes is that no one is manufacturing them in the quantity needed for a small bridge – let alone for a cable 100,000 kilometres long! Space elevator enthusiasts remain undaunted, however, as the materials science community is agog with all the potential applications for carbon nanotubes.

“Long before the space elevator will climb into the sky, you’ll see bridges built in new ways, cars and boats built in new ways, all stronger and lighter because of carbon nanotubes,” says Michael Laine, a former U.S. Marine with a background in finance who formed LiftPort, a Seattle-based company that works on various space-elevator related technologies. “I think they’ll be the building block of the next 100 years. Remember when that guy in The Graduate pulled the kid aside and told him about plastics? It’s like that.”

The other space-elevator technology that’s still not ready for deployment is the laser beam that powers the car up and down the tether. The laser is similar to the tiny light source in a DVD player that reads data – only millions of times stronger. From the ground, this laser beam would be directed at photovoltaic panels on the underside of the climber, providing power to an electric motor that would pull the car up the tether.

Most of the work being done on a laser of this sophistication and power has military applications. “Those are like little blowtorches that you can project hundreds of miles,” says engineer Ben Shelef, co-founder and chief executive of the Spaceward Foundation “Ours will be a wider beam that projects thousands of miles. We presented our space elevator talk to the Directed Energy Professional Society [in 2006], and they’d like to find a use for this technology other than ways to kill people.”

IN OCTOBER 2007, the third annual Space Elevator Games were held in Salt Lake City, Utah. Teams from around the world arrived with their contraptions, vying for a US$500,000 purse in both the Climber (Power Beaming) Competition and the Tether Strength Competition.

The showiest contest was the former, in which teams tried to shimmy their contraptions up a tether at almost two metres per second using only light energy directed at photovoltaic cells. In the past, teams have resorted to a variety of light sources, including multiple spotlights and huge mirrors that bounced sunlight on the climber.

Last year, two teams used lasers but neither they nor their fellow challengers managed a winning performance. Another team excited the crowd by using a tether fashioned from actual carbon nanotubes in the strength competition, but again, nobody won. The games are scheduled again for September 2008 at an as-yet unchosen location in the USA, with total cash awards from NASA of US$2 million. Corporate sponsors have also stepped forward to provide funding and technology.

“It’s not ‘girls gone wild’, it’s climbers gone wild! Engineers gone wild!” says Ken Davidian, who was until recently program manager for NASA’s Centennial Challenges in Washington DC, and former director of operations for the X-Prize Foundation, which in 2004 awarded a US$10 million prize to the first team to build and fly a private spacecraft to an altitude of 100 km and repeat the feat in two weeks. “You’re entering this semi fringe technical world, and that’s kind of cool.”

Beyond the love of gadgets, people are drawn to this project because they believe it will fundamentally change humanity’s interaction with the rest of the universe. In the past, this interaction has been limited by the inherent flaws of rocket propulsion: enormously expensive to build and send into space, and the fuel needed to propel them into space leaves hardly any room for cargo.

“Most people don’t realise how difficult it is to send an object into space,” says Barbara Thompson, a NASA scientist who studies solar physics and space weather in Maryland, USA. “The rocket equations are a real eye-opener to [new] engineers. It adds up to high costs to send even small amounts of mass into orbit.”

Even sending 500 g of cargo into space using rockets costs about US$10,000. A space elevator would reduce this cost dramatically. “It will take shipments almost down to a FedEx price,” quips Edwards. “Sending a package into space will cost about as much as sending one from Seattle to South Africa.”

With this ability to move massive amounts of material and equipment into space, the possibilities for innovation become limitless. We could assemble and deploy huge solar panels to absorb the Sun’s energy, without interference from our atmosphere, and then beam it back to Earth for an infinite supply of clean energy.

Some scientists believe this would end our reliance on fossil fuels – for electricity, at least. The space elevator could also open the door for mining valuable minerals on the Moon and on asteroids. And it could enable us to send out sophisticated weather-monitoring satellites to study the physics and chemistry of our atmosphere much more cheaply and frequently.

Perhaps most significantly, the technology could change the way we launch rockets. The space elevator could transport them into space and then simply let them go. The rockets could use the fuel they no longer need for the launch to travel deeper into space.

THE PATH TO SOLVING many of the Earth’s problems is through space,” enthuses David Livingston, host and producer of The Space Show, a U.S. radio program focussed on space commerce and tourism, which is heard in 50 countries. “Space is not only of great commercial value, but that’s where mankind has always performed [at] its best.”

Space elevator advocates claim that there are likely to be many more benefits which we can’t even imagine until we begin serious exploration of space. As the late Arthur C. Clarke once said, “The analogy I often use is this: if you had intelligent fish arguing about why they should go out on dry land, some bright young fish might have thought of many things, but they would never have thought of fire, and I think that in space we will find things as useful as fire.”

The space elevator would also make large-scale colonisation of space possible, something that can never be achieved by rockets or shuttles. Imagine the possibilities for developers dreaming of space resorts! And one television network has already called Edwards to ask about the feasibility of doing a Survivor-type show on Mars.

Many scientists, including renowned British physicist Stephen Hawking, worry that Earth and much of what lives on it could be wiped out by a disaster such as a rogue virus or severe global warming. They believe the future of the human race depends on moving into space.

“The Earth has been hit by a huge asteroid before,” says Ted Semon, a retired software engineer who lives near Chicago, USA, and moderates the official Space Elevator Games blog. “If something big comes, there’s nothing we can do about it. As the U.S. science-fiction writer Robert Heinlein said, “The Earth is too small and fragile a basket for the human race to keep all its eggs in.'”

NASA’s Centennial Challenges program supports the Space Elevator Games with prize money because it’s interested in power beaming and strong tethers for its own missions, but its involvement isn’t a stamp of approval for the space elevator concept itself.

Still, Centennial Challenges’ former program manager Ken Davidian says NASA wants to encourage private initiatives to explore and commercialise space. “Space [exploration] is not an inherently governmental function,” he says. “Right now, the government is the only one buying services to space. If the industry is going to grow, we can’t be the only customers.”

Davidian, now at NASA’s Exploration Systems Mission Directorate, estimates that the vast majority of the technology community thinks the space-elevator concept is possible, although not necessarily in the time frame that Edwards and his colleagues hope for.

“But the last person you want to ask about this is the experts,” he says. “Number one, no one is good at predicting the future. And number two, if you’re trying to base this on what’s been done in past, then it’s going to seem ridiculous. But I tend to be an optimist. Yes, it’s possible. All it takes is money.”

Kristin Ohlson is a freelance writer and author based in Cleveland, USA.

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