This is the LiftPort Group's basic model for its proposed Lunar Space Elevator Infrastructure, also known as LSEI or "Elsie." LiftPort says the system can be constructed within eight years using commercial technology. Watch on YouTube





The space elevator concept has had its ups and downs — but this year, it looks as if the concept's proponents are definitely trying to push the “up” button again.

There’s a new Kickstarter project, aimed at setting the stage for a lunar space elevator. Space-elevator backers are trying to restart a competition for ultra-strong tethers. And a Japanese company has pledged to get the thing built … by 2050.

But veterans of the movement say one big thing is required: a revolution in materials science, and specifically carbon nanotubes. Or maybe boron nitride nanotubes.

"The materials are still the long pole in the tent, and I don't see the government getting interested in it," Bryan Laubscher, the founder and president of Odysseus Technologies, told me today. "That's disappointing to me."

Laubscher and other space-elevator advocates will take stock of the past year's ups and downs at the annual International Space Elevator Conference, running from Saturday through Monday at Seattle's Museum of Flight.

Railway to the sky

The idea of building a "railway to the sky" has tantalized dreamers for decades: Just send a satellite up to geostationary orbit, 22,000 miles up (36,000 kilometers up). Send one line back down to Earth, and another line up to an altitude of about 100,000 miles (160,000 kilometers) with a counterweight at the end. Secure Earth's end of the line so it's rock-solid, then start sending robotic climbers up and down the line, carrying cargo and passengers.

If the idea can be executed, advocates say it could reduce the cost of access to orbit from its current level of $10,000 or so a pound to $100 a pound — revolutionizing space travel and potentially opening the solar system to human settlement. That's the vision brought to life in science-fiction novels ranging from Arthur C. Clarke's "The Fountains of Paradise," published in 1979, to this year's opus by Kim Stanley Robinson, "2312."

Clarke once joked that the space elevator would be built "about 50 years after everybody quits laughing." Several years ago, LiftPort Group founder Michael Laine set up a countdown clock that predicted the "first lift" would come even sooner, in 2018. Today, six years seems way too soon, but at least people have stopped laughing.

The key sticking point has to do with the tethers, or cables, or ribbons that would be required to connect a terrestrial liftport with the elevator's orbital destination. Whatever they're made of, that connecting material would have to be stronger than any material that's manufactured today. A synthetic polymer called Zylon ranks among the strongest available, and space-elevator advocates measure its strength per unit of density at 3.9 megayuris. (The "yuri" is an unofficial measurement unit that was named after Russian space-elevator pioneer Yuri Artsutanov.) The specific strength of steel is about 0.5 megayuris. But the stuff of space elevators would have to be on the order of 30 to 100 megayuris strong.

For years, NASA offered $2 million in prizes to encourage the development of 5-megayuri material, but that challenge expired after last year's contest. The International Space Elevator Consortium is trying to revive the prize program at a lower level, but that won't happen in time for this year's conference.

"I'm confident there's going to be a well-attended strong-tether challenge next year," Ted Semon, the consortium's president and director, told me. "It's our numero-uno mission."

Who's going to build it?

Laubscher thinks it's going to take a government-backed development effort on the scale of the telecommunications revolution of the 1960s to create the materials required for building space elevators. "I actually think that the first space elevator will be built by the U.S. Department of Defense," he said. "The first one to build the space elevator owns space."

Carbon nanotubes are a good candidate, but lots of technical obstacles will have to be overcome in order to produce long, wide ribbons of carbon nanotubes that are strong enough and resilient enough to do the job. David Horn, the chairman of this weekend's conference, says boron nitride nanotubes offer 75 percent of the theoretical strength of carbon nanotubes and may be easier to manufacture.

"We haven't seen that it can't be done," Horn said of the space elevator concept. "But we really need to get this competition going to give people a financial incentive to do it."

Whether they're made of carbon or boron nitride or polymer, stronger materials will produce a payoff long before the elevator gets built — in the form of lighter, more fuel-efficient automobiles, airplanes, boats and, yes, even spacecraft. Cheaper, safer, easier access to space would make a big difference in the financial calculations underpinning the space elevator dream. "The world that we'll have with carbon nanotubes will demand that we build a space elevator," Laubscher said.

Here are some of the developments along the road to the space elevator:

Liftport Group founder Michael Laine has just begun a Kickstarter campaign to raise $8,000 as the first step in what could be a multimillion-dollar effort to build a lunar space elevator, which is theoretically possible using existing technology. Liftport ran into financial and legal difficulties in 2007, and today Laine admits that "things went south for us" back then. This campaign, he says, marks Liftport's return to the fray after five dark years. "About six months ago, we had a fundamental breakthrough ... and we want you to be a part of it," Laine says in his Kickstarter video. It's debatable whether the lunar elevator concept will get off the ground, but Laine is optimistic. His current countdown clock calls for "first lift" ... presumably from the moon ... by Jan. 1, 2020.

In February, the Tokyo-based construction company Obayashi Corp. unveiled plans to transport goods and passengers in a space elevator as early as 2050, according to a report from Japan's Yomiuri Shimbun. The trip to an orbital station would take seven and a half days. "At this moment, we cannot estimate the cost for the project," an Obayashi official was quoted as saying. "However, we'll try to make steady progress so that it won't end up as simply a dream." Although there haven't been any progress reports lately, Laubscher said "the Japanese are way ahead of America" in their enthusiasm for the space-elevator vision.

Other places to watch for space elevator developments: One of the leading U.S. forums for carbon nanotube researchers is the Nanotechnology Materials and Devices Workshop, sponsored this year by the University of Cincinnati, the University of Dayton and the Air Force Research Laboratory. This year's workshop is set for Nov. 5-6 at the University of Dayton. Also, The New York Times reported last November that space elevators are on the agenda for the secretive Google X lab. "Google is collecting the world's data, so now it could be collecting the solar system's data," Rodney Brooks, an MIT professor emeritus and founder of Heartland Robotics, told the Times.

How realistic are these visions? Feel free to share your views in the comment space below. And if you're in the Seattle area, you might want to head on over to the Museum of Flight on Saturday. Even if you can't attend the three-day technical program for the International Space Elevator Conference, you can check out what's happening at the Family Science Fest.

Past chapters of the space elevator saga:

Alan Boyle is NBCNews.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. To keep up with Cosmic Log as well as NBCNews.com's other stories about science and space, sign up for the Tech & Science newsletter, delivered to your email in-box every weekday. You can also check out "The Case for Pluto," my book about the dwarf planet and the search for new worlds.