Will the space elevator rise?
Posted: Friday, July 18, 2008 7:38 PM by Alan Boyle
Pat Rawlings / NASA file |
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the future, as seen by advocates
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If space elevators work out the way the idea's advocates hope, sending payloads into orbit would become as routine as, say, sending a shipment on a freight train - except that the train would travel straight up for hundreds or thousands of miles, powered by laser beams.
But will such a "railroad to the sky" ever be built? That's the big question hanging over the 2008 Space Elevator Conference, taking place this weekend on Microsoft's Seattle-area campus. And considering that this is an event primarily attended by elevator enthusiasts, you may find some of the answers surprising.
One of the biggest advocates of the concept, the late science-fiction seer Arthur C. Clarke, said back in 1979 that the first space elevator would be built "about 50 years after everyone stops laughing."
There wasn't much laughing to be heard as the talks got under way today at Microsoft's Redmond conference center (which happens to be a five-minute walk from my newsroom at msnbc.com, a Microsoft-NBC Universal joint venture). Instead, there was a long day's worth of serious talks about way-out subjects such as orbital debris threats and power-beaming lasers.
And there were a lot of predictions: On one end of the scale, Bradley Edwards, president of New York-based Black Line Ascension and one of the pioneers of the space elevator movement, said creating a space elevator would require much less time than 50 years - as long as you had $7 billion to $10 billion to spend.
"It's really a cost issue," he told me. "If you could get the money, you could have one up in probably 12 years, 15 years."
On the other end of the scale was Tom Nugent, project manager for Seattle-based LaserMotive, who said the space elevator would never be built, due to technical and safety concerns.
"We don't believe in the space elevator," Nugent told me. The way he sees it, all the activities spawned by the concept merely provide "a useful way to demonstrate our laser power beaming technology."
In between those extremes, there's a Japanese technological road map that calls for building a space elevator and a space solar power system by 2030, and a NASA projection that the elevator would take shape in 200 years or so.
Ted Semon, who presides over the Space Elevator Blog, sized up the potential players and concluded that the builder of the first space elevator would likely be either a U.S. industry consortium supported by the federal government - or an alliance involving the governments of Dubai and India.
"Dubai could fund it just like that," he told me. "And India would love to jump at the chance to leapfrog China."
Even if you scoff at the starry-eyed vision of riding a ribbon to outer space on a laser-powered lift, the technologies that form the foundation of that vision are far more down to earth - and likely to produce profits long before the space elevator sees the light of day. That's what Nugent and many of the conference's other attendees are going after.
The technological road ahead
The two main technologies behind the concept are super-strong, ultra-lightweight materials and power-beaming systems.
A working space elevator would require tethers or ribbons of synthetic material that would extend from Earth's surface up to an altitude of perhaps 62,000 miles (100,000 kilometers). Carbon nanotube fibers are the most popular candidates for the job.
The tethers would be sent into orbit aboard a conventional launch vehicle. One set of tethers would be lowered down from the orbiting craft for connection to an "attach point" on Earth's surface - for example, a floating platform in an area of the ocean that's relatively unaffected by weather. Counterbalancing tethers would spool out spaceward.
Those tethers would serve as the "rails" for robots climbing up and down to the orbital transfer station. Proponents say such robots could carry payloads at a cost of $100 per pound or less - compared with current orbital launch costs that range from $2,000 to $60,000 a pound, depending on what is launched and how high it goes. Other types of robots would build up the system and keep it in repair.
You can't really fuel up a robot for this kind of trek to space, so you'd need to find a wireless, tankless way to transmit power hundreds or thousands of miles. That's where the power-beaming systems come in: Laser light from below would be focused on photoelectric cells to keep the robots running, perhaps supplemented by solar power from above.
If those technologies come together, then what? "There are lots of things we want to do in space, but part of the problem is getting there," Edwards said.
Cheaper access to space could open the way for space solar-power satellite systems that can beam energy back down to Earth. Elevator operators could send people and payloads to orbital hotels, and then onward to the moon and Mars. The elevators might even revolutionize garbage disposal, Edwards said.
"There has been a lot of discussion about using space elevators to take radioactive waste and get rid of it by throwing it into the sun," he said.
Where are those technologies today?
The technological hurdles facing elevator enthusiasts are every bit as high as their hopes. This weekend's conference provided a progress report on how close the reality is coming to the dream.
Edwards pointed to advances in carbon nanotube fabrication, which he saw as essential for space elevator construction. "That's the only thing that's strong enough," he said. He hailed advances that have brought new records for nanotube length as well as new methods for spinning nanotube fibers.
"Some of the work being done is now becoming a business," Edwards said. Nanotubes are already being woven into the marketing hype for bikes as well as golf clubs, and Edwards predicted that a technological tipping point could come sometime in the next year.
Are nanotubes safe? A recent study raised health questions about the stuff but Edwards said the safety concerns were not as serious as some have made them out to be, particularly for space applications.
Ben Shelef, director of the Spaceward Foundation, was hopeful that the nanotube hurdle would be overcome sooner than the skeptics think. "While we're definitely not there, we're not a factor of 50 away. We're a factor of 10 away," he said.
Shelef previewed Spaceward's plans for the fourth annual Space Elevator Games, a double-header competition that focuses on super-strong tethers as well as power beaming. This year, NASA is offering $4 million in prizes for the winners of the games' ambitious contests, and Spaceward is organizing the contests on NASA's behalf.
To take the top tether prize, the winning team will have to develop a material that can take more stress than the other competitors' offerings, and also best a "house tether" that has a 50 percent weight advantage.
Eleven teams have signed up for the power-beaming competition, which involves sending a beam-powered robot up a 0.6-mile-long (1-kilometer-long) tether suspended from a helicopter.
If the robot completes the required length with an average speed of 6 feet (2 meters) per second, it would be in the running for a $900,000 prize. If the average speed reaches 16 feet (5 meters) per second, the prize rises to $2 million.
Shelef said the tentative plan is to conduct the games at Arizona's Meteor Crater in mid-October, but the timing and the venue are still subject to change. So far, none of the teams has satisfied any of the requirements for a prize, and as a result NASA hasn't paid out any money in the Space Elevator Games. That may change this year, Shelef said.
"This is going to be the first year, I think, where [each] team's main enemy is the other teams," he said.
Just this week, LaserMotive announced that it satisfied the power-beaming contest's requirements in a treadmill test. However, the company is expected to face stiff competition from last year's favorites, including the University of Saskatchewan Space Design Team.
If a viable power-beaming system could be developed, it would find almost immediate application. The U.S. military has talked about using beam power to energize balloon-based observation platforms or robotic drone aircraft. Point-to-point power beaming could cut down on risky fuel resupply missions in combat zones.
Beyond the battlefield, NASA could conceivably use power-beaming stations to boost rovers or bases on the moon or Mars. And beaming power down to Earth is key to the space solar power systems I've already mentioned.
So ... will it ever rise?
Even if these technologies bear fruit on Earth, the space elevator's success is not assured. Speakers weren't shy about raising additional questions during today's sessions:
- Will nanotube tethers ever be tough enough to endure buffeting by atmospheric winds? How long can they be expected to stand up to exposure to the elements as well as space radiation?
- Would the Earth stations for space elevator systems become prime targets for terrorism? Who will pay the cost of defending them from earthly threats?
- Will there be an acceptable safety margin for space elevator operations? Nugent said that if the space elevator is held to the same safety standards that other industries have to meet, the concept would clearly become financially untenable.
- Can space elevator systems be designed to stand up to collisions with orbital debris?
Ivan Bekey, president of Virginia-based Bekey Designs, said that last point was a potentially fatal flaw for the space elevator concept. "We've got a very fundamental problem for which I have seen no engineering or cost analysis to solve," he said.
Edwards said there were potential solutions to the debris-collision problem, such as repositioning the elevator's Earth station, which would in turn move the system's tether out of the path of the occasional piece of space junk. However, he conceded that more analysis was needed.
"There's no funding," he said, "and this is a real falling-down for the entire program."
Edwards said several new initiatives were in the works to pool together information and raise public awareness, including a Space Elevator Wiki and a Japanese movie titled "Space Elevator: The Future as Foreseen by Scientists." You can watch a trailer for the movie (in Japanese) as well as a mini-interview with Edwards (in English).
Edwards also hopes to see the rise of a Florida theme park celebrating the space elevator concept. Visitors to the attraction would take a ride on a virtual space elevator to a virtual space station, all enclosed within a 10-story-high structure. Edwards said the land has already been selected for the facility, outside Orlando, and he's working on getting the first $300,000 in seed capital by Nov. 30.
Is the space elevator concept worth the cost of a theme-park ticket? Is it worth the multibillion-dollar cost of building the real thing? Feel free to register your opinion in our unscientific Live Vote, and weigh in with your comments below.
The 2008 Space Elevator Conference continues through Sunday, July 20, at the Microsoft Conference Center in Redmond, Wash. For updates, check in with Ted Semon's Space Elevator Blog. The conference is sponsored by Microsoft Corp., Black Line Ascension and Industrial Nano.
