NASA hosts space elevator competition

Picture a ribbon stronger than steel that stretches from Earth to a satellite and acts as a kind of space motorway, on which robots transport materials back and forth.

That is what scientists call the space elevator. And long before it's ever a reality -- if it is at all -- scientists must discover the materials, mechanisms and wireless power source to make it work efficiently.

Considering it's no small feat of optics, electricity and mechanics, NASA and the nonprofit Spaceward Foundation hosted the first-ever competitions this weekend offering $50,000 to teams with the best design of robot climber and ribbon. The competition, held at NASA's Ames Research Center, is merely a conceptual demonstration of the space elevator.

"It's far-out for us, but we're very interested in the technologies involved," said Brant Sponberg, NASA project manager for the 'centennial challenges', a series of US government-sponsored competitions that support space exploration. Sponberg was overseeing setup and tests of the competition on Friday.

The 'Beam Power' Challenge, which kicked off on Saturday, tested the design and efficiency of robot climbers, machines that can ascend and descend a 50m tether ribbon while carrying a payload.

Seven teams from the Canada and the US had three chances to climb the ribbon, having to travel at a minimum speed of 1m per second. For each climb, teams got a score that was a product of their payload mass and average velocity. The team with the highest score would have won $50,000, although at time of writing, no team had beaten the 1m/s minimum.

Many of the climbers are powered by solar cell panels. The Spaceward Foundation cast a 10 kilowatt light onto the solar panels, if used, to give the bots power up the tether. As the ascent began, the light carried as much intensity as three to four suns, but towards the top, it was only about one sun.

Steve Jones, an engineering and physics graduate student at the University of British Columbia, said his climber needs the equivalent of about two suns to make it up the 50m tether.

He has been working on the team's climber for the last six months, along with 14 other students. Jones said he was excited about the competition because it isn't necessarily obvious how to solve the problem. It's a mixture of optical, electrical and mechanical questions that involve creating a climber, he said, and many teams are coming at the problem differently.

For example, some teams are using solar cell panels, like his, and others, like Starclimber, are relying on a Stirling engine, which can convert heat into mechanical energy with an efficiency of 30 to 40 per cent, on par with a petrol engine and superior to photovoltaic cells.

"This is a great platform for sharing because it's very open. We're seeing each other's designs and it's accelerating the rate at which we learn," said Jones.

The Tether Challenge was designed to help foster the development of strong but lightweight materials that could support the space elevator. The contest required teams to develop a tether that can improve on a commercially available one by 50 per cent in breaking force. Teams competed in a 'pull-off', where each pulled against the other until one breaks, to find the lightest and strongest.

Finally, the best performing tether competed against the 'house' tether, or off-the-shelf material. Again, none of the teams managed to beat the requirements and the $50,000 went unclaimed. The Centaurus Aerospace team were the closest, with a 2g tether loop that supported over 550kg before it broke. The house tether took nearly 600kg, less than 10 per cent ahead.

Most people believe the material for the space elevator will be made of carbon nanotubes, but that technology is still in early development.

"We're trying to use prizes to encourage development of that technology," said one project contractor for NASA.