"It's an interesting concept," said Robert Melton, professor of aerospace engineering. "You'd have access to space for a whole lot lower expense than launching rockets. Someone could use this as a way to build a space tourist industry."

Proponents say it could reduce launch costs from $10,000 to $100 per pound. Melton said it is important that the top of the elevator be placed in what is known as a geostationary orbit, where the time taken to orbit the Earth is exactly 24 hours.

"What's special about that distance is that the station will always be overhead," he said. Current space shuttles orbit the Earth about every 90 minutes because of their lower orbits, between 200 and 500 miles above the Earth's surface.

The biggest hurdle for the space elevator system is creating a lightweight, flexible connection to join the two points -- creating a strong cable on which the car can climb. The cable material should also be porous and flexible, Melton said, to make it less vulnerable to damage such as colliding with space junk and meteorites. Most scientists agree that the cable material will be made of carbon nanotubes, hexagonal rings of carbon atoms with a diameter measured in the billionths of meters.

Digby Macdonald, professor of materials science and engineering, thinks creating a cable that is both long enough and strong enough may be impossible.

"It probably can't be done," he said, "for the same reason humans aren't 50 feet tall. Eventually the structure will collapse on itself."

Even though carbon nanotubes are much stronger than steel, Macdonald said they are not enough to create a working system. "In my opinion, it's science fiction and should not be taken too seriously," he said.

In fact, the idea for space elevators was first proposed in Arthur C. Clarke's 1978 novel The Fountains of Paradise.

Some Penn State students have also begun to join the debate.

"I would definitely say the idea has potential, especially given the exceptional properties of carbon nanotubes. But there are a lot of problems that need to be solved before it's feasible," said Kevin Schlaufman (senior-astronomy and astrophysics).