Scientists Envision ‘Space Elevator’ to Deliver Cosmic Loads

WASHINGTON — Step on the elevator and press the “up” button. Step off eight days later at a platform thousands of miles in outer space.

There will be no blast of rocket fire and smoke. No lift-off “G- forces.” Nobody will count backward from 10. Just get on the “space elevator” and ride.

The term is not a National Aeronautics and Space Administration (NASA) designation for a new space program or a new generation of spacecraft.

Scientists are instead talking about constructing the kind of machine that goes from floor to floor in an office building or hotel — but using it to send cargo and someday people to heights of 22,000 miles and more. They think they can do it within a decade.

The cost could be less than $12 billion, not much more than some bridges on Earth.

The space elevator concept was dramatized in an Arthur C. Clarke science fiction novel, “The Fountains of Paradise,” 26 years ago.

It suddenly became feasible with the 1991 discovery of carbon nanotubes, a superstrong material, said space engineer Bradley Edwards of the Institute for Scientific Research in Fairmont, W.Va., a private study center that works for both government and private clients.

A nanotube “ribbon” — three feet wide and 62,000 miles long — would support an elevator that could carry 13 tons of cargo in a single trip, according to new designs.

The ribbon would be held up by the spinning of the Earth, the way the string of a yo-yo remains taut when a child whirls it around her head.

For the past five years, Edwards has been working on designs for a space elevator, funded chiefly by grants from NASA’s Institute for Advanced Concepts in Atlanta.

“It’s practical and it’s doable,” he said in a telephone interview. “It would cost $6 billion. When you add the cost of dealing with regulations and studies and the international aspects of it, we estimate the cost might be twice that much.”

Bradley will co-chair a meeting here today through Wednesday for scientists from the Institute for Advanced Concepts; the Marshall Space Flight Center in Huntsville, Ala.; Los Alamos National Laboratory near Albuquerque, N.M., and other organizations to talk about the space elevator.

According to a schedule of this “Third Annual Space Elevator Conference,” participants will take up such matters as:

— Whether the “climber” that crawls up and down the nanotube ribbon should be powered by a large laser or by solar energy from space.

— How to deal with the danger that space junk might crash into the elevator and bring it down.

— The possible problem of radiation hazard.

— The economics of the space elevator.

— What is known about the health effects of carbon nanotubes.

Although scientists have speculated about a space elevator for years, the talk never got over the hurdle of what material to use. Anything strong enough would be too heavy.

Some called the hypothetical substance “unobtainium,” Edwards said.

Then in 1991, a Japanese scientist studying fullerenes, newly designed carbon molecules that are shaped somewhat like architect Buckminster Fuller’s famous geodesic dome, discovered an elongated version, which became known as a nanotube.

Although nanotube fibers are 100 times stronger than steel, the substance is almost unimaginably light, Bradley said. The 3-foot- wide “ribbon” that his design envisions would be as thick as a sheet of paper.

It would be 62,000 miles long and weigh only 800 tons. It could easily support a seven-ton “climber” carrying 13 tons of cargo, he estimates.

“We are watching this with great interest,” said Robert Cassanova, director of the Institute for Advanced Concepts. “The basic idea is quite compelling, with the caveat that there are significant questions that have to be answered.”

Cassanova said these questions deal mostly with whether carbon nanotube filaments can in fact be used to construct the central ribbon.

“There are always challenges in anything that stretches our imagination,” he added. “There were questions about the space shuttle.”

Edwards’ plan envisions a base station for the elevator located at sea level in the eastern equatorial Pacific Ocean, an area where weather is calm and lightning rarely strikes.

The physics of building a space elevator are relatively simple, he said.

At an altitude of about 21,700 miles, an object orbits the Earth at a speed that matches the Earth’s rotation.

That is the principle that has made it possible for governments and telecommunication conglomerates to place satellites in geostationary orbit.

At that height and that speed, the gravity that pulls the satellites back toward Earth is perfectly matched by the satellite’s speed and momentum.

Normally, if a ribbon of nanotube fibers were lowered to the Earth from an orbit of 21,700 miles, the whole operation would collapse to the Earth’s surface, Edwards said. This is because everything below that height would be inclined to fall back to Earth.

But if the ribbon also extended beyond the satellite to an altitude of 62,000 miles and were attached to a counterweight on the far end, it would remain in place, provided it were tethered at ground level.

Everything above the geostationary orbit height would pull away from the Earth, as if it were being flung into space, countering the pull of gravity.

As an added benefit, Edwards said, the far end of the ribbon would be moving so fast that launching a space craft to the moon or Mars would be easy. Simply take it up the elevator above the geostationary point and release it.

“Turn it loose in one place and it will go to the moon,” he said. “Turn it loose somewhere else and it will go to Mars.”

Mars was the setting of another science fiction novel that envisions a space elevator, “Red Mars,” by Kim Stanley-Robinson, published in 1993.

Clarke’s “The Fountains of Paradise” described a space elevator that rose to a height of 24,000 miles above the Earth.

Best known for his epic of space travel, “2001: a Space Odyssey,” Clarke was once asked when people would build a space elevator.

“Fifty years after they stop laughing,” he replied.

He revised the estimate last year, when he spoke by satellite to the second annual space elevator conference. The elevator would be built only 10 years after the laughter stopped, he said.

“And they’ve stopped laughing,” he added.

On the Web:

The Institute for Scientific Research: www.isr.us.

Space elevator conference: www.isr.us/SpaceElevatorConference/ index.html.

Institute for Advanced Concepts: peaches.niac.usra.edu