Yet another project is the Propulsive Small Expendable Deployer System (ProSEDS). This unique space tether experiment is being readied for flight next June, said Les Johnson, NASA's principal investigator at Marshall for this project.

Space Architects

Who are the people who design and build launch pads, rockets and spacecraft to carry humans to outer space? Read about these space architects.

The experiment will test deploying in space a tether that's 9.3 miles (15 kilometers) long. Three miles (5 kilometers) of the tether is made to generate electrical current by cutting through the Earth's magnetic field.

This electrodynamic tether test should show that propellant-free spacecraft maneuvers can be made, either speeding up or slowing down by varying the tether's orientation within the magnetic field, Johnson said.

It's an experiment in the true sense of the word," Johnson said. While not being flown to further space elevator work, ProSEDS is "inextricably linked" to the idea, he said.

"I don't know how we ever go about building a space elevator without going through the evolution of space tethers to get there," Johnson said.

Cable operator

Bradley Edwards, a physicist at Los Alamos National Laboratories in New Mexico, is a keen supporter of fabricating an elevator to space. He recently completed research on lengthy space elevators thanks to a NASA Institute for Advanced Concepts grant.

"The space elevator appears much closer to reality than has been suspected in terms of available technology, cost and schedule," Edwards said. "The major hurdle is the required carbon nanotubes, but that's getting closer each day," he said.

Edwards has scripted a plan that suggests an operational cable to space can be installed within 10 to 20 years.

"There doesn't seem to be a whole lot of hurdles," Edwards said. "It looks like there are viable solutions to every aspect," he said.

Across the great divide

Edwards plans to use an old technique for building bridges that span gulfs of space here on Earth.

First thing to do: throw or shoot a small string across a canyon. Then a larger string is attached to this first small string and pulled across. This process is repeated until many ropes and eventually structures are placed across the canyon.

The great gulf between our planet and outer space can be bridged by first having a satellite deploy a small cable back down to Earth. Then a robotic "climber" ascends the string while attaching a second string alongside the first to make it stronger. This process is repeated until a thick, usable, high capacity cable is made.

Edwards said he hopes to do follow-on work, refining his space elevator thinking. He wants to acquire nanotube materials for fashioning short lengths of cable. Those specimens could then be subjected to extensive tests that mimic the space environment.

"With the construction of multiple space elevators, there can be the start of new commercial markets, new resources and possibly a true space-faring society. Just as the transistor was the first small step in the current computer age, the space elevator may be the step that takes our children to the stars," Edwards said.

space.com