GOING UP?

When the Science Fiction Museum and Hall of Fame opened in Seattle, the skateboard from the movie Back to the Future and the teleporting platform from Star Trek were part of the exhibits. But Dr. Donna Shirley, the museum's founding director, believes the most likely concept to become science nonfiction is a space elevator that goes up and down thousands of miles and that can act as a giant slingshot to propel spacecraft far and out. She should know - she used to manage the Mars Exploration Program at the Jet Propulsion Laboratory. Although she relied on rockets to get her probes to Mars, she thinks it's important to break away from total rocket dependency.

Sir Arthur C. Clarke, who put space elevators in his 1978 book The Fountains of Paradise, is another enthusiast who thinks reality could catch up with fantasy. The 1990 discovery of very strong carbon molecules called nanotubes makes the idea even more likely, because their extraordinary strength could help designers overcome previous engineering obstacles.

In October 2005, Spaceward Foundation, which was cofounded by Ben Shelef, helped stage the first Space Elevator Games. They were held to spur inventiveness and to push some buttons to get space elevators moving in the public consciousness in the same way the X-Prize competition triggered private efforts for space travel. NASA's relatively new Centennial Challenge program, designed to accelerate and direct needed innovation, offered cash prizes for the first time ever.

The concept is this: A counterweight in space is connected to an anchor point on Earth via a thin, ribbonlike tether. The rotation of the earth throws the counterweight outward, keeping the ribbon taut. The ribbon is three to five feet wide, thinner than paper, and 62,000 miles long. Robotic cars ride up the ribbon, powered by a light beam that illuminates photovoltaic cells on their underside. Supporters say if it works, cargo and passengers could go up and down 62,000 miles. That's the equivalent of about 33 million stories.Michael Laine, the CEO of LiftPort, a commercial advocate of space elevators, says he plans to have a usable elevator anchored in the Pacific Ocean near the equator by April 12, 2018. LiftPort's outer space precursor hit a 1,000-foot benchmark in September 2005, but it clearly has a long climb ahead. Laine also believes his company can bring payload costs down to $400 a pound, a huge reduction from the many thousands of dollars per pound it currently costs to get people and satellites into geosynchronous orbit via rockets.

HEY, HOT STUFF

Step aside, solids, liquids, and gases. Plasma has arrived, and former astronaut Franklin Chang Diaz, who has been to space seven times on conventional chemical rockets, wants to travel with plasma. "If you heat a gas enough, the atoms break apart, and you get plasma. It's a fourth state of matter that's really, really hot. Plasma is everywhere in space," he says. "It's what our stars and sun are, really."

The hotter the exhaust, the zippier the rockets. Right now, rocket exhaust is in the thousands of degrees. "That's a pretty cold fuel," says Chang Diaz. "Plasma exhaust will be millions of degrees hot."

He's talking about fueling an ionically souped-up engine that can shift gears through space and get humans to Mars in three or four months instead of the minimum 10 months projected for chemical rockets. Better travel speed could greatly reduce the wearying weeks of boredom, the bone weakening of weightlessness, and the dangerous levels of exposure to solar radiation that space travelers face on long trips.

The plasma rocket is too hot (by just a few million degrees) to launch from Earth. One idea is to assemble it in space, like the ISS. Current plans to heat the plasma are for the power source to be electrical - possibly converting solar energy for close to Earth and using nuclear reactors for deep space.