by Carla Sabata
Imagine riding an elevator to space, climbing a cable to the top of the earth’s atmosphere and beyond. What would your journey be like?
“You’d travel from the surface of the earth toward space at about 120 mph,” says Dr. Bryan Laubscher. As the elevator climbs, you’d pass through layers of cumulus clouds that look like giant cotton balls. After about 30 minutes, you’d see the curvature of the Earth’s surface below the deep black of space, outside your porthole.
Space elevators don’t yet exist. Dr. Bryan Laubscher and other scientists continue to explore the possibility of using them to explore space and other planets. Dr. Laubscher is one of the world’s leading experts on the Space Elevator.
If space elevators existed today, you might ride the elevator to a station at geosynchronous earth orbit (GEO) to experience zero gravity. An object at GEO orbits the earth at the same speed as the earth rotates. An orbit is a loop controlled by gravity of one object around another object,
“To board the elevator, you’d sail on a ship to a mobile ocean platform at the equator,” explains Dr. Bryan Laubscher.
The ocean platform anchors one end of the black ribbon that the elevator climbs to reach the space station. As described by Arthur C. Clarke, a captured asteroid forged into a counterweight anchors the other end of the ribbon. The asteroid is above GEO. An asteroid is an object that orbits around the sun.
As the counterweight spins around the Earth, force pulls the counterweight away from Earth and keeps the ribbon straight. Think of the game of tetherball where one end of a rope is attached to a pole and the other end is attached to the ball. As you spin the ball around the pole, the rope stays straight. “The rope is kept straight by the same force that is caused by the ball’s motion,” explains Dr. Laubscher.
The ocean platform can move to reposition the ribbon. “This keeps space debris and satellites from hitting the ribbon, and high winds, storms, and lightning from damaging the ribbon and the elevator,” explains Dr. Laubscher. “Though because the platform sits near the equator, there are few lightning strikes and few storming days,” he says.
“Carbon nanotubes are the strongest material in the world, 100 times stronger than steel,” says Dr. Bryan Laubscher. The strength of the ribbon comes from the structure of the carbon nanotubes. “At the atomic scale the structure resembles chicken wire rolled into a tube,” says Dr. Bryan Laubscher. The carbon nanotubes are thin, lightweight tubes made up of carbon atoms. “A single carbon nanotube is one ten-thousandth the diameter of a strand of human hair,” he explains.
Once you’ve boarded the elevator, it climbs the carbon nanotube ribbon by gripping it with traction-tread rollers at the top of the car. Lasers beam power to photo-voltaic cells that are like solar panels. “Electric power from the cells drives the motor that turns the rollers,” says Dr. Bryan Laubscher.
“As the elevator car travels further from the Earth’s surface, the gravitational pull of the earth slowly decreases and your weight slowly drops,” Dr. Bryan Laubscher explains. When the elevator car reaches GEO, the apparent effect of gravity is zero. Everything inside the car can float. “This is because the forces of gravity and the outward acceleration are equal and opposite, and so cancel each other,” explains Dr. Bryan Laubscher.
Maybe your future trip on the space elevator will take you beyond GEO, where the elevator can launch your spaceship to other planets. Which planet would you like to visit, when you ride an elevator to space?