Nasa is backing the Space Elevator Games held this week
The creation of a space elevator is the future goal of this week's $2 million (£1.21 million) Space Elevator Games in the Mojave Desert.
In a major test of the concept, robotic machines powered by laser beams will try to climb a cable suspended from a helicopter hovering more than a half-a-mile high.
Three teams have qualified to participate in the event on the dry lake bed near Nasa's Dryden Flight Research Centre at Edwards.
Funded by a space agency programme to explore bold technology, the contest is a step toward bringing the idea of a space elevator out of the realm of science fiction and into reality.
Theorised in the 1960s and then popularised by Arthur C Clarke's 1979 novel The Fountains of Paradise, space elevators are envisioned as a way to gain access to space without the risk and expense of rockets.
Instead, electrically powered vehicles would run up and down a cable anchored to a ground structure and extending thousands of miles up to a mass in geosynchronous orbit - the kind of orbit communications satellites are placed in to stay over a fixed spot on the Earth.
Electricity would be supplied through a concept known as "power beaming," ground-based lasers pointing up to photo voltaic cells on the bottom of the climbing vehicle - something like an upside-down solar power system.
The space elevator competition has not produced a winner in its previous three years, but has become increasingly difficult.
The vehicles must climb a cable six-tenths of a mile into the sky and move at an average speed of 16.4 feet (five metres) per second.
The competition is sponsored by the non-profit Spaceward Foundation with support from Nasa's Centennial Challenges programme.
