NEWS
A US Seattle team collected $900,000 (Rs 4 crore) in prize money in a NASA-backed competition to develop the concept of an elevator to space. The team’s robotic machine raced up more than 2,950 ft of cable dangling from a helicopter. Powered by a ground-based laser pointed up at the robot’s photo voltaic cells that converted light into electricity, the LaserMotive machine completed one of its climbs in less than four minutes, good for second-place money. The team could have claimed $2 million (Rs 9 crore) in prize money if its robot had climbed faster. The difficulty of the experiment can be gauged from the fact that success came only in the fourth year of the annual event.

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Why rocket when you can take an elevator? Into space, that is. A contest to encourage development of this very theory originated in the 1960s and was popularised by Arthur C. Clarke’s 1979 novel The Fountains of Paradise. Of the three teams that qualified to participate in the annual event on the dry lakebed near NASA’s Dryden Flight Research Centre at Edwards Air Force Base, California, only LaserMotive could pass muster. Could it be heralded as the first tentative but successful step in the long journey ahead of ‘inventions and innovations’ to realise the more-than-a-century old dream of transporting material from a celestial body’s surface into space?

The concept dates back to 1895 when Russian scientist Konstantin Tsiolkovsky proposed a free-standing tower reaching from the surface of Earth to geo-stationary orbit. Recent efforts, however, have focused on tensile structures (specifically tethers) reaching from geo-stationary orbit to the ground. This structure could be held in tension between Earth and the counterweight in space like a guitar string held taut. On this tether, an elevator or a lift could move up and down, carting men and material to and from space at a fraction of a cost of launching them atop rockets and recovering them in space capsules/shuttles. Conventional rocket designs cost about $11,000 (Rs 5 lakh) per kg for transfer to low Earth or geo-stationary orbit. But with space elevators, current proposals envision prices starting as low as $220 (Rs 10,000) per kg.

Attractive as the concept may seem, it remained within the confines of science fiction till recently, in the wake of advances in nanotechnology. A newly discovered type of carbon nanotube, called the ‘colossal carbon tube’, it is felt, may be strong enough to support a space elevator. Significantly, due to its enormous length (as much as 100,000 km, up to the connection with the counterweight), a space cable must be carefully designed to carry its own weight as well as the smaller weight of the elevators (climbers).

Apart from the tether system, power and energy are significant issues. While nuclear energy and solar power have been proposed, generating enough energy without weighing too much poses a near insurmountable challenge. A possible method gaining ground is laser power beaming, using megawatt powered free electron or solid state lasers in combination with adaptive mirrors around 10 m wide and a photovoltaic array on the elevator tuned to the laser frequency for efficiency, eventually maturing to ensure transmission of energy by laser over long distances. The prize-winning experiment by LaserMotive LLC was a miniaturised manifestation of the same idea.