GRAHAM WARWICK / WASHINGTON DC
Ambitious device could take up to 15 years to construct at cost of more than $7 billion
A US company has been formed to pursue commercial development of a space elevator, first conceived in the late 1890s and seriously espoused in the 1970s by science-fiction author Arthur C Clarke.
Bremerton, Washington-based LiftPort has been formed by Michael Laine, co-founder of HighLift Systems, a Seattle-based company that recently completed NASA-funded feasibility studies of the concept.
The elevator would consist of a 100,000km (62,000 mile)-long carbon nanotube ribbon anchored to an offshore platform in the Pacific Ocean near the equator with a small counterweight at the other end, well beyond geosynchronous orbit (GEO). LiftPort estimates it will take 15 years and $7-10 billion to develop and deploy the first space elevator.
The ribbon would be launched into geostationary orbit, from where one end would be reeled out into space and the other lowered slowly into the Earth's atmosphere, says Laine. The 1m (3ft)-wide "paper-thin" ribbon would have to be attached to a mobile platform so it can be manoeuvred to avoid orbiting satellites, he says. Gravity and centripetal force would keep the ribbon in tension.
Mechanical lifters would climb up the ribbon on "tank treads", reaching low-Earth orbit in 4h and geostationary orbit in a week. Payloads released at the far end of the ribbon would have sufficient energy to escape the Earth's gravity. Solar panels on the lifters would face downwards and laser energy would be beamed up for conversion into electricity to drive the vehicles, which would weigh up to 20t, including 13t of cargo.
Up to five lifters could be attached to the ribbon at any one time, allowing 5t a day to be lifted. The NASA studies estimated launch costs could be reduced from $44,000/kg ($20,000/lb) for rockets to $880/kg. The journey would be one-way until LiftPort could build a second, neighbouring space elevator for the downward leg, with a GEO space station in between the two allowing transfer of the lifters. In the longer term, LiftPort plans a heavylift elevator.
LiftPort hopes to raise $100 million by late 2004, and plans to invest in companies developing carbon nanotube composites, without which the concept will not work. Funds would be raised by licensing the technology to other industries.
The space elevator concept needs a material 30 times stronger than steel for the ribbon, and carbon nanotube composites have the potential to be 100 times stronger. So far only materials three times stronger than steel have been produced, but developers are "making a lot of progress", says Laine.
Source: Flight International
