Highway to Heaven

Brian Turner, designer of Jolly Roger, has sunk about $30,000 into his creation.

His design is a variation on the fabled Archimedes death ray, which the ancient Greek mathematician allegedly devised to set enemy ships ablaze by bombarding them with concentrated rays of sunlight.

The Jolly Roger generates 40,000 watts of power, and its solar cells get so hot they have to be cooled by water.

Death rays? What?

It’s not actually as spectacular as that makes it sound, although the end result could be pretty amazing. What Brian Turner and his group have built is a prototype system for externally powering a cable-car that might climb a future space elevator, and NASA wants to look at that and other prototypes very seriously.

space elevator diagram
image from nanopedia's space elevator page


The putative space elevator(s) would carry loads up to a space station in geosynchronous orbit at 22,000 miles, and would need to be anchored on earth at the equator, and have further cables leading to a counterweight orbiting at 62,000 miles. The counterweight would mean that the elevator would be perfectly suspended in the Earth’s atmosphere, with the anchor only being required to provide a stable base (rather than being required to stop the elevator floating away).

Space elevators were first proposed in the 1960s, and popularised in a novel by Arthur C. Clarke (Fountains of Paradise, 1979), but were not taken seriously by the aerospace industry until the development of nanocarbon filaments, which are theoretically strong enough to make up the immensely long cables while being light enough to actually be carried into space affordably. The theoretical long-term economic benefits are formidable – a cost of $100 per kilo hoisted into space compared with the current cost of $10,000 per kilo.

Because of the length of the cables and weight considerations, the cable-cars will not be able to carry enough fuel to travel to space – their energy source will have to be external. Thus the NASA challenge involves two parts – a Beam Challenge (providing the most power to the cable climbing machines) and a Tether Challenge (providing the best cable material).

The Tether Challenge centers on the creation of a material that combines light weight and incredible strength. Under this challenge, teams will develop high strength materials, such as carbon nanotube-based fabrics that will be stretched in a head-to-head competition to see which tether is strongest.

The Beam Power Challenge focuses on the development of wireless power transmission technologies for a wide range of exploration purposes, such as human lunar exploration and long-duration Mars reconnaissance. In this challenge, teams will develop wireless high-power transmission systems, including beam transmitters and receivers, to power robotic climbers and payloads to the top of a multi-story cable. Racing against the clock, the climber who carries the largest payload to the top in the shortest period of time wins the competition.

I remember reading Clarke’s book in the early 80s and thinking that space elevators were obviously the way to go if the materials issue could be sorted out (some theorists think power simply won’t be a problem, as the cable will be long enough to produce its own magnetic fluxes that can be tapped to produce electricity). I thought then that maybe a grandchild or great-grandchild of mine might ride one to the final frontier. I find all this immensely exciting.

[Cross posted at Larvatus Prodeo]



Categories: Science

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