On the Bottom Half

Elevating.

This one wanders a bit, but remember that 'not all those who wander are lost'.

Once a long time ago, I worked as a surveyor with a very interesting man named Tim. Tim was, among other things, a windmill artist with his own exhibition, an American Scientist-Discover-NewScientist-Nature-Science magazine reading part-time scientist, deaf in one ear from a dynamite explosion, and a surveyor.

He told me that to really succeed I needed to find my question, my one question, which would become a singular underpinning zeal fit to last an entire lifetime. I thought this was germane advice considering my status as a freshly minted first-year university student, but I unfortunately failed to learn that lesson at the time that it was given. I had my questions, but they were numerous and varied. Still, they are numerous and varied.

We spent a lot of time discussing science stuff and one topic that came up was propulsion, which I do find very interesting. I feel quite strongly that we've simply reached the limit of this idea of burning a propellant with an oxidiser out the back end of an impressive bell housing to push a craft through the air, through space, through time... There must be something more powerful, more compact, and more efficient... As a consequence, I thought about how simple a frame within which almost any action can be described, and came to the not ground-shaking conclusion that such a frame is energy. Everything is a question of energy: how to make it, how to use it, how to transport it and store it, how to conserve it. To transport oneself anywhere with a car one burns fossil fuel, which is solar energy transformed into metabolic energy stored as glucose and other carbon molecules by photosynthesis; that carbon then stored, metamorphosed through heat and pressure, later becomes wonderfully compact but high energy-yielding oil. To move one's own body, food is ingested, which is in itself solar energy in modified form - carbon compounds produced by photosynthesis; reprocessed carbon compounds originally produced by photosynthesis but secondarily modified through animal metabolism. The Space Shuttle, thrown into the sky by an 8.5 minute, spectacularly violent display of fire. From Earth, stationary at sea level to 220 miles at 17500 miles per hour in 8.5 minutes. 2045 tonnes at 28800 km/hr - that's eight km or five miles per second. The kinetic energy of which, I might add, must all be dissipated as heat on reentry - that's 6.2 x 10^13 J of energy or enough energy to continually power the average 25 year old human male for 4.9 million days or more than 13500 years (leap years not factored in).

Recently there has been much interest in the idea of a space elevator and the materials that would be required to make such a device. This idea has such an astounding potential to revolutionise orbital flight and beyond, maximising the time available for the necessary paradigm shift away from propellant/oxidiser propulsion to really powerful solutions like zero-point energy (alternatively, Arthur C Clarke's 'The Songs of Distant Earth') or something else (warp drive anyone?) - some sort of fundamental antigravitation, space warping surf propulsion - to finally make interplanetary manned exploration commonplace and at long last crystallise humanity's ultimate exploration of interstellar space and the very mysteries of the universe.

The first thing to consider, however, before shucking the mantle of traditional propulsion methods and Relativity, are tethers that could tie the average ground-based human to geostationary orbit. And this is one mondo tether, too - 35,786 km long, extending straight up from the Earth's equator to some sort of anchor in geostationary orbit. There has been much chatter about using carbon nanotubes (scroll down a bit in the article) for such a tether, which I think is a great idea, as manufacturing problems are steadily being overcome. There're even prizes about to encourage this idea, sponsored by no less than NASA, which the University of Saskatchewan has won two years running.

It occurred to me today that I was wondering exactly where the sorts and quantity of energy required for orbital flight were going to come from as the hardy climbing device attached to it's amazing tether climbs into orbit - sort of redefines the idea of climbing to orbit doesn't it?

Well, NASA, as part of its Centennial Challenge Space Elevator competition, is encouraging a laser energy transmission system, which I think is altogether too complex, and which brings me to the crux of this post - energy!

Theorising assuming a carbon nanotube-like tether: a 35,700km long line of highly conductive carbon tether transgresses the Earth's magnetic field for all of that distance. A conductor immersed in a magnetic field. Is this not the world's most spectacular electricity-generating pole?

Of course, one immediate problem occurs - there's no relative motion between the rotating Earth and the geostationary orbit-anchored tether. However, the Earth's magnetic field is not a purely stationary field and only small fluctuations along a line of this length would surely generate massive current. Does any one have any in-depth knowledge of terrestrial magnetic field motion independent of planetary motion (besides the rotation of the magnetic poles)? Surely this is an elegant idea - a climb to an orbit of the explorer's choosing with the energy provided by electricity generated through the line to orbit. Only relatively small rockets are further required to complete orbital stabilisation.

Anyway, an idea to ponder.

posted by Kyle @ 02:40