Pruning shears

Not a really recent XKCD cartoon (but otherwise which is the meaning of my beloved “random” button on the webpage?), but very keen (ok, probably only for space-oriented guys). Or at least sufficient to wake up my loitering on the space elevator concept. The web is full of papers more or less serious, pictures and reference, e.g. here a nice chronicle of the idea.XKCDspaceelevThe cartoon emphasizes the most important (probably), real (for sure) big issue, single point failure on the whole system (of course not the only one): the tether! Yes, carbon nanotubes are very tough (and ultra-thin, diamond nanothreads, even stronger and stiffer than carbon nanotubes are under development), a double cable redundancy can be implemented (really?), security margins will be taken, but what about the wonderful idea of someone bringing pruning shears (and I don’t want to think about how interesting it would become for any kind of “terrorist attacks” …)? And what about who is running the infrastructure, its location, its ownership, under wich law it fits (… really a modern Babel)?

The science fiction idea (counting among tis fathers Clarke, Tsiolkovsky, Artsutanov) of having a giant cable held in place by Earth rotation to send people and payloads into space (up to geostationary Earth orbit, I mean 35768 km above the Earth surface!) only poses tons of technical challenge although theoretically perfectly feasible. It’s fascinating to think that right now it seems easier and safer to have people and/or payload sit on huge tanks of explosives instead than an old fashion cable-elevator (ah, please, be carefull to the radiation belts if you want to take up people…).

The biggest issue is of course the cable that has to be extremely long, flexible, robust, support not just its own weight (already not enough) but also the capsule weight, withstand a wide array of shearing forces, resist to micormeteroid impacts (although assuring a reduction of further debris generation), experience a thermal excursion of hundreds of degrees, etc. Let’s go over number and unit of measure, but, in short, nothing similar there (still) exists on Earth.

Awesome enough is also the (estimated!) cost. Let’s assume we have such elevator already build (non-recurring costs? what?) instead of 20000$ required for bringing one kg in GEO, it would cost only 500$ (IAA report)! Let’s say that it is exactly what I mean for “enabling technology” and if on Earth it sounds too complicate, why shouldnt we start from the Moon with the Moonelevator?

Concluding quote, from E. Land “Don’t undertake a project unless it is manifestly important and nearly impossible”.


PS. “This is extremely complicated. I don’t think it’s really realistic to have a space elevator […]  it would be easier to have a bridge from LA to Tokyo”. If even Elon Musk believes it is a too far-fetched idea (here)…

PPSS. And from wiki “Other concepts related to a space elevator (or parts of a space elevator) include an orbital ring, a pneumatic space tower, a space fountain, a launch loop, a Skyhook, a space tether, and a buoyant SpaceShaft”.I’ll have a look into these Easter eggs more in detail.

PPSS @ 21.08.15. Also patents are coming… The (canadian) Thot Technology Inc asked for a patent for a 20 km tower to be used as a sort of space elevator. The top of the tower is a space port assuring 30% propellant saving for space travels. The tower is “pneumatically pressurized and actively-guided over its base” and equipped with a 20 km electrical elevator for astronauts. Easy, isnt’it?!


PPSS @ 10.11.15.

Recently I spotted the poster below.


It seems that people are actually working on the space elevator concept! not just for the concept of operation, modelling, fund raising and similar, but in the lower right corner of the poster (that’s what drew my attention) there are shown a couple of PROTOTYPES of key components of the elevator. This means that someone spent his money for moving further toward the idea realization!

However I had the change to talk with one of the poster’s author that revealed me that for the time being the “International Space Elevator Consortium” is actually a self-funded bunch of enthusiastic people (although it seems at some philanthropist offered one-two millions dollar that have not been seen yet…). Let’s see what happen.