~journaling from the near future~

Charcoal, porous, rigid, light, pressed into fractal foam: the solid foot of our first space elevator, floating out by Kiribati, is a pitch-black mushroom cloud. The port’s lev lofts satellites into space — more importantly, it tugs cargo ten miles high, onto broad, marshmallow-winged Zeppelins, which loop the planet on the jet stream and deploy their deliveries in glider-framed crates that skid hundreds of miles to their targets. A space elevator is cheaper than airplanes, faster than ships.

And, an elevator hoists other elevators. That is it’s primary task, rapidly reinforcing a sister lev just north of Belem. The carbon foam has been installed along the lowest three miles, the most difficult part, while further sections are placed in stages. Carbon foam is a perfect gradient of vacuum pressure: tiny bubbles along the outer shell are dosed lightly with atmosphere, a drop in pressure working inward to the core, where ballroom-sized caverns are kept at the vacuum of the thermosphere. Hydrogen floats better than Helium, but a vacuum really floats!

The carbon foam tower, girding against intrusions of weather, holds to the tapered tip of the space elevator’s cable. Here, in the lower 50km, the carbon foam is the bracing strut upon which the lateral and vertical forces of payload acceleration wither, so that elevator pods can ascend safely to GEO in hours, not days. Faster loft, more payload per day, higher ROI, even at a discounted price per kg. Foam towers were the key innovation, the breakthrough that made a space elevator economical. For 32 miles straight up, a widening throat of foam corks vast chasms of vacuum, like a billowing high hot air balloon with a neck all the way to the ground.

Air is prevented from collapsing in on the vacuum by the immense strength of the carbon foam, which is also impervious to leaks, bulletproof, etc. The whole structure even conducts better than copper. Forget power cables! At higher altitudes, where only slight buoyancy is gained from the vacuum, the exterior air pressure is mercifully reduced, so that the rigid carbon foam walls safely thin, while the interior vacuum yawns. Only a half-mile wide at sea level, the tower bulges to three miles across at its apex, 32 miles up. That’s where the cable starts, safe from all the gory circumstances of weather, the vicissitudes of tides, secure against untimely yanks on the chain as gondolas rise.

If the cable had been tied to a rock somewhere, instead of held like a torch above the torrent, it would have snapped in a gale, or snapped when the elevator accelerated slightly, especially during a gale. Or snapped during a terrorist attack. Or a derailed train at the docking station. Or someone with big scissors. The foam tower is our great guardian. And, it cannot be stressed enough, that the tower is the reason for profit, which was the reason for funding. None of this would have been possible, if the cable jutted out of the ground.

Our international transport, gliding from ten miles up, relies completely on the railports that lurch payload to those high platforms, supported by the foam tower’s frame better than the space elevator cable could. That single utility already pays for itself, and copycat ‘marshmallow castles’ are in the works, with or without an elevator on top. By supporting the early acceleration of elevator pods, the foam tower is actually worth more than its weight in gold.

Consider: if a single, $2 trillion elevator can lift all the parts for a second elevator in 4 years, that’s an elevator’s ‘doubling time’. That time depends most upon how much mass you can carry up at once, and how fast those masses are moving. By accelerating the elevator pods, you can carry more pods per day, and more total mass. Yet, the cable can only allow a little acceleration, before it snaps!

So, acceleration occurs in a mass driver running up the spine of the marshmallow foam, keeping the cable safe from snaps. Pods, supported by that rigid structure, traveling 8 times faster, can now lift a new elevator in 6 months. Much of the $2 trillion cost of a space elevator is the rocket power necessary to launch the first one. After that, their price depends upon how quickly the first elevator raises up a second, a third. A pod velocity eight times higher means all future elevators cost half as much, making space travel and international gliders even more economical. Additionally, by carrying 8 times the payload per year, that elevator handles 8 times more business, for a faster return on the initial $2 trillion investment. Rapid acceleration is key to a high return. Space elevators might have languished for another decade or two, with no great economic motive to push them into being. With carbon foam vacuum towers, elevators became a no-brainer. A must.

Written by

Easily distracted mathematician

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