Space Elevator
(*DING!!!*) Going up! Climb aboard, step to the back please, make room for the others… Now, what floor are you going to? Stratosphere? Ionosphere?
Those of you who are into science journals and other techno-geeky publications have already heard of the Space Elevator, a conceptual design for a revolutionary little toy that will change the nature of space travel. For those of you who haven’t, brace yourself. And hold the door for that lady, she’s got a kid in a stroller.
What’s the biggest problem with sending a vehicle into space? While you’re thinking on that one, here’s a related question: what is the biggest payload we take on every single rocket we send up?
Think about the design of the space shuttle. The actual shuttle is just like a weird looking plane: why don’t we just make it take off like a plane does? Just slide it along the runway, ease back on the stick, and glide that sucker right into the great beyond?
The answer is apparent when you look at the shuttle on the launch pad. The shuttle itself is attached to these big honking tanks and rockets. Spoils the whole look if you asked me. Why do they do it that way? Because of the questions I just posed.
The biggest problem we have sending a vehicle into space isn’t breathing or eating or going to the bathroom or astronauts who puke inside their pressure suits. The problem is, breaking free of earth’s gravity. The way we do it is with rockets that propel the vehicle at a ridiculous rate of speed. For this you need a massive amount of thrust — and a massive amount of fuel, which necessarily becomes the biggest payload on board any rocket we send up.
Every shuttle mission uses up something like 95% of its fuel in the first three minutes of the mission. That much fuel requires a pretty big set of fuel tanks, and they are immensely heavy. But the more the vehicle weighs, the more fuel you need. So you need a bigger tank to hold more fuel, which of course weighs more, which requires more fuel, and so on, and so on. The long and short of it is, you reach a certain point past which it is impractical to add size to the machine. We are very close to that point.
But we want to explore Mars and the moons of Jupiter and Saturn and beyond. It takes more than a year to get to any of those places, and in order to make it so people can live for that length of time in space, you need supplies. Food, water, oxygen, toothpaste, reruns of “Grey’s Anatomy” on DVD. But if we build a ship big enough to carry all those things, we can’t get it into space because it’s too big and heavy.
So what’s the solution? Build the vehicle in space, supply it in space, and launch it from space. All of a sudden you don’t have to have umpteen million cubic meters of liquid hydrogen fuel, you can build the vehicle as big as the state of Rhode Island if you want, and to send it on its way you can just give it a shove with your pinky finger. Zero gravity is a beautiful thing.
That solution, given our present means of getting people and stuff into space, is impractical. It costs tens of millions of dollars for one shuttle mission. Each shuttle mission can carry a payload about the size and weight of a Hummer. At that rate, we would spend endless multiples of the GNP of the entire world, only to have a mission that launches sometime in the year 2874. It just won’t work.
Enter the Space Elevator.
Drive a nail into a tennis ball. Tie a string around the nail, and hold the end of the string in your hand. Now stand in the middle of a (large) room. Spin around with your arms outstretched. What happens? Anybody around stares at you kinda funny, and the tennis ball pulls the string taught until you slow down. Okay, so what?
Back in the early part of the 20th century a science fiction writer suggested that this was possible with the earth. Shoot a cable with a weight on it out into space, tether it to the ground, and the rotation of the earth will pull the cable taught and hold it there. Crazy, right?
The best that we can tell, he was right. It works.
Again, so what? Well, what do most elevators run on?
Long cables.
Starting to see this now?
Long story short (too late!) what we’re talking about here is a platform, powered from the ground by a laser, with the capability of lifting (for instance) ten tons, that can run a payload up the cable into low-earth orbit a hundred times a day at a unit cost of enough electricity to power the laser.
This is the Space Elevator. And the new era begins.
So, two components: a cable and a platform. We’re almost there on the platform. A team from the University of Saskatchewan ran a small ground-laser-powered platform up a 100 foot cable in 54 seconds just a couple of months ago. They missed winning the $100,000 prize NASA is offering by just four seconds. They’ll get it next time. Figure in ten years, the platform will be ready.
The problem is the cable. With current materials, any cable strong enough to hold a weight screaming around with the earth at in excess of 1000 miles per hour at an altitude of over 300 miles is so big and heavy we’d never get it off the ground.
But that’s not always going to be the case. Go search the web for something called carbon nanotubes. They are a tubular atom-thickness structure of a carbon allotrope with unique conductive properties and exceptional elastic modulus— Oh, never mind all that. Fashion a woven thread such as you would use to sew on a button made from carbon nanotubes, and that thread will be strong enough to pick your car up off the ground. Put simply, when we are able to manufacture carbon nanotubes in enough quantity and at low enough cost, this is the material that will be used for the cable. The one used for the Space Elevator shouldn’t have to be any more than an inch thick.
Just think of it. Space exploration, sure. But think of the commercial applications! The government builds 200 of these things, uses 20 or so for its own purposes, and funds the entire program by leasing either runs of the platform or entire elevators to private companies. All of a sudden you’re buying a trip around the world (in 45 minutes at an altitude of 240 miles) as a graduation present for your teenager! Low-earth-orbit factories that send up purified titanium alloy and send down geometrically flawless sphere ball bearings — only possible in zero-gravity. Satellite launch platforms, medical research labs, schools, commercial space flight centers, atmospheric and environmental impact study facilities, Starbucks, you name it!
And if it is possible on the earth, it will be possible with other celestial bodies too: the moon and Mars most immediately. From the earth’s surface up the elevator to a platform, onto an interplanetary shuttle, across to a platform outside Mars’ atmosphere, and down the elevator to the surface of Mars. We could have a low-cost supply line of surface-to-surface transfer in both directions: machines and personnel outbound, minerals and scientific samples inbound. Once we find out what’s actually on those rocks, who knows what we’ll be dragging back. This makes outposts (or even permanent colonies) on both of those planets a very real possibility.
My kids will see this in their lifetime. I hope I see it in mine. This, stem cell research and the human genome project will permanently alter our reality in the next 50 years. You heard it here first.










