perfidy

As impressive as they are to watch, rockets are a dangerous and in the end inefficient means of getting to orbit. Burning tons of liquefied oxygen and hydrogen and throwing away the rocket every time you want a satellite is not what your average beancounter would call sound economically. Imagine if, to fly from New York to Los Angeles, you built a brand new 747, flew it across the country, and jumped out over LAX for a parachute landing and let the plane crash into the Pacific. Getting a airline ticket would face a few more difficulties than just avoiding TSA’s watchlist.

This is a sound argument for reusable spaceships. But it is an even better argument for taking a step away from rockets altogether. Instead of rockets, why not have an elevator? Walk through the doors, take a seat, and ride into space with as much fireworks and commotion as getting on the express elevator in the Empire State Building. Building a physical structure that extends from the surface of the earth to orbit and beyond seems fantastical, but the idea actually has an extensive pedigree.

The idea for space elevators goes back to the misty dawn of the space age. Russian space theorist Konstantine Tsiolkovsky first proposed the idea of an orbital tower in his 1895 paper "Day-dreams of Heaven and Earth.”

On the tower, as one climbed higher and higher up it, gravity would decrease gradually; and if it were constructed on the Earth's equator and, therefore, rapidly rotated together with the earth, the gravitation would disappear not only because of the distance from the centre of the planet, but also from the centrifugal force that is increasing proportionately to that distance. The gravitational force drops ... but the centrifugal force operating in the reverse direction increases. On the earth the gravity is finally eliminated at the top of the tower, at an elevation of 5.5 radii of the Earth (36,000 km).

However, it was soon realized that no material could withstand the compressive stress of the weight of the tower. Half a century and more down the road, another Russian, Yuri Artsutanov, proposed what we now think of as the space elevator. Artsutanov suggested using a satellite in geostationary earth orbit (GEO) as a construction base, and extending a cable downward while simultaneously paying out a counterweight upwards to maintain the center of gravity in GEO. Artsutanov also described using a tapered tether to reduce the stress on the cable.

Over the last several decades, many people have examined the idea. Charles Sheffield and Arthur C. Clarke both used the idea as the central focus of their novels Fountains of Paradise and The Web Between the Worlds in the late seventies. And more thorough research has established many of the engineering requirements for a working space elevator. Most of these problems are solvable by a suitable application of engineering or politics – for example, building a working elevator car for the cable would be a straightforward, if difficult, application of the principles currently used in maglev trains.

But the biggest obstacle is the creation of a structural material for the elevator cable. Our strongest materials until recently fell short of the required tensile strength by a large margin. At a minimum, beanstalk cable material should have a tensile strength of 65 GPa (gigapascals, a measure of stress), and a density on the order of graphite. (Too much weight, and it doesn’t matter how strong the cable is.) The strongest steel is at about 5 GPa. Kevlar hits about the same, but is much lighter. We’re off by at least an order of magnitude. Quartz fibers and diamond filaments would reach up to the twenties. But then, in the nineties, came carbon nanotubes. Their theoretical tensile strength is in the range needed for a beanstalk.

But, the strongest actual observed GPa was only in the fifties, and the tensile strength of a cable would likely be less than that of its nanotube components. There are also difficulties with making bulk quatities of nanotubes and making them into suitable strands. Cost is also a factor, as nanotubes run about $25 a gram. But there is hope – carbon nanotubes have applications far beyond making space elevator cables, and someone, sometime, will for his own purposes invent a cable that is suitable for our beanstalk.

These developments in materials science put a working beanstalk in sight. And one company has formed to pursue the creation of a space elevator. I ran into Brian Dunbar of the Liftport Company in the comments section over at Murdoc Online, and asked him if he’d do an interview. He graciously agreed, and below, part one of our interview:

Brian, what is your role at the LiftPort Corporation?

I have two roles at Liftport.

Systems Administration - setup accounts, monitor disk usage, setup the web server

Gadfly - I flit about the Internet, looking for blogs, websites and forums that talk about space access, and specifically Liftport and the space elevator. If there are questions or misunderstandings, I correct them or point to a resource for better answers.

Why? Public support alone won't get us cheap access to space (CATS), but we won't get CATS without it. More specifically to Liftport we'll need a favorable legal and political climate to operate in. This is one way of doing that.

I'm not sure if there is a better way - would you trust us more if we ran commercials on TV? I wouldn't - and we don't have the funds for a massive traditional PR campaign so it's moot.

Could you give us a capsule description (for the sake of those readers who are not space enthusiasts) of what LiftPort is trying to do?

Build a space elevator system. Make money. Have fun.

To do that you need an organization that is going to be around for a few decades. This implies cash flow.

Our answer to that is to use the ancillary technology for a space elevator to build a series of businesses to provide short-term capital and long-term seriousness.

We're talking 'niche market' stuff here. Our robotics group is a good example; a lifter rolls up and down a ribbon to a balloon thousands of feet overhead. Going up it can carry fresh batteries or other consumables. Coming back it brings home the dead battery. This enables your load to have a much longer mission life, and it can power a higher energy device than a solar array could.

Potential uses are for wireless internet connectivity for areas where it's problematic to build towers or the towers have not been built yet, disaster recovery efforts, radio relay for the military.

So .. while it appears to be a two steps up one step back kinda deal this seems to be an optimal way to keep a private organization going while driving onto the main goal.

On your website, you always refer to your goal as a "space elevator." Is this a conscious decision to avoid the (Perfidy preferred) term "Beanstalk?"

Ya it is. 'Beanstalk' is a reference to 'Jack and the Beanstalk' of course and that story may not be known or internalized across the world. Space elevator .. everyone knows what an elevator is.

At this point the term 'space elevator' is more widely known than beanstalk. No one person set out to make this so it just happened.

Do you feel there is a strong analogy between the historical development of railroads and the future development of space elevators? Or does some other analogy present itself?

It's possible to use analogy while recognizing that space is different and analogies to previous eras don't really apply very well.

The railroad analogy is flawed, I believe, if you look at the American West in the 19th century. There the railroad companies gained wealth by owning sections of land adjacent to the tracks, and selling them at a profit. Towns were created by virtue of their being a railroad stop. This falls down with a space elevator - there isn't any value in owning
space next to the ribbon. It's all about the anchor, GEO and the bitter end.

The railroad as experienced in Europe might be a better analogy – there lines were constructed along existing communication links, improving the throughput between established locations. I'm dumbing that down for the sake of brevity of course.

It might be better to state that 'decreasing transaction cost on a transportation link always generates wealth' and leave it at that.

A few questions about technology:

What is the state of the art in materials technology, and how close are we to beanstalk grade materials?

I am no expert - it's not where I work and once you get beyond the most elementary description and math most of it is beyond me. The state of the art appears to be that it's possible to generate the material in the required strength in lengths of a few centimeters but beyond that, nothing. Yet.

Depending on who you talk to we're about a decade, or decade and half from 'space elevator' grade material. Or twenty years to never.

I am confident that the economic benefits of having such material would apply broadly across a number of disciplines - body armor, structural members, etc. So this should keep people beavering away at it.

What technologies need to be developed for a working beanstalk besides ribbon material?

We need a reliable vehicle or system that can traverse a variety of environments, without fail, at high speed. This isn't 'a' technology so much as engineering but neither is it a trivial exercise.

A power system for delivering energy from ground to the lifter needs to be devised. We're pretty sure that microwave aren't going to cut it (the rectenna would be huge) so that seems to leave a free-electron laser. You can't just go get one of these at Ace Hardware but they do exist as tested units in the lab. These need to gone over to see what efficiencies in manufacturing and operation could be had.

Organization. What does an organization that builds and operates a space elevator system (we certainly hope to have more than one in service) look like? We don't know. There have certainly been private operators of launch services but they've been geared around a low launch rate. Things are going to speed up and the org will have to be geared up to that fact.

The anchor. We think that the anchor is going to need to be mobile and capable of an average speed of 12 km/hour. This is faster than deep-sea oil platforms, and we'll move far more often than they're capable of doing. This implies some engineering of the concept.

What alternative uses for this technology is your company pursuing in the short term?

Currently we're standing up a CNT furnace in New Jersey - this will function as a new products integration lab for testing and (we hope) small scale manufacturing of CNT material.

Liftport Robotics to leverage the lifter work into a revenue stream (see above).

Liftport Media is stood up to exploit the media possibilities of the enterprise.

Traditionally, (in science fiction and elsewhere) a space elevator was portrayed as a cable. Why has LiftPort moved to a ribbon concept?

It's easier for the lifter to clamp onto a ribbon. Generally the answer 'cheaper and/or easier' will be valid for most of the choices we'll make.

How does LiftPort envision a beanstalk construction effort? Will it be built incrementally, or constructed in space and then deployed?

Yes.

The Plan calls for a seed ribbon to be built and lofted into orbit, in several loads. Once there we mate them together, then deploy the thing. Once it's down lifters ascend and add on more ribbon until we have 'enough' to support a few 20-ton climbers at a time.