ISEC promotes space elevator as ‘the green road to space’

Presenter: In our look back at conferences held in 2025, the International Space Elevator Consortium, Sept. 6-7. Pete Swan:

Pete Swan: Over the years, the modern-day space elevator has matured from a bright concept in 1895 through a NASA innovation study to an idea that is now ready to start development. In addition, the concept has matured into one that leverages modern materials, space systems, communication strengths, and the concept of intermodal transportation. This new vision enables the development of permanent space access infrastructure, then will enable massive missions to be accomplished much more rapidly and safely.

[00:00:44] In addition, the modern-day space elevator is truly the green road to space while enabling daily, routine, inexpensive infrastructure operations. I mean, that’s the bottom line. Routine, safely, efficiently. I mean, that’s really pretty neat.

[00:01:01] Well, why do I specify the modern-day space elevator? David Raitt wrote a paper for the Quest magazine that defined eight specific architectures, starting with Tsiolkovsky way back when, going through Brad Edwards a few times, then going beyond there. We’ve had eight distinct architectures. Well, this one, the modern-day space elevator, is ready to start. All we need is money to fund the engineering development. And we can get going.

[00:01:29] We’re putting a bridge across a river. It’s permanent, daily, routine, etc., etc.—it’s a stinking bridge. That’s all it is. You build up the bridge, you put a bigger truck on it. That’s as simple as it gets. 

[00:01:44] Let’s talk about daily to Mars. Everybody has always had a restriction of every 26 months we send a flotilla to mars because you can’t send them with minimum energy trajectories and by the way that’s what rockets use, minimum energy trajectories, you can’t send it but every 26 months.

[00:02:05] The students at the Arizona State University did a study for us called the, well, we wrote up the study called ‘Space elevators are the transportation story of the 21st century.’ But they talked about how they can depart every day. Now some of them are 61 days long–that’s the fastest–and some are 400 days long. But you can send your nails and hammers on the 400 days and send pizza on the 61 days.

[00:02:34] So the benefits of transportation infrastructure are remarkable. When we get an operational configuration of three galactic harbors, which each have two space elevators, then we’re going to have a very productive capability to put mass up into space, go to Mars, go to the outer planets, support GEO beautifully for, like, space solar power, stuff like that.

[00:03:01] Let people go on rockets and we’ll send the mass. It’s that simple. Okay. The students even came up with a bus schedule. Can you imagine that? A stinking bus schedule to Mars? You know the bus schedule today is every 26 months, send as many spacecraft as you can. But, you know, this comes up with every day of the year. You can just ship it.

[00:03:25] Benefits, move it faster. You go up you can go fast. If you go to 163,000 km, you can leave the solar system without rockets. It’s got that much velocity around the earth. It’s amazing.

[00:03:41] Now, Mr. Musk is doing a fantastic job. Mr. Bezos is right behind him. Reusability, multiple use of the launch first stage, all that. They’re doing a superb job, and I applaud them all. They still don’t get more than 2% to geosynchronous and a 0.5% to the surface of the moon.

[00:04:00] So why are we doing this? Because we must. It’s in our soul. We must build space elevators. These are elegant answers. We have unmatched efficiencies. We got unmatched velocities. And we move a lot of mass. I mean, we are the green road to space, though, we really are the answer. 

[00:04:18] Presenter: Adrian Nixon:

[00:04:19] Adrian Nixon: So space elevator, it’s a long dangly thing that goes from space all the way down to the earth. It’s a lift goes direct from surface of the earth back up into space. So it’s very big. The key thing I’ll be talking about is the material that the tether is made out of. And that’s a piece of material, 100,000 kilometers long, 100,000,000 meters long.

[00:04:40] So, tether material problem: Imagine you’re standing on the edge of an infinitely high cliff and you are a superhero so you can hold tons of material. And you start lowering a super strong cable over the edge and the material that dangles over the edge eventually acquires more and more weight pulling on it until eventually the cable breaks under its own weight, and that is effectively the problem we have with the materials that are currently available for the space elevator tether.

[00:05:09] The material needs to be super lightweight and super strong. Strength is measured in pascals, and today’s super strong materials such as Kevlar, strengths of around about 4 gigapascals (GPa), something like that. Carbon fiber has gone up to double that. But the space elevator tether requires an order of magnitude stronger, so we’re looking 60 to 100 GPa.

[00:05:29] So what are the candidate tether materials?

[00:05:33] Well, we have flat stuff and tube stuff. So the flat stuff are 2-D materials such as single crystal graphene and single crystal hexagonal boron nitride. And also we’ve got their nanotube equivalents, which are the same material but rolled up into a cylinder a bit like the inside of a toilet roll, and just very, very long.

[00:05:53] And so how do we actually go about making these things? Well, the super strong materials can be made in the lab. And I’m going to concentrate at the moment on graphene because the manufacturing of graphene is more mature than for making longer and larger scale sheets than it is for nanotubes.

[00:06:11] We originally dismissed polycrystalline graphene as being too weak for the work. But over the years of working with ISEC, we’ve discovered that provided the boundaries connect up–that’s what Rod Ruoff refers to as ‘well stitched together’ in his talk–provided things are well stitched together and no vacancies, the polycrystalline material actually is quite strong, so we’re going up to nearly 100 GPa compared to the 130 for graphene single crystal graphene. 

[00:06:37] So back in 2022, we said that we should be able to spot-weld graphene, and in the process make something called hexagonal diamond or Lonsdaleite, the strongest form of diamond in the world, and it’s never been made on earth–usually find it in meteorites.

[00:06:52] A few weeks ago, that was made. So a team in China have actually spot-welded graphene superlaminate, and they took a single crystal of graphite and squished it. And they did indeed form super diamond Lonsdaleite. So we know that the tether material can be spot-welded now, and that’s been proved.

[00:07:11] And in the December, 2020 issue of the newsletter, we said that graphene superlaminate should have a mirror-like appearance and be silver and mirror-like and Rod Ruoff’s team, again, this is just a few weeks ago, less than a month ago, produced a paper in Nature showing that multi-layer graphene. This graphene superlaminate does indeed have a mirror-like appearance when it’s made as large grain graphite films.

[00:07:35] So that’s what the space elevator tether will look like. Perfectly smooth mirror like flat ribbon, 100,000 km long, thinner than aluminum kitchen foil. And that would rise straight up out of the sky, disappearing out of sight, and that very thin, almost fragile-looking material will support climbers of tens of hundreds of tons of weight. 

[00:07:56] Presenter: Blaise Gassend:

[00:07:57] Blaise Gassend: I’m going to be talking about the effect of the wind on the space elevator, you know, what effect the wind has on a tether. I’m going to be looking at ERA5 wind data. The ERA5 database is a database put out by the European Union. They basically have a model of the atmosphere. They constrain it with the actual measurements that we have of the atmosphere. And this basically helps us produce a prediction of what the atmosphere state is across the whole world.

[00:08:22] They provide this for the time range from 1940 to present in a resolution of one hour and 0.25 degrees (that’s about 28 kilometers). They have 37 pressure levels going from the ground up to about 60 kilometers. And this data set includes several data products, including the ones I’m interested, which are horizontal and vertical wind velocity.

[00:08:42] So if you look at a tether that’s at equilibrium among various forces, what you’ll find is that you have two equations: how the elevator tilts, and how the tension varies under the effect of these forces.

[00:08:56] To understand what the forces are from the wind on an elevator, I use the crossflow principle, which says you can take the velocity of the wind and split it up into the normal and tangential components and compute the effect of each one of those independently and then combine them to see what the effect on the elevator is.

[00:09:16] If you have enough wind that your elevator tilts and tilts and tilts and gets to 90 degrees, once you get to 90 degrees or close to 90 degrees, you’re essentially going to get in the situation where the ribbon just kind of rolls itself down onto the ground.

[00:09:30] It’s going to be pulling down on the counterweight. The counterweight will start to descend. That will reduce the centrifugal force on the counterweight, which will further reduce the tension and just make things worse.

[00:09:41] So, you know, once you get close to 90 degrees, bad things are going to happen. You want to stay away from that.

[00:09:45] For this analysis, we collected data for the whole period on the equatorial region with slices every three hours. And it’s a data set that’s about 100 gigabytes in size. Our analysis of that data tells you for various percentiles what the RMS wind speed is as a function of longitude.

[00:10:04] And what do we see? Well, the continents definitely have lower wind speeds than the oceans. The middle of the Pacific is about the worst place you can go for wind. People call it ‘the pacific Pacific’ but you know, from the space elevator point of view, that is not accurate.

[00:10:19] Brad Edwards was placing the elevator 1,000 miles west of Galapagos Islands, and that was supposed to be a place with very low wind, but if you look at the pressure caused by the wind, you know, it’s highest up at 10-15 kilometers. And so while there might not be much wind at ground level, 1,000 miles west of the Galapagos, you really need to be looking higher up to determine what the deal is. And there is a lot of wind there.

[00:10:45] The equator is actually a very calm region compared to higher latitudes. You know, once you start getting past 10 to 15 degrees, the winds get quite a bit stronger.

[00:10:54] This data set goes up to 60 km. When you look at the distribution of winds of function of altitude, you actually find that it would be nice to have a little more height than that. We’re definitely declining in terms of forces on the elevator by the time we get up to 60 km. But I wouldn’t be surprised if there is maybe a 10% error still left with the data we have.

[00:11:13] We can also look at the vertical component of the wind. You can get some pretty high wind speeds, but they are extremely rare. And for some reason, they’re more in the upward direction than the downward direction.

[00:11:24] If you do a cross-section through the atmosphere, you get these very localized regions of updraft, and then much more spread-out regions where downdrafts happen. Fast updrafts aren’t actually that much of a problem because they will tend to curve the ribbon towards being more vertical. And so for us, they’re not going to be a big challenge.

[00:11:44] If you plot wind direction versus altitude, you find that there’s all kinds of interesting stuff going on. The wind will be coming from several different directions.

[00:11:51] We can look at the seasonality of the wind. You know, Pacific has more in the winter, Indian Ocean has more in the summer. We can look at how different years compare.

[00:12:01] So there’s definitely some outliers, this event in 1983 that I looked at a little bit more. That particular event lasted a few weeks and it looked like what happened is that the subtropical jet stream got disturbed by some weather events that were going on and ended up down in the equatorial region where we had this mass of fast-moving air at the subequatorial jet stream altitude.

[00:12:27] So where should we put this space elevator if we want to take into account wind and lightning? In the case of South America, there is a region south of Suriname that has relatively little lightning. But other than that, your best bet is probably to go out in the ocean, probably staying close to land because that’s where the winds are lowest.

[00:12:45] Similar deal in Africa: Kenya has relatively low lightning distribution. But other than that, you’re probably best off going the ocean on either side, where the wind speeds haven’t picked up too much yet.

[00:12:58] If you look at Indonesia and surrounding islands, there’s lightning all over the place. So here you’re probably going to want to be in the ocean on the eastern side. So, you know, if I was China, this is probably the area I’d be looking for to build my space elevator.

[00:13:13] Presenter: The International Space Elevator Consortium hears about progress on tether materials and looks at potential sites based on 85 years of data.