President’s Note

by Dennis Wright

Top Five Challenges for the Space Elevator - Strong Materials

In the next five issues, I’ll discuss the most critical challenges that must be met in building a space elevator and the progress made in each of these areas. Not surprisingly, the first is the tether material.

ISEC has identified graphene super-laminate (GSL) to be the material that will meet the needs of high strength and low mass required by the tether. Much has been said in these newsletters about this material and its superior properties, but to date, it has not been produced. So how close are we to producing it?

The steps along the way, in increasing order of difficulty, are polycrystalline graphene (PCG), single crystal graphene (SCG), multi-layer graphene (MLG), and GSL. PCG—graphene sheets composed of many individual graphene crystals—is already being produced in kilometer lengths. Its strength is such that a reduced-capacity space elevator could be built today, provided enough material can be produced. This is just a matter of scaling up production.

In SCG, all the small crystals must be aligned to make a single large crystal with lengths on the order of tens of kilometers. This material is much stronger than PCG and is the main component of MLG and GSL. Meter-long samples have been produced in the laboratory and the challenge now is to extend this length.

Layering of SCG has been done to make small samples of MLG, but the ultimate material will be GSL in which the graphene layers will be stacked to maximize the Van der Waals forces between them and cross bonding added to increase shear strength. ISEC members have been looking into how this might be done, with one project being a macro-molecular simulation of the material. So, if any of you have an interest in this area, especially in molecular simulation, please let us know.

The next challenge is: can a climber ascend the space elevator? Watch for the answer to this in the next issue.

Dennis Wright

Chief Architect’s Corner

by Pete Swan

Keeping up with the Chief Architect’s Notes 

Over the last few months, I have compiled several more Chief Architect’s Notes for our website to help the full space elevator community come together towards the launch of a major program to fulfill the dreams of many – not only our dreams of the permanent space transportation infrastructure, but the dreams of those who need the capability to put hundreds of thousands of tonnes into GEO and beyond. These five Notes were written during the transition from President to Chief Architect and have fulfilled some of my “scratches”. We need to be able to understand where we are and what we need to explain, ergo the notes below explain:

+ Quick one minute “elevator speech.” [#66]

+ A suitable material is here. [#64]

+ We need to understand the initial steps. [#63]

+ We MUST keep mentioning we are a permanent infrastructure. [#65]

+ Our infrastructure will dwarf historic rocket approaches. [#67]

Each of these quick summaries should help people understand where we are and how to proceed towards a full-up acquisition program. We need to leverage the architectural approach where we explain how passion is needed to proceed—Humanity MUST HAVE permanent infrastructure access to space! They must recognize that the need for full-up engineering details have yet to be finalized until we have a customer to explain their needs. The explanations of the capabilities must respond to the perceived needs of the customer who will then set the high bars to design against.

Abstracts Needed in the Near Future

ISEC has a yearly desire to conduct technical and programmatic presentations of our progress to stimulate motion beyond our little community. This leads to a need to plan ahead and submit abstracts for consideration. Our desire is to have robust and current/future discussions broadcast to the world. These are:

Conference ONE – ISEC: As such, we emphasize our own conference (fall 2025) with the mission of involving our teams and reporting on their progress. (To be announced soon.)

Conference TWO – IAC (29 Sept–3 Oct): Nearest Deadline: 28 Feb 2025

Our first abstract deadline for each yearly conference is for the IAF which is our largest “reach” as it has tremendous attendance from space experts around the world (11,000 in Milan last October). The IAC this year is in Sydney with a full schedule. We must meet the deadline of abstracts if we are to be successful as an outreach program from ISEC. We support with a technical session and attendance by several ISEC members.

Abstracts must be submitted online by 28 Feb 2025 (Paris time).

https://www.iafastro.org/events/iac/international-astronautical-congress-2025/

Our session: “IAC–25, D4.3 Modern Day Space Elevator as a Permanent Transportation Infrastructure”:

“Space elevators position humanity to address Earth’s challenges from a new vantage point. We are on the brink of transforming our relationship with space, offering an eco-friendly, cost-effective, and efficient logistics method to transport large cargoes into space. This gateway will provide unparalleled opportunities in space exploration, resource utilization, and satellite assembly.”

Conference THREE – NSS ISDC (June 19–22): The third conference (with later deadline for abstracts - during March 2025) is the International Space Development Conference. We support with a technical session while many ISEC members participate in other functions. Our session is on Saturday (June 21, 2 pm–6 pm, https://isdc.nss.org) with the following technical session: “SPACE ELEVATORS - Revolutionizing Access to Space.”

“Modern-Day Space Elevators address the huge challenges being embraced by the NSS—moving off planet and saving it in parallel. The success of operating a complex of Modern-Day Space Elevators will transform humanity’s relationship with space with eco-friendly, cost-effective and efficient logistics delivery to GEO and beyond. New opportunities will surface for space exploration, resource utilization and satellite assembly beyond the gravity well.”

Remember: meeting abstract deadlines leads to ISEC’s success in a much larger community­—we need you to participate!

History Corner

by David Raitt

A Lesson in Space Travel

The English bookshop in our nearest town was offering three books for the price of two. A History of Our Universe in 21 Stars was an easy first choice. After some perusal and thought I picked A Brief History of America since it was dated 2024, but out of all the books on offer I was a bit stumped for my third selection – until I spotted, 10 Short Lessons in Space Travel. Authored by Paul Parson and published by Michael O’Mara Books Ltd. the book is dated 2020 (thus probably written about 2019), so I was a bit hesitant – however, on looking through the index I noticed the name Tsiolkovsky. Would the book by any chance mention space elevators? Yup – not much – but enough for me to buy it based on the two index words!

In the chapter entitled Lesson 8: It’s a Small Solar System”, it notes on page 122, (as we have been saying for a while) that the problem for space travel is our current rocket technology. Rockets work by combustion, a chemical reaction and a relatively low-energy process, meaning that rockets must guzzle huge amounts of fuel – which is carried with them – making them rather sluggish. Going on to mention that we can expect to see different and more efficient and faster craft in the coming decades (such as nuclear engines, ion drives, and solar sails), the text continues on the same page with “Even the way in which we leave Earth and access space is set to change. Scientist and author Arthur C. Clarke, for example, was a strong advocate of ‘space elevators’, cables suspended from orbiting platforms to winch payloads up from the Earth’s surface and into space.” The next page gives a brief biography of Clarke and his life and works and including a mention of his 1979 novel The Fountains of Paradise which popularized the concept of the space elevator.

Ten pages further on, the space elevator is mentioned again in its own box:

“Imagine a cable stretching from the surface of the Earth up into space that could be used to ferry payloads from the ground into orbit. This is the space elevator, a novel concept introduced by the visionary Russian space scientist Konstantin Tsiolkovsky at the end of the nineteenth century. It sounds a bit like the Indian rope trick. But the cable is, in fact, in geostationary orbit around the planet’s equator. It extends all the way down to the ground, where it’s anchored, and it’s capped off at the top with a large counterweight ensuring its centre of gravity circles the Earth at the geostationary altitude of 35, 786 km (22,236 miles). In some sense, it’s the centrifugal force of the circling counterweight that holds the entire structure up. Why haven’t we built one? The problem is the cable would be so heavy it would be unable to support its own weight. Even one made from carbon nanotubes, the strongest and lightest material we have, would break once its length exceeded 10,200 km (6,338 miles).”

Interestingly there is Clarke’s quote from 1984 on the next page “The space elevator will be built about fifty years after everyone stops laughing.”

It’s not much, nothing new and is fixed on carbon nanotubes, but at least it is a mention of space elevators in a book on space travel. I looked the author up and found that Dr Paul Parsons has been a science writer and journalist for over 20 years, and is a regular contributor to Nature, New Scientist, and The Daily Telegraph and who has also frequently appeared on BBC radio and television. He was also formerly, editor of the BBC's award-winning science and technology magazine Focus, as well as managing editor of BBC Sky at Night Magazine.

ISEC Intern 2025 Announcement

This year, ISEC is accepting applications from both undergraduates (in their third or fourth year) as well as graduates (Masters and Doctorate) to participate in the 2025 Modern-Day Space Elevator Transportation System research program.

Research Topics for 2025:

1.  Understanding the forces of the Tether Climber from Earth to the Apex Anchor.

2.  Potential Tether Climber configurations to cover: Earth surface to 100Km; 100Km to GEO; and, GEO to Apex Anchor.

3.  Methodology and process regarding the Installation of the 1st Tether.

4.  Research the limitations of the torque-to-mass ratio of an electric motor that would be used on the Space Elevator’s Climber.

5.  Research the thermodynamics of the space elevator’s climber from the surface of the Earth to the Apex Anchor.

6.  Research battery technology to determine the highest power density and lowest mass for the needs of the space elevator’s climber. 

7.  Research the application of space tribology to understand how to modify/redesign the commercial gear boxes shown on the climber conceptual design model to work in a vacuum. 

8.  Research potential techniques of carbon fiber reinforced polymer structural design.

9.  Open Topic addressing a particular aspect of the Modern-Day Space Elevator Transportation System

The interns will be conducting remote research for the months of May through August on a topic agreed upon with their mentors and presenting their results in a research paper. The intern will  be paid $599.00 USD upon completion of the research.

Schedule for 2025 ISEC Intern Program:

5 Feb 2025--Initial announcement on ISEC intern website                                       

15 Apr 2025--Provide potential research abstract to ISEC

1 May 2025--ISEC to select intern’s research topic and assign a mentor           

15 May 2025--Group discussion on Null-Hypothesis testing (if required)

15 May-15 Aug 2025--Intern to conduct research with mentor, including periodic meetings via Zoom with mentor for status/questions

1 Sep 2025--Final research paper submitted to ISEC Intern Director

Sep 2025--Intern can present research (Video) at ISEC Conference

Nov 2025--Intern can present research (Video) at NSS Conference     

Interested applicants need to send their abstract for evaluation to ISEC_InternProgram@isec.org

Paul Phister, Ph.D., P.E.
Director, ISEC Intern Program

Graphene Is in Space

Margherita Sepioni and team at SmartIR have had a successful launch with SpaceX. The Falcon 9 Falcon 9 Block 5 | Transporter 12 mission successfully launched Tue Jan 14, 2025, 19:09 GMT [1].

Smart IR is a spin-out company from the University of Manchester and based at the Graphene Engineering Innovation Centre (GEIC) in the UK. They have equipped a picosat with a new lightweight and cost-efficient graphene radiator that keeps the spacecraft cool. This is cool in all senses of the word! Graphene is now in low earth orbit.

Falcon 9, Block 5 Transporter 12 mission launch. Image credit: SpaceX live feed.

SmartIR Picosat

SmartIR Picosat. Image credit: SmartIR.

References:

Manchester, U. of (2025b). Graphene in Space: A New Milestone for SmartIR and Graphene Commercialisation. [online] Graphene in Space: A New Milestone for SmartIR and Graphene Commercialisation. Available at: https://www.manchester.ac.uk/about/news/graphene-in-space-a-new-milestone-for-smartir-and-graphene-commercialisation/ [Accessed 21 Jan. 2025].

Nextspaceflight.com. (2025). Falcon 9 Block 5 | Transporter 12. [online] Available at: https://nextspaceflight.com/launches/details/7009 [Accessed 21 Jan. 2025].

Solar System Space Elevators

by Peter Robinson

Part 7: ENCELADUS

This is the seventh article of the “Solar System Space Elevators” series. Earlier articles covered Mercury & Venus, the Asteroids, the Moon, Mars, Jupiter, and Saturn.

Last time I concluded that space elevators were unlikely to be feasible (soon) or viable on Saturn or any of the lesser Saturnine moons, except for Enceladus and Titan. Here is my discussion of Enceladus [1].

1. INTRODUCTION

Enceladus is the sixth largest of Saturn’s moons, orbiting close to Saturn within the outermost ‘E’ ring. It is mostly covered by fresh ice, making it one of the most reflective bodies in the solar system and resulting in a surface temperature of no more than 75 K. Substantial tidal heating results in sub-surface liquid water and frequent water geysers, with the ejected water being the major source of the material of the ‘E’ ring as shown in Figure 1 below.

Enceladus from Cassini

Figure 1: Enceladus from Cassini orbiter and within the ‘E’ ring. Image credit: NASA/JPL.

The sub-surface water makes Enceladus a fascinating location for science, meaning regular surface access would be valuable for research and exploration. A recent article by Monisha Ravisetti in Space.com says: “The golden child in Saturn's system is named Enceladus, and it's so special because scientists believe it to be a prime location to search for life beyond Earth…” [2]. There is little doubt that tidal heating means plentiful liquid water under the frozen surface of Enceladus, but the precise extent and temperature of the water requires detailed study. Figures 2 and 3 below illustrate the sub-surface and surface conditions.

hydrothermal activity on Enceladus

Figure 2: Artist's impression of possible hydrothermal activity on Enceladus's ocean floor. Image credit: NASA/JPL.

Enceladus geysers

Figure 3 : Water sprays into space from Enceladus, from Cassini spacecraft in 2010. Credit: NASA/JPL-Caltech/Space Science Institute.

2. ENCELADUS ELEVATOR CONCEPTS

Spacecraft could potentially land and launch from the surface, but the resulting disturbance to the otherwise pristine icy surface may be undesirable. An Enceladus ‘L1-type’ space elevator would avoid these issues and perhaps reduce the risk of biological contamination.

Relevant parameters for Enceladus are:

Saturn Orbit Radius = 238,000 km

Saturn Orbital Period = 32.9 hours (2:1 orbital resonance with Dione)

Diameter = 500 km

Surface Gravity = 0.113 m/s^2 (0.0116 g)

Atmospheric Pressure: trace only (91% water)

L1 Altitude = 687 km (nominal, my calculation)

The precise L1 position will vary slightly due to orbit eccentricity and the gravity of other moons, but such a low L1 altitude means that an elevator tether might be only of the order of 2000 km long. A number of configuration concepts are as follows.

2.1 Concept 1: Conventional Ribbon

The simplest concept might be a conventional ‘ribbon’ tether extending from the surface of Enceladus towards Saturn to the L1 point and on to an Apex Anchor.

An ‘Operations Centre’ might be positioned at the L1 point, to include spacecraft docking/berthing capability, habitation & work modules, power systems, etc. Climbers would travel the 687 km to/from the surface ‘Enceladus Port’, where there would be payload transfer mechanisms. The surface port would also require a ‘Reel-In-Reel-Out’ (RIRO) winch mechanism to control tether tension and dynamics as climbers ascend and descend.

The low surface gravity of Enceladus (0.012 g) makes secure retention of the Port to the surface critical, but this should be possible by drilling into the ice surface. Drills or piles could be initially heated to melt the ice for easy insertion, then by allowing the ice to freeze, could secure the system.

The Enceladus Port location could be some surface distance from the point with Saturn at the zenith (the ‘sub-planetary point’) to allow direct access to other locations of interest, but this would increase the cable tension and impose a lateral force on the ice. A number of Surface Ports and tethers could be installed, but they would require careful balancing of the multiple cable forces to maintain the stability of the single Operations Centre at the L1 Point.

There would be little need for climbers to travel from the L1 point to the Apex, so the tether above L1 could be either a ribbon or (static) cable(s).

2.2 Concept 2: Hybrid

One potential difficulty with Concept 1 is the need for the RIRO system to operate and be powered in the extremely low temperatures of the surface of Enceladus, together with the risk of ice accumulation from geysers. This means it may be best to minimise the surface systems, and the relatively short length suggests that a ‘conveyor-type’ system could be used. This would avoid the need for an active ‘Reel-In-Reel-Out’ (RIRO) system, requiring merely the attachment of a pulley and other components on the surface.

(A conveyor system was first proposed for a Phobos-to-Mars elevator by Weinstein in 2003 [3] as discussed in my first ‘Mars’ article [4])

Figure 4 below shows a schematic of a hybrid elevator system concept, requiring climbers above 100 km.

Enceladus-SE-(Concept-2)

Figure 4: Enceladus SE (Concept 2). Schematic by P. Robinson, Image Credit: NASA/JPL.

The Apex altitude of 2000km is arbitrary: if it were higher the Anchor mass would be less but the total tether mass more. No mass is given for the Operations Centre as this is at the Saturn-Enceladus L1 point, effectively a zero-g stationary altitude.

In this concept the Node on the surface of Enceladus could simply be a pulley, though a powered secondary assist drive motor might be required. Other mechanisms would be required for cargo transfer to/from the cable-car modules.

2.3 Concept 3: No Climbers

The need for climbers (and cargo transfer at the Winch Node) could be eliminated entirely by extending the winch/cable-car system as far as the Operations Centre, as shown in Figure 5 below. The conveyor drive motors would then be within the Operations Centre.

Enceladus-SE-(Concept-3)

Figure 5: Enceladus SE (Concept 3). Schematic by P. Robinson, Image Credit: NASA/JPL.

There could be significant advantages (and cost savings) in not operating climbers, but extending the conveyor cables to 687 km may result in greater engineering challenges than might be seen at 100km. It may, for example, be necessary to have a third static cable supporting cable guides to prevent oscillation and displacement of the moving cables.

2.4 Concept 4: No Surface Attachment

Another option would be for the lower pulley to be suspended some distance (perhaps several km) above the Enceladus sub-planetary point. Such a ‘Skyhook’ would eliminate the need for any anchoring to the icy surface and improve biological security but would require some form of winch (or ‘Sky-crane’) for transfer of payload to/from the surface.

The mass of this suspended ‘Pulley Node’ would need to be sufficient to maintain adequate tension in the conveyor cable under only the local 0.0116g gravity, and thrusters may be necessary to maintain dynamic control. Further detailed work is needed to assess the viability of this option.

2.5 ‘L2-type’

Any of the above options could be duplicated on the opposite face of Enceladus extending away from Saturn through the ‘L2’ point. The L2 nominal altitude of 707 km (my calculation) is only slightly higher than the L1, meaning any elevator system would be very similar.

A disadvantage of an L2 elevator is that all personnel at the Operations Centre would not get to enjoy the magnificent view of Saturn (angular size = 29.2 deg), it being permanently hidden behind Enceladus (angular size = 30.5 deg)!

3. ANALYSIS

My analysis of the above concepts 2.2 and 2.3 used my spreadsheet method as described in earlier articles and papers. With Graphene Super Laminate (GSL) material this yields a working stress of around 10 GPa, less than 12% of that required for an Earth Elevator but similar to the figure I proposed for a Mars Elevator [5].

I assumed a cross-sectional area for the conveyor cable of 5 mm^2 (2.5 mm diameter), with a tether area of 10 mm^2 (perhaps 0.5m x 20 micron) above the Winch Node or Operations Centre for a similar working stress. This design yields sufficient cable tension to support a single 5 tonne climber accelerating at 0.5g.

The total system mass for the cable and tether of either concept would be c. 45 tonnes of GSL, plus the mass of the lower pulley and associated systems (for surface attachment, cargo transfer, etc.), plus the mass of any climbers, plus the mass of the Operations Centre. The Apex Anchor mass would be approximately 2800 tonnes at 2000 km altitude, perhaps using material collected from the Saturn ring system held in spent fuel tanks or netting.

The Option 3 Apex mass is slightly less than Option 2 as the Anchor does not have to support the weight of the Pulley Node. Further analysis is needed to establish the precise masses for Options 1 and 4, but these are unlikely to be significantly different.

4. RISKS

One potential risk factor is impact with the material of the ‘E’ ring around the orbit of Enceladus, thought to be comprised of ice and other material ejected from surface geysers. The risk of tether damage from impacts with ring material could be low given the likely strength and robustness of GSL material, but work is needed to establish E-ring particle size and relative velocity distributions. The safety margin could be improved by using a heavier tether or cable.

Loss of surface integrity due to surface instability or geyser eruptions must be another concern, but in such an emergency the surface station design could allow much of the Surface Node to be rapidly detached from the sections embedded in the ice. The system could then be reattached to the surface at some later time with minimum replacement components.

5. CONCLUSIONS and SUMMARY

The pristine nature of the surface of Enceladus and the possibility of it harbouring extra-terrestrial life means that repeated surface access using rockets may be inadvisable and might even be prohibited should regulations be imposed. A relatively short ‘L1-type’ or ‘L2-type’ space elevator system could be built using a conveyor belt and/or winch arrangement to minimise surface disturbance or contamination and eliminate the need for potentially unreliable ‘climbers’.

Final elevator system concept selection must await further analysis and availability of a suitable cable/tether material. A total system mass of only a few hundred tonnes could be feasible, assuming a sufficiently strong tether material and the collection of additional ballast mass from the Saturn ring system for the Apex Anchor.

NEXT TIME: TITAN!

5. REFERENCES

[1] ‘Enceladus’ Wikipedia page: https://en.wikipedia.org/wiki/Enceladus

[2] Article in Space.com “There's a weird, disappearing dark spot on Saturn's moon Enceladus”, Monisha Ravisetti, 15-Dec-2024: https://www.space.com/space-exploration/search-for-life/theres-a-weird-disappearing-dark-spot-on-saturns-moon-enceladus

[3] “Space Colonization Using Space-Elevators from Phobos”, Leonard M Weinstein, 2003: https://ntrs.nasa.gov/citations/20030065879

[4] ISEC September-2024 Newsletter, ‘Mars 1’: https://www.isec.org/space-elevator-newsletter-2024-september/#solarsystem

[5] ISEC October-2024 Newsletter, ‘Mars 2’: https://www.isec.org/space-elevator-newsletter-2024-october/#solarsystem

Tether Materials

by Adrian Nixon 

A Closer Look at Carbon Fibre as a Candidate Tether Material

Carbon fibre is a very strong material. However, tether materials require a material at least ten times stronger than the strongest carbon fibre manufactured today. The two important characteristics of a material are its tensile strength and density. Charting the tensile strength on the vertical (y) axis and the density on the horizontal (x) axis gives an Ashby plot that maps out the strength of various classes of materials.

Ashby plot for tether materials showing carbon fibre

Figure 1: Ashby plot of various materials including carbon fibre.

The Ashby plot shows the approximate region where the current candidate tether materials are clustered. These materials are Graphene, hexagonal boron nitride (hBN), carbon nanotubes (CNT) and Boron nitride nanotubes (BNNT).

Carbon fibre is well below the strength required and this is the reason we rarely refer to the material when discussing tether materials.

At ISEC we like to keep an open mind about materials technologies and so we thought it was time for a fresh look at the technology.

The manufacture of carbon fibre can be summarised as follows:

+ Start with a linear polymer

+ Spin the polymer molecules together to form a strand

+ Then heat it in the absence of oxygen to char

+ Leaving a fibre made from very strong chains of carbon atoms spun together.

There is more to it than this, as I have learned recently.

Carbon fibre can be made from any polymer with a carbon backbone. The most used polymer is polyacrylonitrile (PAN). The material starts its journey as polymer molecules that are spun into a yarn. This PAN yarn is heated to between 200°C and 300°C to start a reaction between the polymer molecules.

This reaction between polymer molecules forms a heterocyclic structure with nitrogen in each carbon ring(fig1). This ring is a rearrangement of the existing structure which is more stable than the C= N triple bond.

Carbon fibre manufacture from polyacrylonitrile

Figure 2: Manufacture of carbon fibre from polyacrylonitrile.

The heterocyclic yarn is then heated at a higher temperature 1000 to 2000°C. This carbonises the yarn by allowing the nitrogen atoms to leave the ring structure as more molecular strands connect. Further heating anneals the defects in the structure and graphitises the yarn to its final form [1].

If this final graphitised structure looks familiar, then you are right to think of stacks of graphene. More particularly, because the graphene-like stacks are formed from long molecular strands of PAN, they have a structure that is long, thin and flat. This is like graphene nanoribbons. These stacks of graphene-like nanoribbons overlap and form the individual carbon fibres. Figure 2 shows a stylised version of this structure [2].

The-structure-of-carbon-fibre

Figure 3. The structure of carbon fibre

These individual carbon fibres are then wrapped around one another from the spinning process creating the macro scale carbon fibre product we are familiar with.

Manufacturers have learned that carbon fibres can be made stronger by using longer polymer molecules of PAN to start with. The length of polymer molecules is expressed as the molecular weight (mol wt.). In the case of high strength carbon fibres, the mol wt. is approximately 429,000 g/mol [3]. This means the graphene-like nanoribbons inside the carbon fibres are approximately 2.5 microns in length [4].

Carbon fibres made from high molecular weight PAN have a tensile strength of 7 GPa [3]. Which is nearly twice that of ultra strong materials such as Kevlar. This high strength means that they must be bonded at the edges between nanoribbons. The higher the molecular weight of the original PAN polymer the longer the polymer chain and therefore the more likely to overlap and cross link between polymer strands, and subsequent nanoribbons, leading to the higher tensile strength. If the manufacturing process can be improved to make the carbon nanoribbons into true graphene nanoribbons, then the resulting carbon fibre will be even stronger.

Should carbon fibre be considered a 2D material? The answer is both No and Yes. If you are considering the carbon fibre at the macroscale, it should be a three-dimensional bulk material. However, looking down at the micro scale and below, it becomes apparent that carbon fibres are composed of graphene-like nanoribbons. So, at the micro and nanoscale, carbon fibres are made of 2D materials.

This nanoscale view of carbon fibre gives us some new insights into how these fibres could be made even stronger than the current high strength yarns. Dear reader, you may recall in a previous tether materials newsletter article, that we explored the possibility to form covalent bonds between layers of graphene tether material and ‘spot weld’ them together [5]. It should be possible to apply this technology to the graphene-like nanoribbons in carbon fibre, provided the layers are aligned with one another.

If this spot-welding technique can be applied to carbon fibre production, then the strength improvements would be increased by an order of magnitude. This would make the enhanced carbon fibre have a tensile strength of 50 to 70 GPa and this could just be strong enough to make a space elevator tether.

So, in summary, carbon fibre is not strong enough to be considered a candidate tether material at present. However, we can see an innovative technology path to improve the strength by an order of magnitude. If someone chooses to invest time and money, it might be possible to extend existing manufacturing methods to make super strong carbon fibre variants.

References:

1. Anon (2020). What is Carbon Fiber? Toray CFE explains it all. [online] Toray-cfe.com. Available at: https://toray-cfe.com/en/what-is-carbon-fiber/ [Accessed 29 Dec. 2024].

2. Takahashi, K. (2015). Development of Carbon Fiber Composite Materials for Lightweight Commercial Airplanes. [online] JACI, Tokyo: Toray Industries Inc., p.4. Available at: https://www.jaci.or.jp/english/gscn/GSCpdfs/gsc_guide_no03.pdf [Accessed 29 Dec. 2024].

3. Ahn, H., Yeo, S.Y. and Lee, B.-S. (2021). Designing Materials and Processes for Strong Polyacrylonitrile Precursor Fibers. Polymers, 13(17), p.2863. doi:https://doi.org/10.3390/polym13172863.

4. Calculation for the length of a polyacrylonitrile (PAN) molecule from its molecular weight:

Key assumption is that The PAN molecule is linear with no branching

The repeating unit in PAN consists of three carbon atoms, three hydrogen atoms, and one nitrogen atom. Using atomic weights (Carbon: 12 g/mol, Hydrogen: 1 g/mol, Nitrogen: 14 g/mol), the molecular weight of the repeating unit is 53 g/mol

The polymer molecular weight is 429,000 g/mol. Therefore 429,000 / 53 = 8,094 repeating units

The length of the carbon – carbon bond in acrylonitrile is 0.154nm

Estimate the length of each repeating unit as two carbon bonds so 0.154 x 2 = 0.308nm

The length of the original polymer is 0.308 x 8094 = 2,493 nm

Therefore, the length of the carbon nanoribbons in the carbon fibre is 2.5 microns

5. Nixon, A. (2022). Thinking About How to Prevent Slipping in a Layered Tether. [online] International Space Elevator Consortium. Available at: https://www.isec.org/space-elevator-newsletter-2022-september/#tether [Accessed 27 Jan. 2025].

Social Media Update

Breaking News (for some of us!): Reddit has a ‘Space Elevator’ community with 290 members. It was created in 2012, around the time of the first ‘proper’ space elevator conference and perhaps by one of the founders of ISEC. It is no longer managed by anyone at ISEC and has only been intermittently active recently. Since late January 2025, we have created an account and become involved, and we’ll post this newsletter there each month and more.

If you already use Reddit, follow the community at r/spaceelevator and engage in the discussion.

If you don’t use Reddit, try it out! It’s great for exchanging ideas on a vast range of topics, including space elevators!!

Elsewhere, LinkedIn continues to grow as our primary social media outlet, now with well over 2100 followers. We see a steady growth in followers on the new Bluesky platform, but there is a small decline on X, Instagram and Threads.

After polling our followers on Threads, with little response, we have taken the decision to discontinue activity there. (I only have limited time!!)

We will continue to review our activity. Please comment on our latest post on your favourite site to let us know your views. For links to all our social media outlets go to https://www.isec.org/social-media.

ISEC Media Mogul

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Upcoming Events: 

International Space Development Conference 2025
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76th International Astronautical Congress
Sponsored by the International Astronautical Federation (IAF)
https://www.iac2025.org/about/
Monday, September 29th, through Friday, October 3rd, 2025
International Convention Centre, Sydney, Australia

77th International Astronautical Congress
Sponsored by the International Astronautical Federation (IAF)
https://iac2026antalya.com/
Theme: “The World Needs More Space”
Proposed Dates: October 5th through October 9th, 2026
Antalya, Turkey

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