Editor’s Note

Dear Space Elevator Enthusiasts,

In the article submitted by the Chief Architect, below, he talks about how to manage mega projects and quotes Lee Battle. I did a little bit of research and found a story that explains how Battle came up with these laws at https://www.thespacereview.com/article/1333/1.There is also a document that contains “Battles Laws” (some even in his own handwriting) in this PDF document from The Space Review. https://www.thespacereview.com/archive/1333.pdf. 

For further reading on how to manage projects, I would like to recommend a book to you that I read called “How Big Things Get Done: The Surprising Factors That Determine the Fate of Every Project, from Home Renovations to Space Exploration and Everything In Between” by Bent Flyvbjerg and Dan Gardner. In my opinion, this is a must-read before we get to the construction phase of the space elevator.

Sandee Schaeffer
Newsletter Editor

President’s Note

by Dennis Wright

Top Five Challenges for the Space Elevator - “Climbability”

Last month we discussed the strong materials challenge for the space elevator and how it is being met. Once a tether is built, the most important questions become: how can the tether be climbed? Can a climber be built that will pull itself up the tether? What physics conditions must be met before this is possible? What requirements does climbing produce for the construction of the tether and the climber? These questions and more can be collected under the heading of “climbability”. An ISEC group made an extensive study based on this and its conclusions were published in Acta Astronautica. The article is available for free on the ISEC website at https://www.isec.org/studies/#ClimberTetherInterface.

Many critical conditions are established at the climber-tether interface: the place where a device in the climber grips or pulls on the tether. Two of the most important conditions on the tether were found to be the minimum coefficient of friction at the tether-climber interface and the minimum shear strength of the tether. Current samples of graphene do not meet these minima, but proposals for improving them have been developed and can be integrated into the tether manufacturing process.

Another major conclusion of the study is that a 20-ton climber with a 10-ton payload could be built with present-day or soon-to-be-available technology. Sufficiently high-torque motors to power the climber do not yet exist commercially, but could be designed today. Other challenges remain, such as powering the climber and heat dissipation. Powering the climber is the subject of a current ISEC study.

The next challenge: can the space elevator survive the debris field in Earth orbit? The answer is coming up in the next newsletter – stay tuned.

Dennis Wright

Chief Architect’s Corner

by Pete Swan

Guidelines for Mega-Project Development

In the early days of space, a remarkable set of management guidelines surfaced to help lead the development of national space systems. As many of the circumstances are similar to the development of mega-projects such as “modern day space elevators”, there could be some lessons to be learned from a remarkable series of space successes. These fall under: (1) mega-projects (huge funding & significant development schedule), (2) nationally significant development such as leadership in space infrastructure, and (3) requiring embryonic technical approaches. These guidelines worked and were refined by Lee Battle, so they were called “Battles Laws.” A summary, from the view of this Chief Architect with today’s circumstances are:

+ Keep the program office small and quick-reacting at all costs.

+ Exercise extreme care in selecting people, then rely heavily on their personal abilities.

+ Make the greatest possible use of supporting organizations.

+ Cut out all unnecessary paperwork.

+ Control the sub-contractors by personal contact. Each person on your team has a particular set of contractor’s contracts.

+ Hit all flight and checkout failures hard. A fault uncorrected now will come back to haunt you.

+ Rely strongly on sub-contractor technical recommendations, once the contractor has given the problem sufficient effort.

+ Don’t over communicate with higher headquarters.

+ Don’t make a federal case out of it if your budget seems too low. These matters usually take care of themselves.

+ Don’t look back, history never repeats itself.

And of course: “Judge results. Let God determine luck or skill.”

As we move forward on Modern Day Space Elevator development, these Battle’s Laws could help us “stay on course” and effectively proceed down the path towards operations.

Winners for the Academic Challenge 2025

by Dr. Paul Phister, Chair, SEAC-25

ISEC/NSS is Proud to Announce the Winners of the Academic Challenge 2025

This year there were two challenges. One at the high school level and the other at the University level. Here is a short description of the winner’s papers. The papers can be located under the “Academic Challenge 2025” section of the ISEC website.

Challenge-1: High School

Development of a Settlement on the Space Elevator’s Earth Apex Anchor

1st Place: “SE Apex Anchor Station” by Lee Ee Hank
Reward: $2,000 USD
Video Link: https://youtu.be/ULHLexMBhbk

"Housing over 10,000 individuals in space is a very costly endeavor, even with the support of multiple space elevators at full operational capacity (FOC). This study assumed that there is a large and mature deep space industry that employs many people in deep space. Additionally, the study assumed that 6600 individuals are directly employed at the Anchor Station, working jobs such as a (space) shipbuilder, a port operations officer, a life support system engineer, a waitress, and many more. These individuals will stay at the Anchor Station for extended periods of time (but not permanently). Another 3300 + individuals are staying on the Anchor Station as space tourists, travelers taking a rest in their journeys between Earth and Outer Space, or relatives paying a visit. They will only take a short stay at the Anchor Station. In addition, this study assumed that there is multiple space elevators set up across the Solar System, such as on Luna and the various other moons in space, or on asteroids. It is also assumed that there is a flow of cargo and resources between the Earth Elevator and the other space elevators."

2nd Place: “Apex Settlement” by Martina Zagonel and Ginevra Gaviraghi
Reward: $1,000 USD
Video Link: https://youtu.be/Z7vYye4XOBU

"This challenge invites the design of an 'intermediate space settlement' on the Space Elevator’s Apex Anchor to accommodate over 10,000 individuals. This settlement will act as a 'waystation' for missions to the cosmos and other business activities specific to its space location and terrestrial connection. Key considerations include: Size and structure requirements: What dimensions and configurations are necessary? Optimal balance of functionality and sustainability: What is the best way to achieve this balance? Utilizing the Space Elevator's lift capabilities: How can it provide a 'Green Road to Space'?"

3rd Place: “Maglev Space Elevator” by Leo Shiina and Maiya Qiu
Reward: $500 USD
Video Link: https://youtu.be/hrUwmJe4R60

"The central proposal of this report is a magnetically driven space elevator. Currently, research on climbers is primarily focused on wheel-driven systems, but considering the wear and heat generated by friction with the tether, as well as the strain on the tether during emergency stops, we believe it is not the optimal method. Magnetic propulsion avoids direct contact with the tether, thereby avoiding these issues. Furthermore, by designing propulsion coils using lightweight, high-strength, and highly conductive crystalline graphene, we believe it will contribute to the realization of a maglev space elevator. Of course, many challenges remain, but we believe all of them can be solved in the near future."

Challenge-2: University

Development of a Space Settlement at the Earth-Moon L5 Point—Utilizing Earth’s Space Elevator

1st Place: “Team Celestial” by Muhir Kapoor
Reward: $2,000 USD
Video Link: https://youtu.be/xcGijZnxn4E

"The settlement will be located at an orbit around the Earth-Moon L5 Lagrange point, ensuring stability and minimum station-keeping requirements. The design is inspired by the Kalpana One and the O’Neill Cylinders. It will house a population of 20,000 people within four cylinders, each supporting up to 5,000 individuals."

2nd Place: “Presenting Nexus” by Saadhika Prakash, Jia Chadha, Siddh Tolia, and Anikait Gupta.
Reward: $1,000 USD
Video Link: https://youtu.be/pa_jyGT_I0o

"Nexus is located in the Lagrange 5 point between the Earth and the Moon. This Settlement will have a vertical central holding facility that connects to the space elevator. There will be a ring that surrounds it, facilitating transportation between the 'tori.' On this ring, there will be 10 tori, housing 17,000 people each. Opposite tori will rotate in opposite directions to prevent moment instability. Each 'tori' will be pressurized and have a tram to allow for internal transportation. Each 'tori' will have a tram that also runs to the pressurized central ring. Here, residents can travel between different 'tori' through the external transportation system."

3rd Place: "Space Habitat at L5 Point” by Akinari Ogawa, Yoshinao Kobayashi, and Ryo Kuzuno
Reward: $500 USD
Video Link: https://youtu.be/420ujLoqass

"This paper examines the feasibility of a new construction concept at the Earth Moon L5 point using a space elevator and discusses an efficient energy transferring model in order to realize a green road to space. Space settlement has been one of the major topics for the advancement of space exploration. Until now, it has been proposed to build space habitats at the L2 point just above the equator, but due to the instability of the mechanical structure and public safety issues for people living near the equator, it has not been feasible to build such structures in space. However, the L5point, which is expected to remain a stable balanced point for tens of thousands of years, has made this possibility larger. In addition to considering the construction and maintenance of appropriate space habitats through the application of space elevators, this study also focuses on the utilization of thermal energy to conclude that space elevators are a sustainable option to create a space settlement."

History Corner

by David Raitt
ISEC Chief Historian

Who influenced Whom?

In this day and age of influencers, it is interesting to speculate on whether anyone had an influence on anyone else when it came to early space elevator concepts.

A month or so ago, Adam Crowl contacted ISEC to mention a story written by Charles Fontenay about a Phobos “space elevator” that had appeared in ‘If - Worlds of Science Fiction’ in April 1956 (https://s3.us-west-1.wasabisys.com/luminist/SF/IF/IF_1956_04.pdf). Charles Louis Fontenay (17 March 1917 – 27 January 2007) was an American journalist and science fiction writer, born in Sao Paolo, Brazil, who wrote a large number of science fiction novels and short stories as his Wikipedia and other sources attest (https://sf-encyclopedia.com/entry/fontenay_charles_l). This particular story titled ‘Atom Drive’, is about a tug - an atomic power plant - towing a massive cargo and an accompanying passenger compartment. Initially in orbit around the Earth, the tug and its cargo were bound for Mars. In the course of its journey, a saboteur severed the two mile long cable attaching the tug to the cargo. What to do? Well, most of the cargo was 6,000 miles of cable intended to lay a television network between Martian cities. The cable was bound in flonite - a new fluorine compound strong enough to tow the whole cargo. However, there was nothing aboard the spaceship ship that would be able to cut off a length of it to act as the tow rope. After some thought and calculations, the cable’s end was shot down from Phobos to the Martian surface, the space plane was attached to it and hauled up to Phobos.

Since this story appeared before Yuri Artsutanov’s article in 1960, Adam Crowl believed this was the oldest reference to a Phobos cable system and speculated that perhaps both Artsutanov as well as Jerome Pearson might have been influenced by it.

Although Artsutanov describes Earth-to-orbit transportation using a cable system extending from geostationary orbit, and attached to a location on the Earth's equator, he probably didn’t see the story in English; Pearson would have been about 18 years old at the time and, if he was a sci-fi fan, he might have read it and it could possibly have prompted some of his ideas. Arthur C. Clarke was quite a bit older and already writing sci-fi stories, so he may also have read the tale or been aware of Fontenay’s works.

I have done a little checking and, so far as I can discover, neither Pearson nor Clarke refer to Fontenay’s novelette, nor does David Smitherman who covered tethers, (https://nss.org/wp-content/uploads/2000-Space-Elevator-NASA-CP210429.pdf) and neither does Weinstein in his 2003 paper on ‘Space colonization using space-elevators from Phobos’ (https://ntrs.nasa.gov/api/citations/20030065879/downloads/20030065879.pdf).

I think it is perhaps unlikely that they would have been influenced by Fontenay - although I must admit that Clarke did publish a novel in 1986 entitled ‘The Songs of Distant Earth’ which describes a kind of very strong cable that is used to pull massive blocks of ice from the surface up to a spaceship in orbit around a fictitious planet in order to repair its protective ice shield. The novel is based on Clarke’s much earlier novelette published in 1958 in which “the visitors had built a squat and heavily-braced monster of metal girders, housing some obscure mechanism, on a rocky headland overlooking the sea.” The idea was to harness the water from the sea - “A cone of water was rising from the sea, becoming taller and thinner with every second…the spinning tower of water was climbing swiftly up the sky, piercing the clouds like an arrow as it headed towards space…The water to rebuild the Magellan’s shield was on its way out into space, to be shaped and frozen by the other strange forces that these men had made their servants.” (https://s3.us-west-1.wasabisys.com/luminist/SF/IF/IF_1958_06.pdf.)

Adam Crowl points out that there are three versions of Clarke’s story - the original 1958 version using antigravity to create the waterspout lifting water to geosynchronous orbit; an outline script in the 1983 anthology ‘The Sentinel’, and the later 1986 novel - the latter two versions both use the term space elevator.

However, I do think it may be possible that Fontenay himself was influenced by the SF writings of Tsiolkovsky who was writing from 1895 on. In the ‘Call of the Cosmos’ (https://archive.org/details/tsiolkovsky-the-call-of-the-cosmos) Tsiolkovsky mentions Phobos briefly but wrote quite a lot about Vesta and its inhabitants (who move about like fish - and, it should be noted, a fish is a key element in Fontenay’s tale!). In another section on astronautics, Tsiolkovsky mentions rotation and gravity and notes "it is possible to dispense with a movable support and the throwing of objects (which leave us never to return), if attached to the dwelling by a rope or a cable. We can then push ourselves from it in the desired direction and fly away until the rope pulls us up short. Then, in order to return, we pull ourselves back by the rope to the dwelling.” This seems somewhat analogous to the winching up of the craft in Fontenay’s story! True, the main English translations of Tsiolkovsky’s works were published in 1960, but he was writing in Russian well before that, and probably some stories were available in English earlier, too. But who knows?

IF-Worlds-of-Science-Fiction

One of our Youngest Supporters 

by John Knapman & Ariana Rosser

At a recent conference in London organised by the British Interplanetary Society (BIS), Alex Rosser impressed us with his interest in space generally and space elevators in particular. He has also impressed his school.

His mother writes: “Alex was very busy in January doing multiple presentations about what he learnt at the BIS 'Beyond the Moon' Conference in November. He has given his presentations to each year group at his London Park School and a final presentation to the teachers. He had 10 minutes to summarise the Conference day which includes your Space Elevator project and it was his preferred choice during the questions session.”

His head teacher writes: “Alex impressed everyone with his knowledge of physics and passion for space. He also showed no fear in presenting a multitude of assemblies at school, even to the older Year 11 students.”

Alex Rosser Image 1

Photo Credit: Ariana Rosser

Alex Rosser Image 2

Photo Credit: Ariana Rosser

Tether Materials

by Adrian Nixon

How the Edges of Graphene Affect the Tensile Strength

Dear Reader, you will know from previous articles that graphene can be made as a monolayer (a one atom thin sheet of graphene) by the chemical vapour deposition (CVD) method. This involves passing methane gas over a flat metal surface at temperatures around 1000°C. The metal is usually copper or nickel and this acts as a catalyst allowing the hydrogen to separate from the carbon in methane. The metal helps the carbon atoms connect with one another and the one atom thin coating of graphene forms on the surface.

This is not the sort of experiment you can do at home. There are few places in the world with the equipment and expertise to do this. One of the most successful, working on graphene, is the Institute for Basic Science (IBS) Center for Multidimensional Carbon Materials (CMCM), located in Ulsan, in the Republic of Korea.

We also know that graphene can be made at large scale, in lengths of up to 1 kilometre [1]. However, testing the material is usually done at the micro and nano scales. The CMCM team has the capability to make and test single crystal graphene at centimetre scale and they have just published their latest results [2].

The team made single crystal graphene at the square centimetre scale in the laboratory. Single crystal in this context means a single molecule of graphene. This was achieved by carefully controlling the gas feedstock pressure and flow and temperature in the CVD furnace. The copper forming surface is also critically important. At the microscale normal copper foil contains multiple crystal domains that influence the formation of multiple crystal domains of graphene. The team annealed the copper by careful heating and cooling to merge the crystal domains into a single coherent surface.

This single crystal of copper enables the single crystal of graphene to form on the surface. The annealing also removed dissolved carbon from the copper and prevented multiple layers (adlayers) of graphene forming. Once the monolayer graphene had formed, the copper was removed from the CVD furnace and the ‘dog-bone’ shape for tensile testing stamped out in a 10mm x 2mm shape. Figure 1 shows the overview.

tensile-testing-graphene

Figure 1: Making tensile test samples of single crustal graphene

The stamping process was also finessed in this work. To understand why this was important, we need to appreciate the different types of edges in sheet graphene. These are zigzag, armchair, and chiral. Figure 2 shows the shapes of each.

graphene edges

Figure 2. Zigzag, Chiral and Armchair edges in graphene

The copper used in the CVD process contains microscopic marks made by the rolling process used to make the foil. The team knew that the edges in graphene are associated with the rolling marks. Graphene domains perpendicular to the rolling marks correspond to the zigzag edge and those parallel to the rolling marks correspond to the armchair edge of single crystal graphene. So, test samples can be made with different edges to study the effect on the tensile strength of the edge type.

The team now had the ‘dog bone’ samples stamped out with a great deal of control over the edge type being tested. The graphene was still on the copper foil. The metal was removed by etching leaving the graphene floating on the surface of the liquid. They had previously prepared samples of sheet polycarbonate 200nm thin. The team used a custom-made float transfer device to capture the graphene onto the polycarbonate film. This was then used in the tensile tester. The tensile tester applied a strain at one end with a displacement motor and the other end was anchored to a force sensor that measured the tensile strength.

The team found that the graphene failed due to cracks that start at the edges and propagate across the graphene sheet causing it to separate. This meant that defects at the edges profoundly affect the tensile strength of the sheet of graphene.

The team also found that the edge types confer different strengths to the graphene:

graphene-edges-and-strength

The strongest edge is the zigzag type and was measured at 27 GPa. As a comparison ultra-strong carbon fibre has a tensile strength of 7 GPa [3].

Graphene has a theoretical maximum strength of 130 GPa. Even at 27 GPa, this work is an astonishing achievement. This is the strongest ever measurement of single crystal graphene (and any material) tested at centimetre scale. It paves the way for the manufacture and testing of ever larger samples of this superlative material.

This work focuses on just one atomic thin layer of graphene. A space elevator tether will be made from many thousands of layers of graphene. So, we need to understand what happens to the strength of graphene as we increase the number of layers. That, dear Reader, will be the subject of our next newsletter article.

References:

1. Nixon, A. (2021). 2021 August International Space Elevator Consortium Newsletter. [online] International Space Elevator Consortium. Available at: https://www.isec.org/space-elevator-newsletter-2021-august/#tether [Accessed 27 Feb. 2025].

2. Kundu, A., Jalali, S.K., Kim, M., Wang, M., Luo, D., Lee, S.H., Pugno, N.M., Seong, W.K. and Ruoff, R.S. (2024). The Mechanical Behavior of Macroscale Single-crystal Graphene. [online] arXiv.org. Available at: https://arxiv.org/abs/2411.01440 [Accessed 23 Feb. 2025].

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

Solar System Space Elevators

by Peter Robinson

Part 8: TITAN

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

Last time I discussed conceptual options for space elevators on Saturn’s moon Enceladus, concluding that to be a more feasible location than Saturn or any of the other lesser Saturnine moons. Here is my discussion of Titan.

1. INTRODUCTION

Titan is the largest moon in the Saturn system, the second largest moon in the solar system, and larger than Earth’s Moon and Mercury; see [1] for more. It is the only moon known to have an atmosphere denser than that of Earth and is the only other object in space with clear evidence of stable bodies of surface liquid.

Titan is thought to be a prebiotic environment rich in complex organic compounds with its surface in a deep freeze at −179°C (−290°F; 94K). It is currently understood that life cannot exist on the moon's frigid surface, but Titan seems to contain a global ocean beneath its ice shell with conditions potentially suitable for microbial life. This means ready access to and from the surface could be highly valuable for research and other purposes, as well as perhaps for resource extraction.

The thick atmosphere makes surface access far less simple than for a ‘normal’ moon with no atmosphere, with both landings and launches hazardous and fuel expensive. Oxygen, hydrogen, and methane (or other hydrocarbons) could be extracted from surface ice and the atmosphere for direct use as rocket propellant for launches, but all these processes would require significant power sources and processing equipment on the Titan surface.

Construction of a Space Elevator might therefore be an attractive proposition, reducing the surface infrastructure requirements whilst also minimising the risk of surface biological contamination.

Titan layers

Figure 1: Titan in visible light + surface make-up. Credit: NASA / Wikipedia

2. TITAN ELEVATOR CONCEPTS

A Titan space elevator would be an ‘L1’ type, extending from the surface sub-planetary point through the L1 point. Relevant parameters are:

Saturn Orbit Radius (semi-major axis) = 1,221,870 km

Saturn Orbital Period = 15.9 days

Titan Diameter = 5,149 km (1674 km more than Earth’s Moon)

Titan Surface Gravity = 0.138 g

Surface Atmospheric Pressure = 147 kPa (1.45 atm)

L1 Altitude = 49,450 km (88% of that of Earth’s Moon)

The precise position of the L1 gravity balance point varies slightly due to Titan’s orbit eccentricity (2.88%) and the influence of other moons, but its substantial altitude means that an elevator tether length might need to be 80,000 km or longer (see ‘Analysis’ below), more than that required for a Mars Elevator and similar to that of an Earth Elevator.

Configuration concepts include the following.

2.1 Concept 1: Conventional Ribbon

A conventional Space Elevator ribbon attached to the surface using wheeled powered climbers is unlikely to be practical in the foreseeable future due to potential high wind load forces on any ribbon wide enough to be climbed.

This problem was explored in detail for the Earth in the IAC paper presented by John Knapman and myself in Paris in 2022 [3]; the atmosphere of Titan is also known to possess ‘weather’ events. Figure 2 below compares the atmospheres of Titan and Earth.

Titan-and-Earth-atmospheres

Figure 2: Comparison of Titan and Earth Atmospheres. Credit: NASA (Public Domain)

Much more study is needed to establish wind speed profiles and other details of Titan’s atmosphere, and it is possible that intermittent wind loadings could result in similar or greater difficulties than would be seen on Earth. Weather events may be less severe than on Earth due to lower solar heat input, but this requires further study. The surface pressure is 45% more than at Earth’s sea level and the gas density may be four times higher due to the lower temperatures, these factors mean wind load forces may well be higher for any given wind velocity. The vertical extent of the Titan atmosphere is also far greater than that of Earth due to Titan’s lower gravity.

2.2 Concept 2: Hybrid

One solution to the ‘atmosphere problem’ described above is for a ‘conveyor belt’ or ‘cable car’ configuration. This would comprise of a cable ascending and descending through the atmosphere carrying payloads, looped around pulleys on the surface and at some powered ‘Winch Node’ above the atmosphere. The cable would be of circular cross-section and as thin as possible to minimise wind loads, dictating the use of some ultra-strong material such as GSL. (I proposed a similar concept in my last article for Enceladus, though for a different reason [4].) 

For Earth, the powered Winch Node would be on the surface, with a plain Pulley at 60-80 km altitude; for Titan, the powered pulley may best be above the atmosphere at perhaps 250km altitude, minimising the surface infrastructure and simplifying power supply options.

Figure 3 below shows a Cassini photograph of Titan’s atmosphere with my schematic of the lower part of the system. My calculations can be found in the ‘Analysis’ section below.

Titan-hybrid-concept

Figure 3: Hybrid Titan Concept. Cassini Photo (credit NASA) + Schematic (credit P. Robinson)

2.3 Climbers or No Climbers?

The conventional journey for interplanetary payloads to the top of the conveyor system would be for spacecraft to dock with a node on the tether at the zero-g L1 point. From there, the cargo would be transferred to a ‘climber’ to travel to the Winch Node above Titan’s atmosphere; the cargo would then be transferred to some ‘cable car’ on the conveyor cable for the descent to Titan’s surface.

This strategy requires reliable and durable climbers for the long 49,000+ km journey: even if those could average 200 km/hr the travel time would be over 10 days. The climbers would be complex vehicles, perhaps similar to those developed for Earth or Mars space elevators.

An alternative would be to avoid the need for any climbers by having the interplanetary spacecraft stay in a low Titan parking orbit. Cargo could then be carried directly to/from the Winch Node on a small transfer vehicle. This vehicle would be captured and berthed to the Node in the local 0.125g environment.

This ‘no climber’ strategy would require a heavier Winch Node for the systems needed to capture the visiting transfer vehicle, perhaps with moveable balance weights to keep the Node centre-of-gravity aligned with the tether and cables. This additional mass would increase the tension in the tether above the Node and require a heavier Apex Anchor counterweight, but the simplicity of not requiring climbers may well justify this arrangement.

3. ANALYSIS

My analysis used my spreadsheet method as described in earlier articles and my IAC-2022 paper [5].

For the concept shown in Figure 2 above, with Graphene Super Laminate (GSL) material and supporting an additional 5 tonne cable-car payload accelerating at 0.5g., the working stress would be around 15 GPa. This is much less than that required for an Earth Elevator but similar to the figure I proposed for a Mars Elevator [6].

If the Winch Node mass is increased to 100 tonnes (for the transfer vehicle berthing option), the peak tether stress would increase to 38 GPa if the tether size is unchanged, around half of the specific strength needed for an Earth Elevator.

Figure 4 below shows the effective gravity along the tether from Titan’s surface to the Apex, highlighting a difficulty associated with all L1-type elevator systems, especially those on a large moon at a relatively high orbit (such as Titan or Earth’s Moon). The effective gravity above the L1 point reduces very slowly with altitude, resulting in the Apex Anchor mass requirement being far higher than for an equivalent planetary centrifugal-type elevator.

Titan-effective-gravity

Figure 4: Effective Gravity above Titan Sub-planetary point. Analysis: P. Robinson

Inspection of the data behind the above figure shows that at 100,000km altitude the effective gravity acceleration towards Saturn (= Saturn’s gravity - centrifugal force – Titan’s gravity) is only 0.00062g, resulting in the need for a very high Apex Anchor mass.

Figure 5 below plots the Apex Anchor and total Tether masses for Anchor altitudes up to 105,000km with the tether configuration described above.

Titan-tether-and-anchor-masses

Figure 5: Titan Tether and Anchor Masses v Altitude. Analysis: P. Robinson

The tether mass of 910 tonnes at 80,000km (or 1130 tonnes at 100,000km) could be reduced if some tapers were to be introduced, but the assumed tether cross-sectional area is already low: 5 mm^2 might be achieved by a tether 0.5m wide and only 10 micron thick.

It may be of interest to note that this Anchor mass at 100,000km altitude would be an order of magnitude greater than what would be required for an Earth Centrifugal Elevator of similar length and with a similar lift capacity.

4. DISCUSSION

The high mass of the Apex Anchor effectively prohibits it from being shipped from Earth, but it could perhaps be assembled from ice or other material collected from elsewhere in the Saturn system. The rings are one obvious potential source of material but only extend to 80,000 km above Saturn’s surface, which is over one million km below the orbit of Titan. A closer source of mass might be from one of the many (over 100) smaller moons of Saturn by making use of asteroid mining techniques to gather the material, but clearly much survey work would be required.

Whatever the source of the Anchor material it could perhaps be collected by a swarm of small vehicles for amalgamation at the Titan L1 point prior to Elevator construction. The deployment of the Elevator would commence from the L1 point, with the Anchor gradually propelled away from Titan while the lower components were allowed to descend towards Titan, the tether tension gradually increasing. The high mass of the anchor would require significant thrusting during deployment, but perhaps the swarm of collection vehicles could be repurposed for this task.

All the above analysis and discussion concentrate on an Elevator through the Titan-Saturn L1 point, towards Saturn. A similar system could be built away from Saturn through the Titan-Saturn L2 point but would need to be either longer or have a more massive Apex Anchor.

5. CONCLUSIONS and SUMMARY

Access to Titan would benefit from a Space Elevator to facilitate access to and from the surface given the difficulties associated with the dense and active atmosphere. The atmosphere is likely to prohibit the use of a wide ribbon tether, preventing the use of wheeled climbers for that stage of the journey. One option to address this difficulty would be some form of conveyor or ‘cable car’ system from the upper atmosphere to the surface.

As Titan is tidally locked with Saturn, any elevator must be an ‘L1’ type, similar to that proposed for Earth’s Moon. Unfortunately, orbital mechanics mean the L1 point is a significant distance above Titan, with a shallow gravity gradient towards Saturn: these factors mean the elevator would be of a similar length to that proposed for Earth, but with a far more massive Apex Anchor.

Thus, a Titan Elevator is feasible and would be of great value for easy surface access, but construction would be more complex and costly than at many other solar system locations.

NEXT TIME: Uranus and Neptune

6. REFERENCES

[1] ‘Titan’ Wikipedia page: https://en.wikipedia.org/wiki/Titan_(moon)

[2] ‘Atmosphere of Titan’ Wikipedia page: https://en.wikipedia.org/wiki/Atmosphere_of_Titan

[3] “Space Elevator Tether Atmospheric Wind Loading and a Cable Lift Concept.” P. Robinson & J. Knapman, IAC2022 paper IAC-22,D4,3,15,x71307: https://www.isec.org/s/ISEC-2022-IAC-space-elevator-tether-atmospheric-wind-loading-paper.pdf

[4] ISEC February-2025 Newsletter, ‘Enceladus’: https://www.isec.org/space-elevator-newsletter-2025-february/#solarsystem

[4] “Space Elevator Climber Dynamics Analysis and Climb Frequency Optimisation.”, P. Robinson, IAC2022 paper IAC-22,D4,3,8,x68299: https://www.isec.org/s/ISEC-2022-IAC-space-elevator-climber-dynamics-paper.pdf

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

Social Media Update

LinkedIn remains our primary ‘business’ social media outlet, with the number of followers now approaching the slowly falling number on Facebook. If you’re not already following us on LinkedIn, here’s the link: https://www.linkedin.com/company/international-space-elevator-consortium/

For less formal discussion of Space Elevator news and related matters we are finding that the (just rediscovered) Reddit community is a useful forum. If you’re a Reddit user, join the conversations on r/spaceelevator.

We are seeing a small reduction in our following on X (Twitter). It is unclear how many of our followers there have migrated to the Bluesky platform, but our numbers there are growing slowly. Here’s a link: https://bsky.app/profile/isecdotorg.bsky.social

In contrast to Bluesky, we are seeing few interactions on the alternate short-message site, Mastodon, with stagnant growth. As discussed last month, we have discontinued activity on Threads, we may also discontinue Mastodon in the new few months. If you are a Mastodon user, please send a message there to encourage us to stay!

We will continue to review our activity on all platforms, 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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Over 800 references and citations with access to videos and articles/papers/studies and more! 

The Proceedings of the 2024 ISEC Conference in Chicago are now available. They're free to access and posted at https://www.isec.org/recent-publications . If you weren't able to attend, this is a good way to keep abreast of the latest space elevator developments.

Around the Web

Check out these previews of Japanese media that both feature a space elevator:

https://www.youtube.com/watch?v=e-E2RACD1xc
is of a Japanese movie called, "Previously Saved Version".

https://www.youtube.com/watch?v=S45MTxLCT_4
is a video game trailer based on an animation series turned into video game called Eureka Seven: Astral Ocean Hybrid Pack - TGS 2012.

Upcoming Events:

International Space Development Conference 2025
Sponsored by the National Space Society
https://www.isec.org/events/isdc2025
https://isdc.nss.org/
Thursday, June 19, through Sunday, June 22, 2025
Space Elevator Session TBD
Rosen Center, Orlando, FL, United States

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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