Editor’s Note

Our Media Mogul has submitted an article for this newsletter about ISEC’s presence on various platforms (see Social Media Updates below).

In it, he encourages you to sign up for LinkedIn if you haven’t yet. I admit that I was hesitant to join another platform. I primarily use Facebook, and it takes up enough of my time! I also didn’t feel that it would have any relevance to me as I do not have a job. I do spend a lot of time with my non-profit agencies (I work with a few others, besides ISEC) but I don’t have gainful employment. The members of the board and contributors to the newsletter would send me articles that were on LinkedIn, and I could only open them by forwarding them to my husband and asking him to open them for me on his profile. After a few years of doing this, I finally broke down and established an account. 

My unsolicited review: LinkedIn is what I wish Facebook was. Yes, there are ads, but they are far more relevant to my feed. Yes, there are suggestions for people to follow, but I can reject them just as I do with Facebook. I do receive suggestions for employment seminars and resume building even though I checked some box somewhere saying that I wasn’t looking for work, but I don’t receive solicitations for job applications.

If you were considering establishing an account, I’d say give it a go. If you weren’t considering one, I just want to help plant that idea to perhaps sprout in the future like it did for me.

Sandee Schaeffer
Newsletter Editor

Chief Architect’s Corner

by Pete Swan

The Green Road to Space is the Essence of
Developing Sustainable Space Operations 

The United Nations is spearheading a huge movement across the globe trying to improve the human condition by setting goals for development that lead to sustainable living. These 17 goals are comprehensive while trying to establish a better world.

The image shows the titles and illustrates the breadth of activities. However, the one I want to talk about is: #18 -- “Sustainability Development of Space.” If we look at history, we see that along the paths followed and roads/rail lines built, settlements and businesses grew rapidly, becoming cities and states. We see this historic action of building transportation avenues as an approach to creating and sustaining communities and we should look at space with a parallel view. When we establish permanent space access transportation infrastructures, the natural assumption is that massive growth will occur with the development of businesses, habitats, and settlements. Once those start growing, the sustainment of the facilities and improvement of life in the settlements will be remarkable. When we recognize that Modern-Day Space Elevators are no more than a huge transportation infrastructure, we can see that it will be the instrument for sustainability development across space. This Green Road to Space (one of the pillars of sustainability is environmental) will greatly enhance the human condition in space, on Earth, and into future worlds such as the Moon, asteroids, Mars, and elsewhere. As such:

The Green Road to Space is the essence of developing sustainable space operations.

Note: Hap Arnold is working within the NSS and the UN as our representative.

Definition of Space Sustainability -

“The long-term sustainability of outer space activities is defined as the ability to maintain the conduct of space activities indefinitely into the future in a manner that realizes the objectives of equitable access to the benefits of the exploration and use of outer space for peaceful purposes, in order to meet the needs of the present generations while preserving the outer space environment for future generations.” (Andrew Ross Wilson, Massimiliano Vasile, The space sustainability paradox, Journal of Cleaner Production, Volume 423, 15 Oct 23)

ISEC 2025 Mid-Year Interns Announcement

This year, ISEC will be 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.

As with past years, the selected students will each be awarded $599.00 (USD) through PayPal.

Research Topics for 2025:

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

Mentor: Dr. Pete Swan


2. Potential Tether Climber configurations to cover the following regions:

a. Earth's surface to 100Km

b. 100Km to GEO

c. GEO to Apex Anchor

Mentor: Dr. Paul Phister

 

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

Mentor: Dr. Paul Phister

 

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

a. Torque is proportional to the volume of the rotor/magnetic field of an electric motor.

b. How does the mass of the rotor vary with its volume?  Graphing the distribution of torques in commercially available motors versus rotor mass may identify theoretical limits to torque production.

c. Research Konigsegg’s hybrid axial/radial gap motor designs as a potential solution.

Mentor: Larry Bartoszek

 

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

a. Research a recirculation system for lubricants around the bearings.

b. Research the liquid cooling of the motors. The fluids used around the bearings are completely different from those used to cool the motors.  Both of these liquids have a maximum operating temperature of around 200C max.

c. Limiting the space radiator around the climber to 200C makes it very large.  The only way to reduce the area of this radiator is to make it hotter.

d. The goal is to design a heat exchanger/refrigeration system that keeps the circulating fluids at their desired low temperature but allows the space radiator/condenser to be as hot as possible.  Finding the right refrigeration circulation fluid is key to this design.  Estimating the mass and power required for this system is crucial feedback for the climber design.

Mentor: Larry Bartoszek

 

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

a. The volume of batteries shown in the conceptual design represents the theoretical volume of lithium-sulfur batteries that can deliver the full power required of the motor system for five minutes.

Mentor: Larry Bartoszek

 

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

a. These gearboxes may also be connected to the main bearing oil recirculation system. 

b. One of the issues is identifying very low vapor pressure oils compatible with vacuum use.

c. Another issue is to determine the maximum pressure differential that a rotating bearing seal can take before lubricant is forced out of the seal.  The seals shown in the climber conceptual design are normally used on Earth in components where there is no pressure differential between the inside and outside of the gearbox. 

d. The goal is to ensure that gearboxes on the climber do not leak significant amounts of lubricant during their travel.

e. Lubricant failure leads to mechanical component failure, which leads to disastrous climber failure.

Mentor: Larry Bartoszek

 

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

a. Determine how the shapes required for the space elevator’s climber may be manufactured.  Carbon fiber reinforced polymer (CFRP) fabrication differs from metal fabrication techniques and the shapes shown were originally designed for metal techniques.  Determining how the structural shape geometry needs to change to accommodate the different manufacturing techniques is critical feedback for climber design.

b. Research techniques for joining CFRP structures to other CFRP structures and also to metal structures.

c. Research how to minimize stress concentrations, especially at joints.

Mentor: Larry Bartoszek

 

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

Mentor: Depends on the Topic

 

The interns will be conducting research for the months of June through August on a topic agreed upon with their mentors and presenting their results in a research paper. We are also including, at the Masters and Doctorate level, research on any of the topics above. For the Master’s (Thesis) and Doctorate (Dissertation) Level, this will be their Chapter 1 (Hypothesis, approach, and Literature search) section of their research endeavor.

For 2025, the selected students will be able to:

1. Present their research paper (10-minute video) at ISEC’s Conference in September 2025.

2. Present their research paper (10-minute video) (if applicable) at NSS’s Space Settlement conference in November 2025.

Schedule for 2025 ISEC Intern Program:

1. Initial Submission of Proposals: 1 Dec 24

2. Potential research abstract: 15 Apr 25

3. Selection of Researchers: 1 May 25

4. Group Discussion on Null-Hypothesis testing (if required): 15 May 25

5. Conduct Research and Present Paper: 15 May 25 - 15 Aug 25

6. Periodic meetings (zoom) for status/questions: 15 May 25 - 15 Aug 25

7. Present Research (Video) at ISEC Conference: Sep 25

8. Present Research (Video) at NSS Conference: Nov 25

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

Paul Phister, Ph.D., P.E.

Chair, ISEC Intern Program

Tether Materials

by Adrian Nixon

A Prediction: Graphene Will be Found on the Planet Mercury

Dear reader, the famous physicist Niels Bohr wryly observed that, “Prediction is very difficult, especially if it is about the future”. So why am I making one of these difficult forecasts? Well, partly for fun, partly curiosity driven, and partly because this has a high probability of being true based on what we already know.

I’ll take you through my thinking and see if you agree…

Mercury

Composite image of the planet Mercury taken by NASA's MESSENGER spacecraft. Image credit: NASA.

So far there are no reports of graphene discovered on Mercury. This planet is mysterious in many ways. For example, it is the only other rocky planet apart from Earth to have a magnetic field and believed to have an outsized core of liquid iron. No one is quite sure how the planet formed and what is its composition. We do know that the surface is much darker than expected [1].

The MESSENGER mission discovered the reason for the darker surface being attributed to Mercury being bombarded with carbon rich meteorites [2]. As Mercury rotates in front of the Sun, the intense heat boils away lighter compounds leaving behind forms of carbon from soot (amorphous carbon) to graphite and nanodiamonds [3].

The presence of graphite gives us the first clue to why we believe graphene will be found on Mercury. You will know that graphite is a material made of countless billions of microscopic stacks of layers of carbon. Each of these individual layers is graphene. The same carbon containing meteorites have pummelled the surface of our Moon and graphite has been discovered there too. A few weeks ago, China announced that samples of the Moon brought back to Earth by the Chang’e-5 Lunar mission contained graphite and graphene [4].

You can see that what works on the Moon will also work on Mercury. So why hasn’t graphene already been found on the planet? The answer is because no one has been looking for it.

The Europeans have launched the BepiColombo mission to orbit Mercury (launched October 2018, arriving at Mercury November 2026). Will the BepiColombo Mission find graphene? Er, probably not. The orbital components of the spacecraft are miracles of modern engineering. These include the MERTIS radiometer and thermal infrared spectrometer, the MIXS Imaging X-ray spectrometer and MGNS gamma-ray and neutron spectrometer. They have been designed to probe the geology and chemical composition of Mercury’s surface [1]. What they do not include is a Raman spectrometer. This is the instrument capable of detecting graphene directly.

Even if the spacecraft could contain a Raman spectrometer, it would be very difficult to make it work from orbit. The technology works by illuminating a surface with laser light of a very precise wavelength, then filtering out that same wavelength in the reflected light. One in a million photons has its wavelength altered and returned to the detector where it carries the information about the surface it interacted with. A Raman spectrometer would work best on a lander rather than speeding by hundreds of kilometres away. The lander was called the Mercury Surface Element (MSE) of the BepiColombo mission. It fell victim to budgetary constraints and didn’t make the journey [5].

It doesn’t seem like we’ll get the predicted announcement that graphene has been found on Mercury. Yet there might just be a chance if some strange, brilliant sparkles are discovered on the surface of the planet.

A recent paper in the journal nature, has reevaluated data from previous missions to Mercury and proposes that carbon dissolved in the liquid iron core of the planet will form a huge diamond bearing region at the core-mantle boundary as the carbon crystallises out of solution [6].

Diamonds will not be the source of mysterious sparkle that we speculate. Natural diamond looks like lumps of mucky misshapen glass. It is the skill of the jeweller that creates the sparkle.

This crystallisation will not only form diamond. There is another form of carbon that can be made by this process; large-area-single-crystals of multilayered graphene are also made by the crystallisation of carbon from molten iron. Once formed, this material will last forever. We know this indestructible material as Graphene Super Laminate (GSL) [7]. GSL looks like a silvery metallic substance and forms crystals with flat surfaces that reflect light in the visible and infrared regions of the electromagnetic spectrum [8]. These GSL crystals are quite different from graphite and once at the surface will act like highly reflective mirrors making the surface sparkle and glitter in reflected light.

The BepiColombo mission has far more sophisticated instruments than previous missions. It just might be sensitive and lucky enough to spot strange sparkles of reflected light on the surface of the planet. The mission scientists may think this is diamond, then rule that out as their instruments tell them the material looks more like graphite. Eventually, they may realise they have found huge single crystals of large-area-multilayer-graphene. You and I know this as GSL, the material that will make the space elevator tether.

Time will tell whether graphene will have been found on the surface of the planet Mercury. In the meantime, I hope you can understand my confidence in making a difficult prediction.

References:

1. Anon (2020). Top Five Mercury mysteries that BepiColombo will solve. [online] www.esa.int. Available at: https://www.esa.int/Science_Exploration/Space_Science/BepiColombo/Top_Five_Mercury_mysteries_that_BepiColombo_will_solve.

2. Perkins, S. (2015). Why is Mercury so dark? Science. [online] 30 Mar. Available at: https://www.science.org/content/article/why-mercury-so-dark [Accessed 25 Sep. 2024].

3. Syal, M.B., Schultz, P.H. and Riner, M.A. (2015). Darkening of Mercury’s surface by cometary carbon. Nature Geoscience, 8(5), pp.352–356. doi:https://doi.org/10.1038/ngeo2397.

4. Nixon. A., 2024. Graphene found in samples from the Moon. Nixene Journal, 8(7), p.15

5. Coradini, M. (2018). NASA - NSSDCA - Spacecraft - Details. [online] nssdc.gsfc.nasa.gov. Available at: https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=2018-080A.

6. Xu, Y., Lin, Y., Wu, P., Namur, O., Zhang, Y. and Charlier, B. (2024). A diamond-bearing core-mantle boundary on Mercury. Nature Communications, [online] 15(1). doi:https://doi.org/10.1038/s41467-024-49305-x

7. Nixon, A. (2022). 2022 August International Space Elevator Consortium Newsletter. [online] International Space Elevator Consortium. Available at: https://www.isec.org/space-elevator-newsletter-2022-august/#tether [Accessed 26 Sep. 2024]

8. Nixon. A., 2021. The graphene and graphite landscape: Indications of unexplored territory. Nixene Journal, 5(10), pp.9-20

History Corner

by David Raitt

The History of Space Elevators as Compiled by ChatGPT

For this month’s newsletter, I thought I would see what ChatGPT had to say about the history of space elevators. There has been a large expansion of texts on which the system has learned, and there have been more than a few recent articles and reports on the space elevator. My first question was, “what is the history of space elevators?” and the unedited answer is given below. The answer also provided a couple of suggestions to follow up: one was on lunar space elevators and the other was, “how close are we to building a space elevator?” Clicking on that gave an answer and suggested asking, “are space elevators practical?” That too suggested asking other questions. I will incorporate some of these answers in another History Corner.

 

The History of Space Elevators

A space elevator is a conceptual structure designed to transport materials from Earth directly into space. The idea has evolved significantly over time, combining early scientific imagination with modern technological advancements. Here's a breakdown of the history of space elevators:

1. Early Concepts (19th Century)

The roots of the space elevator idea can be traced back to the 19th century:

+ Konstantin Tsiolkovsky (1895): The first conceptual leap toward a space elevator was made by Russian scientist Konstantin Tsiolkovsky. He was inspired by the Eiffel Tower and envisioned a tower reaching from Earth's surface into geostationary orbit (about 35,786 km above Earth). Tsiolkovsky's vision involved a structure supported by compressive forces like a giant tower. However, this idea was impractical due to the immense material challenges.

2. From Towers to Tethers (Mid-20th Century) The concept of a space elevator began to shift away from building a physical tower toward using tethers:

+ Yuri Artsutanov (1960): In the early 1960s, Russian engineer Yuri Artsutanov proposed a more refined version of Tsiolkovsky's idea. He suggested lowering a cable from a satellite in geostationary orbit down to Earth. This method would allow the structure to remain balanced under tension. Artsutanov’s paper, published in a popular science magazine, laid the groundwork for future space elevator concepts, but it didn't gain much attention in the West at the time.

+ Isaac Asimov (1966): In science fiction, author Isaac Asimov explored the idea of space elevators in his short story “The Gods Themselves". Asimov described a massive structure that could reach into space.

3. Modern Theoretical Development (Late 20th Century) The idea of space elevators gained more serious attention during the space age as materials science advanced:

+ Jerome Pearson (1975): American engineer Jerome Pearson independently revisited the space elevator concept and published detailed studies about it. Pearson’s work focused on the physics of a tether, providing more rigorous mathematical modeling of the forces involved. He suggested that a space elevator could be built using a counterweight beyond geostationary orbit, balancing the centrifugal forces.

+ Arthur C. Clarke (1979): Science fiction again played a role in popularizing the space elevator idea. Arthur C. Clarke’s novel "The Fountains of Paradise" described the construction of a space elevator in great detail. Clarke drew inspiration from both Tsiolkovsky and Pearson's work, and his novel brought the concept to mainstream attention.

4. Material Science and the Rise of Carbon Nanotubes (1990s-2000s) One of the biggest technical challenges for building a space elevator is finding materials strong enough to withstand the immense tension forces.

+ Carbon Nanotubes (1991): The discovery of carbon nanotubes in the early 1990s by Sumio Iijima offered a potential solution. These materials are incredibly lightweight and strong, with theoretical tensile strengths that would make a space elevator cable feasible. However, large-scale production and practical use of carbon nanotubes are still in development.

+ NASA Institute for Advanced Concepts (NIAC, 2000): In 2000, NASA’s NIAC funded studies exploring the feasibility of a space elevator. Bradley Edwards, a physicist, published a comprehensive study on the technology. Edwards’ research suggested that the elevator could be built within 50 years at a cost of about $10 billion using modern technology, provided suitable materials could be developed.

5. Challenges and Current Research (2010s-Present) While the space elevator concept has not yet been realized, it continues to inspire research and innovation in space infrastructure:

+ Advances in Materials Science: Although carbon nanotubes remain a potential candidate, other materials like graphene have also shown promise. Research into manufacturing long, strong, and lightweight materials continues.

+ Technological Competitions: Space organizations and universities have held competitions to design and build prototype climbers for space elevators. For example, NASA's Space Elevator Games ran between 2005 and 2009, encouraging innovation in tether and climber technology.

+ Japanese Research (2018): Japan has been active in space elevator research. In 2018, Shizuoka University launched an experiment to test mini-elevator climbers in space, marking a step toward understanding the mechanics of such a system in microgravity.

6. Future Prospects:

+ Theoretical proposals for space elevators continue to be explored, with ideas such as using lunar space elevators (where the reduced gravity of the Moon would make construction easier) or starting with an anchor in the ocean.

+ Companies like Obayashi Corporation (a major Japanese construction firm) have announced plans to develop a space elevator by 2050, though these remain speculative without breakthroughs in materials.

7. Major Challenges:

+ Material Strength: Current materials, even the strongest, are not yet sufficient to withstand the stress over such vast distances.

+ Orbital Debris: Space junk poses a risk to any tether structure, as even a small impact could sever the cable.

+ Cost and Construction Feasibility: While more cost-effective than rockets in the long run, building a space elevator would require significant upfront investment.

8. Conclusion:

The space elevator has evolved from early theoretical musings into a serious subject of scientific research. While there are still many hurdles to overcome -- especially in terms of materials and safety -- advancements in technology may make it a reality in the coming decades.

Solar System Space Elevators

by Peter Robinson

Part 4: Mars (2)

This is the second part of the fourth article of the “Solar System Space Elevators” series.

Earlier articles covered Mercury & Venus, the Asteroids, and the Moon. The first half of this "Mars" article described several concepts, including a "long" Mars Elevator option extending past the orbits of moons Phobos and Deimos.

In this second half I discuss my preferred "short" option of a Space Elevator extending to an Apex Anchor below the orbit of Deimos. An important background is the Areostationary Mars Orbit (AMO) altitude of 17031.45 km. This is the equivalent to Earth’s Geostationary Earth Orbit (GEO) altitude.

1. CONCEPT

The "short" Mars Elevator variant was described in my 2017 ‘Solar System Space Elevators’ BIS presentation and by other researchers.

One strategy to avoid a Mars Elevator tether impacting Phobos is to position the ‘Mars Port’ surface connection a few hundred km from the Mars equator, thus deflecting the tether sufficiently to avoid the near-equatorial orbit of Phobos. My preferred alternative is to rely on dynamic control of the tether motion.

The orbit of Deimos is some 3000 km above AMO, allowing a relatively heavy Apex Anchor to be located below Deimos avoiding the need for any evasion strategies.

Figure 1 below depicts the ‘short elevator’ option.

Figure 1: scale view of Mars and a ‘Short’ Elevator. Credit: Wikipedia and P. Robinson

In this article I will concentrate on the design and analysis of a system with sufficient capacity to carry some limited payload whilst also perhaps acting as a technology demonstrator for Earth systems.

2. DESIGN

I selected the following design parameters:

 + Tether Length at maximum strain (“Apex Anchor” Altitude) = 20,000 km, around 100km below Deimos orbit.

+ Mars Surface (“Mars Port”) tether tension = 37.1 kN for a tether supporting no climbers. This is the weight of 10 tonnes mass at Mars equatorial gravity and enables climbers of 5 tonne mass with some residual retention force. With supported climbers the peak tension in the tether would be controlled by the Port RIRO (Reel-In-Reel-Out) winch system, but I will not address RIRO operation or system dynamics in this summary.

+ The tether is tapered to minimise mass, with the cross-sectional area defined by the taper equation originally described in Pearson’s 1975 paper [1].

The equation defines the area at any altitude as a proportion of the area at the synchronous altitude (AMO, GEO, …) dependent on planet gravity & rotation, tether stress and tether material density, yielding constant stress at all altitudes with no additional supported weights. The maximum area is at the synchronous altitude, adjusted to yield an area at the planet surface defined by the tether stress and chosen retention force.

The key parameter required for a tether design is the working stress. A figure of 88 GPa has been used for Graphene Super Laminate (GSL) material in earlier analysis of an Earth Elevator, but the lower Mars gravity means that such a high value is not essential.

3. ANALYSIS

3.1 TETHER

I used a variant of my spreadsheet technique [see ref 2] to calculate the taper profile for a range of working stress values.

Figure 2 below shows the tether area against altitude for a range of working stress values with GSL material, including the assumed Earth Elevator stress (88 GPa).

Figure 2: Mars Tether Area v Altitude v Working Stress. Analysis: P. Robinson

The fixed surface retention force means the area at the base is inversely proportional to the working stress. The lower working stress values result in higher taper ratios and hence far greater AMO areas, in turn leading to a considerable increase in the total tether mass (up from 23 tonnes at 88 GPa to 388 tonnes at 15 GPa).

Figure 3 below shows more details from this analysis, plus analysis results for one of the strongest existing composite materials, Zylon. (See the earlier ‘Moon’ article in this series for discussion of this material [3]).

Figure 3: Effect of working stress on Taper Ratio and system masses. Analysis: P. Robinson

One key observation from the above is the high tether mass (2353 tonnes) stressed at the full Zylon UTS (Ultimate Tensile Stress), meaning no operational safety margin. A more practical stress of 50% of the UTS means even higher taper ratios and even less feasible masses for the tether (60,252 t) and anchor (205,680 t). The conclusion must be that a material significantly stronger than Zylon is essential for a Mars Elevator.

The data table shows that a specific stress of 6.6 MYuri (GSL density at 15 GPa) is a feasible initial option for a Mars Elevator, requiring a tether mass within the capacity of only a few heavy-lift spacecraft currently under development. I can speculate that GSL manufactured using an early production process might not safely be used at the forecast stress of 88 GPa (38.9 MYuri) but could perhaps operate at 15 GPa. A Mars Elevator built using such material might be a valuable technology demonstrator before material production processes improve enough to achieve the working strength needed for an Earth Elevator.

Early tethers would be shipped from the Earth, but the more massive Apex Anchor could be sourced locally: Deimos regolith could be mined and transferred to some suitable vessel. Simulations of deployment scenarios suggest that all system components would start at AMO, the Apex Anchor mass, then raised to the final altitude close to Deimos orbit whilst balancing other components being lowered to the Mars surface.

3.2 CLIMBERS

The above analysis assumes a single 5-tonne climber on the tether at the Mars surface. The effective weight of an ascending climber falls as gravity falls and centrifugal force increases, eventually becoming zero at AMO as shown in Figure 4 below (g = 1 Earth Gravity).

Figure 4: Effective Gravity along ‘Short’ Mars Elevator tether. Analysis: P. Robinson

The effective gravity directly yields the climber drive power requirement along the tether, given that Power = Force * Velocity. In this case, the force is the climber weight and the velocity is the speed along the tether. Figure 5 below shows the specific power (kW/tonne) for an arbitrary climber speed of 200 km/hr.

Figure 5: Specific Climber Power along ‘Short’ Mars Elevator tether. Analysis: P. Robinson.

As with the Earth Elevator, the cost (financial and mass) of power and motor systems means it is best not to attempt to reach the very highest climb velocity at the lowest altitudes. The optimum climb power can be found using trade-off analysis as discussed at length in my 2022 IAC paper [2].

A maximum power of 4 MW for a 20 tonne Earth climber (200 kW/t) has been assumed in some earlier studies, but I suggest 100 kW/t is an appropriate value for Mars. The lower Mars gravity means that less power is needed, but this exact figure means that an Earth solar-powered climber design* could be usefully tested on a Mars Elevator, given that Mars solation is 50% that of Earth.

*NOTE: an on-going ISEC Study is investigating power beaming alternatives to solar power, but cost and support infrastructure requirements mean that solar power could well be the simplest initial choice for Mars.

A power of 100kW/t leads to a Mars surface departure speed of 97.7 km/hr, reaching 200 km/hr at 1520km altitude after 13.5 hrs. For a solar-powered climber the climb would continue for another three hours to 2100 km (for a dawn start at Mars Equinox) until the start of a 5.2-hour night. (The night duration falls with altitude as the apparent size of Mars falls, I must credit John Knapman for his night duration algorithm.) During the second day the climber would reach 6300 km, at which point the second night of 2.8 hrs would start. Eventually AMO would be reached at 102.4 hrs elapsed time (91 hrs climbing).

As climber(s) ascend the tether stress could be held constant using the RIRO system to adjust the surface retention force to minimise longitudinal dynamic effects. Additional climbers can be launched before the first reaches AMO, perhaps daily. With RIRO control the stress distribution might be as shown in Figure 6 below. (NOTE: My analysis is simple steady-state, confirmation using a dynamic analysis tool is essential.)

Figure 6: Tether Stress at dawn v climber departure options. Analysis P. Robinson.

This shows the tether stress (a) with a single climber at the surface of Mars (b) with the climber positioned after one day of climbing (c) with multiple daily solar-powered climbers at the start of each day. In each case the RIRO system is used to yield the same peak stress. Each additional climber leads to a step change in stress, with the step reducing with altitude as the climber weight drops. The surface retention force falls as more climber weight is supported by the tether, but the initial design choice of 5000kg excess weight (18.5 kN) allows some surface retention force even with four daily climbers supported.

This is a complex topic which could be explored in more detail for Mars, but this would be a full technical paper. The topic is covered extensively for Earth in my 2022 IAC paper [2].

Climbers descending from AMO to Mars have a negative power requirement, the negative of that shown in Figure 5 above. This means the descending “climbers” will need brakes and some power dissipation system (probably thermal radiators). Radiators would be larger than those required to solely dissipate excess motor energy, as discussed for Earth descending elevators in my 2023 IAC paper [4].

3. CONCLUSIONS and SUMMARY

The two parts of this “Mars Elevator" article describe several potential tether configurations for Mars and its moons, all of which have their merits. As with any Space Elevator system, the key factor that would lead to such a “mega-project” moving forward would be economic demand: there would have to be significant potential traffic on the Elevator to justify the cost of construction and operation. At present the descent to the Mars surface (that has been called “seven minutes of terror”) is the most challenging, though it remains to be seen if this would be resolved by large aero-braking spacecraft capable of a propulsive landing (such as the SpaceX Starship).

Another potential Mars Elevator use case is the raising of material from the surface, but the lower gravity and option for using refuelled spacecraft means the mass to be raised would have to be substantial.

A shorter-term Mars Elevator use case might be as development support for the Earth Elevator. Any Earth Elevator mega-project will have many preliminary stages, and most formal processes require a small-scale demonstrator system. A Mars Elevator might be suitable to demonstrate tether deployment strategies, durability, dynamic control, and climber operation, gaining valuable experience in the space environment prior to the massive task of deploying the Earth Elevator.

The above represents my personal views, I am sure the Newsletter Editor would welcome articles from other Mars Elevator advocates.

Peter Robinson

NEXT TIME: Jupiter’s Moons!

REFERENCES

[1] “The orbital tower: a spacecraft launcher using the Earth’s rotational energy”, J. Pearson, 1975 Acta Astronautica Vol. 2. pp. 785-799, https://linkinghub.elsevier.com/retrieve/pii/0094576575900211

[2] “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

[3] ISEC August-2024 Newsletter, https://www.isec.org/space-elevator-newsletter-2024-august

[4] “The Space Elevator Payload Journey Beyond GEO: Climber Concept and Options.”, P. Robinson, IAC2023 paper IAC-23,D4,3,11,x76283 : https://www.isec.org/s/ISEC-2023-IAC-space-elevator-payloads-beyond-GEO-paper.pdf

Social Media Update

We recently reached a milestone on our LinkedIn page, passing 2000 followers at the start of October 2024 and now (October 10th) with 2010 followers.

LinkedIn remains our primary social media, appearing to be the best forum for technology and science matters. If you're reading this and do NOT follow us there, please do so, following this link: https://www.linkedin.com/company/international-space-elevator-consortium/. If you don't have a LinkedIn account, please reconsider; it is NOT just about finding employment!

The plot shows that our follower count on Facebook and X are static, and we notice that when we do post on those platforms, we receive very few 'likes'. Should we reconsider our engagement there? If you think so, or if you would like to help us manage those accounts, please leave a comment on our most recent post.

We will continue with Instagram, though we cannot often find suitable images.

Our follower count on Threads is growing slowly, and we will also continue there for the time being: if you're not familiar with Threads, it's a messaging system similar to X managed by Meta, and appears to be attracting some who are not happy with the climate on X.

As always, whichever social media platform you use, please 'like', re-post and/or comment on any ISEC posts that you find of interest. All engagements result in posts being seen by more people, and spreading the word about Space Elevators is what we're trying to do!

ISEC Media Mogul

Editor's Remarks: Thank you to Peter Robinson for providing the above graphic!

Writer’s Circle

The space elevator appears in the second book of the Marauding Stars series, Leviathan Dives by Wells Carroll.  

Leviathan Dives

Leviathan Dives was released October 1. 

Kali Rises, the first in the series, was released in February. Leviathan picks up where Kali left off.

Kali Rises

You can find Kali Rises here: https://www.amazon.com/dp/1963833007 for the hardback, but that'll lead you to the eBook and trade paperback as well.

Leviathan Dives is here: https://www.amazon.com/dp/B0DJ31TGLF for the eBook, and that will lead you to the hardback and trade paperback as well.

Around the Web

Watch this "reel" from Japan describing the future possibility of a space elevator becoming a reality and encouraging discussion in the comments.

https://www.instagram.com/reel/C_yjw9vylfa/?igsh=MTc4MmM1YmI2Ng==

Steven Lyth tells us that graphene has now reached a 20-year milestone and points out that, while we still do not yet have our space elevator, other changes have been implemented:

https://theconversation.com/graphene-at-20-still-no-sign-of-the-promised-space-elevator-but-heres-how-this-wonder-material-is-quietly-changing-the-world-239223

Upcoming Events

75th International Astronautical Congress
Sponsored by the International Astronautical Federation (IAF)
https://www.iafastro.org/events/iac/international-astronautical-congress-2024/
Theme: “Responsible Space for Sustainability”
Monday, October 14th, through Friday, October 18th, 2024
Milan, Italy

21st Reinventing Space Conference
Sponsored by the British Interplanetary Society
https://www.bis-space.com/reinventingspace/
Theme: “The Commercial Revolution”
Monday, November 11th, through Wednesday, November 13, 2024
Royal Aeronautical Society, London, England

Xploration Conference and Expo
By Spaceport Norway
https://www.spaceport-norway.no/
Tuesday, November 12th, through Wednesday, November 13th, 2024
Oslo Event Hub, Oslo, Norway

IPSPACE 2024
https://iaaspace.org/event/international-symposium-on-the-peaceful-use-of-space-technology-health-2024/
Theme: Peaceful Use of Space Technology - Health
Tuesday, December 3rd, through Thursday, December 6th, 2024
Hainan, China

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

Contact Us:

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