Editor's Note

Dear Fellow Space Elevator Enthusiast,

I have missed attending the Space Elevator Conference for the last three years! We had a virtual one, but it wasn't quite the same. This year's conference is being held in-person! I have already booked my flights and reserved my hotel room. I look forward to making those personal connections with my fellow enthusiasts and listening to the latest technology updates! If you would like to join me, scroll down to the Space Elevator Conference & Call for Proposals article below.

Sandee Schaeffer
Newsletter Editor

President's Corner

by Pete Swan

Unmatched Efficiency in Logistics Delivery

One of the questions asked most often is, "Why Space Elevators?" This question has puzzled me from the start as I know that Space Elevators will open up the heavens for humanity because it lifts off our planet with unmatched efficiencies. If our Space Elevator Community is to progress aggressively, we must all present concepts in a convincing way. We must believe in the strengths of Space Elevators and develop these concepts up front in our presentations and discussions. Our future is in the hands of Space Elevator enthusiasts. As such, I suggest the Leadership Approach starts with the concept that our transformational characteristics are powerful when we realize that the space elevator concept has an "Unmatched Efficiency" of liftoff to GEO and beyond. Essentially, rockets deliver a mere 2% of the launch mass to GEO altitude and 0.5% of the launch mass to the surface of the Moon. The efficiency of space elevators is in the range of 70% of liftoff mass arriving at its destination, with the remaining 30% surviving in the form of a reusable tether climber!

This capability of Space Elevators dwarfs advanced rockets rapidly because of its unmatched efficiency of delivery and environmentally friendly operations. Indeed, Space Elevators answer the conundrum of rockets which is the simple realization that the delivery of mass to its destination is an insignificant percentage of the mass on the launch pad. The glaring example is the delivery of half percent of the launch pad mass to the surface of the Moon for Apollo 11. It is up to 2% for delivery to GEO and woefully small for delivery to Mars' orbit.

rocket equation

My question is, "Why would you employ a methodology for delivery that only delivers less than one percent of the payload to your desired location?"

Pete

Space Elevator Conference

Our Space Elevator Conference is
Coming Together

And it’s only two months away! It will be held Saturday, August 12th and Sunday, August 13th, 2023.

This year’s conference is sponsored by both the International Space Elevator Consortium and Slalom, Inc., who will be hosting the event in the Aon Center Building, Chicago, Illinois, and will be co-chaired by Dan Gleeson and Karyn Gleeson.

Registration fee is tentatively set at $350 US per person. Included in the registration fee is:

+ Admission on Saturday August 12 and Sunday, August 13
+ Continental breakfast both days
+ Lunch both days

If you are interested in attending, please complete the interest form on our website: https://www.isec.org/events/isec2023. 

If you have any questions, please email Karyn.Gleeson@ISEC.org.  

The Call for Proposals for the
2023 ISEC conference are OPEN! 

Authors are invited to submit titles and abstracts of proposed papers and contribute to the latest research, knowledge, stimulating discussions, and exchange of ideas on space elevators for the Space Elevator Conference at this link: https://www.isec.org/call-for-proposals.

Please note that if your proposal is accepted, you must be a registered attendee and will be expected to present in person at the conference in Chicago.

Please submit your idea as soon as possible to be considered.

ISEC Mid-Year Interns Announced

Each year, ISEC accepts applications from students in their third or fourth year of university to participate in space elevator research. Three interns have been chosen and are excited to conduct research toward advancing Space Elevator knowledge. This year’s research should be a challenge for each of them. The focus will be “Space Elevators have transformational characteristics and will revolutionize the movement off-planet.”

The interns will be conducting research during the months of June through August on a topic agreed upon with their mentors and presenting their results in a paper and presentation.

The interns are:

Souvik Mukherjee, an engineering student at Vellore Institute of Technology, India. He has been active and fascinated with space exploration. He is also a leader for ISEC inside India and the National Space Society (Mumbai chapter).

Sofia Stahl, an aerospace engineering student at the University of California, Davis campus. She is very interested in materials sciences—especially as the study relates to Space Elevator Tethers.

Matthew DiCairano, an Astrophysics and Astronomy student at Florida Institute of Technology. He has long believed in space elevators and looks forward to the internship tied to coursework in the same field.

SpaceFlight Articles

by Pete Swan

SpaceFlight Features Articles by ISEC

It is always wonderful when the Space Elevator is featured in a major international magazine. The British Interplanetary Society (BIS) has a marvelous monthly global magazine called SpaceFlight covering space activities. Our History Chair, David Raitt, Ph.D., led the writing team that produced the articles shown below.

SpaceFlight magazine graphic

See the complete articles on our website at https://www.isec.org/spaceflight-june-2023.

One element of this process is that SpaceFlight requested a few articles to cover the modern-day space elevator and its associated parts. David led the effort to create, refine, and present the 2023 status of ISEC’s and Obayashi’s understanding of space elevators and their progress. This June issue is now available for purchase and will portray much of the remarkable progress on the project to date. I love the title "The Right Stuff" for the materials article. In addition, the Modern-Day Space Elevator, Galactic Harbours, and Cooperation and Competition articles are excellent portrayals of our efforts to move the architectural structure forward, while the Incredible Engineering article shows the Obayashi Corporation’s insights into their design.

It is wonderful to see these published. Thanks David!

Pete

Zotero

ISEC Members are reminded that they have access to our Zotero library of papers and other Space Elevator material. Did you know that Zotero can be linked to your Word Processor software (Mac or Windows) and will then automatically add citations to your paper?

To gain access, you need to register for a free Zotero account using the email address we have on file, then search for the ISEC group. You should have received an email from Zotero when we added your name to the list.

We will leave your name there for one year, pending, but your access will be indefinite after you register.

Please note: a subscription to this newsletter does NOT mean that you are an ISEC member. Follow this link to join: https://www.isec.org/membership.

Email peter.robinson@isec.org if you are a new member, would like to request upload permission, or need more details.

For more information about Zotero, see www.zotero.org.

Tether Materials

by Adrian Nixon, Board Member, ISEC

A Graphene Super Laminate Tether
may be More Resilient to Heating
than We Thought

In our last newsletter, we examined how the strength of a tether is affected by heat. This prompted a dialogue with some of the ISEC members, and as usual, you made me think more deeply about the way tether materials respond to heating. For this article, I shall focus on a tether made from graphene. More specifically, multi-layered graphene super laminate (GSL).

You will recall we found that the tensile strength decreases proportionately depending on how hot the material becomes. In the temperature range encountered in space around the Earth, this amounted to a 10% reduction in the strength of the candidate materials.

On to our dialogue…

Can we shadow or shade the tether to mitigate the heat effects?

Creating a sunshade for the tether probably means building some kind of tube inside of which the tether and the climber will operate. Making the tube will be a bigger challenge than making the tether.

Therefore, the answer would be a straightforward, No.

Does the tether heat and cool quickly?

To answer this, we need to know the speed with which the heat carriers operate. These heat carriers are waves or ripples in the graphene sheet (crystal lattice) and are called acoustic phonons (they are called acoustic because they move at the speed of sound in a material)

A Chinese Academy of Sciences team has done this work [2]. They found that "The corresponding sound velocities 12.9 to 19.9 km/s of graphene have been accessed."

This means that heat transfer in graphene is fast, at least 13 kilometres per second—so any heat generated won't hang around locally for very long and will be distributed to the edges and down the whole tether at high speed.

A tether made from GSL will heat and cool very quickly.

How long does it take to go from a weak tether to a strong tether?

Take away the heat, and the strength returns. We know from the work in China [2] that this will be instant.                           

How large is the heat transfer?

Graphene has one of the highest in-plane thermal conductivities of any material (5000 W/mK) [3]. The bigger the number, the better the heat transfer. To give you an idea of how good this is, the following table has some other materials for comparison.

tether materials table

Note that graphene has the highest in-plane thermal conductivity, the x/y direction. Graphene also has the lowest cross-plane thermal conductivity, nearly one thousand times less in the z direction. It is an anisotropic material with respect to its response to heat.

Graphene also has the highest melting point of any known material. The initial stages of melting of graphene are between 4000 K and 6000 K [6].

How localised is the heat transfer?

Graphene (and GSL) will want to move the heat away from the local area as fast as possible so the heat will be distributed across the material at very fast speeds.

The heat transfer is not localised at all.

What happens to the heat?

Heat is dissipated in two ways:

1. Conduction: Transfer of heat where the tether is in physical contact with gases, liquids, or solids. As we have seen from the thermal conductivity of graphene, the heat will spread rapidly through the tether material as vibrations in the crystal lattice (acoustic phonons). The heat will then be conducted away from the tether depending on what medium it is in contact with. When the tether is in the vacuum of space, heat energy transfer by conduction is not possible because there is nothing for the tether to be in physical contact with. This is when emissivity predominates.

2. Emissivity: This is the other way for heat energy to be dissipated. The energy is emitted as infrared radiation. The efficiency of the heat transfer is measured by its emissivity. A number close to one is more efficient than a smaller number. Laboratory tests heating multilayer graphene by electricity on a glass substrate have found emissivity values in the range from 0.91 to 0.72 when the number of graphene layers was changed from 1 to 12 [7]. This indicates a high level of heat transfer by emissivity for a tether made from graphene, as the heat will be contained in the outer layers of the material.

thermal conductivity and emissivity

Conclusion: The tether will be more heat resistant than we thought.

The dialogue with my ISEC colleagues made us realise that the exceptional thermal conductivity properties would mitigate the adverse effects of heat on the tensile strength of a tether made from two-dimensional materials. Heat is spread far and wide through the material at speeds of over 13 kilometres per second. Also, the anisotropic thermal conductivity makes heat percolate between graphene layers in GSL nearly one thousand times less than within each layer. This means a tether made from GSL will just heat up in the outer few layers while the inner structure is insulated by the layers on the outside.

A final thought: The academic results that show the loss of strength with heating contain an important assumption. The whole structure is heated at the same time. A graphene tether will only heat up in localised parts, and the heat will be rapidly spread and dissipated throughout the whole of the structure. This means a tether made from GSL will be far more resilient to heating than we originally thought.

My thanks go to Michael (Fitzer) Fitzgerald and Larry Bartoszek for improving the critical thinking of this topic.

References:

1. Zhang, Y.Y. and Gu, Y.T. (2013). Mechanical properties of graphene: Effects of layer number, temperature and isotope. Computational Materials Science, 71, pp.197–200. doi: https://doi.org/10.1016/j.commatsci.2013.01.032.

2. Cong, X., Li, Q.-Q., Zhang, X., Lin, M.-L., Wu, J.-B., Liu, X.-L., Venezuela, P. and Tan, P.-H. (2019). Probing the acoustic phonon dispersion and sound velocity of graphene by Raman spectroscopy. Carbon, 149, pp.19–24. doi: https://doi.org/10.1016/j.carbon.2019.04.006.

3. Anon (2010). Scientific Background on the Nobel Prize in Physics 2010 Graphene, compiled by the Class for Physics of the Royal Swedish Academy of Sciences. [online] Nobelprize.org, Sweden: Nobel Foundation, p.8. Available at: https://www.nobelprize.org/uploads/2018/06/advanced-physicsprize2010.pdf [Accessed 12 Jan. 2023].

4. Anon (n.d.). Nondestructive Evaluation Physics : Materials. [online] www.nde-ed.org. Available at: https://www.nde-ed.org/Physics/Materials/Physical_Chemical/ThermalConductivity.xhtml [Accessed 25 May 2023].

5. Ouyang, W., Qin, H., Urbakh, M. and Hod, O., 2020. Controllable Thermal Conductivity in Twisted Homogeneous Interfaces of Graphene and Hexagonal Boron Nitride. Nano Letters, 20(10), pp.7513-7518.

6. Ganz, E., Ganz, A.B., Yang, L.-M. and Dornfeld, M. (2017). The initial stages of melting of graphene between 4000 K and 6000 K. Physical Chemistry Chemical Physics, 19(5), pp.3756–3762. doi: https://doi.org/10.1039/c6cp06940a.

7. Kyung Woo Park, Lim Mikyung, Jung, H.-J. and Jae Nyoung Kim (2021). Thermal Radiative Properties of Multilayer Graphene/Glass Structure. The journal of the Korean Institute of Electrical and Electronic Material Engineers, 34(1), pp.27–32. doi: https://doi.org/10.4313/jkem.2021.34.1.27.

Around the Web

In the March newsletter, I provided a link to a video by Alejandro Forero. It seems that he has been busy because he has another video that he has made to represent his dream of how the space elevator might be built. This one is called “Space Elevator: Only up to GEO!!!”

https://www.youtube.com/watch?v=5otutgDhuK4&t=3s

Upcoming Events

Space Elevator Conference
Sponsored by the International Space Elevator Consortium and Slalom, Inc.
https://www.isec.org/events/isec2023
Saturday, August 12th and Sunday, August 13th, 2023
Downtown Chicago, Illinois, USA
Theme: “Permanent Space Access Transportation Infrastructure”

74th International Astronautical Congress
Sponsored by the International Astronautical Federation (IAF)
https://www.iafastro.org/events/iac/iac-2023/
Theme: “Global Challenges and Opportunities: Give Space a Chance”
Monday, October 2nd through Friday, October 6th, 2023
Baku, Azerbaijan

42nd International Space Development Conference
Sponsored by the National Space Society
https://isdc2024.nss.org/
Thursday, May 23rd through Sunday, May 26th, 2024
Los Angeles, California, USA

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

76th International Astronautical Congress
Sponsored by the International Astronautical Federation (IAF)
Monday, September 29th through Friday, October 3rd, 2025
Sydney, Australia

Contact Us:

You can find us on Facebook, Twitter, Flickr, LinkedIn, Instagram, YouTube, and Mastodon.

Our website is www.isec.org.

Support us:

Sign up to be a member at: https://www.isec.org/membership

You can also give directly using the “Donate” link at the bottom of our website page.

Does your place of employment do matching funds for donations or volunteer time through Benevity? If so, you can make ISEC your recipient. Our 501(c)(3) number is 80-0302896.