Space Elevator: A Futuristic Application of Carbon Nanotubes

The dream of easy and cost-effective access to space has fueled the imaginations of scientists, engineers, and space enthusiasts for decades. NASA, in collaboration with other space agencies and private entities, is embarking on an ambitious project to construct a space elevator—an engineering marvel that could revolutionize space travel. 

At the heart of this endeavor lies the use of Carbon Nanotubes (CNTs), a revolutionary material with incredible strength and lightness. Explore Nanografi's cutting-edge carbon nanotube products, leveraging the strength and lightness essential for the future of space exploration.

Introduction

Today, the only system for space exploration and transmission is rockets. No successful alternative that would offer lower costs, ease of operation, or better results is currently realized. However, at the beginning of the space age, 60s, and 70s, an innovative alternative was proposed: the space elevator. In this article, we will delve into the concept of a space elevator, explore the unique properties of CNTs, discuss NASA's involvement, and analyze the challenges and potential benefits of such a groundbreaking project.

What is Space Elevator?

A space elevator is a towering structure designed to transport payloads from the Earth's surface to space using a long, strong tether. Unlike conventional rocket launches, a space elevator relies on a balance of gravitational and centrifugal forces to lift payloads into orbit. The concept was first introduced by Russian scientist Konstantin Tsiolkovsky in 1895 and has since captured the imagination of scientists and science fiction writers alike. 

This innovative transportation idea would revolutionize the transport and connection between Earth and space by providing easier, safer, faster, and more economic access to space. However, this idea was left behind because of the lack of suitable cable material. The long carrier cable must be built from strong yet light material for the construction of the space elevator. This is why until the discovery of carbon nanotubes (CNTs), the idea of a space elevator was merely science fiction.

Figure 1. Concept of the space elevator.

Advantages of a Space Elevator 

Cost Efficiency: One of the primary advantages of a space elevator is the potential for significantly reducing the cost of space travel. Traditional rocket launches are expensive and resource-intensive, making space exploration financially prohibitive for many endeavors.

Environmental Impact: Launching rockets into space generates substantial environmental impact due to the burning of fossil fuels and the disposal of rocket stages. A space elevator could offer a greener alternative with minimal environmental consequences.

Regular Access to Space: With a fully operational space elevator, access to space could become routine and predictable. This would open up new opportunities for scientific research, commercial ventures, and even space tourism.

The Role of Carbon Nanotubes (CNTs)

Carbon Nanotubes (CNTs) are cylindrical structures composed of carbon atoms arranged in a hexagonal lattice. These nanotubes exhibit extraordinary mechanical, electrical, and thermal properties, making them a promising material for various applications, including space elevator construction.

For the space elevator applications, the tensile strength and density of CNTs are the most important characteristics. The tensile strength of CNTs has been theorized as ≈150 GPa which is superior to steel at 5 GPa. Furthermore, the density of CNTs is 1300 kg/m³ almost six times lower than that of steel. Furthermore, the unique electrical properties of CNTs allow the detection of any atomic deformation within the cable structure rapidly. Therefore, the breakage of the CNT tether can be detected almost immediately and can be repaired before any serious accident. 

The studies on CNTs show that a CNT based cable can provide the required strength-to-weight ratio. Theoretically, the strength of CNTs is about three times the strength needed for the construction of the space elevator cable. But practically, CNTs can provide only two-third of needed strength. Due to several different factors such as structural defects and external effects, the practical strength of CNTs cannot reach the theorized values. The strength of a real, thus defective, carbon nanotube based space elevator mega cable is expected to be reduced by a factor of at least ≈70% with respect to the theoretical strength of a carbon nanotube and reach an approximate strength of 45 GPa. Thus, the studies on optimizing the CNT mega cable structure are still in progress.

NASA's Involvement in the Project

NASA has expressed a keen interest in exploring the feasibility of a space elevator as a potential game-changer for space exploration. The agency views this concept as a futuristic yet viable solution to overcome the limitations of traditional rocket launches.

NASA has been investing in research and development related to space elevator technology, with a specific focus on the utilization of Carbon Nanotubes. Collaborating with experts in materials science, engineering, and physics, NASA aims to address the technical challenges associated with building and operating a space elevator.

Recognizing the enormity of the project, NASA has actively sought collaboration with international space agencies and private enterprises. The pooling of expertise, resources, and funding is crucial for turning the concept of a space elevator into a reality.

Figure 2. Illustration of a space elevator made of carbon nanotubes stretches from Earth to space.

What are the Challenges for Building a Space Elevator?

The studies on space elevator focus on several different issues apart from the practical strength of CNTs mega cable. The general concerns are about the micrometeorite impacts, spacecraft impacts, radiation damage, and effect of natural frequency and oscillations on the cable, deployment locations, risks of damaged cables, and malfunctioning climbers.

Micrometeorite Impact Concerns

One of the first concerns that come to mind is micrometeorites with dimensions of 1-5 cm. Due to meteoric effects; researchers have concluded that the optimum design of the cable would be ribbon-type which means one cross-sectional dimension of the cable is smaller than the other. Assuming that these meteorites are not scattered by the external parts of the space elevator, they can cause serious damage to cables with maximum dimensions of less than several centimeters. Hence, a bundled structure is suggested for the cable design. A bundled design gives the opportunity to repair the structure before irretrievable damage.

Space Debris and Avoidance Strategies

Even though space exploration has just started, we have already collected a considerable amount of junk at the low-Earth-orbit. This cloud of junk orbiting the Earth is called debris which includes meteors and leftover spacecraft parts from previous missions. The dimensions of objects in the debris can vary from 10 cm to several meters. One way to avoid damages by these objects is to incorporate tracking systems and movable anchors on Earth to try and circumvent collisions.

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Radiation Damage Resilience

The Earth’s radiation belt containing energetic electron and protons would create radiation damage on the CNT cable however; the studies show that radiation damage is not as destructive when compared to other environmental problems. CNT cable can survive Earth’s radiation for over 1000 years. Atomic oxygen content in the atmosphere causes more severe damage to the cable and requires durable coating applications for protection.

Natural Frequency and Oscillations

Natural frequency and oscillations caused by the gravitational force of the Sun and the Moon create stress on the cable. However; these problems can be avoided by the variations in counterweight location and the damping at the anchor.

Anchor Station Location and Optimization

An important problem which requires a detailed analysis and optimization is the choice of anchoring station on Earth. The location would affect the power transmission to climbers and the effect of extreme weather conditions on the cable. Anchor location should be on the equator otherwise a constant out-of-plane force on the cable and counterweight and an additional time-variant force when climbers are on the cable would be observed. The altitude of the station must be decided considering the absorption of microwaves for powering the climbers and the human operation conditions. Studies suggest a 5 km altitude can be suitable considering both factors. Avoiding the effects of extreme weather conditions such as lightning strikes, storms, and jet streams is tricky. These factors can severely damage the cable. Selecting an equatorial site avoids both the jet streams and cyclonic storms, however; the thread of lightning strikes remains. Heavy lightning frequencies can be avoided at higher altitudes or on ocean sites.

Potential Benefits of a Space Elevator

Revolutionizing Space Travel

The successful implementation of a space elevator could revolutionize the way humans and payloads are transported to space. Routine, cost-effective access to space would pave the way for unprecedented advancements in scientific research, resource exploration, and commercial activities.

Space Tourism and Commercial Opportunities

A fully operational space elevator could open up new frontiers in space tourism, allowing civilians to travel to space more affordably and safely. Additionally, commercial enterprises could benefit from reduced launch costs, leading to increased interest and investment in space-based industries.

Sustainable Space Exploration

By reducing the environmental impact of space launches, a space elevator aligns with the growing emphasis on sustainable space exploration. This shift could play a vital role in fostering international collaboration for the responsible and ethical use of space resources.

Conclusion

In conclusion, the concept of a space elevator built with Carbon Nanotubes represents a bold vision for the future of space exploration. NASA's involvement in this project underscores the agency's commitment to pushing the boundaries of human achievement. While significant challenges remain, the potential benefits, including cost efficiency, regular access to space, and sustainable exploration, make the pursuit of a space elevator a worthy endeavor. As technological advancements continue and international collaboration strengthens, the dream of an elevator to the stars may one day become a reality, ushering in a new era of human presence in space.

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References

A giant elevator could connect Earth to space using current technology, experts say - here’s how that might work. (n.d.). Retrieved March 4, 2024, from https://www.businessinsider.in/science/news/a-giant-elevator-could-connect-earth-to-space-using-current-technology-experts-say-heres-how-that-might-work/articleshow/71467258.cms

Ahmed, K., Avi, S. D., Tanvir, M. S., Rahman, M. M., Shufian, A., Sagor, M. M. I., & Farrok, O. (2019, September). Transportation in Between the Earth and Space by Using Carbon Nanotubes as the Elevator Cable. In 2019 5th International Conference on Advances in Electrical Engineering (ICAEE) (pp. 426-430). IEEE.

Analyzed: Carbon Nanotubes - Nanografi Nano Technology. (n.d.). Retrieved March 4, 2024, from https://nanografi.com/blog/analyzed-carbon-nanotubes/

Edwards, B. C. (2000). Design and deployment of a space elevator. Acta Astronautica, 47(10), 735-744.

Engineers Are Creating a Real Space Elevator. Can They Succeed? - Interesting Engineering. (n.d.). Retrieved March 4, 2024, from https://interestingengineering.com/innovation/can-engineers-create-a-real-space-elevator

Ishikawa, Y., Fuchita, Y., Hitomi, T., Inoue, Y., Karita, M., Hayashi, K., ... & Baba, N. (2019). Survivability of carbon nanotubes in space. Acta Astronautica, 165, 129-138.

Micrometeorite - Wikipedia. (n.d.). Retrieved March 4, 2024, from https://en.wikipedia.org/wiki/Micrometeorite

People Are Still Trying to Build a Space Elevator | Innovation| Smithsonian Magazine. (n.d.). Retrieved March 4, 2024, from https://www.smithsonianmag.com/innovation/people-are-still-trying-build-space-elevator-180957877/

Pugno, N. M. (2007). Space elevator: out of order?. Nano Today, 2(6), 44-47.

Pugno, N. M. (2007). The role of defects in the design of space elevator cable: from nanotube to megatube. Acta Materialia, 55(15), 5269-5279.

Space Elevators Are Less Sci-Fi Than You Think | Scientific American. (n.d.). Retrieved March 4, 2024, from https://www.scientificamerican.com/article/space-elevators-are-less-sci-fi-than-you-think/

Space elevator - Wikipedia. (n.d.). Retrieved March 4, 2024, from https://en.wikipedia.org/wiki/Space_elevator

The Best Way to Utilize Carbon Nanotubes in Industry with Potential Applications - Nanografi Nano Technology. (n.d.). Retrieved March 4, 2024, from https://nanografi.com/blog/the-best-way-to-utilize-carbon-nanotubes-in-industry-with-potential-applications/

Why Space Elevators? — International Space Elevator Consortium. (n.d.). Retrieved March 4, 2024, from https://www.isec.org/why-space-elevators

YAZICI, A. M. (2020). An Investigation on The Economic Feasibility of Space Elevator. Havacılık ve Uzay Çalışmaları Dergisi, 1(1), 33-47.