Looking At Space Elevators Through The Lens of Physics

The first time I discovered the idea of Space Elevators, I was fascinated. It showed people effortlessly ascending into space like they were taking a routine elevator ride to the penthouse. My mind was buzzing with questions, my imagination captured by the possibilities. But as much as I was intrigued, I was also skeptical. I have always been a fan of ambitious, bold, and innovative ideas, and this one was no exception. But that’s just me — I’m always the voice of reason in a sea of grandiose ideas. I refuse to be a downer, but I can’t help but examine the feasibility from a physics perspective.

The concept of space elevators

The concept of a Space Elevator has been around for over a century, first proposed by Russian scientist Konstantin Tsiolkovsky in 1895. It wasn’t until the 1960s that the idea started to gain traction, thanks to the work of American engineer and futurist Jerome Pearson.

It is a futuristic way to get to space that’s still in the development phase. Imagine a long, super strong cable reaching from the ground to space, with a counterweight on the other end to keep it in place. You would have a special vehicle, called a climber, traveling up and down the cable, taking you to space just like getting on an elevator.

The reason why this is seen as a big deal is because getting to space currently requires a lot of fuel and is expensive. With a space elevator, you could save all that energy and money since the only power you would need is to get the climber up the cable.

NASA and JAXA (the Japanese space agency) are among the organizations working to make the Space Elevator a reality. Private companies like LiftPort and Obayashi Corporation are also in the mix, trying to tackle the many challenges of building a space elevator.

Now put on your PHYSICS GLASSES!

Tension in the cable

The cable of a space elevator is a crucial component, as it must be able to support the weight of the vehicle and withstand the forces acting upon it, such as wind, gravitational pull, and atmospheric drag. The cable works by resisting the forces that cause the structure to collapse or tip over. To do this, the cable must be under constant tension, which means there must be a continuous force pulling on it from both ends. Tension must be maintained in the cable to ensure stability, which requires careful calculation of its mass, length, and strength.

For example, if the cable is too light, it may not be able to hold the tension required to keep it stable. On the other hand, if the cable is too heavy, it may become too difficult to transport and launch into space. Additionally, the cable’s strength must be sufficient to resist breaking under the tension and any other forces acting upon it.

Orbital mechanics

Orbital mechanics refers to the study of the motion of objects in space, including satellites, spacecraft, and celestial bodies. It involves using mathematical models and physical laws to understand the motion and behavior of objects in orbit.

In the case of a space elevator, the structure must be placed in a stable geostationary orbit. This means that the space elevator must remain stationary relative to the Earth, appearing to stay in the same position in the sky.

To achieve this, a precise understanding of orbital mechanics is required. The space elevator cable must be placed in an orbit that is precisely calculated to counteract the effects of the Earth’s gravitational field on the cable. This is essential to ensure the cable remains stable and does not drift away from its intended orbit.

Additionally, the effects of other factors, such as atmospheric drag, the pull of other celestial bodies, and the impact of space debris, must also be considered when calculating the cable’s orbit.

Cable strength and materials

The cable must support its weight and resist bending and breaking under the strain of gravitational pull. It must also be able to withstand the effects of wind, earthquakes, and other environmental factors that could cause it to vibrate or twist. In addition, the cable must be strong enough to support the weight of vehicles traveling along it and any payloads.

Carbon nanotubes and other advanced materials, such as graphene and composites, are being explored as potential solutions due to their strength and resistance to damage. The exact materials and design for a space elevator are yet to be determined.

Apparent gravitational field

The space elevator must be placed at a specific point in the Earth’s gravitational field where the gravitational pull is balanced by the centrifugal force of the Earth’s rotation. This is known as the geostationary orbit, approximately 36,000 kilometers above the Earth’s surface. The concept of the apparent gravitational field helps to understand why this location is ideal for a space elevator, as it provides a stable platform.

Environmental factors

The space elevator must withstand the harsh conditions of space, including high levels of radiation, extreme temperature fluctuations, and micrometeoroid impacts. The cable must be protected from the potential damage caused by space debris and micrometeoroids. This requires the development of effective shielding or other protective measures.

Energy requirements

Energy requirements are a crucial aspect in the design and operation of a space elevator. For the space elevator to function as intended, it must be powered by enough energy to lift vehicles, payload up the cable, and keep it stable. This energy is also used to counteract any gravitational or centrifugal forces that might cause the cable to become unstable. This energy source could be solar, nuclear, or any other energy generation system capable of providing the necessary power. The amount of energy required will depend on the size and design of the space elevator, as well as the type of vehicles and payloads that will be transported along it.

The space elevator concept proposes various strategies for powering the climber, including wireless energy transfer through laser power beaming, storing energy within the climber using high energy density sources, and using solar power after the first 40 km of the climb. Wireless energy transfer via laser power beaming is considered the most feasible option and requires megawatt-powered lasers, adaptive mirrors, and a photovoltaic array on the climber. Efficiency of the climber design is crucial as unused energy must be re-radiated. A Japanese professor has suggested a second cable and the conductivity of carbon nanotubes as another option. — Wikipedia

Dynamic stability

The space elevator must maintain stability under various conditions, including the Earth’s changing gravitational field and the cable’s motion.

In conclusion, space elevators are a fascinating idea that could revolutionize how we access space. With advancements in materials science and a deeper understanding of the physics involved, it’s exciting to think that we could one day see these towering structures reaching all the way to the stars. Until then, we’ll have to keep researching and calculating!