What is a Space Elevator?
A space elevator is a device designed to transport people and objects into and out of space. It is also known as an orbital lift, star ladder or space bridge. The component of a space elevator is a cable anchored to a surface and then extending into space. It is usually depicted in science fiction.
The concept of building a space elevator is a long-standing futurist dream. If a space elevator was built, the process of transporting people and goods from Earth to orbit and back again would be much easier. It would also be safer.
However, building a space elevator from carbon nanotubes is a daunting task. For starters, the material needs to be strong. A single atom out of place can weaken the whole tube. That’s why it’s important to consider the defect density of the nanotubes when building a space elevator.
Another factor is the length of the cable. The tether must be sturdy enough to hold up in the wind, gravity, and the motion of payloads. An upper section of the cable has to account for the centrifugal force. This could mean a longer section at the bottom and a thinner section at the top.
In theory, it should be possible to build a space elevator with carbon nanotubes. However, it will require drastic improvements to the manufacturing process. While there are still challenges, the material has great potential.
Carbon nanotubes are very strong. Their atomic structure gives them tensile strength that can be as high as 100 GPa. They can be used for racing bikes, computer components, and biomedical devices.
However, they are extremely difficult to manufacture. To make a meter-long nanotube, it would take eleven days. As a result, a Space Elevator will be years away.
In the meantime, researchers are still working on finding ways to improve the production of carbon nanotubes. One method is to place shorter nanotubes inside a polymer matrix. Currently, these polymers don’t bond well to the carbon nanotubes.
Apparent gravitational field
The apparent gravitational field of an elevator is a fancy way of saying, “the net force of gravity applied to objects attached to the cable”. The cable exerts an external force, and is supported at both ends by a counterweight.
A space elevator is a concept that would allow regular interplanetary travel. The idea is to attach a cable to the equator of a planet, and to climb or descend down it.
Several planets have been considered for such a system. In the novel Red Mars by Kim Stanley Robinson, colonists build a space elevator on Mars. Several designs have been proposed, including a cable and base station.
In addition to gravity, the space elevator also experiences a centrifugal force, which opposes less gravity. This helps to keep the cable taut.
An object that is thrown away from the cable would deflect westward along the cable. It would follow this trajectory until it reaches its destination.
Aside from gravity, the upward centrifugal force of the Earth’s rotation would also help. The upward centrifugal force would be greater than the downward gravitational force, resulting in a hyperbolic excess velocity.
Another important component is the normal force. It is not as strong as the gravitational force, but it’s still a big deal.
For the astronauts of the Space Shuttle, the normal force is about 98 N. That’s not bad, but it doesn’t compare to the apparent weight of a 150 pound person on the ground.
As for the space elevator, the most important part is funding. A well designed and funded space elevator would enable regular interplanetary travel. If the politicians of the world could get their act together, we might just be able to send humans into space on a regular basis.
Apparent gravity minus centrifugal force
A space elevator is a proposed method for transporting people and payloads from one place to another. It is usually described as a rotating cable that has a counterweight at its upper end.
The idea of building a space elevator was first conceived by Russian scientist Konstantin Tsiolkovsky. He studied the Eiffel Tower and was inspired to think of a similar structure for the space station.
In the 1960s, no money was available for a space station. A more feasible scenario was for a spacecraft to accelerate and simulate gravity.
To create artificial gravity inside a spinning object, the standard formula is a=((2p)/T)2)R. This means that the normal force must be less than or equal to the gravity.
One way to calculate the net force is to subtract the centrifugal force from the gravitational force. For example, if the Earth were not rotating, the upward and downward forces would be equivalent. However, as the Earth rotates, the centrifugal force on the counterweight increases.
Using Newton’s second law of motion, we can predict the varying contact forces on an elevator ride. If the forces are in balance at all times, the normal force will be greater than the gravity.
We can also see that an upward force of 100 N “wins” a tug of war between a normal force of 100 N and an upward force of 10 N. Similarly, an upward force of 50 N “wins” a tug of battle against a normal force of 5 N.
While the concept of an elevator was initially considered, it was not until 1966 that four American engineers reworked the concept. Their report, entitled “Space Elevators,” was published in the magazine Science.
Vibrations and wobble
Space elevators are a convenient means of reaching geostationary orbit. However, they have some serious issues with cable movement. These include angle related vibrations and wobble.
The concept of a space elevator originated with Russian physicist Konstantin Tsiolkovsky. His plan for a free-standing tower to geostationary orbit was inspired by the Eiffel Tower in Paris. He also proposed a structure to support weight from below.
While most designs use a climber, there are many others that use moving cables. Some designs call for a base station or a tether to hold the whole system to the surface of Earth.
A tether swing can boost the velocity of a spacecraft exiting the elevator. This can also result in an end-point far from the intended orbit.
Angle related vibrations are more noticeable when the cable is moving uphill, while shuddering is more prominent on accelerating. Angle related vibrations usually vanish when the gas is let off or the spool is tilted into neutral.
Space elevators could be constructed on asteroids or on the moon. But the materials needed to construct the elevator would be different on these planets.
One of the most promising materials is carbon nanotubes. These tiny tubes are a few inches long and a nanometer wide. They are also touted as a wonder material. It will take time to develop these materials, however.
Another potential issue with the cable is its tendency to vibrate under solar wind stresses. This can shake the cable into space debris or satellite traffic.
There are also many non-technical issues that can pose problems for a space elevator. For example, a terrorist attack might be a huge blow to the space elevator. In addition, environmentalists may have concerns.
Cost of a space elevator
The cost of a space elevator is no joke. You’re going to need to put billions of dollars into research and development to make it happen.
A space elevator construction will require a very long cable to be able to support all of the weight. This cable will need to be very strong. It will also need to be able to withstand the harsh conditions of space.
The NIAC, or NASA Institute for Advanced Concepts, has funded several studies into the feasibility and cost of a space elevator. They have found that it could cost between $4 and $400 billion.
Fortunately, this doesn’t mean it will be built anytime soon. It could be several decades away. However, new technologies have been developed that promise to make this dream a reality.
In the meantime, a lunar space elevator could help send payloads into space. These payloads could include satellites, GPS systems, and other technologies.
During the course of a space elevator’s lifetime, it could carry over 40,000 pounds of cargo at a time. That would be a lot of cargo.
If you were to build a space elevator, you would have to consider some important factors, such as how long it would take to build and how it would be protected from acts of terrorism. Additionally, you would have to keep the cables strong enough to withstand re-entry.
Finally, you’ll need to consider how much fuel you’ll need to launch it. Space shuttles cost about $10,000 per pound. Considering the fact that you’d be sending a 200-pound man into space, this would be a significant expenditure.
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