I've been working on space elevators for almost 20 years. Although there are still challenges to overcome, we're getting closer to making them a reality. Space elevators are often dismissed as science fiction, but I believe they could become a reality within two or three decades. As an aerospace engineer and physics professor, I've always been fascinated by the idea of a cable stretching from Earth to space, allowing easy travel for people and cargo. Recently, researchers and I have made significant progress in refining designs and addressing the technical
questions surrounding space elevators.There are many compelling reasons to build a space elevator. The most obvious one is the significant energy and cost savings compared to using rockets to reach orbit. Another often overlooked reason is accessibility. Instead of "space missions," we would have "transits," making trips to space routine and mostly unaffected by weather conditions. Human transits would be safer than current methods, which involve considerable risk to astronauts' lives with each launch. A space elevator could act as a bridge to the entire solar system. Releasing a payload from the lower portion allows it to orbit Earth, while releasing it from the upper portion sends it into orbit around the sun, all without the need for fuel.
Although I might come across as an advocate for space elevators, I simply enjoy studying their mechanics. In a world with monumental problems, dreaming of such projects allows me to envision a scenario where we become responsible stewards of our planet.
My story begins in 2004, when I was a master's degree student seeking a thesis supervisor. I met with Professor Arun Misra, the leading space expert in McGill University's mechanical engineering department. I was more than a little intimidated. The conversation went something like this:
Me: What kind of research do you think I might do?
Misra: Have you ever heard of a space elevator?
Me: No. What is it?
Misra: Imagine a 100,000-kilometer-long cable extending from Earth's equator, fixed to a satellite at the far end. The system spins with the Earth. Climbers can scale the cable, transporting payloads and releasing them into space. I was thinking you might study the dynamics of this system.
Me: That sounds... hard.
Misra: Your work will not be hard. Building an actual space elevator here on Earth... that will be hard.
Fast forward a few years. I had recently published my master's thesis, "The Dynamics of a Space Elevator," and was working as an engineer in satellite design. While out one weekend, my friend introduced me to his buddy Colin as "the space elevator guy." My wife rolled her eyes. I explained to Colin how a space elevator could work.
Me: If you stood on the equator and looked up at a satellite in geosynchronous orbit (about 36,000 kilometers in altitude), it would appear fixed in space, rotating with the Earth because its speed is just right. Now, imagine the satellite drops a cable to Earth while simultaneously using fuel to ascend higher. The cable is anchored on Earth as the satellite reaches the perfect altitude, and the system rotates with the Earth. The cable becomes the track for mechanical climbers to scale, like trains on a vertical railroad, delivering payloads to space.
Colin: But what keeps the cable taut?
Me: A combination of gravitational and centrifugal forces, which vary along the cable's length. Below geosynchronous orbit, gravity wins, and above it, centrifugal forces win. The result is tension throughout, with the maximum at geosynchronous orbit.
Colin: It's Friday night. Use smaller words.
Me: We need a material with a specific strength about 50 times higher than steel to build it. In the meantime, a handful of us are pretending this problem will be solved and tackling other engineering aspects of space elevators while we wait.
Colin: Rad.
My wife and I ran into Colin again in 2014. "How is that space elevator going?" he asked. My wife's face said, "Please, no."
Colin: Why doesn't the whole cable get yanked down when a climber is loaded onto it at the bottom?
Me: When a climber is below GEO, near Earth, the tip of the cable moves down slightly, and the tension profile along the cable changes. The real issue is the portion of the cable between the climber and Earth experiences a drop in tension. If the tension drops to zero, the cable would lose its stability. It turns out a climber can have a maximum mass of about 1 percent of the total cable mass, which is still a lot because the cable is expected to be hundreds of tonnes.
Colin: How is that cable material coming along?
Me: That's not my specialty.
Colin: Get on it, man!
It is now 2022. I recently presented a summary of my nearly two decades of work on space elevators in a seminar at Vanier College, where I teach physics. During the Q&A session, a student asked:
Student 1: When will the material for building the elevator be ready?
Me: The synthesis of potentially suitable materials has progressed in recent years, but we're still at least 10 years away from having a material with the necessary properties that can be manufactured reasonably quickly and at a reasonable cost. It's not unusual for new technologies to await advancements in material science, and fortunately, materials research is ongoing for reasons unrelated to space elevators.
Student 2: It sounds really cool. But why should we build it?
Me: Rockets are an inefficient means of transportation. For a typical space mission, over 90 percent of the total mass on the launchpad is fuel. We need to replace this method with a greener, more efficient road to space.
NASA plans to get humans to Mars before 2040. While people might indeed walk on Mars before we have an operational space elevator, for this endeavor to be sustainable, we'll need infrastructure like a space elevator, and the sooner, the better.
Student 3: So, when do you think one will be built?
Me: Famed author and engineer Arthur C. Clarke once said, "Probably about 50 years after everyone quits laughing." A modern answer might be, "We'll know we're close when Elon Musk starts taking credit for it."
Today, I feel much like I did sitting nervously in Arun's office. This elegant pathway to space captures my imagination and fills me with hope.
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