It’s Time We Left the Cradle
Konstantin Tsiolkovsky: A Visionary and the Grandfather of Modern Rocketry
I began the serialisation of “Orphans of Apollo” with a quote that has long resonated with me, from the man who is often hailed as the father of astronautics: Konstantin Tsiolkovsky.
“Earth is the cradle of humanity, but one cannot live in a cradle forever.”
This quote is more than just a poetic statement; it encapsulates the entire ethos of exploration. We should cherish Earth, protect it, and look back on it fondly, much like an adult reminisces about their childhood home. Yet, just as a child must grow and leave the comfort of the cradle, humanity, too, must eventually step beyond our home planet. Tsiolkovsky’s vision was not only profound but also profoundly inspiring. But who was this man who dared to dream so far beyond his time?
Born in 1857 in the Russian Empire, Tsiolkovsky’s early life was marked by hardship. At ten he contracted scarlet fever leaving him nearly deaf. Then, aged only thirteen, he lost his mother. His hearing difficulties meant he was not admitted to elementary school and became a reclusive home-schooled child.
But it was within this solitude that Tsiolkovsky’s genius began to bloom. I find it fascinating how many influential figures are self taught. Take for example, the Wright Brothers, Michael Faraday and Thomas Edison. It’s perhaps hard for us in the modern world to imagine what this isolation would be like. Even if physically isolated, for us it is easy to connect with others around the world. Tsiolkovsky once wrote a paper titled “Theory of Gases,” only to discover that his findings had already been made public twenty-five years earlier. Today, such a realisation would come with a simple search online prior to even beginning work.
Yet, Tsiolkovsky’s vision was never limited by the barriers of his time. He was a man of grand ideas, some of which might seem impractical to us today. Take, for instance, his obsession with all-metal airships. In an age when air travel was still in its infancy, Tsiolkovsky imagined a world where massive, rigid airships made of metal would dominate the skies. It was a concept as visionary as it was impractical—an interesting contradiction for a man whose other ideas would lay the groundwork for human space exploration.
One of Tsiolkovsky’s most fascinating ideas was the concept of the space elevator—a structure that, even today, sounds like science fiction. He envisioned a tower reaching from the surface of the Earth to geostationary orbit, allowing humans to travel into space without the need for rockets. While the technology to build such a structure remains beyond our current capabilities, the idea itself has inspired countless scientists, engineers and science fiction writers.
But perhaps Tsiolkovsky’s most enduring legacy is his development of the rocket equation and his work on the concept of the multistage rocket. These ideas are fundamental to modern rocketry and space travel. The rocket equation, or Tsiolkovsky’s equation, is a mathematical formula that describes the motion of vehicles that follow the principle of conservation of momentum. It is expressed as:
Where:
This equation is crucial because it quantifies the relationship between the velocity a rocket can achieve and the amount of propellant it carries. It highlights the challenges of space travel, where achieving higher speeds requires exponentially increasing amounts of fuel. Getting above the atmosphere is one thing, but to stay there you need velocity and lots of it. To remain in low Earth orbit, a spacecraft must reach a velocity of 7.8 kilometres per second or 17,500 miles per hour. To leave Earth's orbit, this is even higher.
To achieve significant increases in velocity, the rocket must carry a much larger amount of fuel compared to its payload. This is because the equation is logarithmic in nature—the velocity increase is proportional to the logarithm of the mass ratio, not the mass itself.
This exponential relationship poses a significant engineering challenge. To reach higher speeds, rockets need to carry more fuel. However, more fuel increases the rocket’s mass, which in turn requires even more fuel to propel that extra mass. This creates a compounding problem where achieving high velocities necessitates disproportionately large amounts of fuel. Hence the reason for multistage rockets. In a nutshell, this relationship is one of the principal reasons rocket science is hard.
Another critical factor in the rocket equation is the effective exhaust velocity. This value represents the speed at which exhaust gases are expelled from the rocket engine. Higher exhaust velocities are desirable because they lead to greater changes in the rocket’s velocity for the same amount of fuel. However, the exhaust velocity is limited by the chemical properties of the propellant and the design of the engine.
Improving the exhaust velocity can lead to more efficient rockets, which is why ongoing research into advanced propulsion technologies—such as ion drives and nuclear thermal propulsion—focuses on achieving higher exhaust velocities. These technologies could one day allow for more efficient space travel, enabling missions to more distant destinations within our solar system and beyond.
Interestingly, the rocket equation was independently derived by several other pioneers in rocketry. In 1813, British scientist William Moore arrived at a similar formulation in his work on artillery. American physicist Robert Goddard also independently derived the equation in 1912, while Hermann Oberth, a key figure in the German rocket program, did so in 1920.
Tsiolkovsky is rightly called the father of rocketry, and his influence can be traced through the generations, from his early musings to the rockets of today. After World War II, as Soviet search teams scoured Peenemünde where the V-2 rocket was developed, they discovered a book by Tsiolkovsky, filled with Wernher von Braun’s annotations. Von Braun of course went on to become the architect of the Apollo programme.
Perhaps Tsiolkovsky would be a little disappointed we are still to venture beyond the moon, but hopefully he would be pleased to see his photograph alongside that of Yuri Gagarin in the Russian section of the International Space Station.
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Orphans of Apollo - Start Here
From the ashes of forgotten space dreams, a new era of exploration begins.
The rocket equation makes space travel extremely hard. Yet, the goal of any species, including ours, in survival. We have no choice but to use our brains to find ways to make humanity multiplanetary.