From Earth to moon
One giant leap for mankind
Jules Verne (1828–1905)
Works like ‘From the Earth to the Moon’, ‘20,000 Leagues Under the Sea’, or ‘Around the World in 80 Days’ make Jules Verne one of the earliest science fiction authors. ‘From the Earth to the Moon’ is considered the first science fiction novel in literary history.
Science Fiction Meets Reality
One hundred years before the first moon landing, Jules Verne wrote of a flight to Earth’s moon. In his science fiction novel, “From the Earth to the Moon”, the honorable gentlemen from the Baltimore Gun Club launch a manned projectile into space using a giant cannon. The actual moon landing took place in 1969 when a rocket brought three astronauts to the Moon. But could Jules Vernes’ idea of a cannon actually have worked? How realistic was his vision in 1865?
In order to answer this question, one must first consider two aspects in more detail: the escape velocity and the acceleration forces that affect the capsule.
A spaceship must reach the so-called escape velocity of 11.2 km per second in order to escape the Earth’s gravity. Could the Gun Club’s space gun achieve this muzzle velocity? The barrel (a vertical, cast-iron shaft) had a length of 274.3 m and the propellant for the 9t heavy aluminium projectile conisted of 191 tons of explosives (nitrocellulose). Under idealized, heavily simplified conditions, the literature has come to the conclusion that the cannon would have only managed an escape velocity of 3,00 m/s – far too little to be able to leave the Earth. The capsule and its passengers would have crashed back to the Earth before reaching space.
But problems emerge from another detail: With an acceleration of 0 to 11.2 hm/s over just 274 m, the occupants would have experienced G-forces more than 20,000 times that of Earth’s gravity (g). In comparison, untrained people will become unconscious when moving upwards at just 5 to 6g (the blood flows from the head towards the feet). The maximum value that trained astronauts in an Apollo capsule had to withstand when reentering the Earth’s atmosphere was 7 g, and up to 10 g in the Russian Soyuz capsule. This means that astronauts would not have have survived the launch. In order to reduce the accleration to a still bearable 20g, one would have to extend the acceleration path to 300 km.
Jules Verne – a brilliant visionary
Jules Verne correctly foresaw and illustated many aspects of modern space travel.
// The Tampa launchpad in Florida is almost at the same degree of latitude as Cape Canaveral. Both are rather close to the equator, which makes a launch easier.
// Vernes correctly described weightlessness: he and his contemporaries believed that this only existed for a short time, where the gravity of the Earth and the Moon cancel each other out. It was only discovered that this was not the case by Albert Einstein in 1907.
// Jules Verne knew that leaving the Earth is a matter of speed. At 12,000 yards per second (10.97 km/s), he was quite close to the actual escape velocity (11.2 km/s) for the times.
// Aluminium and nitrocellulose were the height of technolgy in 1865. Space travel today primarily uses high-tech materials.
// He also correctly foresaw water landings in the ocean when returing from space.
What actually happened on the flight to the moon?
The Apollo rockets were also launched vertically, but from launchpads LC-39A and LC-39B of the Kennedy Space Centers in Cape Canaveral in Florida – just 200 km from Jules Vernes’ launchpad in Tampa.
They were propelled by a series of jet engines that were composed of a thrust chamber and a noozle. In these jet engine thrust chambers, the rocket fuel RP-1 (Level 1) as well as hydrogen (Levels 2+3) are mixed with liquid oxygen and ignited. The combustion gas expands within the chamber ans escapes through narrow nozzles. The resulting thrust propels the rocket forward. When doing so, the launch is relatively slow. At level 1 cut-off, it flies at a mere 2.39 km/s. Only when it reaches the edge of the atmosphere does it accelerate to the third level, to its macimum speed (10.8 km/s). Air resistance is reduced (a factor that Jules Verne did not consider) and the G-forces on the astronauts sink to a manageable 3 to 4 g (which only acts upon the back due to the seated position).
After numerous test flights, the Apollo 11 launched on July 16, 1969. Four days later, on July 20 at 7:17 p.m. German time, the lunar module, the Eagle, landed on the surface of the Moon and said something that Jules Verne must have thought: “This is one small step for a man, one giant leap for mankind.”
