Four Centuries of Space Travel
Have you ever wondered who invented the idea of space travel? In terms of practical reality, human spaceflight has only been around since the middle of the 20th century – but how about as a purely speculative concept? You might imagine it’s been kicking around forever, but that’s not the case. People couldn’t start thinking about space exploration until they’d got their heads round two even more basic ideas: that there might be earth-like worlds up there in the sky, and that it might be possible to reach them by mechanical rather than magical means. As obvious as these propositions seem today, they were revolutionary when first propounded by a young English clergyman named John Wilkins – arguably the “man who invented space travel”. It seems appropriate to look back on his work now, since he was born in 1614 – 400 years ago this year.
In 1640, at the age of 26, Wilkins wrote “A Discourse Concerning a New Planet”. This sounds like a mistake – or maybe a work of fiction – since history records no new planets discovered around that time. But the planet Wilkins is referring to is the Earth! The book’s subtitle is “Tending to prove that ‘tis probable our Earth is one of the Planets”.
What was Wilkins talking about? Of course the Earth is a planet – it’s the most thoroughly studied and documented planet of all! But no-one thought of the Earth as a planet in those days. The world “planet” was shorthand for aster planetes – Greek for “wandering star”. In those simpler times, a star was nothing more than a point of light in the night sky. A planet was a star that changed position relative to the other stars. It was nothing short of revolutionary to suggest that the Earth – a gigantic ball of rock with human beings crawling all over it – was simply another planet. Wilkins even felt the need to prefix his remarks with the warning that “the seeming novelty and singularity of this opinion can be no sufficient reason to prove it erroneous”.
If the Earth is just a planet, does that mean the other planets are just like the Earth? Wilkins thought it was highly likely. Telescopes – invented just thirty years earlier – had shown Mars and Jupiter to be globes like the Earth, with distinct surface features. Closer to home, the Moon was now known to have mountains, valleys and plains just like the Earth. The significance of this wasn’t lost on Wilkins. His first book, published in 1638, was called “The Discovery of a World in the Moon”. The work drew numerous parallels between the Earth and the Moon, going so far as to suggest (erroneously) that the Moon might harbor Earth-like oceans and an atmosphere… and even that “there may be inhabitants in this other world, but of what kind they are is uncertain”.
Strikingly, Wilkins wrote that “as their world is our Moon, so our world is their Moon”… anticipating the famous image taken by the Apollo astronauts of Earthrise over the lunar horizon. And Wilkins anticipated the Apollo missions in other ways, too. In 1640, he added a supplement to his “World in the Moon” book entitled “A Discourse Concerning the Probability of a Passage Thither”.
Wilkins wasn’t the first person to write about a journey to the Moon, but he was the first to give the subject a serious, “non-fiction” treatment. Previous authors had confined themselves to fiction, with their protagonists transported to the Moon by magical or supernatural means, or through some unlikely accident. In stark contrast, Wilkins addresses practical issues such as how to propel a “flying chariot” through the air, how it could escape from Earth’s gravity and how the crew would breathe in a rarefied atmosphere. He was aware that a vast distance needed to be traversed; his estimate of the journey time was 180 days, comparable to the longest sea journeys of his day.
The analogy of a long sea voyage was clearly something he had in mind. He says “We have not now any Drake or Columbus to undertake this voyage”… but then adds “Why may not succeeding times raise up some spirits as eminent for new attempts and strange inventions as any that were before them?” So it’s clear that he saw a trip to the Moon as something that lay in the future, although he remained confident “that ‘tis possible for some of our posterity to find out a conveyance to this other world, and if there be inhabitants there to have commerce with them.”
What makes John Wilkins so prescient is the mere fact that he gave practical thought to the possibilities of space flight. The actual thoughts he had are not so prescient, in hindsight. He believed the Earth’s gravity only extended for a few miles above the surface of the Earth, which was later shown to be incorrect. He also believed the air would be breathable, if thin, all the way to the Moon – again something we now know to be untrue. Yet his vision of a mechanical vehicle flying all the way to the Moon is still pretty remarkable, considering that he lived at a time when real-world transportation was limited to horse-drawn carriages and sailing ships.
Wilkins returned to the idea of flying chariots in a later book, “Mathematical Magic”, published in 1648. Arguably his best known work, this describes numerous mechanical contraptions – including submarines and perpetual motion machines as well as aircraft. Sadly the book doesn’t contain any illustrations of Wilkins’ flying chariots… but these land-based “horseless carriages” give an indication of his DaVinci-esque ingenuity.