Space will never be conquered! Sad, but true. Let me explain how I’ve reached this conclusion.
Planet Earth is big! The furthest you can travel from home across the Earth’s surface is about 20 000 km (any further and you’re on the way home again). How long would it take to walk this? Assuming you can walk on water and land at a steady 5km/h for 12 hours a day, what do you think the answer is? Walking from side of the Earth takes 333 days. Imagine you’re a multi-billionaire and have your own Concorde. It will take you nearly nine hours to fly that distance. Spreading across the Earth and making it our own were easy; early humans wandered out of Africa about a hundred thousand years ago, now we’re everywhere!
The Moon is far away! If you rise from Earth you’ll have to cross about 380 000 km before you reach the Moon. Your Concorde will fly you there nonstop in just under a week (and yes, I know that jet planes can’t operate in space, this is an imaginary Concorde). Hope the inflight catering is good!
The Sun is far away! Travelling 150 million km from Earth to the Sun by Concorde will take you more than seven and half years.
The Solar System is big too! There isn’t really a line in space that everyone agrees marks the edge of the Solar System, but let’s assume that Eris, the most distant known dwarf planet, is the last stop before you leave the Sun’s neighbourhood. On average it is 10 billion km from the Sun. Imagine you’re a multi-trillionaire and have bought your own exact copy of NASA’s New Horizons Pluto probe. For the record, New Horizons is the fastest spaceship ever built (by Earthlings anyway, if you know differently please me know) It is travelling at 58 000km/h with respect to Earth (more than 25 times the speed of Concorde), launched in 2006, it will fly by Pluto and its moons in 2015. If you fire your private New Horizons clone towards Eris and wait for it to report back you will hear from it in just under twenty years.
By the way, all these examples are based on straight line distances. In practise you would fly curved trajectories to compensate for the movements of the planets so your mileage will vary.
The Solar System is pretty big. Eventually though we’ll get bored and look outside. Let’s go to the nearest star system to our own, the triple star system of Proxima Centauri, Alpha Centauri A and B which everyone knows is 4 and a bit light years away.
To be precise, the Centauri system is 4.36 light years away. “4.36 light years”, just rolls off the tongue, doesn’t it? Let’s convert it to kilometres, we get 41 trillion km. That sounds impressive, but just how big is a trillion? Start counting with me, a number every second, 1…2…3…4…
When we get to 600, ten minutes will have passed. We get to 10,000 and two hours 47 minutes have gone by, keep going, don’t stop! A million seconds takes us 11.5 days. By the time we reach a billion seconds more than 31 years have gone by. Counting to trillion, a number every second takes more than 31 thousand years. A trillion is a ludicrously big number.
Let’s point the New Horizons probe at Alpha Centauri, start the clock and see how long it takes to get there. Expect a long wait!
The journey lasts 80 thousand years! While we sit waiting for our probe to call back I would expect us go through Global Warming, a zombie apocalypse then maybe an ice age or two, a robot uprising and probably by the end we’ll have evolved heads like space hoppers. And that is only the distance to the nearest star! The whole galaxy is 100 000 light years across and Earth is about 26 000 light years from the centre. Imagine we launch New Horizons towards the galactic core. Expect a journey time of 480 million years. If the Burgess Shale fauna had launched such a probe to the centre of the galaxy it would arriving now.
It is 13.8 billion light years to the edge of the observable universe and estimating travel times across this distance seems silly. Suddenly our Solar System is rather small and cosy by comparison.
And that is why we will never conquer space. It’s too darn big! I can believe that one day travel to the planets will be easy as travel between continents is today. Epic journeys to nearby stars may even be feasible, but treking across the galaxy or beyond will never be achieved by humans.