There is third obstacle we would have to surmount if humans like us were to colonize another planet even after we'd found it. That's the problem of getting there in the first place. To put this in perspective, it was a mere four centuries ago that Europeans began sailing across the Atlantic to what we now call the Americas. It was a perilous journey that thousands did not survive. Many ships were lost at sea, and illness killed many more on the journey. Nor was survival assured once they hit land. Even though it was already inhabited by earlier arrivals, many newly founded colonies died out, killed by starvation and disease.
How much more challenging would be a trek to another planet? How much more treacherous surviving once the space ship touched down?
First of all the trip itself. We don't know how far the nearest habitable planet we might find is, but the best candidate so far is more than 20 light years away. A light year is the distance light travels in a year which is 186,282 miles a second. Multiplied by 60 is the distance in a minute, multiplied by 60 again is the distance in an hour; multiplied by 24 is the distance in a day; and multiplying that by 365 is the distance in miles light travels in a year. That's 5,874,589,152,000 miles.
The fastest astronauts have ever travelled so far is 7 miles a second. That means it would take more than 26 thousand years for us to travel the distance of a light year. The good news is that optimistic scientists think we could eventually multiply the speed of human space travel by 100, so that it would take only 260 years to travel the distance of a light year.
The bad news is that the nearest scientists think an inhabitable planet might be is 10 light years away, and the nearest planet scientists have at this point actually found that might be potentially inhabitable is 20 light years away. So optimistically, we would have to assume that it would take between 2,600 and 5,000 years for us to reach the nearest inhabitable planet.
So the trip itself poses gigantic obstacles.
First, we would need volunteers to go into space where they would spend the rest of their lives, with no expectation that they or any of their offspring for thousands of years would reach land. Space stations that we set up along the way might help break up the journey, but it would also slow it down. And space stations themselves as permanent support stops are not yet feasible.
Second, we would have to solve the problems associated with the fact that humans have evolved to live in a world with certain levels of gravity and pressure. Without it, our bones tend to disintegrate. So far, we haven't any idea of how the human body would cope with living from birth to death in an atmosphere without gravity. The question of whether new human life could be conceived and nurtured successfully in a space ship is an obvious one that would need to be solved. So would questions of disease, and the inevitable friction that would develop when a small group of people are living permanently in a cramped space – not even able to get out for a walk.
Of greatest concern would be one of genetic diversity. Would the original humans take along a large gene pool so that the pioneers would not eventually become a small incestuous group highly vulnerable to disease?
Then, of course, we would have to build a space ship that could fuel itself for 5,000 years and provide food for its passengers.
When I think about it, I think it might be easier to save this planet. Because the problems don't stop with getting to a new planet.
Awesome site by the way.
