Space travel might not be for us

Zakkary Gaston and kiersynn bush

Will humans travel to space?

The Russian rocket scientist Konstantin Tsiolkovsky wrote that humans will eventually travel to and inhabit space beyond Earth. He said, “Earth is humanity’s cradle, but you’re not meant to stay in your cradle forever.” Since then, the idea has become part of an image of humanity’s future. Going to the stars is often regarded as humanity’s destiny, even a measure of its success as a species. But in the century since this vision was proposed, we have learned things about the universe and ourselves. What we have learned suggests moving out into space may not be humanity’s destiny after all.

The main problem with interstellar travel is the sheer size of the universe. Its size was not known when people first imagined we would go to the stars. Tau Ceti, one of the closest stars to us, is 100 billion times farther from Earth than our moon. We can’t simply send people over such immense distances in a spaceship, because a spaceship is too poor an environment to support humans for the centuries it would take. Instead of a spaceship, we would have to create some kind of space-traveling ark. The ark would need to be big enough to support a community of humans and other plants and animals in a fully recycling ecological system.

On the other hand it would have to be small enough to move at a fairly high speed. A smaller ark would shorten the voyagers’ exposure to radiation in space and to breakdowns in the ark. The bigger the ark is, the more fuel it would have to carry along to slow itself down on reaching its destination. For that reason and others, smaller is better. But smallness creates problems for ecologic balance. The needs for bigness and smallness may cross each other, resulting in an imperfectly designed spacecraft.

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space ark

Another problem is the effects on our microbiomes. About eighty percent of the DNA in our bodies is not human DNA, but the DNA of smaller creatures, called microbes. Together they make up a system in the human body called a microbiome. Our microbiome has to be balanced for us to be healthy. The microbiome system co-evolved on Earth in a particular set of physical influences, including Earth’s gravity, atmosphere and chemical make-up. Traveling to the stars means leaving all these influences, and trying to replace them artificially without knowing what might happen. Any ark would therefore be an experiment, its inhabitants lab animals. The first generation of the humans aboard might have volunteered to be experimental subjects, but their descendants would not have. These generations of descendants would be born into a set of rooms a trillion times smaller than Earth, with no chance of escape.

Rules would have to be enforced to keep the experiment functioning. Having children would not be a matter of free choice, as people would have to maintain the population in the ark. Many jobs would be required to keep the ark functioning, so work too would not be a matter of free choice. Living in the ark would require following strict rules.

History has shown that people tend to react poorly in rigid states. There is a high chance people would face mental and emotional difficulties. Over several generations, it’s hard to imagine any such society staying stable.

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problems may multiply

Still, humans can adjust. It’s conceivable that all the problems outlined so far might be solved, and that people enclosed in an ark might cross space successfully to a nearby planetary system. But if so, their problems will have just begun.

Any planetary body the voyagers try to inhabit will be either alive or dead. If there is life, the problems of living in contact with an alien environment could range from harmless to fatal. On the other hand, if the planetary body is dead, then the newcomers will have to make it livable using only local supplies and the power they have brought with them. The process will take centuries. Meanwhile, the ark would have to continue to work without failures.

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success is unlikely

So, to conclude: an interstellar voyage would present one set of extremely difficult problems, and the arrival in another system, a different set of problems. All the problems together create not an outright impossibility, but a project of extreme difficulty, with very poor chances of success. Pursuing the project would require many preconditions before it was undertaken. First, there would need to be a sustainable human civilization on Earth itself to teach us many of the things we would need to know to construct a viable ark. Second, there would need to be a great deal of practice in an ark orbiting our sun, where we could make repairs and study the ark. Third, there would need to be robotic explorations of nearby planetary systems, to see if any are suitable candidates for inhabitation.

Unless all these steps are taken, humans cannot successfully travel to and inhabit other star systems. The most important step is the first, which is to create a sustainable long-term civilization on Earth. If we don’t create sustainability on our own world, there is no Planet B.


star-a ball of gas that is at extremely hot temperatures and produces light.

asteroid-very small rocks that are in space.

astronomers-people who study objects in space.

comet-a ball of ice an rock that is in space and looks like a streak across the sky.