One reader wanted to know if we can build our own planet when we can no longer live on Earth. We decided to ask two space explorers about this.
If we, humans, were sent into this world to be the shepherds of the Earth, then we, to put it mildly, are not doing our job well enough.
Forests are disappearing, plant and animal species are being destroyed, and the seas are filling up with plastic. And we have not yet started talking about climate change.
Perhaps the prediction that at some point we will destroy everything to such an extent that we do not want and will not be able to live on Earth any longer is not so unrealistic. And what are we going to do then?
Our reader Kim Kristianson is also asking this question.
What will we do? Can we build new planets to live on? Ideally, I imagine 500 planets at the right distance from the Sun, so that at least the temperature is right,”he writes in his email.
It's easier to take care of the old earth than to build a new one
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To answer Kim's question, we contacted two space explorers who may be helping Kim find a new place to live. They are Professor Anja C. Andersen and Professor Morten Bo Madsen, both from the Niels Bohr Institute at Copenhagen University.
Scientists have some guesses about what we will do on the day the Earth becomes uninhabitable, but they propose to first invest more resources in preserving the planet that we already have.
“It would be cheaper and easier to solve our current problems on Earth than to find a new place where billions of people from Earth could settle,” says Anja Andersen.
Morten Bo Madsen completely agrees with her.
“In fact, there is no real alternative but to take care of the Earth, because all potential solutions will require all the resources that are on our planet,” he says.
Scientists already want to establish a colony on Mars
However, as a thought experiment, we ask scientists to imagine that a huge asteroid is flying towards Earth and there is no way to avoid a collision that will destroy all life.
What will we do?
The scenario, by the way, is not so unrealistic, because this has already happened in the past, which means it may repeat itself in the future. True, no one knows if this will happen tomorrow or in a few million years.
The problem is that, although we track most of the large asteroids in the solar system, an asteroid can appear from outside, and then we will need to detect it before it's too late.
So Morten Bo Madsen believes that we must now prepare for such a scenario, however, then Kim will probably live not on a planet built with his own hands, but on Mars.
“For human survival in the long term, we need to establish a permanent colony on Mars now. Do not wait until a real danger arises, because then it will be too late. Right now, we need to establish a colony on Mars, which will eventually number 10-20 thousand people, which will ensure the survival of mankind in the event of a disaster. Perhaps such a colony will even help to repopulate the Earth when the disaster is over,”says Morten Bo Madsen.
You can move to Mars now
Anja Andersen agrees that Mars is the best contender for a future new home for humanity.
However, she would prefer to live on Earth, because the red planet is not a hospitable place at all.
In addition to the fact that there is no atmosphere and oxygen, the planet constantly receives dangerous radiation from the Sun and from space.
Therefore, people will have to live mainly underground in order to avoid radiation injuries for a long time. Nevertheless, this scenario is quite real.
“The only question is to make a decision to do it, because we already have the technology,” says Anja Andersen.
The atmosphere on Mars is a matter of the distant future
If you look a little further into the future and imagine the creation of an atmosphere on Mars so that people can safely run on a dusty surface without any spacesuit or oxygen mask, then here we will talk about "terraforming" - this is the name of the process of cardinal change of the entire planet.
This is a bit like how we have changed the Earth over the past 150 years, almost doubling the CO2 in the atmosphere. Just to make Mars habitable, the scale of such activity would have to be much larger.
However, such decisions are a matter of a very distant future, and even if it were realistic to start doing it right now, the process of transforming Mars into a habitable place would take hundreds or even thousands of years.
“This is not something that you can just take and do. We can develop technologies that will allow us to do this in a very long time, although I do not exclude that at some point in the future we will have a way to carry out this process, say, in 500 years. But it is still very long,”says Morten Bo Madsen.
Perhaps we will settle on an asteroid
If we specifically take on Kim's proposal to build planets in order to move there, finishing off our own Earth, it turns out that this idea is even more difficult to implement than resettlement to Mars, which already exists in nature.
We, of course, under no circumstances will carry cart after cart with earth from Earth to build a planet for Kim, but, according to our two scientists, you can imagine that people would catch an asteroid and send it into orbit around the Sun.
In this case, you need to pay attention to some things that will make the asteroid habitable.
First, the surface of the new planet Kim will bathe in dangerous cosmic radiation, so Kim will have to dig deep inside the asteroid to defend himself.
The second problem is that gravity is very low on asteroids, and without it, Kim will not stay long on his new planet.
Our new home must have gravity
Lack of gravity is a problem, because the human body is adapted to life with a certain gravity of the planet. That is, we are physiologically very bad at coping with its absence. For example, astronauts who have lived on the International Space Station for a long time are well aware of this.
The heart muscles weaken, bones suffer, vision deteriorates and back pains appear, as the spine begins to stretch.
“Danish astronaut Andreas Mogensen, for example, was four centimeters taller when he returned to Earth after his time at the space station,” Anja Andersen said.
Easier to build space stations
Instead of placing a new "planet" in orbit around the Sun, it would probably be more profitable to build it like a space station.
Then we could still make it rotate, thereby creating a centrifugal force that replaces gravity.
In addition, we could also create a shield to protect us from hazardous radiation.
The only problem is that these "planets" are likely to be so expensive to build that we cannot create enough of them to accommodate anyone other than Kim himself and a handful of his friends.
“This is not to say that this is impossible, but if we want to relocate even a minimal part of the world's population in this way, it will become too serious a task,” says Morten Bo Madsen.
114 thousand years to the nearest star
What should Kim do if, choosing his future home, he does not want to live either on a space station, or on an asteroid, or on Mars, and also does not wait until the terraforming of the red planet is completed?
Yes, then Kim will have to look outside our solar system, but in this case he will need to be patient, according to Anja Anderson.
This is because the nearest planet outside our solar system orbits the star Alpha Centauri, which is just over four solar years away. It's very, very, very, ooooooooooooo far away.
Let's imagine as a thought experiment that this planet near Alpha Centauri is an analogue of Earth with magical beaches, great weather, life, and so on.
Sounds great, but unfortunately, in any case, Kim's foot is unlikely to ever set foot on its surface, because with current technology, it will take us about 114 thousand years to get there.
“If we ever invent engines that can propel a spacecraft to 10% of the speed of light, the journey will still take 40 years, and such a long space trip can be really exhausting,” explains Anja Andersen.
Thanks for the question
We hope Kim realized that there is no good alternative to Earth, so we hope that he will take care of her.
So that he doesn't forget about it, we'll send him one of our wonderful Ask Science T-shirts.
We also thank Anne Andersen and Morten Bo Madsen for their help with the answers.
Kristian Sjøgren