The first living organism on Earth emerged approximately three and a half billion years ago. Since then, life has evolved into countless forms and colonized the planet. But the story of life is not a rosy one. At least five mass extinctions have occurred, and nearly all species that have ever existed on our planet are now dead. One of the most well-understood mass extinctions occurred when the Alvarez asteroid impacted Earth and, likely combined with other factors, killed many dinosaurs and other species. Life then had no tools to detect the coming asteroid or to be able to plan proactively to ensure its survival.

In order to avoid sharing the same fate as the dinosaurs, scholars argue that humans should become a multi-planetary species. We spoke with Professor Gonzalo Munevar, Emeritus Professor at Lawrence Technical University, to hear his thoughts on the existential risks we face and how colonization of the cosmos can help us address them. He has written extensively about the philosophy of space exploration and human consciousness.

Why do you argue that “failure to move into the cosmos would condemn us to oblivion”?

By having a significant presence in the solar system in the next few thousands of years and beyond, we will be in a better position to deflect asteroids and comets that might bring the end of humanity, and much other Earth life, in a horrible collision. And if perchance one such catastrophe proves inevitable (e.g. a rogue planet passing through the solar system), humanity would still survive by having colonized Mars and other bodies, as well as by having built artificial space colonies of the type advocated by Gerard O’Neill.

Once the sun begins to turn into a red giant in a few billion years, we must have long moved into the outer solar system. In the very long run, we have to move into other solar systems. Relativistic-speed starships would be nice, but they are not necessary for the task of moving humanity to the stars. We can reach them, slowly but surely, by propelling some of our space colonies away from the sun, carrying perhaps millions of human beings. They would take advantage of the many resources to be found in the Oort Cloud, and then of equivalent clouds in other solar systems. Even interstellar space has resources to offer. Nuclear energy, probably fusion, would likely be required. It may take us tens of thousands of years, but in the cosmic time scale, that is but a blink in the eye.

What are these catastrophic threats? Are there any records of catastrophic events happening before humans appeared on Earth?

I have already mentioned collisions with asteroids and comets. Although the active geology of our planet tends to erase the record of many collisions, we can find a well-preserved record on the Moon and Venus, the two closest bodies to Earth. On the 600-million-years-old Venusian surface, the spacecraft Magellan discovered about one thousand impact craters at least twice the diameter of meteor craters on Earth. This impact record makes it reasonable to estimate a catastrophic impact on Earth every half a million years or so. Collisions with bodies of 5 km across would happen, on the average, every 20 million years. Apart from the Alvarez asteroid (crater near Yucatan) that led to the extinction of the dinosaurs and the majority of species on Earth 65 million years ago, there have been at least two more impacts by asteroids 10 km or larger in the last 300 million years.

How could human colonization of outer space save other terrestrial life?

On both O’Neill types of colonies as well as on colonies on other planets, and particularly on terraformed planets, we would need all sorts of organisms like bacteria and plants for food, medicine, and ornamentation, as well as many animals for food and other purposes. We cannot have a proper colony without an Earthly environment to surround and nourish us. So, we have to take much other terrestrial life with us in order to survive and flourish. And given the value of biodiversity we would make it a point to take a great variety of organisms that contribute to our biosphere. Of course, we should heed Mark Twain and be sure not to include mosquitoes in our future space arks. I myself would keep out tarantulas and some other obnoxious viruses, bacteria, plants, and animals.