COULD HUMANS FIND HOMES ELSEWHERE IN THE UNIVERSE?

As there are billions of planets in our universe, it is likely that some of them could support life, but the vast distances that would have to be travelled to reach them are at present an immense problem. More possible is the idea that humans could build self-supporting communities on nearby planets. Ideally, these would need to be enclosed, containing their own atmosphere and able to support a variety of plant and animal life just as our planet does. Experiments are being made t9 see if it is possible to build artificial ecosystems like this here on Earth.

We know of only one living planet: our own. But we know it very well. As we move to the next stage in the search for alien life, the effort will require the expertise of planetary scientists, heliophysicists and astrophysicists. However, the knowledge and tools NASA has developed to study life on Earth will also be one of the greatest assets to the quest.

There are two main questions in the search for life: With so many places to look, how can we focus in on the places most likely to harbor life? What are the unmistakable signs of life — even if it comes in a form we don’t fully understand?

“Before we go looking for life, we’re trying to figure out what kinds of planets could have a climate that’s conducive to life,” del Genio said. “We’re using the same climate models that we use to project 21st century climate change on Earth to do simulations of specific exoplanets that have been discovered, and hypothetical ones.”

Del Genio recognizes that life may well exist in forms and places so bizarre that it might be substantially different from Earth. But in this early phase of the search, “We have to go with the kind of life we know,” he said.

Further, we should make sure we use the detailed knowledge of Earth. In particular, we should make sure of our discoveries on life in various environments on Earth, our knowledge of how our planet and its life have affected each other over Earth history, and our satellite observations of Earth’s climate.

Above all else, that means liquid water. Every cell we know of — even bacteria around deep-sea vents that exist without sunlight — requires water.