The search for evidence of extraterrestrial life is one of the greatest constants in science. And fantasy too. Be testimonies of a civilization, like fossils on other planets, even if they are microbes. But what if we are looking in the wrong places? What would happen if we removed the word “terrestrial” from “alien”? A team of Harvard scientists has asked themselves this question and has explored the possibility that alien life does not need a planet to sustain itself.
At first glance, planets seem like the ideal places to find life and for a logical reason: Earth is the only known place where life is known to exist. Our planet has such a gravity that it keeps everything in its place and an atmosphere that maintains surface temperatures in the appropriate ranges to maintain liquid water and facilitate biology. We have an abundance of elements such as carbon and oxygen to form the building blocks of biological organisms. And we have plenty of sunlight shining down on us, giving us an essentially unlimited source of free energy.
It is from this basic configuration that we organize our searches for life in other parts of the universe. The “problem” is that life can be different in other environments: other gravities, other chemistries and different atmospheres. In a study published in Astrobiologya team led by Robin Wordworth of Harvard University, explores this possibility by asking whether It is possible to build an environment that allows life to thrive without a planet.
This idea is not as far-fetched as it seems. In fact, we already have an example of creatures living in space without a planet: the astronauts aboard the International Space Station. Those astronauts require enormous amounts of Earth resources to be constantly transported to them, but humans are incredibly complex creatures. Perhaps simpler organisms could achieve this on their own. At least a known organism, the tiny tardigrades that live in waterare capable of surviving in the vacuum of space.
According to the study, any community of organisms in space needs to face several challenges. First, it needs to maintain an internal pressure against the vacuum of space. Therefore, a space colony would need to form a membrane or shell to protect them. Fortunately, this is not that important; is the same pressure difference that exists between the surface of the water and a depth of approximately 10 meters. Many organisms, both microscopic and macroscopic, can handle these differences with ease.
The next challenge is maintaining a warm enough temperature for liquid water. Earth achieves this through the greenhouse effect of the atmosphere, which is not an option for a smaller biological space colony. The authors point to extant organisms, such as the Saharan silver ant (Cataglyphis bombycina), that They can regulate their internal temperatures by varying the wavelengths of light they absorb and those that reflect, in essence, creating a greenhouse effect without an atmosphere. Therefore, the outer membrane of a colony of free-floating organisms would have to achieve the same selective capabilities.
Next, they would have to overcome the loss of light elements. Planets maintain their chemical elements through the force of gravitybut an organic colony would have difficulty with this. Even optimistically, a colony would lose light elements over the course of tens of thousands of years, so it would have to find ways to replenish itself.
Finally, the biological colony would have to be located within the habitable zone of its star, to access as much sunlight as possible. As for other resources, such as carbon or oxygen, lThe colony would have to start with a constant supplysuch as an asteroid, and then move to a closed-loop recycling system between its various components to maintain itself in the long term.
By putting all this together, researchers paint a portrait of an organism, or a colony of organisms, floating freely in space. This The structure could be up to 100 m wide, and would live inside a thin, hard, transparent “shell.”. This shell would stabilize its interior water at the proper pressure and temperature and allow it to maintain a greenhouse effect.
While these organisms may or may not exist in the universe, research has Important implications for future human endeavors in space. While we currently build habitats with metal and supply our stations with air, food and water transported from Earth, future habitats may use bioengineered materials to create self-sustaining ecosystems, the authors argue.