Beyond Earth: The quest for life in the universe

The prospect of life beyond Earth is one that commenced with the ancient Greeks, dating back at least as early as 400 BC, a very long time before science fiction emerged. But until today as we gaze up at the night sky and marvel at the landmarks of the universe, it is still hard not to wonder: are we alone in the universe or is there life out there? The question of whether we are alone in the universe is one that may never be fully answered, but the search for the answer will continue for generations to come.

The mystery around imagined extraterrestrial life has waxed and waned over decades, stirring provocative and useful thinking amongst scientists and the public alike. Nearly every single one of us has imagined extraterrestrial beings to be bizarre and somewhat human-like. In fact, they are always depicted as such in books and movies. But, while extraterrestrial life searching has evolved from fantasy to advanced space imaging, there is still much we must learn before extraterrestrial life could be confirmed. Today, with rapid advances in technology and space exploration, the search for extraterrestrial life has become more pressing than ever before. This transition rested in part on the discovery of exoplanets – planets that orbit stars outside of our own solar system – and over the past few decades, astronomers have identified a thousand of them. Some of these are located in the habitable zone around their star – the region where conditions are just right for liquid water to exist. Water is considered a crucial ingredient for the development of life, and so the discovery of habitable exoplanets has led to the tantalising possibility that life could exist beyond our own planet.

Our understanding of life is restricted to the observable and quantifiable processes that take place on Earth. However, under the premise that extraterrestrial beings share fundamental principles of physicochemical parameters as living organisms on Earth, scientists search for biosignatures – molecules that are generated during biological processes. These could include oxygen and methane in a planet’s atmosphere. The search for biosignatures is not only crucial to determine the likelihood of microbial organisms on other cosmic bodies, but also to find evidence of extinct life. But while the detection of biosignatures is still a challenging task, recent advances in technology such as NASA’s James Webb Space Telescope have made it more feasible than ever before.

In recent decades, the boundary conditions under which life can flourish have been stretched in every possible direction, embracing broader expanses of temperature, pressure, salinity and many more harsh conditions that we previously regarded as inhospitable to life. Aptly, these organisms are called extremophiles – organisms that can survive in extreme environments, such as deep under the ocean, in hot springs, or in the frozen tundras of Antarctica. The discovery of these organisms has expanded our understanding of the conditions under which life can exist and has opened up the possibility that life could exist in even more extreme environments on other worlds, such as planets or moons in our own solar system, e.g. Jupiter’s moon Europa and Titan, the largest moon of Saturn.

Beyond the ongoing search for biological signs, is the search for extraterrestrial intelligence (SETI). This field seeks to detect signals from intelligent civilisations that may exist in the universe. It is an important aspect of the search for aliens which is based on the notion that if there are intelligent life forms out there with remote communication technologies, we might be able to detect some technological artefacts. These signals can come in different forms, such as radio- or visible-wave regions of the electromagnetic spectrum. This study provides insights into the nature and distribution of life in the universe. Additionally, the discovery of SETI could have profound implications for our understanding of the universe and our place within it.

The search for extraterrestrial life is one of the most monumental and significant endeavours humankind has ever undertaken. It is also an exploration full of subtleties and complexities. One of the biggest challenges faced is simply the vastness of the universe. Even if life does exist on other planets, the distances involved are so great that it may be impossible to detect or to establish communication. Another challenge is the limitation of our technology. Our current methods for detecting exoplanets and searching for signs of life are still relatively crude, and it may be many years before we have the tools we need to make more precise measurements and observations.

In spite of the world’s seemingly endless string of catastrophes, the search for extraterrestrial life remains one of the imperative scientific frontiers of our time. The possibility of finding life beyond Earth opens up new avenues for scientific exploration and discovery. It has the potential to provide us with valuable insights into the origins of life, the evolution of species and the potential for life elsewhere in the universe.

Irrespective of whether we find definitive evidence of extraterrestrial life or not, the search itself is a testament to the human spirit of curiosity and exploration, and a reminder of the vast mysteries that still await us.

Victoria N Nakafingo