Astrobiology: Finding the Answers in the Stars
Astrobiology, the branch of science that seeks to understand the origin, evolution, distribution, and future of life in the universe, can seem like an intimidating and vast field of inquiry. But at its core, astrobiology is simply the open exploration of the answer to one of the most fundamental questions of all: Are we alone in the universe?
Astrobiologists work to answer this question by studying the physical and chemical aspects of life, within the extreme environments of the Solar System, and beyond. By combining its multi-disciplinary approach to studying life on Earth with astronomical observation, astrobiologists hope to identify and understand the possible sites of past, present, and future life outside of our planet’s boundaries.
The Origin of Life
Astrobiology is closely associated with the study of origins of life on Earth. Despite the fact that the very first life on the planet could have sprung up billions of years ago, and indeed, may have first begun on another celestial body, science is only still working to uncover the specific paths that lead to the evolution of life in various forms.
Astrobiologists believe that the earliest forms of life most likely emerged from a 'primordial soup' of organic molecules. Initially generated by geological or chemical processes, this prebiotic soup might have formed the basis for the evolution of various organisms specifically featuring biological macromolecules such as proteins, lipids and nucleic acids.
A generally accepted hypothesis is that these molecules, which in essence possess the key characteristics of any living organism, began to assemble themselves over time, forming the basis of the first self-replicating structures, which then evolved further to give rise to the earliest life forms.
Extremophiles: Life Beyond Earth
Astrobiology is also concerned with the study of extremophiles - organisms that thrive in extreme environments that are too harsh for the majority of life forms. From volcanoes to arctic permafrost, hot springs to mile-deep ocean trenches, these uniquely adapted organisms are an intriguing part of astrobiology’s scope.
Extremophiles, it is thought, have evolved unique means of survival in order to survive in their often extreme habitats. For example, Archaea, a type of primitive organism known for their tolerance of extreme conditions, possess a resistance to heat that other organisms simply don’t have.
Furthermore, studies of extremophiles suggest that life may be capable of thriving in space — even in the hostile environment of other planets. Indeed, astrobiologists continually search for signs of extremophilic life on other planets, such as within the atmospheres of Venus and Mars, or the ice-entombed subsurface oceans of Jupiter’s moon, Europa.
Hope for a Habitable Zone
With the discovery of exoplanets - planets that orbit distant stars - outside of our own Solar System and in the throngs of other galaxies, astrobiologists naturally want to explore the possibility of life existing on these distant planets.
In order to do so, astrobiologists are particularly interested in the concept of the ‘habitable zone’ - the region around a star that has temperatures that could sustain liquid water, and thus life, at the surface of a given planet.
In our Solar System, the planets Venus and Mars appear to lie within the habitable zone. Though current conditions on the surfaces of these planets suggest that they are not likely to support any form of simple life (though the polar ice caps on Mars are still being explored) astrobiologists remain open to the possibility of these planets once possessing — or still having — some form of extraterrestrial life.
The Search for Extraterrestrial Life
At the heart of astrobiology lies the search for extraterrestrial life. While the quest for extraterrestrial life on other planets is still ongoing, there are numerous space-based and ground-based facilities that are exploring the possibility.
The Kepler Telescope, for example, has identified thousands of planets, some of which exist within the circumstellar habitable zone. On the ground, scientists examining the possible life on Mars are using the Curiosity Rover to explore the Martian landscape and analyze soil samples for any signs of life.
But beyond the search for present-day life, astrobiologists also seek to answer deeper questions. How and why did life come to exist in the first place? How long ago did life emerge on our planet? How does life evolve over time, and ultimately, what do these evolutionary paths mean for us?
Investigating the Far Reaches of Space
astrobiology not only takes into account current and past evidence for life outside of the Earth, but also strives to venture beyond the boundaries of the Solar System to explore the potential for life in the wider universe.
Recent advances in space technology have opened up the possibility of reaching distant exoplanets and examining them in detail. These activities can involve probes sent to explore the environment of a target exoplanet, as with the Mars Curiosity mission, or direct imaging of potentially habitable planets. In terms of imaging, the new James Webb Space Telescope, to be launched in 2021, promises significant advances in this field.
Another area of research in this discipline is the potential for interstellar travel. In this context, astrobiologists consider the effects of space travel on the human body as well as the possibility of life on other planets and even in other stars.
Final Thoughts
At the end of the day, astrobiology is about striving to gain a better understanding of the origin and evolution of life. It is an ambitious field of study, full of unknowns.
The answers to the biggest questions will only be found through continued study and exploration. Astrobiology is a rapidly developing field of science that promises to eventually solve the biggest riddle of all: Are we alone in the universe?