Join expert guests Jayne Birkby, an exoplanetary sciences professor, Saidul Islam, a chemist focused on life's chemistry, and Oliver Shorttle, a natural philosophy professor, as they explore the origins of life and what makes planets habitable. They discuss the conditions needed for life to thrive on Earth and beyond, the search for Earth-like planets, and the significance of cosmic chemistry. Dive into the fascinating world of potential extraterrestrial life and the future of astrochemistry.
Theories about the origin of life on Earth suggest it may have begun in extreme environments like deep-sea vents or warm ponds.
Efforts to detect life beyond Earth involve studying Mars and icy moons while focusing on identifying suitable conditions for habitability.
Upcoming astronomical missions will enhance our ability to detect chemical signatures in exoplanet atmospheres, reshaping our understanding of potential life.
Deep dives
The Origins of Life on Earth
There are multiple theories regarding the origin of life on Earth, with two prominent ideas suggesting life began either in deep-sea hydrothermal vents or in warm ponds on the surface. The chemistry of these environments must support the formation of complex molecules by providing necessary building blocks and energy sources. Factors such as temperature regulation are crucial; extreme heat can destroy molecular integrity, while a variety of conditions may facilitate the gradual evolution of life. Evidence points to the earliest signs of life dating back about 3.5 billion years, potentially indicating a significant gap in our understanding of early biological emergence.
Searching for Extraterrestrial Life
Efforts to find signs of life beyond Earth focus on both our solar system and exoplanets orbiting other stars. Mars and icy moons like Europa and Enceladus are prime candidates for exploration, as they may harbor environments conducive to life. When seeking twin planets, it’s essential to identify those with a suitable distance from their stars to ensure liquid water can exist, which is considered vital for life. Advanced techniques like spectroscopy are used to analyze planetary atmospheres for signature elements like oxygen, which can signify biological processes.
Chemical Foundations of Life
Life on Earth is fundamentally composed of a limited set of molecules, including nucleic acids, proteins, and fats, all of which are constructed from specific elements such as carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur. Understanding how these elements transitioned from inorganic to organic forms under the early Earth conditions is crucial for unraveling the origins of life. Reactive molecules, like hydrogen cyanide, may have played a pivotal role in prebiotic chemistry by driving the formation of biological building blocks. This transformation likely occurred through a stepwise, gradual process rather than an instantaneous reaction.
Habitability and Environmental Factors
The concept of habitability extends beyond mere presence of water or energy; it encompasses a range of conditions that foster biological diversity and evolution. Factors like environmental stability and nutrient availability are essential for life to flourish; extreme fluctuations may hinder population survival. Learning about life’s adaptability on Earth sheds light on potential life-supporting environments elsewhere, where conditions vary tremendously from those on our planet. The characteristics of planets, their star systems, and cosmic events play a critical role in determining their ability to support life.
The Future of Astrobiology Exploration
Upcoming astronomical missions, including the Extremely Large Telescope (ELT) and the James Webb Space Telescope, are set to revolutionize our understanding of life potential on distant planets. These advanced tools will facilitate detailed observation of exoplanet atmospheres, searching for chemical signatures indicative of biological processes. A successful identification of life-supporting conditions could reshape our understanding of life's prevalence across the universe. Collaboration across disciplines—astronomy, chemistry, and geology—is essential for addressing life's origins and the conditions necessary for its existence beyond Earth.
Melvyn Bragg and guests discuss some of the great unanswered questions in science: how and where did life on Earth begin, what did it need to thrive and could it be found elsewhere? Charles Darwin speculated that we might look for the cradle of life here in 'some warm little pond'; more recently the focus moved to ocean depths, while new observations in outer space and in laboratories raise fresh questions about the potential for lifeforms to develop and thrive, or 'habitability' as it is termed. What was the chemistry needed for life to begin and is it different from the chemistry we have now? With that in mind, what signs of life should we be looking for in the universe to learn if we are alone?
With
Jayne Birkby
Associate Professor of Exoplanetary Sciences at the University of Oxford and Tutorial Fellow in Physics at Brasenose College
Saidul Islam
Assistant Professor of Chemistry at Kings College, London
And
Oliver Shorttle
Professor of Natural Philosophy at the University of Cambridge and Fellow of Clare College
Producer: Simon Tillotson
Reading list:
David Grinspoon, Venus Revealed: A New Look Below the Clouds of Our Mysterious Twin Planet (Basic Books, 1998)
Lisa Kaltenegger, Alien Earths: Planet Hunting in the Cosmos (Allen Lane, 2024)
Andrew H. Knoll, Life on a Young Planet: The First Three Billion Years of Evolution on Earth (Princeton University Press, 2004)
Charles H. Langmuir and Wallace Broecker, How to Build a Habitable Planet: The Story of Earth from the Big Bang to Humankind (Princeton University Press, 2012)
Joshua Winn, The Little Book of Exoplanets (Princeton University Press, 2023)
In Our Time is a BBC Studios Audio Production
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