Astrobiology – How Did We Get Here?
In 1955, Stanley Miller and Harold Urey’s now-famous experiment simulated prehistoric ocean-atmospheric conditions on Earth, resulting in the synthesis of twenty-two amino acids (the building blocks of proteins) and, consequently, life, from inorganic components. What could this experiment, which gave insight into the chemical origins of life on Earth over sixty years ago, have to do with the NASA Perseverance rover’s touch-down on Mars in mid-February? The answer lies in astrobiology, an expansive and fast-developing field of research that is kicking off a new era in space exploration and deepening our understanding of life everywhere.
Astrobiology studies the origin, evolution, and distribution of life on Earth and (potentially) throughout the universe. According to the 2018 NASA Astrobiology Institute website, “Astrobiologists address three fundamental questions: How does life begin and evolve? Is there life elsewhere in the Universe? What is the future of life on Earth and beyond?” Thus, astrobiology research investigates the origins, evolution, and diversity of life on Earth as well as habitable environments in our Solar System and beyond.
Of course, stargazers and philosophers have pondered whether we are alone in the universe for millennia, dating back to Thales (600 B.C.), Metrodorus (400 B.C.), Leucippus, Democritus, Epicurus, and Plutarch, to name just a few thinkers in the Western tradition. However, until quite recently, humans did not have the scientific tools to answer these questions. Astrobiology (which in various forms has gone by the names exobiology, bioastronomy, and cosmobiology in the past) emerged as a field only in the late 1990s, propelled by several developments in the preceding decades: a growing understanding of terrestrial extremophiles beginning in the 1970s; the discovery of the first exoplanets beyond our solar system in the early 1990s and the launch of the Hubble Space Telescope in 1990 (which would later contribute to an explosion in discoveries of exoplanets); and then, in 1996, two events: NASA scientists’ claims to have found signs of fossilized life in the Allan Hills Martian meteorite (ALH84001), and evidence from the Galileo spacecraft that Europa’s icy crust had fractured in the past and might overlie a subsurface ocean. These developments contributed to the rebirth of exobiology (astrobiology’s predecessor, which had stagnated following the 1975 Viking missions’ “failure” to find life on Mars) as astrobiology. Thus in 1998, NASA’s Strategic Plan vowed to “expand our understanding of the evolution of the universe and its galaxies, stars, planets, and life” (emphasis added) in its Space Science Roadmap, and assigned the astrobiology mission to Ames Research Center. By 2002, NASA’s annual spending on astrobiology had reached almost $50 million, and seven hundred scientists attended the world’s second Astrobiology Science Conference (the first was held at NASA Ames in 2000). Then-NASA Administrator Sean O’Keefe explained part of the agency’s new vision: “To improve life here, to extend life to there, to find life beyond.”
Today, astrobiologists represent a wide variety of disciplines, from microbiology and geology to chemistry and engineering. Their research focuses on topics as diverse as sedimentology, remote life detection, instrument design, exoplanet habitability, Earth-analogue environments, the study of terrestrial extremophiles, geodynamics, and the origins of life. It is also the impetus behind inspiring solar system exploration projects such as NASA’s Perseverance rover, the United Arab Emirates’ Hope Mars mission, and China’s Tianwen-1, all of which have travelled from Earth to Mars since their launch last summer.
It’s been a long and meandering journey from Plutarch to Perseverance, but scientific questions that double as fundamental philosophical ones are unlikely to go away anytime soon. As we look back on the history of astrobiology, it’s with hope that future research will help us understand how we got here, where we’re going, and whether we’re alone.
Jessica Wahl is a senior in Georgetown University’s Science, Technology and International Affairs program, focusing on environment. Her thesis research explores the ethical commitments, responsibilities, and motivations that astrobiologists recognize and prioritize as they search for life beyond Earth. She is interested in combining her passions for environmental sustainability and space exploration.
Tim Chiu is a Junior in Georgetown College studying Computer Science and Biology. He is interested in aerospace medicine and space exploration technologies, specifically on how to accommodate life in extreme environments like space and potentially Mars. He hopes to attend medical school in the future and potentially become an aerospace medicine physician.