Astrobiology
What if life outside Earth wasn’t truly fiction? Aliens have been an enigma since the beginning of time. Many find it unbelievable that life exists solely on Earth without any biota in the universe. Others find it absurd that scientists have not found any signs of life given the depth of astronomic discovery in the 20th and 21st centuries. This belief has taken on the form of the “Fermi Paradox,” highlighting that it is impossible that organisms on Earth are the only forms of life in the universe while it is also impossible that any other organisms in the universe exist because no scientific or mathematical discovery has shown life outside Earth (Shostak, 2019). This paradox has puzzled astrophysicists and ordinary stargazers alike. The confusion around life outside Earth has been expressed heavily in popular cinema such as Steven Spielberg’s E.T. and in literature under the science fiction genre, such as books by Isaac Asimov.
Astrobiology is the field of science that intersects biology, the study of life, with astronomy, the study of space. Astrobiologists' primary focus is searching for extraterrestrial life and biota (living things) in the universe. Scientists do this by first understanding what conditions allow life to thrive. To survive, life typically requires liquid water and a “habitable zone” to live in, which is the sweet spot regarding the distance to a nearby star. The Earth exists in a habitable zone as it is rich in liquid water and is the right distance from the sun to allow organisms to thrive. There are also abnormal habitable zones such as the habitable zone on Saturn’s moon Titan which holds methane and ethane, other substances necessary for life. Titan is way farther than the normal habitable zone yet it still has some of the building blocks of life so astrobiologists have classified Titan as a habitable zone even though it is not the right distance from the sun (Shostak, 2019).
As astrobiologists have defined habitable zones, their main task is to search for habitable zones outside this solar system. Advanced telescopes such as the Hubble telescope can find thousands of exoplanets (planets outside our solar system), but there are strict criteria that narrow which exoplanets could be habitable. The first criterion is that the exoplanet is a smaller and Earth-likein appearance. The second criterion is whether astrobiologists can measure the light emitted from the atmosphere to determine whether there are sufficient oxygen and methane levels in the atmosphere (Shostak, 2019).
NASA has a specific astrobiology program that uses additional methodology to understand life outside Earth. NASA runs experiments on Earth to simulate life on other planets. For example, an experiment simulated Mars in the remote Atacama desert to search for biomarkers (signs of life) that could be found on Mars. In addition to the experiments on Earth, the Curiosity and Perseverance Rovers on Mars determined through testing samples of soil and rock that Mars was previously a wetter and warmer planet, thus, the possibility of once containing life is more prominent. Additionally, if astrobiologists can prove life existed on Mars previously, then there is likely life outside the solar system at the moment if there are two signs of life inside one system (Kaufman, 2022).
As NASA continues to conduct experiments, astrobiologists are focusing on analyzing using steps of a strategy that they created that they believe is crucial in determining life in the universe. The first step is to analyze inanimate materials such as rocks, minerals, or sediments on various planets to see if they are conducive to facilitating the reproduction of organisms. The second step is to consider how water could have appeared on different exoplanets, as water is key to life. Another way that NASA astrobiologists are trying to find life is by understanding the chemical structure of a planet to see if the chemical information reveals anything about whether life is feasible on the planet. The last idea is performing experiments to determine whether life can exist without carbon or methane to see if there are different ways that life can exist (Kaufman, 2022).
Astrobiology is an emerging field working to solve the puzzling questions of human's solitary existence in the universe. Understanding astrobiology for humanity and to better understand life in space can help answer science’s age-old questions about what life is outside of Earth. By understanding and creating a definition of what life looks like outside the universe, astrobiologists can be key in informing what life truly is and whether there are intelligent beings in the vastness of space.
References
Kaufman, M. (2022, October 12). Life, here and beyond. Astrobiology at NASA.
Retrieved November 5, 2024, from https://astrobiology.nasa.gov/about/
Shostak, S. (2019, February 14). Astrobiology. Britannica. Retrieved November 5,
2024, from https://www.britannica.com/science/astrobiology
