Posted by Gonzo on August 29, 2023 10:54 PM
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Science holds onto a firm belief in extraterrestrial life; yet robot planetary explorers sent through our solar system during the 1960s and 1970s came up empty-handed.
Searching for alien life has become more complex. And even if we do encounter life on other planets, it remains unclear what next steps should be taken.
What is life?
Searches for life on other planets has given birth to a new scientific discipline known as astrobiology, which studies the conditions needed for life to emerge and flourish on other worlds. This multidisciplinary field encompasses everything from extreme biology, prebiotic chemistry and molecular evolution – as well as extreme biology itself!
Astrobiologists face an acute challenge when trying to define life. It is a subjective and unknowable concept, leaving scientists often baffled as they grapple with its definition. Nature contains numerous entities which resist easy categorization; this difficulty will only grow as more bodies become available for study.
Scientists have proposed various definitions for life, but all agree on its core features: self-sustaining chemical systems that undergo Darwinian evolution and possess energy flow and cell membranes. Some researchers even theorize that life could even exist within the plasma of stars; this however seems highly improbable.
Life definition is critical to science for numerous reasons. It sets expectations about what scientists should find on other worlds; if alien organisms bear no resemblance to terrestrial ones, what experimental evidence will enable their recognition? Researchers may use existing definitions – for extremophile organisms for example – or create their own, such as one suggesting self-replicating reactions of carbon and oxygen in liquid water as one possible definition for life.
What is the origin of life?
Origin of Life Is At the Center of Extraterrestrial Life Hunts […] Scientists argue that simple microbial life may be ubiquitous throughout the Universe, as evidenced by carbon molecules (the building blocks for biological molecules) being present in interstellar clouds, planet atmospheres and meteorite and comet surfaces – and by Abiogenesis’s widespread process; hence its chances of producing living forms outside Earth increase dramatically.
Conversely, other scientists tend to be more pessimistic. They contend that complex multicellular life may not exist in the Universe and may be difficult or impossible to detect. Furthermore, their origins remain difficult to grasp while it could be that fundamental physical processes operate which do not involve life at all.
Scientists are undertaking efforts to understand the origin of life on Earth by studying fossils, abiogenesis, prebiotic chemistry and other aspects of biology. Additionally, they are searching for signs of life throughout the Solar System; specifically Mars which likely had liquid water early on.
What is the nature of extraterrestrial life?
19th century philosophers assumed life existed on other planets after discovering our Solar System was heliocentric and modern science emerged; exobiology is the field of astronomy that studies this possibility.
Recently, exobiology could only be approached cautiously optimistic. Astronomers speculated that planets orbiting stars other than our Sun might host life; it took many years for actual observations to back this idea up with tangible proof. Now scientists are discovering more and more distant planets that appear to possess characteristics indicative of living systems – so the subject could become much more optimistic in coming years.
Scientists are exploring other planets for signs of life. Biosignatures can be detected through certain spectral features that indicate disequilibrium in carbon dioxide molecules; an excellent way of finding evidence could be looking for amino acids within Murchison meteorite.
Although scientists realize the search for astrobiology should not be undertaken hastily, a voracious appetite remains for knowledge that life might exist beyond Earth. Theories range from fictional accounts depicting sapient beings to microbes on bacteria-level colonies. Some exobiologists are confident that all life follows similar basic physical principles and uses the same building blocks for macromolecules regardless of where it originates; others contend that convergence evolution dictates considerable similarities between Earth-bound life forms and extraterrestrial ones (Pace, 2001).
What is the future of extraterrestrial life?
Astrobiology studies the search for extraterrestrial life, with scientists seeking two hallmarks to indicate its existence: biosigatures and technosignatures. A biosignature indicates past life such as fossilized feathers in rocks. On the other hand, technosignatures indicate technological life like radio waves from distant stars or emission from pulsars.
Scientists are actively engaged in searching for life on other planets, particularly Mars which may have harbored primitive bacteria four billion years ago and Jupiter’s icy moon Europa where there may be liquid water present. Missions have also been planned to look for extremophiles – organisms capable of living in caustic chemical pools or superheated vents on the ocean floor – which might provide clues as to where life may exist on other worlds.
No one knows for certain what to expect when encountering extraterrestrial life forms, though. While science fiction tends to depict alien life forms with light green or grey skin and four-limb, two-to-five digit structures indicative of intelligence, reality could be much different. With astrobiology research progressing apace, perhaps realizing that all life isn’t necessarily structured like our own could prove liberating!
