More recently, a team announced the discovery of a bacterium they claimed could substitute arsenic for phosphorus in its DNA (Wolfe-Simon et al., 2011). Additionally, astrobiologists were forced to reexamine what constitutes conclusive evidence for past or present life. have not been generally accepted, in the process of testing them astrobiologists advanced research on a variety of topics, including the minimum size of an individual cell and production mechanisms for tiny grains of magnetite. were structures in the meteorite that appeared to resemble fossilized bacteria when viewed under an electron microscope, but later work showed that similar structures can be produced as an artifact of the techniques used to prepare mineral samples for electron microscopy (Bradley et al., 1997). For example, one of the “biosignatures” cited by McKay et al.
As a result, we now know that abiological processes could have created these signals, and the meteorite is not therefore widely considered proof of life beyond Earth (Bradley et al., 1996, 1997 Frankel and Buseck, 2000 Buseck et al., 2001 McKay et al., 2003 Treiman, 2003). In subsequent years, astrobiologists completed research on the meteorite itself and on the types of “biosignatures” contained within it. In 1996, scientists announced that they had found evidence of fossilized life contained within martian meteorite ALH84001 (McKay et al., 1996). Two high-profile announcements within the field of astrobiology illustrate this. Whether the new idea is ultimately accepted or not, the process of testing the evidence results in increased knowledge and understanding, not just about the possibility for life beyond Earth but about our own planet as well. This can lead to lively debate within the scientific community and sometimes within the public arena. Only ideas that are considered to be well-supported by evidence are accepted by the scientific community as a whole. But like all areas of science, new ideas are subject to detailed scrutiny by the scientific community as part of the quality control process. The search for life beyond Earth has therefore only just begun.Īstrobiology is an exciting subject with new ideas that can easily capture the imaginations of both scientists and nonscientists. Space missions have explored only a tiny portion of our solar system, and in the few years since we first discovered planets around other stars, the number of such exoplanets known has increased into the hundreds.
That does not necessarily mean life exists only on Earth, but only that there is not yet compelling evidence for its existence elsewhere. There have been many exciting discoveries that suggest life is possible on other planets and moons, but we have not yet detected any definite signs of life beyond Earth.
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In seeking to understand the full story of life in the Universe in a holistic way, astrobiology asks questions that transcend all these individual scientific subjects.Īstrobiological research potentially has much broader consequences than simply scientific discovery, as it includes questions that have been of great interest to human beings for millennia ( e.g., are we alone?) and raises issues that could affect the way the human race views and conducts itself as a species ( e.g., what are our ethical responsibilities to any life discovered beyond Earth?).ġ.2. Have we already found life beyond Earth? However, astrobiology is more than just a collection of different disciplines. It therefore requires knowledge of physics, chemistry, biology, and many more specialized scientific areas including astronomy, geology, planetary science, microbiology, atmospheric science, and oceanography. Astrobiology includes investigation of the conditions that are necessary for life to emerge and flourish, the origin of life, the ways that life has evolved and adapted to the wide range of environmental conditions here on Earth, the search for life beyond Earth, the habitability of extraterrestrial environments, and consideration of the future of life here on Earth and elsewhere. Marina Walther-Antonio (Editor Chapter 4 and Author)Ī strobiology is the science that seeks to understand the story of life in our universe.Kelsi Singer (Co-Editor Chapter 5, Editor Chapter 6, and Author).Paulino-Lima (Editor Chapter 8 and Author) Marie-Eve Naud (Co-Editor Chapter 7 and Author).Kennda Lynch (Co-Editor Chapter 5 and Author).
Dartnell (Co-Editor Chapter 7 and Author)
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