A common first step when discussing the search for life beyond Earth is identifying the best places to look in our solar system. This usually includes Mars and several Jovian moons. A useful way to frame this discussion is around environments on Earth that are similar to environments on other solar system planets or moons. Such environments are often inhabited by extremophile lifeforms and are known simply as “analog environments.”1,2
Extremophiles, a term first coined in the 1970s3 after the discovery of microbes in hot springs in Yellowstone National Park in 1965,4 are microorganisms that are more tolerant of excessive heat, cold, pressure, acidity, or other factors than most organisms and can therefore exist in more extreme conditions.3,4 Extremophiles are discussed in astronomy textbooks,5,6 but although the environments on Earth where they are found are mentioned, they are not specifically identified as analog environments.
Several...