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Why must spacecraft be sterilized before searching for life on another world?
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extraterrestrial intelligence
An artist's conception depicts Kepler-186f, the first Earth-sized extrasolar planet found in its star's habitable zone.
Spacecraft must be rigorously sterilized before searching for life on another world to prevent the contamination of the target environment with terrestrial microorganisms.12
This practice, known as planetary protection, is essential for two primary reasons:
- Scientific Integrity: The primary goal of these missions is to assess the potential for indigenous life. If a spacecraft carries living organisms from Earth, those microbes could be mistakenly detected and reported as extraterrestrial life, leading to false positives and compromising the mission's scientific validity.12
- Environmental Preservation: Introducing Earth-based life to another planet could interfere with or potentially destroy native ecosystems, making it impossible to study the environment in its natural, pristine state.1
Because no single, unambiguous "life detector" exists, scientists must rely on an array of instruments to identify potential life-forms. Ensuring that these instruments are free from "hitchhiking" terrestrial life is a fundamental ethical and scientific requirement to ensure that any findings are truly representative of the target world.2