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How do spacecraft search for life directly on another planet or moon?
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extraterrestrial life
An illustration of the Earth-size planet TOI 700e orbiting within the habitable zone of its star. The habitable zone is the area around a star where liquid water, and thus possibly life, can survive on a planet's surface. Its Earth-size sibling, TOI 700d, can be seen in the distance.
Spacecraft search for life directly on other planets or moons through in situ studies, which involve landing instruments on the surface to analyze samples directly. Because no single "life detector" exists, missions typically employ an array of general and specific instruments to establish or preclude the existence of biological activity.1
Key methods and instruments include:
- Chemical and Metabolic Analysis: Landers may use gas chromatography and mass spectrometry to detect organic molecules. Other experiments test for metabolic processes, such as the fixation of gases like carbon dioxide or tests for optical activity in soil and water samples.1
- Microscopy: A camera coupled with an optical or electron microscope can be used to identify microorganisms directly.1
- Sample Collection: Rovers, such as those sent to Mars, often use drills to collect core samples of rock and soil for onboard analysis or potential return to Earth.2
- Environmental Monitoring: Instruments analyze the local geology, meteorology, and the chemistry of the atmosphere to assess habitability.2
A critical challenge in these missions is preventing contamination, as spacecraft must be rigorously sterilized to ensure that any detected life is not simply hitchhiking from Earth.1