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Viking labeled release biology experiment: interim results
Science (New York, N.Y.)
|December 11, 1976
Summary
The Mars labeled release experiment detected a radioactive gas, suggesting microbial life. However, the "active" agent was inactivated by heat, and further tests are needed to confirm if it
Area of Science:
- Astrobiology
- Planetary Science
- Microbiology
Background:
- The search for extraterrestrial life is a primary objective in planetary exploration.
- Previous experiments aimed to detect signs of life on Mars.
- The labeled release experiment was designed to identify metabolic activity in Martian samples.
Purpose of the Study:
- To summarize the results of the labeled release life detection experiment on Mars.
- To investigate the nature of the active agent detected in Martian soil samples.
- To compare Martian sample responses with terrestrial and lunar controls.
Main Methods:
- Addition of a radioactive nutrient to Martian soil samples.
- Monitoring the evolution of radioactive gas.
- Heat inactivation tests at various temperatures (18°C, 50°C, 160°C).
- Comparison with terrestrial soils and a lunar sample.
Main Results:
- Remarkably similar radioactive gas evolution was observed at both Mars landing sites.
- The active agent was stable at 18°C but inactivated by heat treatment at 50°C and 160°C.
- The response did not appear to depend on recent direct ultraviolet activation.
Conclusions:
- The heat sensitivity of the active agent is consistent with a biological origin (microorganisms).
- Nonbiological explanations, such as ultraviolet irradiation effects, were considered but appear less likely.
- Available data are insufficient to definitively conclude the existence of life on Mars; further experiments are planned.
