Search for extraterrestrial life: We can also learn from failure
So far, no evidence has been found that life exists on other planets. If this does not change with better instruments, it will also be instructive.
So far we only know of one inhabited planet, too little to say anything about its distribution as a whole.
(Image: NicoElNino/Shutterstock.com)
The search for extraterrestrial life is currently one of the most important projects in astronomy, but we may still be a long way from finding it. However, even from a futile search, quantitative data on the distribution of extraterrestrial life forms can be inferred. At least that is the opinion of a research team from the Swiss Federal Institute of Technology (ETH) in Zurich. If, for example, 40 to 80 exoplanets could be “perfectly” proven to be devoid of life, this would mean that less than 10 to 20 percent of similar worlds harbor life. This would still mean that there could be life on at least 10 billion exoplanets in the Milky Way alone.
Asking the right questions
The research was led by physicist Daniel Angerhausen. He and his team wanted to find out the minimum number of exoplanets that need to be researched “to obtain meaningful answers about the frequency of potentially inhabited worlds”. However, Angerhausen admits that the result now obtained has a decisive catch. It must be possible to rule out the existence of life on an exoplanet to draw such far-reaching conclusions. However, every observation remains fraught with uncertainty. He therefore also advocates not having too much confidence in a possible result, but working on formulating the right questions.
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The group advocates asking specific and measurable questions, such as “What proportion of rocky planets in the habitable zone of a solar system show clear signs of water vapor, oxygen, and methane?”. These can be answered clearly, unlike “How many planets have life?”. This is the only way to draw useful conclusions from the persistently fruitless searches for traces of extraterrestrial life. The ESA LIFE mission, for example, is expected to collect enough data for this. At the same time, however, the team admits that “a single positive finding would change everything”. The study is now being presented in The Astronomical Journal.
(mho)
