A new mission concept called LIFE, which aims to detect biosignatures from Earth-like planets in their star’s habitable zones, could help answer a question that has puzzled scientists for decades. Will we be rare in the universe or is life common? The proposed mission would use four space telescopes to fly around a central “combiner” spacecraft and observe dozens of exoplanets.
Astronomers Daniel Angerhausen from ETH Zurich and his team used statistics to determine how many planets they need to observe before drawing conclusions about the prevalence of life in the universe. They found that between 40 and 80 exoplanets would need to be observed with no detectable biosignatures to conclude with confidence that fewer than 10-20% of similar planets have life.
The LIFE mission won’t directly image exoplanets, but instead use spectroscopy to measure their light and reveal the presence of atmospheric gases. If no biosignatures are detected on its sample of planets, it can place a maximum limit on how many planets in the galaxy do have life.
While there will be uncertainties, such as missed biosignatures or incorrect observations, Angerhausen emphasizes that “it’s not just about how many planets we observe, but also asking the right questions and being confident in our abilities to identify life.” The study was published in April 2023.
Source: https://www.space.com/space-exploration/search-for-life/how-rare-are-inhabited-worlds-in-the-universe-the-life-space-telescope-fleet-could-find-out