The validation of methods that a network of satellites could potentially employ in the quest to discover life outside our solar system has been confirmed by applying these techniques to Earth, the sole known abode of life. Despite the significant difference in observation distances between Earth and distant exoplanets, this milestone represents a crucial step forward.
The astronomers leading the Large Interferometer for Exoplanets (LIFE) mission showcased their ambitious vision through the selection of the acronym LIFE. By harnessing the capabilities of five satellites, the LIFE project aims to achieve what even the James Webb Space Telescope (JWST) cannot—detect signs of biological activity on rocky exoplanets orbiting neighboring stars.
Operating in unison, these proposed satellites will utilize interferometry to merge the light captured by each satellite, functioning collectively as a singular, potent telescope surpassing current launch capabilities.
While this collaborative approach may not replicate all functions of a larger individual telescope, it remains inconsequential when the primary objective is singular. Professor Sascha Quanz of ETH Zurich, the project lead, articulated, “Our objective is to identify chemical compounds within the light spectrum that may indicate the presence of life on exoplanets.”
To assess the feasibility of this concept prior to substantial investment, Quanz and a team of three researchers analyzed Earth’s spectrum in the mid-infrared range using data from the Atmospheric Infrared Sounder on NASA’s Aqua satellite.
If observers from another star system were to scrutinize Earth using a LIFE-like instrument, they would perceive a faint blue dot devoid of the resolution to distinguish oceans from landmasses. Instead, they would encounter an averaged spectrum representing Earth as a whole, gathered over an extended duration to accumulate adequate photons for meaningful analysis, potentially blurring seasonal variations.
Considering Earth from various vantage points, including over the North Pole, Antarctica, and the equator, the team validated LIFE’s methodology by examining a subset of Aqua Earth’s data equivalent to the radiation collected by a telescope at vast distances. The study affirmed LIFE’s capability to detect carbon dioxide, ozone, and methane in Earth’s atmosphere up to distances of at least 33 light years across all three perspectives.
While nonliving planets can harbor carbon dioxide in their atmospheres, the presence of water, methane, and ozone collectively serves as a compelling indicator of inhabited worlds. LIFE’s potential to assess the habitability or even the presence of life on nearby temperate terrestrial exoplanets underscores its significance in advancing our understanding of extraterrestrial life.
Despite the necessity for extended observation periods, up to 100 days, to gather substantial data on these gases, the efficiency of LIFE in analyzing priority targets makes it a promising tool in the search for life beyond our solar system. Additionally, the pursuit of more definitive biosignatures, such as dimethyl sulfide or methylbromide, may be constrained to a range of 16 light years, as indicated by recent studies.
The comprehensive findings of this research are openly accessible in the publication mentioned in the original text.