by After doing a bit of research, scientists came to a potentially redundant conclusion: Life could exist on Earth.
Of course, you’re probably thinking “Well, duh.” In fact, it might feel more accurate to say that life does exist in the world – it simply isn’t could. But here’s the thing. The team’s conclusion is not the focus of the research. It’s just a means to an end. Rather, the plot of this story fits precisely why these scientists reached the result.
People are interested in the possibility of discovering life on planets outside the solar system, known as exoplanets. So, to see things from a different perspective, this team of researchers considered how life and behavior would look on an alien Earth that would see our world as an exoplanet. How could they spy on us from afar? What would tell them that our planet is occupied?
These questions go far beyond philosophical thoughts. The answers are also put to practical use. They will be used to validate an upcoming space mission, called the Large Exoplanet Interconnector or “LIFE” mission, which will search for habitable exoplanets. The mission will consist of five spacecraft that make up one mid-infrared interferometer. They will sit relatively close to the James Webb Space Telescope (JWST) in orbit around the sun called Lagrange Point 2, or L2.
So the team, from ETH Zurich, turned the technology that will support LIFE back to Earth to ensure that the mission will be able to hunt for distant life when it launches late in 2026 or early 2027. If so. that cannot confirm life on Earth, how does it confirm life outside?
Related: The habitable exoplanet Trappist-1 may have been caught destroying its own atmosphere
LIFE’s primary target is rocky or terrestrial planets similar in size and temperature to Earth. It is being built to receive thermal emissions from these worlds and use their light spectra to determine the elements and chemicals in their atmosphere.
This could be done because elements and compounds absorb and emit light at specific wavelengths. This means that light passing through the planet’s atmosphere, perhaps from a star or in the form of thermal radiation, will carry the spectral fingerprint of those chemicals. This would also apply to so-called “biomarker” molecules, such as methane, which are often produced by the biological processes of living things.
“Our goal is to detect chemical compounds in the light spectrum that indicate life on the exoplanets,” said Sascha Quanz, leader of the LIFE initiative, in a statement.
A distant world
Instead of testing LIFE’s capabilities using the simulated light spectrum of an exoplanet, the team behind this research decided to validate the mission using the only planet where life has been found. That is our planet, Earth.
The team took data from NASA’s Aqua Earth observation satellite and used it to create the mid-infrared emission spectrum that would be expected from Earth if it were viewed as an unobserved speck from a great distance. Far away, the beautiful mountains and blue seas of our planet would be unrecognizable.
The team then averaged the spectrum, and considered how seasonal fluctuations and the geometry of our planet would affect the result. The researchers accounted for three possible views, two from the Earth’s poles and one from its equator. They also focused on data collected between January and July 2017 to calculate seasonal variations.
The team concluded that if LIFE or a similar instrument were to observe Earth from as far away as 30 light years, it would succeed in determining that our planet is a warm, habitable world. The team also determined that atmospheric gases such as carbon dioxide, methane and water, which are important for life or created by life, would be visible in the spectrum of our planet.
Therefore the conditions necessary for our planet to support liquid water on its surface would be shown when observing the Earth from a distance with a telescope like LIFE.
Related Stories:
— An exoplanet in the Trappist-1 system is more likely to be habitable than scientists once thought, according to a study
— TRAPPIST-1 solar system not bombarded by space rocks like early Earth, study finds
— The James Webb Space Telescope could help search for habitable alien life
The team found that the same results were delivered regardless of geometry, which is positive because scientists will not know the geometry of the exoplanets seen by LIFE. However, less reassuringly, they also found that seasonal variations would not be observed in detail in LIFE.
“Even if atmospheric seasonality is not easily observed, our study shows that next-generation space missions can assess whether nearby temperate terrestrial exoplanets are habitable or even inhabited,” Quanz said.
The team’s research was published on Monday (February 26) in The Astrophysical Journal.
