If aliens had our life hunting equipment, could they find us?

By | March 5, 2024

After doing quite a bit of research, scientists have come to a conclusion that may sound redundant: life could exist on Earth.

Of course, you’re probably thinking, “Well, duh.” In fact, it may feel more accurate to say that life do exists on earth – and not only that could be. But here’s the thing. The team’s conclusion is not the focus of the investigation. It’s just a means to an end. The plot of this story is precisely in precise Why these scientists achieved the result.

People are fascinated by the possibility of discovering life on planets outside the solar system, also known as exoplanets. To look at things from a different perspective, this team of researchers wondered what life and habitability on Earth would be like for an alien who saw our world as an exoplanet. How can they spy on us from a distance? What would be an indication to them that our planet is occupied?

These questions go far beyond philosophical musings. There is also a practical use for the answers. They will be used to validate an upcoming space mission called the Large Interferometer for Exoplanets or ‘LIFE’ mission, which will hunt for habitable exoplanets. The mission will consist of five spacecraft forming a single mid-infrared interferometer. They will sit relatively close to the James Webb Space Telescope (JWST) in an orbit around the sun known as Lagrange Point 2, or L2.

So the team, from ETH Zurich, has converted the technology that will support LIFE back to Earth to confirm that the mission will indeed be able to hunt for life on distant worlds when it launches in late 2026 or early 2027. cannot confirm life on earth, how could it confirm life outside?

Related: Possibly habitable exoplanet Trappist-1 destroying its own atmosphere

LIFE’s primary targets will be rocky or terrestrial planets similar in size and temperature to Earth. It is being built to capture the thermal emissions from these worlds and use their light spectra to deduce what elements and chemicals are in their atmospheres.

This would be possible because elements and compounds absorb and emit light at characteristic wavelengths. This means that light passing through a planet’s atmosphere, perhaps from a star or in the form of thermal radiation, carries with it spectral fingerprints 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 exoplanets,” Sascha Quanz, leader of the LIFE initiative, said in a statement.

Earth from afar

Instead of testing LIFE’s capabilities using simulated light spectra associated with an exoplanet, the team behind this research decided to validate the mission by using the only planet on which life has been discovered. That is our planet, the earth.

The team collected 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 seen as a modest speck from far away. At such a distance, our planet’s beautiful mountains and blue seas would be indistinguishable.

The team then averaged the spectra and considered how the result would be affected by seasonal variations and the geometry of our planet. The researchers were responsible for three possible views, two from the Earth’s poles and one from the equator. They also focused on data collected between January and July 2017 to calculate seasonal variations.

NASA's EPIC camera aboard the DSCOVR spacecraft captured this photo of the October 14, 2023 annular solar eclipse from a distance of nearly 1.6 million kilometers.NASA's EPIC camera aboard the DSCOVR spacecraft captured this image of the October 14, 2023 annular solar eclipse from a distance of nearly 1.6 million kilometers.

NASA’s EPIC camera aboard the DSCOVR spacecraft captured this photo of the October 14, 2023 annular solar eclipse from a distance of nearly 1.6 million kilometers.

The team concluded that if LIFE or a similar instrument were to observe Earth from as far away as 30 light-years, it could successfully determine that our planet is a warm, habitable world. The crew also determined that atmospheric gases such as carbon dioxide, methane and water, all important to or created by life, would be visible in our planet’s spectra.

A remote observation of Earth through a LIFE-like telescope would therefore reveal the conditions necessary for our planet to support liquid water on its surface.

Related stories:

– Research shows that exoplanets in the Trappist-1 system are more likely to be habitable than scientists once thought

– The TRAPPIST-1 solar system isn’t bombarded by space rocks like early Earth, research suggests

– James Webb Space Telescope could help in the hunt for habitable alien worlds

The team found that the same results were achieved regardless of geometry, which is positive news because scientists won’t know the geometry of the exoplanets that LIFE observes. Less positively, however, they also found that seasonal variations would not be observed in detail by LIFE.

“Even though seasonality in the atmosphere is not easy to observe, our research shows that next-generation space missions can assess whether nearby exoplanets with temperate climates are habitable or even inhabited,” Quanz concludes.

The team’s research was published Monday (Feb. 26) in The Astrophysical Journal.

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