NASA image of a super-Earth exoplanet

We’re creating alien atmospheres in a lab to see how likely we are to find aliens 

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Apr 9, 2018

Because E.T. isn’t going to phone home anytime soon, the latest way to determine whether there could be life (at least life as we know it) on distant exoplanets has just emerged from a lab.

Atmospheric haze may be able to tell us how likely it is we could find organisms crawling on a planet besides earth. Johns Hopkins University assistant professor of Earth and Planetary Sciences Sarah Hörst and colleagues recently conducted a study, published in Nature Astronomy, that simulated the atmospheres of distant worlds and could indicate whether or not they may be spawning life.

“One of the reasons why we’re starting to do this work is to understand if having a haze layer on these planets would make them more or less habitable,” Hörst said.

Even the powerful vision of telescopes can’t always penetrate a planet’s haze. Because those nebulous clouds of haze are actually solid particles floating around in gas, the particles mess with the spectral fingerprints created when light interacts with that gas. Telescopic eyes must proverbially squint to be able to tell which gases and how much of of them are swirling in an exo-atmosphere. Even Hubble would get a headache from this.

“Each gas has a fingerprint that’s unique to it,” Hörst explained. “If you measure a large enough spectral range, you can look at how all the fingerprints are superimposed on top of each other.”

creating exoplanet atmospheres in a lab

Sarah Hörst and colleague Chao He creating far-out atmospheres here on Earth. Credit: Johns Hopkins University

If a telescope is not able to accurately make out these fingerprints through the fog, it could mean that scientists are missing out on planets that are potentially habitable. The super-Earths and mini-Neptunes that orbit outside of our solar system are more difficult to zoom in on and search for signs of what could be life.

Enter Hörst’s lab-conjured atmospheres that sought to answer the question of which alien atmospheres would end up being hazy. Her team brought exoplanets to earth by using computer models that proposed different percentages of dominant gases (carbon dioxide, hydrogen, and helium) and other gases (helium, carbon monoxide, methane, and nitrogen), heated at three sets of temperatures in a chamber, to create nine possible “planets.” Each heated mass of particles had chemical reactions initiated within that chamber as it flowed through a discharge of plasma.

Haze occurred in all nine, but what the team wasn’t expecting was that the water-dominant variants produced the most haze. What surprised Hörst was that the methane atmospheres were not the haziest, because there was a long-standing idea that methane was the ultimate ingredient in making a haze. The particles also turned different colors, and besides sounding amazing cool, this told the scientists how much heat a haze could trap.

“Having a haze layer can change the temperature structure of an atmosphere,” said Hörst. “It can prevent really energetic photons from reaching a surface.” She did acknowledge that we still have a long way to go when it comes to figuring out which actual atmospheres out there are hazy and the impact of those haze particles.

This is just the beginning of haze research that could help anyone analyzing data from the James Webb Space Telescope n the near future know what to look for. Aliens? Maybe.

(via Johns Hopkins University)