A new 'atmospheric disequilibrium' could aid researchers in detecting alien life on distant planets in the cosmos.
According to a new study by scientists from the University of Washington, a simple approach to look for life might be more promising than just searching for oxygen.
The recently published study offers a revolutionary new recipe that could help astronomers find evidence whether or not a distant planet may harbor life.
"This idea of looking for atmospheric oxygen as a biosignature has been around for a long time. And it’s a good strategy — it’s very hard to make much oxygen without life,” said corresponding author Joshua Krissansen-Totton, a UW doctoral student in Earth and space sciences. “But we don’t want to put all our eggs in one basket. Even if life is common in the cosmos, we have no idea if it will be life that makes oxygen. The biochemistry of oxygen production is very complex and could be quite rare."
The new technique has experts looking for a gas mixture that includes abundant methane and carbon dioxide but lacks carbon monoxide.
To come up with the new technique, scientists from the University of Washington looked back at the history of life on Earth and searched for times when Earth's atmosphere had a mixture of gases that were out of equilibrium, which could only be present if there were living organisms on Earth.
Researchers note in the article that life's ability to produce vasts amount of oxygen can be traced back relatively recently, to one-eighth of Earth’s history.
This is why scientists decided to look back further and identified a new combination of gasses that may help scientists find traces of life on other planets: methane plus carbon dioxide, minus carbon monoxide.
"We need to look for fairly abundant methane and carbon dioxide on a world that has liquid water at its surface, and find an absence of carbon monoxide," said co-author David Catling, a UW professor of Earth and space sciences.
"Our study shows that this combination would be a compelling sign of life. What’s exciting is that our suggestion is doable, and may lead to the historic discovery of an extraterrestrial biosphere in the not-too-distant future."
The new study offers a revolutionary new way by which scientists can hunt for aliens.
The paper looks at different ways a planet can produce methane, and scientists take into consideration asteroid impacts, outgassing from the planet’s interior, reactions of rocks and water, discovering that it would be extremely difficult to produce methane on rocky, Earth-like planets without the presence of living organisms.
Researchers note that if methane and carbon dioxide are detected together on a planet, and without the presence of carbon monoxide, then that is a chemical imbalance that suggests there is life.
"Carbon monoxide is a gas that would be readily eaten by microbes,” Krissansen-Totton said. “So, if carbon monoxide were abundant, that would be a clue that perhaps you’re looking at a planet that doesn’t have biology."