Saturn moon gives clues about early life on Earth

Scientists conduct lab experiments based on conditions in Titan’s atmosphere measured last year by Huygens probe
Will Dunham Washington :

Billions of years ago, Earth may have been shrouded in a blanket of atmospheric haze like that seen on Saturn’s moon Titan, providing organic material that

nourished our planet’s earliest life forms, researchers said on Monday.
Some scientists look to Titan as a model for what early Earth’s atmosphere may have looked like. They think Titan’s atmosphere, packed with organic aerosol

particles created when sunlight reacts with methane gas, may offer clues about Earth’s climate when primitive organisms were first arising 3.6 billion years

ago.

University of Colorado scientist Margaret Tolbert and her colleagues conducted lab experiments based on conditions in Titan’s atmosphere measured last year

by the Huygens space probe.

They irradiated methane gas with an ultraviolet lamp, then mixed in carbon dioxide to see whether conditions that may have existed eons ago on Earth could

yield a comparable organic haze.

They found that such a haze formed in the lab using various methane and carbon dioxide concentrations. Tolbert said the chemical composition of the haze was

organic molecules that are digestible to organisms alive today and could have nourished simple living organisms along ago.

“That would have been a food source for any budding life,” Tolbert said. “And it would have been, importantly, a global food source. And so life could have

thrived in every puddle.” Scientists previously have concentrated on isolated, extreme environments such as hydrothermal vents bursting with energy and

nutrients to understand primordial life.

Beyond merely providing a food source for early life forms, this organic haze also may have played a role in providing the very building blocks needed for

living organisms to first form, Tolbert said.

Earth was formed perhaps 4.6 billion years ago and liquid water was present about 3.8 billion years ago. Tolbert said this haze may have been a dominant

feature of Earth’s early atmospheric landscape from about the time of the first evidence of life 3.6 billion years ago until the rise of the oxygen content

about 2.3 billion years ago.

The thick haze not only may have nourished organisms, but may have protected them from harmful ultraviolet rays.

The haze may have placed more than 100 million metric tons of organic material on Earth’s surface annually, the study estimated.

Titan factfile Titan is the largest moon of Saturn and is about 1.5 times larger than Earth’s moon.

Titan was discovered on March 25, 1655 by Christiaan Huygens and was the first satel lite in the Solar System to be discovered after Jupiter’s moons.

It is the only moon in our solar system to have a dense atmosphere.

Scientists look to Titan as a model for what early Earth’s atmosphere may have looked like 3.6 billion years ago.

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