An Icy Comet May Have Kick-Started Life on Earth

Icy comets likely helped life 'find a way' on Earth.
Brad Bergan

Way back in 2016, a tiny icy wanderer from the fringes of our solar system shot past Earth at incredible speeds. During its flyby, it was momentarily visible to stargazers — called Comet Catalina — before it slingshotted around the sun, and disappeared from us forever.

However, using NASA's plane-based telescope called Stratospheric Observatory for Infrared Astronomy (SOFIA), scientists detected a crucial fingerprint of life, according to a recent study published in the Planetary Science Journal.

Within the dusty majesty of the comet's tail, SOFIA detected carbon.

An icy comet may have kick-started life on Earth

This single-serving visitor to the inner solar system is helping scientists come to understand the origins of life on Earth — as it's become likely that comets like Catalina may have played an essential role as a primary source of carbon on planets like Earth and Mars during the very young era of our solar system.

"Carbon is key to learning about the origins of life," said Charles "Chick" Woodward, lead author on the paper, in a NASA blog post. Woodward is also an astrophysicist and professor at the University of Minnesota's Minnesota Institute of Astrophysics — based in Minneapolis.

"We're still not sure if Earth could have trapped enough carbon on its own during its formation, so carbon-rich comets could have been an important source delivery this essential element that led to life as we know it," added Woodward.

Primordial Earth was too hot to retain carbon

Comet Catalina came from the Oort could on the farthest fringes of the solar system — where similar comets have long, elliptical orbits that cause them to enter our proverbial doorstep with little-to-no interference in their cosmic trajectory. This makes them a celestial time capsule in space, giving researchers a rare chance to study the conditions of the early solar system during which the comets formed.

The infrared observations from SOFIA provided data on the composition of dust and gas as it evaporated off of the comet's surface, creating the tail. These observations revealed that Comet Catalina is rich in carbon, which means it formed in the outer regions of the primordial solar system, which contained a reservoir of carbon that may have been critical to seeding the origin of life on Earth.

Carbon is an essential ingredient of life, but the young Earth and other terrestrial planets of this era of the inner solar system were so indescribably hot from the perils of formation that elements like carbon were simply lost, or depleted.

Comets like Catalina may have also seeded Mars

Researchers think a minor shift in Jupiter's orbit enabled small, early precursors of comets to mix carbon from outer regions into inner ones, where it was then pulled into planets like Mars and Earth. Comet Catalina's carbon-heavy composition helps show how planets forming in hot, carbon-lacking regions of the young solar system were able to evolve into rich, life-supporting environments.

"All terrestrial worlds are subject to impacts by comets and other small bodies, which carry carbon and other elements," said Woodward, in the blog post. "We are getting closer to understanding exactly how these impacts on early planets may have catalyzed life."

Without carbon, life as we know it would never have evolved on Earth. We've yet to confirm the existence of life on Mars, but since we know it has salty, subsurface lakes and suspect it once had oceans, life may be in the cards for the Red Planet. And if life found a way, it might have comets like Catalina to thank for seeding it with carbon, just like us.

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