A recent study on the evolution of comets suggests that objects in deep space, such as Kuiper belt object 486958 Arrokoth, may act as time capsules preserving ancient ice from billions of years ago. A new study shatters what scientists thought they knew about distant objects at the farthest reaches of the solar system, starting with an object called the ‘cosmic snowman’.

Researchers from Brown University and the SETI Institute have discovered that the two snowman-like winged objects, officially named Kuiper Belt Object 486958 Arrokot, may have ancient ice stored deep from the time it formed billions of years ago. But this is only the beginning of their exploration.

Using the new model they developed to study the evolution of comets, the researchers found that this persistence is evident not only in Arrokot, but also in the outermost regions of the Solar System, dating back to B.C. The initial formation of the Solar System, about 4.6 billion years ago, may have included the ancient ices from which they formed.

“In our study, we showed with a pretty simple mathematical model that you can keep these primitive ices deep inside these objects for very long periods of time,” said Sam Birch, a planetary scientist at Brown and one of the paper’s authors. . “Many of our community believed that this ice had long since disappeared, but we now believe that may not be the case.”

Birch describes her work in the magazine Icarus With co-author Orkan Umurkhan, senior scientist at the SETI Institute.

Re-evaluation of thermal evolution models

So far, it has been difficult for scientists to figure out what will happen to the ice on these space rocks over time. The study questions commonly used models of thermal evolution, which fail to explain the lifespan of ice, which is as sensitive to temperature as carbon monoxide. The model the researchers created for the study explains this change and suggests that the highly volatile ice in these objects persists much longer than previously thought.

“We’re essentially saying that Arrokoth is extremely cold, and in order for more ice to sublimate (or to go directly from solid phase to gas, bypassing the liquid phase inside it), the gas it sublimes has to escape through the pores. It’s like a sponge inside,” Birch said. “The focus is that to move the gas you also have to sublimate the ice, so you get a domino effect: the air gets colder in Arrokot, the ice sublimes less, less gas moves, it gets colder, etc. Eventually everything shuts down and What you’re left with is an object filled with gas, slowly leaking out.”

The study suggests that Kuiper belt objects may behave like inert “ice bombs”, storing volatile gases within themselves for billions of years until orbital changes bring them closer to the Sun and heat makes them unstable. This new idea could help explain why these icy objects in the Kuiper Belt explode so violently when they first approach the sun. Suddenly, the cold gas inside them rapidly compresses and these objects turn into comets.

“The important thing is that we corrected a deep flaw in the physical model that people had assumed for decades for these very cold and old objects,” said Umurkhan, Birch’s co-author of the paper. “This study may be an impetus for a re-evaluation of the theory of comet internal evolution and activity.”

Overall, the research challenges current predictions and opens new avenues for understanding the nature and origins of comets. Birch and Umurkhan are co-investigators on NASA’s Comet Astrobiology Research Sample Return (CAESAR) mission, which aims to retrieve at least 80 grams of surface material from Comet 67P/Churyumov-Gerasimenko and return it to Earth for analysis.

The results of this study can help deepen our understanding of the evolution and activity of comets by helping CAESAR determine research and sampling strategies.

“There may be vast reservoirs of these primitive materials trapped in small bodies throughout the outer solar system, materials that are waiting to explode for us to observe, or are sitting in the deep freeze until we can retrieve them and bring them home to Earth,” Birch said.