New data from New Horizons’ Arrokoth flyby hints at how planets formed – Astronomy Magazine
A view of MU69 (aka Arrokoth) from New Horizons, showing craters and intriguing hints of layering. The larger lobe appears to have a thick-pancake shape.
NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute/National Optical Astronomy Observatory
Coming together
Early data from New Horizons last year hinted at a gentle crash between the two lobes that make up Arrokoth, evidence for the collision theory of solar system formation.
But, says Stern, with ten times as much data and many months of computer modeling, they now see a different story, one that involves Arrokoth forming much more placidly.
“There are five different lines of evidence for cloud collapse,” he says, all pointing to the gentler formation theory. And if Arrokoth formed that way, it’s a sign the rest of the solar system’s building blocks may have also emerged from a cloud of dust, rather than from the violent collisions of countless objects.
“Arrokoth has provided a decisive test between the two,” Stern said during the press briefing. “I believe this is a game changer.”
With more of the data now on Earth, researchers are re-visiting their theories about this distant world. Arrokoth has a recognizable snowman shape, though the data seemed to indicate it might be flattened, more like two pancakes than two spheres. Updated observations show the pieces are still mostly round, and only slightly flattened.
The data also reinforces Arrokoth’s red hue, a feature it shares with many other distant solar system objects. Scientists think the red color is due to organic molecules similar to tholins, thought to be the building blocks of life.
Data on Arrokoth is still flowing from New Horizons to Earth, and won’t finish for another year and a half. But spacecraft managers sorted the data from highest priority to low, so it’s unlikely that data yet to be downlinked will dramatically change the picture.
In the future, mission planners would like to see New Horizons buzz by one more Kuiper Belt object on its trip out of the solar system. Stern says that unless the spacecraft malfunctions, it can continue collecting data until the late 2030s. But it should leave the Kuiper Belt in the late 2020s, so it has only a few years to scan the skies for its next target.
The new results were published in a series of papers February 13 in Science.
