2014 MU69: New Horizons Space Mission Discovers Distant Object in Kuiper Belt Rich in Complex Sugars

Organics formed in a distant world in the Kuiper Belt indicate that it is rich in sugars with a surprising amount of methanol.

Beyond the Solar System

In 2015, the New Horizons space mission became the first spacecraft to approach Pluto up close, exploring the dwarf planet and its moons. On January 1, 2019, it passed 2014 MU69, located around 4 billion miles (6.4 billion kilometers) from Earth in the Kuiper Belt, a region of icy cosmic bodies beyond Neptune.

Formerly known as Ultima Thule, 2014 MU69 was discovered on June 26, 2014 using NASA's Hubble Space Telescope. It was given the minor planet number 485968 and was nicknamed Arrokoth which means "sky" in the Native American term.

The New Horizons mission's flyby provided detailed images and data of Arrokoth which is considered to be the most distant object ever reached. Arrokoth was found to have a distinctive reddish color. As a matter of fact, it is the reddest object in the outer solar system visited by a spacecraft thus far.

A Sugar World

In a recent study, it was revealed that Arrooth contains significant amounts of organic molecules such as complex sugars. In the paper "Ionizing radiation exposure on Arrokoth shapes a sugar world," the researchers offer new insights into the chemical process that took place on early Earth and the early Solar System.

Led by planetary scientist Alan Stern, the research team from the Southwest Research Institute analyzed data from the New Horizons and linked Arrokoth's red color to the presence of complex organic molecules. These molecules include water ice, methanol, and different types of carbon-rich compounds.

When exposed to cosmic rays, methanol ice on Arrokoth was found to create a variety of organic compounds like sugars (ribose and glucose). This suggests that over billions of years, the surface of Arrokoth has undergone crucial chemical processing, which transformed simple molecules into more complex ones.

According to study co-author Will Grundy, it is amazing to see a distant cosmic object so well preserved that its appearance reveals the details of its formation from a set of building blocks which are very similar to one another. The discovery of these molecules is also considered important in understanding the chemical process that might have contributed to the emergence of life on our planet.

There are also mounds found on the surface of Arrokoth, which are large relative to the object itself. Scientists believe that these mounds are some of its original building blocks. Such features offer important clues regarding the conditions and processes that were present in the early Solar System.

As Stern noted, if the mounds are indeed representative of the building blocks of early planetesimals like Arrokoth, the planetesimal formation models need to explain the preferred size for the building blocks.

The New Horizons spacecraft continues to provide information that can widen our understanding of the Kuiper Belt and its objects. It is expected to explore additional targets in the Kuiper Belt in order to expand our understanding of the early Solar System.