ON NEW YEAR’S day, NASA’s New Horizons spacecraft carried out a historic flyby of a distant object called Ultima Thule (pronounced “thoo-lee”), followed by beaming back of the first images Wednesday. It is the most distant object ever visited, which is one of the reasons that make the mission special.
Officially named (486958) 2014 MU69, it earned the nickname Ultima Thule following a public contest in 2018. It is located in the Kuiper Belt, a disc in the outer Solar System (beyond Neptune) that consists of small bodies including Pluto. 2014 MU69 was discovered in June 2014 by astronomers using the Hubble Space Telescope but is so distant that many of its characteristics remain to be understood.
Located about 6.5 billion kilometres from Earth, 2014 MU69 is believed to be a peanut-shaped space rock about 32 km long and 16 km wide. Its shape has given rise to the theory that it might actually be two rocks moving in tandem. It orbits the Sun once every 298 years.
In March 2018, NASA invited suggestions for a nickname for 2014 MU69. Out of 34,000 submissions, NASA chose Ultima Thule, which means “beyond the borders of the known world”.
In July 2018, scientists calculated that they would be able to see the object’s shadow from the southern tip of Argentina. They deployed a fleet of telescopes and at least five of them caught the shadow.
New Horizons, a space probe that was launched in 2006, became the first mission to visit Pluto in 2015. Travelling farther into the Kuiper Belt, the nuclear-powered space probe has come within 3,500 km of Ultima Thule.
Images taken revealed that the object may have a shape similar to a bowling pin, or a “snowman”, or a peanut spinning end over end, or could be two objects orbiting each other. Flyby data showed that Ultima Thule is spinning like a propeller with the axis pointing approximately toward New Horizons.
The mission will look for more exact details of the object’s size, shape, orbit and environment. The probe is important because it holds remnants from the birth of the Solar System. Many Kuiper Belt objects have remained unchanged for billions of years, and could provide clues to the history of the Solar System, and possibly the conditions that led to the evolution of a habitable world like Earth.
NASA released a composite of two images taken by New Horizons’ high-resolution Long-Range Reconnaissance Imager. The spacecraft will continue sending images and other data, completing the return of all science data over the next 20 months.