NASA's New Horizons unravels mysteries of Ultima Thule

LOS ANGELES, March 18 (Xinhua) -- NASA's news.cn/en/tag/i0xngaj3163f76200c981b/index.html" target="_blank">new Horizons mission team on Monday unraveled mysteries of the Kuiper Belt object (KBO) nicknamed Ultima Thule, the most distant object ever explored by mankind.

news.cn/en/tag/i0xngaj3163f76200c981b/index.html" target="_blank">new Horizons performed the farthest flyby in history at 12:33 a.m. EST (0533 GMT) on news.cn/en/tag/i0xngaj3163f76200c981b/index.html" target="_blank">new Year's Day, as it approached Ultima Thule within 2,200 miles (about 3,540 km) of the surface at a velocity of 31,500 miles (about 50,694 km) per hour.

Analyzing the data news.cn/en/tag/i0xngaj3163f76200c981b/index.html" target="_blank">new Horizons has been sending home since the flyby, mission scientists are learning more about the formation, geology and composition of this ancient relic of solar system formation, said a NASA release.

Ultima Thule is the first unquestionably primordial contact binary ever explored, said the mission team. Approach pictures of Ultima Thule hinted at a strange, snowman-like shape for the binary, but further analysis of images taken near closest approach uncovered the object's unusual shape.

Ultima Thule consists of a large and flat lobe (nicknamed "Ultima") connected to a smaller and rounder lobe (nicknamed "Thule").

"We've never seen anything like this anywhere in the solar system," said news.cn/en/tag/i0xngaj3163f76200c981b/index.html" target="_blank">new Horizons Principal Investigator Alan Stern. "It is sending the planetary science community back to the drawing board to understand how planetesimals - the building blocks of the planets - form."

Scientists believe Ultima Thule's two lobes once orbited each other, like many so-called binary worlds in the Kuiper Belt, until something brought them together in a "gentle" merger.

The "neck" connecting Ultima and Thule is bent, and could indicate shearing as the lobes combined, said Kirby Runyon, a news.cn/en/tag/i0xngaj3163f76200c981b/index.html" target="_blank">new Horizons science team member.

In terms of color and composition, Ultima Thule is very red - redder even than Pluto, which news.cn/en/tag/i0xngaj3163f76200c981b/index.html" target="_blank">new Horizons flew past on the inner edge of the Kuiper Belt in 2015, and about the same color as many other so-called "cold classical" KBOs, said the team.

news.cn/en/tag/i0xngaj3163f76200c981b/index.html" target="_blank">new Horizons scientists have also seen evidence for methanol, water ice and organic molecules on the surface.

Currently the news.cn/en/tag/i0xngaj3163f76200c981b/index.html" target="_blank">new Horizons spacecraft is 4.1 billion miles (6.6 billion kilometers) from Earth, operating normally and speeding deeper into the Kuiper Belt at nearly 33,000 miles (53,000 kilometers) per hour.