NASA's New Horizons mission reveals entirely new kind of world

"This flyby is a historic achievement," said New Horizons Principal Investigator Alan Stern of the Southwest Research Institute in Boulder, Colorado. "Never before has any spacecraft team tracked down such a small body at such high speed so far away in the abyss of space. New Horizons has set a new bar for state-of-the-art spacecraft navigation."

The new images -- taken from as close as 17,000 miles (27,000 kilometers) on approach -- revealed Ultima Thule as a "contact binary," consisting of two connected spheres. End to end, the world measures 19 miles (31 kilometers) in length. The team has dubbed the larger sphere "Ultima" (12 miles/19 kilometers across) and the smaller sphere "Thule" (9 miles/14 kilometers across).

The team says that the two spheres likely joined as early as 99 percent of the way back to the formation of the solar system, colliding no faster than two cars in a fender-bender.

"New Horizons is like a time machine, taking us back to the birth of the solar system. We are seeing a physical representation of the beginning of planetary formation, frozen in time," said Jeff Moore, New Horizons Geology and Geophysics team lead. "Studying Ultima Thule is helping us understand how planets form -- both those in our own solar system and those orbiting other stars in our galaxy."

Data from the New Year's Day flyby will continue to arrive over the next weeks and months, with much higher resolution images yet to come.

"In the coming months, New Horizons will transmit dozens of data sets to Earth, and we'll write new chapters in the story of Ultima Thule -- and the solar system," said Helene Winters, New Horizons Project Manager.

The Johns Hopkins Applied Physics Laboratory in Laurel, Maryland, designed, built and operates the New Horizons spacecraft, and manages the mission for NASA's Science Mission Directorate. The Southwest Research Institute, based in San Antonio, leads the science team, payload operations and encounter science planning. New Horizons is part of the New Frontiers Program managed by NASA's Marshall Space Flight Center in Huntsville, Alabama.

Follow the New Horizons mission on Twitter and use the hashtags #UltimaThule, #UltimaFlyby and #askNewHorizons to join the conversation. Live updates and links to mission information are also available on http://pluto.jhuapl.edu and www.nasa.gov.