Ultima Thule does not look like Snowman.
Recent photos taken by NASA's New Horizons probe during Ultima Thule's January 1 flyby show that the distant object is far flatter than scientists thought, mission team members announced today ( 8th of February).
"We had an impression of Ultima Thule based on the limited number of images returned in the flyby days, but seeing more data has significantly changed our vision," New's lead investigator said Horizons, Alan Stern from the Southwest Research Institute in Boulder, Colorado. [New Horizons at Ultima Thule: Full Coverage]
"It would be closer to reality to say that the shape of Ultima Thule is flatter like a pancake," Stern added. "Above all, the new images create scientific puzzles about how such an object could be formed, and we've never seen anything like this orbiting the sun."
New Horizons' $ 720 million mission began in January 2006 to complete Pluto's first ever flyby. The probe triggered this encounter in July 2015, revealing the dwarf planet as a spectacularly diverse world with surprisingly diverse and harsh landscapes.
New Horizons then launched an expanded mission that focused on a near flyby of Ultima Thule officially known as the 2014 MU69. This object is approximately 34 kilometers long and is located 1 billion kilometers behind the orbit of Pluto. (Ultima is currently 4.1 billion miles or 6.6 billion kilometers from Earth.)
Initial images taken by New Horizons indicated that Ultima Thule is shaped like a bowling pin. However, this impression changed shortly before the next approach, which occurred shortly after midnight on New Year's Day and brought the probe within 3.540 km of the mysterious body. Photos from this period show that Ultima Thule consists of two lobes, both appearing roughly spherical.
A snowman with a distinct reddish hue.
The newly published images, however, have called for further rethinking. New Horizons took the long exposure photos about 10 minutes after approach; The central frame in the sequence was ripped from a distance of 8,894 km, so the members of the mission team.
The new views were shot from a different angle than the images the snowman suggested, and Ultima Thule's outlines show a number of background stars. When they realized which of these stars was getting dark when Ultima faded them out, mission scientists could determine the (surprisingly flat) shape of the object.
"This is truly an incredible sequence of images taken by a spaceship exploring a small world 4 billion miles from Earth," said Stern. "Nothing like that has ever been captured in pictures."
Although the newly published images are the last ones New Hawkes has taken from Ultima, they are far from the last data we'll see from the probe. Mission team members have said that New Horizons has to send home all its images and measurements in flyby.
And Ultima Thule may not be the final flyby target of the probe. New Horizons is in good health and has enough fuel to zoom in from a distant location if NASA grants another mission extension, Stern said. (The current expanded mission runs until 2021.)
Mike Wall's book on the search for extraterrestrial life "Out There" (Grand Central Publishing, 2018, illustrated by Karl Tate) has now appeared. Follow him on Twitter @michaeldwall . Follow us @SpaceTotcom or Facebook. Originally published on Space.com.