Just hours before the historic event with Ultima Thule, the farthest object ever visited by the spacecraft, scientists with NASA's New Horizons mission received a first glimpse into their goal.
By Sunday, a distant body located more than one and a half kilometers away from Pluto, appeared as no more than one pixel in the spacecraft's camera. But by Monday, with the New Horizons investigation, still closer to a speed of 14.4 kilometers per second, Ultima Thule finally began to reveal its form.
"We know it's not rounded up – that's one thing we can say with certainty," said John Spencer, a member of the mission's scientific team, during a briefing Monday afternoon at the Laurel Laboratory of Physics Laboratory, MD, which is headquarters for New Horizons.
Dr. Spencer, who is with the Boulder Southwest Research Institute, Colo., Confirms that the latest picture reveals that Ultima Thule is an elongated body, about 30 kilometers long, although it is not yet clear whether it is a single object or two or more in contact .
The image was taken on Sunday, when the spacecraft was still 1.5 million kilometers from its 12:33 am ET rendezvous on January 1st. Due to the great distance of the Earth from the probe and the relative weakness of its signal, it takes several hours for scientists to receive and process the image.
The view is consistent with the information astronomers occupied for the object over the past two years, as they have noticed that the distant stars are passing in front and darkening. The version of the image with superimposed lines shows where the stars flickered while they passed behind Ultima Thule, and two red circles show how Ultima Thule will be oriented if it really is a pair of objects.
Scientists have been puzzled why Ultima Thule does not change in brightness, which would be expected from an elongated object that alternately shows its short and long sides while rotating.
JJ Kavelaars, a member of the scientific team and an astronomer with the National Research Council in Canada, said New Horizons have now confirmed that the subject turns, but it's still not clear at what speed.
The new horizons, flown by Pluto in 2015, are now on a mission to discover the Kuiperai belt, a region extending far from the outermost planets of our solar system and inhabited by tens of thousands of dark, frozen bodies more than 100 meters are relics from the formation of the solar system.