A series of images from NASA's New Horizons spacecraft contains important scientific information on the actual shape of the Kuiper Belt object, Ultima Thule (2014 MU69). These images represent the final views taken by New Horizons on Ultima Thule during a race at over 50,000 km / h on January 31, 2019.
Members of the New Horizons team created this & # 39; starting movie & # 39; from 14 different images taken by the LORRI (Long Range Recognition Imager) instrument of New Horizons, shortly after the passage of the probe in Ultima Thule on 1 January 2019. The central frame of this sequence was taken at 05 : 42: 42 GMT (00:42 EST), when New Horizons was 8,892 km beyond Ultima Thule, some 6.6 billion km from the Earth. The bright crescent of the object is blurred in the individual images because a relatively long exposure time was used during this fast scan to increase the signal level of the camera. However, the team combined and processed the images to remove the blur and accentuate the thin crescent. It is the most distant film of all the objects of our solar system ever made by a spaceship. The images reveal an outline of the "hidden" part of Ultima Thule that was not illuminated by the Sun when the spacecraft was zipped, but can be "traced" because it was blocking the view to the stars in the background. Image credit: NASA / Johns Hopkins Applied Physics Laboratory / Southwest Research Institute / National Observatory of Optical Astronomy.
In the first close-up images of Ultima Thule – with its two distinct and apparently spherical segments (lobes) – observers called him a "snowman".
However, further analysis of the approach images and these new images changed this view, in part by revealing an outline of the part of the object that was not illuminated by the Sun. but that could be "drawn" because it blocked the view in the background. stars.
Now members of the New Horizons team can confirm that both lobes of Ultima Thule are not spherical.
The largest lobe, Ultima, looks more like a giant pancake and the smaller lobe, Thule, has the shape of a battered walnut tree.
"It's really an incredible sequence of images taken by a spaceship exploring a small world 4 billion kilometers from Earth. Nothing like it has ever been captured in the images, "said Dr. Alan Stern, principal investigator at New Horizons, a researcher at the Southwest Research Institute.
The scientists' understanding of Ultima Thule changed as they examined additional data. The "old view" of this illustration is based on images taken on January 1, 2019, approaching the day closest to the object of New Horizons, suggesting that "Ultima" is the "oldest view" of this illustration. (the largest lobe) and & # 39; Thule & # 39; (the smallest lobe) were almost perfect spheres barely touching each other. But as more data were analyzed, including several highly evocative images of the crescent taken close to 10 minutes after the closest approach, a "new view" of the shape of the object appeared. Ultima looks more like a "pancake" and Thule a "bumpy walnut". The bottom view is the team's best current form template for Ultima Thule, but there is still some uncertainty, with an entire region essentially obscured and not lit by the sun while flying over New Horizons. The dashed blue lines cover the uncertainty of this hemisphere, which shows that the Ultima Thule may be flatter or flatter than the one shown in this figure. Image credit: NASA / Johns Hopkins Applied Physics Laboratory / Southwest Research Institute.
"We had an impression of Ultima Thule based on the limited number of images returned in the days that followed, but having more data dramatically changed our vision."
"It would be closer to the reality to say that Ultima Thule's shape is flatter, like a pancake. But more importantly, the new images create scientific puzzles on how such an object could even be formed. We have never seen anything like that in orbit around the Sun. "
"While the very nature of a quick flyby somehow limits the actual ability to determine the actual shape of Ultima Thule, the new results clearly show that Ultima and Thule are much flatter than we originally thought, and much flatter than expected, "said New Hal Weaver, Horizons Project Scientist, a researcher at Johns Hopkins Applied Physics Lab.
"This will undoubtedly motivate new theories about planetesimal formation at the beginning of the solar system."