Just shy of two months after its historic flyby, New Horizons has finally delivered the most detailed image of its target, Kuiper Belt object 2014 MU69, aka Ultima Thule. The image was not easy to obtain as the spacecraft passed the distant world at a speed of 14.3 kilometers (8.88 miles) per second.
The image was snapped just 6.5 minutes before the closest approach. The picture has an incredible resolution of about 33 meters (110 feet) per pixel, showing important details of the distant object’s surface. The team dubbed these observations the “stretch goal” because they were extremely difficult to achieve. MU69 is only 31 kilometers (19 miles) across so there was a chance that as the spacecraft whizzed past, the tiny world might fall out of the camera's narrow field of view.
"Getting these images required us to know precisely where both tiny Ultima and New Horizons were – moment by moment – as they passed one another at over 32,000 miles per hour in the dim light of the Kuiper Belt, a billion miles beyond Pluto. This was a much tougher observation than anything we had attempted in our 2015 Pluto flyby,” New Horizons Principal Investigator Alan Stern, of the Southwest Research Institute (SwRI), said in a statement.
"These 'stretch goal' observations were risky, because there was a real chance we'd only get part or even none of Ultima in the camera's narrow field of view," he continued. "But the science, operations and navigation teams nailed it, and the result is a field day for our science team! Some of the details we now see on Ultima Thule's surface are unlike any object ever explored before."
The image gives us a better look at the curious features that have come into focus since the flyby on New Year’s Day. These include circular bright patches in the terrains as well as bright stripes across both lobes and around the object's “neck”. There are also dark pits seen near the boundary between day and night, whose history is at this time unclear.
"Whether these features are craters produced by impactors, sublimation pits, collapse pits, or something entirely different, is being debated in our science team," added John Spencer, deputy project scientist at the SwRI.
This image is the highest resolution picture taken by New Horizons and even if the mission is extended and another suitable object to visit is found, it might not get anything sharper than this. New Horizons flew just 3,500 kilometers (2,200 miles) above MU69, three times as close to this distant world as it got to Pluto in July 2015.
The spacecraft is now nearly 6.64 billion kilometers (4.13 billion miles) from Earth and the full data set of observations of MU69 will continue to be downloaded until September 2020.