More than just being dark, the surface of 2014 MU 69 is strongly red. New Horizons scientists created the composite color image at right by combining the visible-light and near-infrared map of 2014 MU 69 seen at left with a higher-resolution image from the spacecraft's LORRI camera at center, This composite emphasizes the overall red color of both lobes, as well as the relatively bright (and less-red) ring of material around the object's "neck". So far, investigators can only guess how and when it got there. The evidence suggest a gentle merger - there are no "splat" deposits or stress fractures, for example - and the contact is girded by a thin "collar" that's both brighter and less red than elsewhere. Much of the team's attention has focused on the narrow "neck" where the two lobes join. (This is a close match to the reflectivity of the Moon.) The brighter spots might mark the locations of degraded impacts, but the "high-Sun" illumination makes it difficult to know if they're depressions or something else. Overall both lobes are dark, 7% reflective on average with a few brighter spots here and there. In fact, a large depression on Thule that the team has dubbed Maryland might be the only large crater in view. The two lobes have a lumpy uneven texture that investigator Kirby Runyon (also at SwRI) likens to round loaves of "monkey bread." A few small pits appear around the edges, but overall the surface isn't heavily cratered. But as more images reached Earth, it became clear that both lobes have a flattened shape, with the larger one (dubbed "Ultima") more so than somewhat smaller "Thule." A Flattened SnowmanĮarly returns from New Horizons revealed an object 35 km (21 miles) long with two like-sized lobes that resembled a backyard snowman. So, crucially, the spacecraft had the good fortune to examine a pristine relic that formed at the outer fringe of the solar nebula 4½ billion years ago. This body has a dynamically "cold" orbit: Its low inclination and eccentricity suggest that nothing has perturbed its motion significantly. Most intriguing are the results that detail 2014 MU 69's surface geology and composition - and what those reveal about this curious object's origin. As principal investigator Alan Stern (Southwest Research Institute) points out in his most recent blog for S&T.com, "Every planned observation, by every one of the scientific instruments aboard New Horizons, performed according to plan." In a sense, the 40 flyby-related presentations at LPSC represent the science team's first "victory lap" with their peers. Note the distinct depression on Thule and the small craters along the top limbs of both lobes.
The larger lobe (dubbed "Ultima") is about 12 miles (19 km) across smaller "Thule" is 8½ miles (14 km) across. It resolves details as small as 440 feet (135 meters) per pixel. New Horizons captured this image of 2014 MU 69 from a distance of just 4,200 miles (6,700 km).
Since the flyby, enough observations have trickled back to Earth to start to piece together this object's remarkable story - and this week those first chapters are being presented at the annual Lunar and Planetary Science Conference. That body, formally designated (486958) 2014 MU 69 and nicknamed "Ultima Thule" by mission scientists, wasn't even discovered until 8½ years after the spacecraft's launch. It's been 2½ months since NASA's piano-size New Horizons zipped past a tiny target in the Kuiper Belt in the first hours of New Year's Day. As observations trickle in from NASA's New Horizons spacecraft, mission scientists have new insights on how their two-lobed target formed in the Kuiper Belt.
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