Ultima Thule: NASA Probe Spots A Mystery En Route To The Outer Solar System

"Ultima is guarding her secrets well." 

Just a week before NASA’s New Horizons mission is scheduled to arrive at the most far-flung object ever studied, mission scientists have noticed something that raised their eyebrows. The object they’re planning to approach around New Years Eve is behaving strangely — and at this point, they can only guess as to why.

The New Horizons mission was first launched in 2006, as part of NASA’s plan to study the remote, icy regions of our solar system. In 2015, New Horizons completed a 6-month study of dwarf planet Pluto, but New Horizons has always had its sights set on probing deeper regions of the Kuiper Belt — an area beyond Neptune which NASA calls “a region of leftovers from the solar system’s early history.” In December the team behind the project revealed that they are headed deeper they intend to approach an object called KBO 2014 MU69, or “Ultima Thule” which is roughly 4 billion miles from the sun.

But on Sunday, the project

scientists noticed something weird about Ultima Thule: it wasn’t reflecting light the way you would expect from an object of that nature.

An artists rendering of Ultima Thule, the object that New Horizons will fly by just after midnight on January 1, 2019. 

 NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute/Steve Gribben
"“Ultima is guarding her secrets well, but we’re getting closer and flyby is only a week away."

Earlier images of Ultima Thule revealed that it’s actually two objects that are either joined at the hip or very closely orbiting one another. These objects reflect sunlight, you would expect light to pulsate as the strangely shaped object rotates and the light reflects differently off of it — these changes are also called a light curve. But Ultima Thule’s isn’t getting brighter or dimmer as it rotates.

So far, scientists have posed three potential explanations behind the missing light curve. Marc Buie, Ph.D., an astronomer at the Southwest Research Institute who collaborates on the New Horizon missions, suggested that it might just be a matter of orientation. He proposed that the rotational pole of Ultimate Thule is just pointed at New Horizons, which would affect how much light actually reaches the spacecraft.

Mark Showalter, Ph.D., a senior research scientist at the Seti Institute suggested that the object might simply be obscured by a dust cloud. And finally, in a more out-there explanation, a New Horizons assistant project scientist Anne Verbiscer, Ph.D., added that Ultima Thule could potentially be surrounded by “many tiny tumbling moons,” which could interfere with Ultima Thule’s light curve.

Which one of these three ideas might it be? Alan Stern, Ph.D., the project’s principal investigator tells Inverse isn’t ready to throw his weight behind any of the ideas just yet.

“We don’t know which is more likely or whether something else is up. Ultima is guarding her secrets well, but we’re getting closer and flyby is only a week away.”

How To Watch The Flyby During A Government Shutdown

Stern expects to get some answers once the probe actually gets close enough to see Ultima Thule for itself. New Horizons will pass 2,200 miles from Ultima Thule at approximately 12:33 a.m. EST on New Years Day. In the meantime, he added that the team is hard at work — even during Christmas Eve — preparing for their flyby. But largely as Stern indicated, the mission is proceeding as planned.

The Kuiper belt, a donut shaped area of the outer solar system 


The only change will be that we won’t be able to watch the live coverage of the event on NASA TV because of the government shutdown, which commenced at midnight on December 21st. Instead, Stern added that they will be streaming their coverage on the Johns Hopkins Applied Physics Laboratory Youtube channel.

“The pace of activity here at mission control at the Johns Hopkins Applied Physics Laboratory is intense and exciting,” Stern says. “Mission operations, encounter operations, navigation operations, and science team operations are all proceeding in parallel. We will soon know.”

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