AP NEWS

Boulder’s Southwest Research Institute Shows Few Small Objects in Kuiper Belt

March 1, 2019

The pockmarked peanut one billion miles past Pluto known as Ultima Thule does not have a lot of company in the cold vastness of the Kuiper Belt, scientists based at Boulder’s Southwest Research Institute have discovered.

Data from the NASA’s New Horizons mission, which accomplished a flyby of the Pluto-Charon system in July 2015 have indirectly found what scientists term a surprising lack of very small objects in the Kuiper Belt, a donut-shaped region of icy bodies beyond the orbit of Neptune that includes Ultima Thule, according to a news release.

More recently, New Horizons, led by SwRI’s Alan Stern as principal investigator, achieved a flyby of Ultima Thule , formally known to science as 2014 MU69, just before midnight Colorado time on New Year’s Eve,

The evidence cited for the lack of small Kuiper Belt objects is New Horizons imaging that showed a dearth of small craters on Pluto’s largest satellite, Charon, indicating that impactors from 300 feet to 1 mile in diameter must also be rare.

“These smaller Kuiper Belt objects are much too small to really see with any telescopes at such a great distance,” SwRI’s Kelsi Singer, lead author on a paper to be published Friday in the journal Science and a co-investigator the New Horizons mission, said in a statement. “New Horizons flying directly through the Kuiper Belt and collecting data there was key to learning about both large and small bodies of the Belt.”

Stern called New Horizons’ findings a “breakthrough discovery” with deep implications.

“Just as New Horizons revealed Pluto, its moons, and more recently, the KBO nicknamed Ultima Thule in exquisite detail, Dr. Singer’s team revealed key details about the population of KBOs at scales we cannot come close to directly seeing from Earth.”

Craters on solar system objects provide a record of smaller bodies’ impacts, giving hints about the history of both the object, and its place in the solar system. Because Pluto is so far from Earth, little was known about the dwarf planet’s surface until the historic July 14, 2015 flyby .

Observations of the surfaces of Pluto and Charon showed a range of features, including mountains that reach as high as 13,000 feet and vast glaciers of nitrogen ice. Geologic processes on Pluto have erased or altered some of the evidence of its impact history, but Charon’s relative geologic stasis has provided a more stable record of impacts, the release stated

“A major part of the mission of New Horizons is to better understand the Kuiper Belt,” said Singer.

“With the successful flyby of Ultima Thule early this year, we now have three distinct planetary surfaces to study. This paper uses the data from the Pluto-Charon flyby, which indicate fewer small impact craters than expected. And preliminary results from Ultima Thule support this finding.”

Charlie Brennan: 303-473-1327, brennanc@dailycamera.com or twitter.com/chasbrennan