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Canada New Horizons probe discovers that Ultima Thule is two bodies joined together

This image made available by NASA on Jan. 2, 2019, shows images with separate colour and detail information, and a composited image of both, showing Ultima Thule, about 1 billion miles beyond Pluto.

The Associated Press

Scientists have had their first good look at the distant solar system object nicknamed Ultima Thule and have realized they’re seeing double. Ultima Thule turns out be a pair of rounded bodies that have been gently pushed together to resemble a flying interplanetary snowman.

Images snapped by NASA’s New Horizons probe on Tuesday and released on Wednesday show that the larger of the spherical components making up Ultima Thule is about three times the size of the smaller.

“You can see that there are clearly two separate objects that have come together,” deputy project scientist Cathy Olkin said during a news briefing at the Johns Hopkins Applied Physics Laboratory in Laurel, Md. “This shape informs our models of planetary formation.”

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The new view suggests that Ultima Thule is everything scientists were hoping for – a telltale snapshot of the process that once led to the birth of the planets, in which small bodies called planetesimals aggregate to build up larger ones.

With data continuing to stream in from the spacecraft on Wednesday, team members said they expect the results to significantly refine their understanding of how the solar system originated.

New Horizons left Earth nearly 13 years ago and became the first spacecraft to provide closeup images of Pluto in 2015. It then spent three and half years enroute to Ultima Thule, which lies 1.5 billion kilometres beyond Pluto’s orbit in a region known as the Kuiper Belt.

Travelling at more than 51,000 kilometres an hour, New Horizons skirted past Ultima Thule early Tuesday morning with cameras and instruments busily recording whatever it found there. Ten hours later, the raw data from the fleeting encounter began arriving via radio link from the rapidly receding spacecraft and team members spent the next 24 hours assembling images and debating the implications of what they were seeing.

Even now, with only 1 per cent of the data from the encounter already in hand and the best images still to come, scientists said they are convinced that Ultima Thule has changed little since it emerged out of the swirl of dust and gas that surrounded the infant Sun about 4.5 billion years ago.

“We think what we’re looking at is perhaps the most primitive object that has yet been seen by any spacecraft,” said Timothy Moore, a science team member with NASA’s Ames Research Center in California.

Dr. Moore noted that Ultima Thule’s shape supports a view of planet formation in which small pieces that range in size from pebbles to boulders accumulated to form spherical objects that are roughly 10 kilometres across. The two parts of Ultima Thule match this description and both appear somewhat mottled – a possible hint that each is made up of smaller chunks fused together.

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A colour image shows that the object is reddish, which suggests its surface contains carbon-bearing molecules such as methane and carbon monoxide in frozen form. After billions of years of exposure to cosmic radiation, such a surface would typically turn reddish brown as the carbon atoms react chemically and are linked up into longer tar-like compounds.

Equally striking is the apparent lack of craters, a result that is consistent with a study published last week that suggests the Kuiper Belt is relatively free of small chunks of debris that have thoroughly scarred many of asteroids and moons that lie closer to the Sun. And because objects in the region are thought to be travelling at low speeds relative to one another, even those craters that do form would be expected to look like mere dents.

Brett Gladman, an astronomer at the University of British Columbia and co-author of the crater study, said that as sharper images are downloaded from the spacecraft, a few of the bright splotches that appear in the news images may turn out to be shallow craters made by objects that were moving slowly enough to survive crashing into Ultima Thule.

“I’ll be very curious to see if those are boulders basically sitting in divots,” Dr. Gladman said.

JJ Kavelaars, an astronomer with Canada’s National Research Council who was involved in the search for a Kuiper Belt object for New Horizons to visit and is a member of the mission’s science team, said the experience of watching the images arriving this week has been almost otherworldly.

“It’s been sitting out there in space for four and a half billion years and now humans have managed to get out there and see it. … I’m in awe of this accomplishment," he said.

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to pluto and beyond

New Horizons’ successful flyby of the Kuiper

Belt Object nicknamed Ultima Thule is the most

distant encounter by any spacecraft in history.

The fast-moving probe is on a trajectory to

eventually leave the solar system altogether.

New Horizons

Cost: Approx.

US$700-million

Launched:

Jan. 19, 2006

Mission:

To explore Pluto

and its moons then

move on to survey the

mysterious Kuiper Belt at the

edge of our solar system.

New Horizons

Kuiper Belt

Ultima Thule

Pluto

Trajectory

Saturn

Jupiter

Mars

Neptune

Earth

Uranus

ivan semeniuk and JOHN SOPINSKI/

THE GLOBE AND MAIL

SOURCE: NASA/JHUAPL/SWRI

to pluto and beyond

New Horizons’ successful flyby of the Kuiper Belt Object

nicknamed Ultima Thule is the most distant encounter by

any spacecraft in history. The fast-moving probe is on a

trajectory to eventually leave the solar system altogether.

New Horizons

Cost: Approx.

US$700-million

Launched:

Jan. 19, 2006

Mission: To explore

Pluto and its moons

then move on to

survey the mysterious

Kuiper Belt at the edge

of our solar system.

New Horizons

Kuiper Belt

Ultima Thule

Pluto

Trajectory

Saturn

Jupiter

Mars

Neptune

Earth

Uranus

ivan semeniuk and JOHN SOPINSKI/

THE GLOBE AND MAIL, SOURCE: NASA/JHUAPL/SWRI

to pluto and beyond

New Horizons’ successful flyby of the Kuiper Belt Object nicknamed Ultima Thule

is the most distant encounter by any spacecraft in history. The fast-moving probe

is on a trajectory to eventually leave the solar system altogether.

New Horizons

Kuiper Belt

Ultima Thule

Pluto

Trajectory

New Horizons

Cost: Approx.

US$700-million

Saturn

Launched:

Jan. 19, 2006

Jupiter

Mars

Neptune

Mission: To

explore Pluto

and its moons

then move on

to survey the

mysterious

Kuiper Belt at

the edge of our

solar system.

Earth

Uranus

ivan semeniuk and JOHN SOPINSKI/THE GLOBE AND MAIL, SOURCE: NASA/JHUAPL/SWRI

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