Monday , October 18 2021

NASA New Horizons probe to visit the most distant object of all time, Ultima Thule


NASA scientists are about to make the story, piloting a probe that passes through a mysterious object the size of a mountain beyond the orbit of Pluto.

If the overfly is as planned, it will be the farthest object in space that humanity has tried to visit.

The spacecraft New Horizons, powered by NASA's nuclear power, will attempt the maneuver on New Year's Day. The object the probe is approaching is called Ultima Thule (pronounced "tool-ee") or 2014 MU 69, as is formally known.

NASA did not know that Ultima Thule existed when New Horizons was launched toward Pluto in 2006. There was not even a reliable way to detect it until astronauts flew to the Hubble Space Telescope in May 2009 and connected a updated camera.

Hubble first definitely photographed the Ultima Thule in June 2014 – about a year before New Horizons passed Pluto. Now, 4 billion kilometers from Earth, New Horizons has the goal in view.

Deep uncertainty about Ultima Thule causes planetary science researchers such as Alan Stern, who heads the New Horizons mission, to become even more enthusiastic about flying.

"If we knew what to expect, we would not be going to Ultima Thule. It's an object we've never encountered before," Stern told Business Insider. "This is what exploitation is all about."

Where and what the heck is Ultima Thule?

An illustration of Kuiper Belt Objects (points) with the flight path of New Horizons (yellow), Pluto and Ultima Thule / 2014 MU69.
NASA / JHUAPL / SwRI / Alex Parker

New Horizons is crossing an area called the Kuiper Belt, a region where sunlight is as weak as the full moon. Far away, frozen remains of the formation of the solar system – Kuiper Belt Objects, or KBOs – lurk in large numbers (including Pluto).

Ultima Thule is one of those untouched remnants. Presumably, it has remained in its distant and icy orbit for billions of years, and it is not a planet that has deformed under its own mass and erased its initial history. That means studying can help reveal how the solar system evolved to form planets like Earth, Stern said.

"Ultima is the first thing we have done that is not big enough to have a geological engine as a planet, and also something that has never been very warmed by the sun," he said. "It's like a time capsule 4.5 billion years ago. That's what makes it so special."

Stern added that the overflight will be the astronomical equivalent of an archaeological excavation in Egypt.

"It's like the first time someone opened the pharaoh's tomb and entered, and you see how the culture was a thousand years ago," he said. "Only this is exploring the dawn of the solar system."

Rendering of planetesimals by an artist.
NASA / JPL-Caltech

Stern considers Ultima Thule a "planetesimal" or seed that could have formed a planet if it had acquired enough material.

"It's a building block of larger planets, or a planetary embryo," Stern said. "In that sense, it's like a paleontologist who finds the fossilized embryo of a dinosaur. It has a very special value."

In the first images of New Horizons, researchers will be aware of the outward appearance of Ultima Thule. Learning whether the surface is relatively smooth or features a mixture of pebbles, huge boulders, cliffs and other features will bring clues about how the planets form.

Each bit of New Horizons image data, moving at the speed of light like radio waves, will take about six hours to reach antennas on Earth.

Journey into the unknown

In June, New Horizons woke up from half a year of hibernation to start zeroing the Ultima Thule.

After a series of tests, mission managers fired the probe mechanism in October to put it on a more precise path to Ultima Thule.

This week, the researchers concluded by confirming that there are no obvious moons, wreckage, or other objects floating in the New Horizons flight path (and that they can enter), so they kept the robot en route to its historic encounter.

The overflight is scheduled to start late on New Year's Eve. New Horizons will begin taking hundreds of photos in a highly choreographed and pre-programmed sequence.

"Finding something the size of a big, dirt-covered mountain, a billion miles away from Pluto, is about 10,000 times harder than reaching Pluto," Stern said. "That's because it's about 10,000 times smaller. The achievement of getting to it is unbelievable."

The target of New Horizons cameras and other instruments will not just be Ultima Thule itself.

"We are encompassing all the space around for moons, rings and even an atmosphere," Stern said. "If any of these things are there, let's see them."


At 12:33 ET on New Year's Day, the spacecraft will be its closest point – about 2,175 miles – to the mountain-sized object. New Horizons will also turn around to photograph their output at a speed of 35,000 mph.

Stern said that the initial images will take two hours to be transmitted, and the first images will be released early on January 2.

However, these first photos will be small (as they were for Pluto). It will take months to receive the most detailed and full resolution images due to the power, antenna and other physical limitations of the spacecraft. The first high resolution images will not arrive until February.

Stern, who recently helped write a book entitled "Pursuing New Horizons: Inside the First Epic Mission to Pluto," said that Ultima Thule was named after a Nordic phrase that means "beyond the farthest frontiers." He shied away from making any predictions about what the images might show, citing just how shocking the first images of Pluto were.

"I do not know what we're going to find," he said. "If it's something as surprising as Pluto, it will be wonderful."

How to watch live coverage of the New Horizons flyby of Ultima Thule

Members of the New Horizons team of scientists react to seeing the last and clearest image of the Pluto spacecraft before the nearest approach

Those keen to watch expert reviews on the fly-over and see if it managed to get in tune with a live broadcast on New Year's Day.

Michael Buckley, a spokesman for Johns Hopkins University's Applied Physics Laboratory (which hosts NASA's New Horizons mission), said the YouTube channel will broadcast a video as soon as scientists discover the spacecraft has passed Ultima Thule.

The show will continue, even if the administration of President Donald Trump is suspended by border wall funds, silencing NASA's TV in 2019.

"We're still planning one going forward with the schedule we're scheduling," Buckley told Business Insider. "The biggest change is that we would not be using any NASA platform."

He said the live coverage should start on January 1, around 9:30 am, and the New Horizons "ok" signal should arrive after 10:00 am.

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