Tuesday , October 26 2021




A NASA probe is at full speed to fly over the farthest celestial object ever studied, an icy relic of the early days of the solar system called Ultima Thule, on a journey that should culminate on New Year's Day.

The unmanned probe called New Horizons goes to its destination, about 6.4 billion kilometers from Earth, where it is scheduled to arrive to fly over this space object at a distance of 3,500 kilometers at 5:33 GMT on 1 January.

That is more than three times closer than the distance that the same probe approached Pluto in 2015.

ButWhat is this strange celestial object, which bears the name of a distant island of medieval literature, and whose overfly will have its own anthem, composed for the occasion by Queen guitarist Brian May?

"This is actually the most primitive object a probe found," says Hal Weaver, a scientist at the Johns Hopkins University Applied Physics Laboratory. Scientists are not sure of its exact size, but believe it to be about 100 times smaller than Pluto, which measures about 1,500 km in diameter.

The Ultima Thule is located in an icy area of ​​space, suggesting that it is well preserved.

"It's really a remnant of the formation of the solar system," says Weaver.

Attic of the solar system

Ultima Thule is located in the Kuiper Belt, a vast disk that results from the time of the formation of planets that astronomers call the "attic" of the solar system.

Scientists did not know that this Kuiper belt existed until the 90s.

It is about 4.8 billion kilometers from the Sun, even further than the orbit of Neptune, the planet farthest from the star.

This belt "is literally replete with billions of comets, millions of objects like Ultima Thule – called planetesimals, the elements from which the planets were formed – and a handful of continent-sized dwarf planets like Pluto," explains Alan Stern, researcher at New Horizons.

"This is important to us in the science of the planets because this region of the solar system, far from the Sun, retains the original conditions of 4.5 billion years ago", he adds.

"So when we fly over Ultima, we can see how things were at the beginning."

Very fast, very close

The New Horizons spacecraft travels through the universe at a speed of 51,500 kilometers per hour, or about 1.6 million kilometers per day.

At this speed, if you hit an object as small as a grain of rice, the probe can be destroyed instantly.

But if it survives the voyage, the ship will take hundreds of photos of the Ultima Thule, hoping to reveal its shape and geology.

New Horizons sent impressive images of Pluto in 2015, some of which showed a heart shape on the surface of the planet never seen before.

This time around, "we're going to try to take pictures with a resolution three times larger than we had for Pluto," says Stern.

But overflight "requires extremely accurate navigation, much more than we've ever experienced before, maybe we'll get there, maybe not."


Ultima Thule was discovered by the Hubble Space Telescope in 2014. Scientists noticed in 2017 that Ultima Thule is not spherical, but possibly elongated. It may even be two objects.

And that does not project the light that scientists expect to see on a rotating object, which raises many questions. It may be that it is surrounded by cosmic dust. Little moons? Oriented in such a way that its poles face the approaching ship?

The US space agency hopes the mission will provide answers.

The first images should arrive the afternoon of January 1 and be published the next day.

Although it is not possible to transmit live images at this distance, NASA plans to broadcast live during the fly-over with the soundtrack to Brian May's Ph.D. in astrophysics.

"Gathering these two aspects of my life, astronomy and music, was an interesting challenge," said former singer Freddie Mercury's partner at Queen.

Alan Stern hopes this mission will not be the last for New Horizons, launched by NASA in 2006. Scientists plan to hunt for other Kuiper belt artifacts and "fly over 2020," according to Stern.

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