Mission New Horizons, Pluto up close

Etxebeste Aduriz, Egoitz

Elhuyar Zientzia

In July the New Horizons probe arrived next to Pluto and we could see closely what until then was a diffuse point. Surprises came with the first images, the dwarf planet was not an icy rock full of craters. It became clear that we were facing a strange world.
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After nine and a half years of travel and about 5 billion kilometers, last July 14, New Horizons, the NASA probe, closest to Pluto. “Following in the footsteps of planetary missions such as Mariner, Pioneer, Voyager, etc., New Horizons has triumphed in Pluto,” Mission Chief Alan Stern said the next day when he confirmed that everything had gone well.

In this image, taken on July 11 at 4 million kilometers from Pluto, you can see the difference I did not see in the days when the probe was closer. You see a band of dark dots and a circular and hexagonal shape at the top. Scientists don't know what they can be. As Pluto takes 6.38 days to turn around himself, in the closest 3 days, the probe could only observe the other side. In any case, the route was designed so that, while moving away, this difference could be studied with the light reflected by Karon. Ed. : The SWRI.

“It seems amazing to me,” says astronomer Jesús Arregi and a member of the UPV Group of Planetary Sciences. “When he left in 2006 and spent about a year with Jupiter and we were attentive. Then you forget, but when you arrive, and in the sight of what you see, you realize what is a journey of almost ten years, at such a high speed, communicating to you at such a distance, and after ten years, that all the teams work well, and that Pluto, who is so far away, and what we least knew, look almost closely. It seems surprising and admirable to me.”

Astronomers began to surprise as they approached New Horizons Pluto. The first images showed that the surface of the dwarf planet was complex: some parts were light and some were dark. For example, there was a gigantic heart and luminous region and a very dark whaling zone (the heart has been called the Tombaugh Region and the whale the Cthulhu Region). “It has been seen to have a rather confusing surface,” explains Arregi, “it has very old parts in which there are very old craters and other surfaces are very young.”

As he approached Pluto a complex surface was observed. The cleared heart-shaped area has been called the Tombaugh Region and the dark area they initially called “whale” has been called the Cthulhu Region. Ed. : The SWRI.

There are also 3,500 metres of mountains. They believe it may be made up of water ice. Although on the surface of Pluto there is a lot of methane and nitrogen ice, these are not as strong as to form mountains. Water ice at the temperature of Pluto is like a stone. It is estimated that the mountains do not exceed one hundred million years. “It’s one of the youngest surfaces we’ve ever seen in the Solar System,” said Jeff Moore, a member of the Geology, Geophysics and Image Group of the New Horizons mission.

The presence of these characteristics on the surface of Pluto is a geological action. “For this the interior has to be quite hot,” says Arregi, “and we don’t know what that heat source is. Being a small body cannot be influenced by gravity. Perhaps the source is radioactivity, it is not clean.” However, being such a small body, it is curious. “It is less than the Moon and in it there is no geological activity or any other. In Pluto there is something. It’s amazing.”

Karon has a dark pole. In the center you can see cliffs and depressions. And on the lower and right edge some craters and a giant cannon, longer and deeper than the Grand Canyon of Arizona. Ed. : The SWRI.
New Horizons has also sent an image of the small moons Nix (above) and Hydra (below). Estix and Zerberorena will send them later. Ed. : The SWRI.

And it seems that Pluto's biggest moon, Karon, also has geological activity. The researchers have been surprised because there are very few craters and those that there seem very young. And there are a couple of giant cannons, the largest is longer and deeper than the Grand Canyon of Arizona. “These are surprising issues, as they are small bodies and are mostly composed of light elements. But, perhaps, we also had prejudices. We imagined something frozen, everything cold, everything slow and without big changes. But nature often surprises us.”

As for the composition, there have not been many surprises. “At the moment no special issue has been seen, what was expected has been found. But the atmosphere is remarkable, because it is greater than was thought,” said Arregi.

Astronomers have detected that in the Tombaugh region the ice moves. They are believed to be nitrogen glaciers. In addition to nitrogen ice, the New Horizons LEISA spectrometer has detected the abundance of carbon monoxide and methane ice in this region. The left lobe area of the “heart” has been called Sputnik Plain. To the south of the Tombaugh region are the Norgay and Hillary mountains. The higher ones are about 3,500 meters and are believed to be formed by water ice. Ed. : NASA/JHUAPL/SWRI/Herobrine.
Seven hours after passing through Pluto, two million kilometers away, New Horizons took this image out. Sunlight is reflected by Pluto's atmospheric particles. Astronomers knew that Pluto had an atmosphere, but thanks to this image they could see it. And they have clarified that it is much greater than they expected: It has about 160 kilometers, five times more than expected, and has also been structured in layers. Ed. : The SWRI.

In the hours near Pluto, New Horizons received a lot of information. And all this will take about 16 months to get to Earth. “Then the study phase will come, which will also take a few years,” explains Arregi. “However, if there is something surprising or curious, we will soon know.”

“From a technological point of view, the importance of mission is enormous,” says Arregi. But he also stressed the importance of “everything that contributes to knowing our solar system. And know also what related to metaphysics, our origin. Seeing these things gives an overview that can even change the human mentality. I think opening new paths always makes society’s mentality more open.” On the other hand, “be so successful, get there well, and send images like this, etc. This will surely give strength to this field of science. And that is also important.”

Looking ahead, the objectives are yet to be realized, but the intention is to analyze some other body of the Kuiper belt. “That will also be very interesting,” says Arregi, “because that will also change the current image of these bodies.”

A dwarf planet and five moons
This is the first time an object of Kuiper's belt has been closely observed. And not only one, the New Horizons probe has had the opportunity to observe six objects: Pluto and its five moons, Karon, Estix, Nix, Zerbero and Hydra.
When he left, he supposedly headed for the last planet in the Solar System, but that changed that same year. In fact, it was decided that Pluto was not a planet, but a dwarf planet. And it would not be the only change along the way. The moons Nix and Hydra had just been discovered (2005) when New Horizons came out, but the other two were not known. The Hubble Telescope detected Zerbero in 2011 and Estix in 2012. It was a great surprise. The system was more complex than expected.
The dwarf planet Pluto and its major moon, Charon, form a binary system. They spin together through the same center of gravity between them, always showing the same difference. And they are surrounded, quite chaotic, by the other four small moons, all much smaller than in Charon.
Since it was discovered by Clyde Tombaugh in 1930, the apparent diameter of Pluto has been decreasing. Now, for its part, New Horizons has determined that it is 70 km higher than the last calculations: 2.370 km. Karon has also confirmed a diameter of 1,208 km.
On the other hand, New Horizons has also sent an image of Hydra and Nix. Hydrates very irregularly, 55 x 40 km. Nixe, meanwhile, has 42 x 36 km and a pink tone.
Journey of nine and a half years
New Horizons was launched on January 19, 2006 from Cape Canaveral (Florida) with the maximum escape speed achieved: 16 km/s (58,536 km/h). In 2007 it passed by Jupiter and with its gravity increases the speed by 4 km/s. Thus, New Horizons has taken three years less to reach Pluto than at initial speed. To save energy, in the same year 2007 it was introduced in the fire pit until 2014.
Ed. Information
On 14 July 2015, at 13:49, the probe arrived closer to Pluto, 12,500 kilometers. Later, at 14:04 he passed near Karon, although he stayed much farther than in Pluto, at 29,000 kilometers. The tour was then designed to pass through the shadow of Pluto and Karón. In this way he could study his atmospheres. During this time the mission members had no knowledge of the probe. He called his house at 2:53 to tell him that everything went well.
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