Pluto a year from closer acquaintance. New wonderful world

Almost a year ago, on July 14, 2015, the New Horizons probe, as planned, reached its minimum distance of about 13. km to Pluto (1). Then, using her on-board equipment, she took a series of photographs and analyses. When we saw the first photos, we immediately fell in love with this dwarf planet. In the following months it became more and more interesting. And it's not over yet...

2. Mountains and plains on Pluto (Pluto's surface in the closest approximation 🙂

During this close meeting, the probe collected about 50 gigabits of data. Once it completed its passage through the Pluto system, it set up its antennas on Earth and began transmitting. After a series of successive photos of the surface, you can tell a lot about Pluto, but certainly not that it has a dull, uniform landscape (2). As commented by Alan Stern, co-lead of the probe data research program at the Southwestern Research Institute in Boulder, Colorado, no known body in the solar system has as many formations as Pluto.

We have it scattered over the surface craters and mountain ranges stop large ice fields, consisting of both water and nitrogen ice. The formations, reminiscent of those known from our deserts, amaze the imagination. dunes. Their presence seems unusual, as Pluto's atmosphere is very thin and the winds cannot exert enough pressure on the landscape features. It also turned out that Pluto is a little bigger than we thought so far. According to photos from New Horizons, its diameter is 2370 km, which is about 2 km more than expected. It may not seem like much, but from a scientific point of view, the difference is huge.

A larger diameter primarily means a lower object density and a different structure. NASA says there is more ice and fewer rocks below Pluto's surface than expected.

The beautiful images of Pluto were taken with cameras - (LORRI), which takes black and white photographs, and the Ralph Multispectral Visible Imaging Camera (MVIC), which takes both black and white and color photographs. Also, be aware that New Horizons also conducts various tests using on-board equipment.

And he has a lot of equipment with him, which we write about in the box attached to our report.

Nitrogen glaciations

The first photograph sent to Earth showed a large heart-shaped area that has since become, in a sense, Pluto's calling card. “We saw a rich world with diverse and active geology, exotic surface chemistry, complex atmospheres, mysterious interactions with the Sun and an intriguing system of small moons,” said Alan Stern at one of the conferences.

“We see significant differences in the distribution of volatile ice on Pluto, indicating a fascinating cycle of evaporation and condensation,” echoed Will Grundy of the Lowell Observatory in Arizona, lead author of a March 2016 Science paper. “These cycles are much richer than on Earth, the rebo does not have only one substance that condenses and evaporates - like water. They interact with each other in such a way that we are not yet able to fully understand and evaluate the effects across the board.”

The New Horizons spacecraft has tracked several objects on the surface of Pluto that prove that liquid matter existed millions of years ago - or even billions of years ago (when the pressure in the atmosphere was much higher than now and the climate on the surface is much warmer) capable of swimming. on the surface of Pluto is a distant globe.

3. Trace of a lake of nitrogen on Pluto

The object (3) shown in the photographs from the probe appears to be a frozen lake, once liquid nitrogen, located in a mountain range north of the area informally known as Satellite Planum. At its widest point, the lake stretches for 30 km. “In addition, we see fragments of channels through which liquid substances could flow in the past,” explains Stern.

Scientists have found that This dwarf planet's atmosphere is made up of many layers of haze, cooler and denser than previously thought. "Vapours hovering low over the surface of Pluto are a signal to us that the weather there changes in a day-night cycle, just like on Earth," Will Grundy said two months after last year's encounter with Will's planet. Grandi. Along with other photos taken recently, this could also be one of the evidence for the water cycle - just like on our planet. However, there in It's not water that circulates in the atmosphere, it's nitrogen.

“We did not expect the discovery of a nitrogen ice cycle in freezing conditions at the edge of the solar system. Fueled by residual solar rays, it is directly comparable to the hydrological cycle on Earth, when water evaporates from the oceans, falls as snow on glaciers and returns to them, ”added Alan Howard, a member of the New Horizons geological team at one of the many conferences.

4. Mountains on Pluto against the backdrop of the setting Sun.

Methane is like water

Mountain range (4), shown in one of the latest photos, from a distance of 77 thousand km from the surface of Pluto, it rises sharp cliffs up to 3,5 km above the surrounding plains. Scientists suspect these hills are based on water ice because the methane, nitrogen, and carbon monoxide ice is too soft to support such large mountains. In addition, it is a relatively young geological formation - estimated to be no more than 100 million years old, making it one of the youngest mountain ranges in the solar system.

A chain of exotic snow-capped mountains stretches through the dark regions of Pluto, known unofficially Ktulhu Regal. It runs along the middle of the equator, beginning in the west with large plains of nitrogen ice (Sputnik Planum). With a length of 3 thousand km and a width of 750 km, Cthulhu is slightly larger than Alaska.

In appearance, Cthulhu differs from the rest in a dark color. Scientists believe the color is caused by a layer of dark compounds known as tolinii. They occur when methane, sublimating, rises to a height of about 100 km. Due to the interaction of the UV rays of the Sun, methane molecules are synthesized with the formation ethylene Oraz acetylene. These molecules are further combined into heavier hydrocarbons called tholins. Then they fall to the surface of the planet, creating a characteristic reddish areas. The tholins are already known to us from Titan, Saturn's moon, which, it has been suggested, might even be fuel for simple microbes. The geology of the Cthulhu region is very diverse - from mountainous to flat, densely covered with craters and cracks. The ridge is located between craters, and its peaks are separated only by narrow valleys. The slopes of the highest peaks are covered with a light-coloured material that contrasts sharply with the dark red color of the surrounding plains. Scientists believe that this bright material consists mainly of methane, which has solidified into ice at the tops. "The fact that this material only covers the tops of the peaks suggests that methane ice could behave like water in Earth's atmosphere, condensing as frost at high altitudes," said John Stansberry, a member of the New Horizons science team at the Space Telescope Science Institute. This was reported by the media in Baltimore, Maryland. The chemistry data collected by the MVIC camera show that the position of the bright ice on the mountain peaks almost exactly matches the distribution of methane ice shown in the purple images (5).

5. Methane ice sheet in the mountains of Pluto.

Light plains with a width of 1 sq. km. km called Sputnik Planum are covered with ice from nitrogen and carbon dioxide. There are practically no craters on their surface, which suggests that geological activity continues to this day. Right next to the plains are the cratered regions that have witnessed the impacts that Pluto has experienced over millions and billions of years. The edges and hills in these areas are completely covered with ice and frost.

6. Color photo of Wright Mons cryovolcano

“One of the most interesting features is the two tall mounds with sinkholes in the center that look like volcanoes,” says Ross Beyer, senior fellow at the SETI Institute. "Wright Mons its height is more than 3 km, and the diameter at the base is more than 200 km (6). It could be cryovolcanoes, but we have yet to find out.”

The snake swims in the water

Over the winter, more photos came in from New Horizons, making Pluto's story known again in the media and on the internet. For there were pictures surprising and mysterious at the same time. They reveal many previously unseen topographical details. One of the now very famous photographs shows extensive cracks and unusual linear edges, called "snakeskin" (7).

“This is an unprecedented and amazing landscape, stretching for hundreds of kilometers,” said William McKinnon, who transferred from the New Horizons mission team, at the conference. “In the photo, it looks more like tree bark or dragon scales than typical geological features. It will take a long time to explain what this area looks like. Who knows, maybe it's a combination of internal tectonic forces and ice sublimation."

NASA specialists studied data obtained using the LEISA (Linear Etalon Imaging Spectral Array) spectrometer, which allows detecting water and ice, assessing their depth and thickness. It turned out that under a layer of methane, nitrogen and ammonia ice is a huge amount of water ice, forming a statue of Pluto.

7. Snake skin on the surface of Pluto

On July 14, 2015, the LEISA instrument performed two scans from a distance of about 108 meters. km from the surface. The data led to the conclusion that Pluto's surface is covered in icy water to a much greater extent than previously thought. Almost all areas, except for the poles, as well as Tombo regions (The "heart" of the dwarf planet takes its name from astronomer Clyde Tombaugh, who discovered Pluto in 1930) and Lowellcovered with a thick layer of frozen water. The map provided by LEISA shows that the icy water is in the half of Pluto's hemisphere that the New Horizons probe passed by - these areas are marked in blue on the surface (8).

8. The emergence of water and water ice on Pluto

However, the map shows very little water ice in the area of ​​the Sputnik Plateau. Lowell Reggio. This indicates that, at least in these regions, Pluto's icy bedrock is well hidden under a thick layer of other ices such as methane, nitrogen, and carbon monoxide.

Water ice has a lower density than nitrogen. Scientists believe that the icebergs there are floating in an ocean of icy nitrogen, just like the well-known icebergs in the Arctic. Pieces of ice hills, breaking off, flow in accordance with the movement of the glacier, creating original chains and local accumulations. The latter are formed due to the movement of other glaciers, due to the movements of icy nitrogen, which “drive” huge pieces of water ice into one place, just as debris or other types of floating objects often accumulate in one place on terrestrial waters. We observe a large accumulation of pieces of water ice (60 × 35 km) in the named place Pretendant Kolles (Challenger - in memory of the tragically lost crew of the Challenger ferry) (9).

Geological mosaic

Scientists from the New Horizons mission team recently created geological mapwhich makes it possible to understand variety of landforms and the history of the evolution of the surface of Pluto (ten). It includes a fragment of the surface at a height of 10 km, with vast plains of Sputnik Planum nitrogen ice and adjacent territories. The map has colors corresponding to different geological forms. Each type of terrain is defined by its texture and morphology, such as smooth, cracked, or hilly. The accuracy of determining this fragment directly depends on the resolution of the photographs of the given area. The entire area depicted on this map was visualized by the probe at a scale of 2070 m per pixel or better, so scientists were able to determine individual elements relatively accurately. The map is based on twelve photographs taken with the LORRI instrument.

10. Pluto geology map

The blue and greenish patches that fill the center of the map represent the various landforms seen on Sputnik Planum, from tile regions in the center and north to smooth plains in the south. The black lines mark the cracks that are visible between the cellular regions in the nitrogen ice. Purple indicates the chaotic mountain ranges on the western borders of Sputnik Planum, while pink indicates the scattered floating hills on the eastern edge. The probable cryovolcano Wright Mons is marked in red in the southern corner of the map. The jagged, rugged highlands of the Cthulhu region are depicted in dark brown along the western edge, with yellow blotches in the area marking large impact craters.

By studying how the boundaries between individual fragments interact, New Horizons scientists can try to determine which layers overlap which, allowing them to create a timeline for the formation of individual fragments. For example, the yellow craters (on the left, on the western edge of the map) should have formed after the surrounding terrain formed.

11. Blue glow around Pluto

"Living world" shrouded in blue

The atmosphere around Pluto glows in a beautiful blue halo (11). The same phenomenon is observed from the surface of this planet. At least that's what NASA scientists say, who published a new photo sent by the New Horizons probe and emphasized that the colors seen in it in certain positions will be visible to a person.

The above decomposition of methane leads to the formation of more complex gaseous hydrocarbons such as ethylene and acetylene. These hydrocarbons sink into Plutonium's lower, colder atmosphere, where they condense and then freeze into very fine ice particles, similar to diamond dust. Ultraviolet radiation turns it into a specific tholin fog. The bluish hue of the haze above Pluto is the result of the refraction of sunlight only by particles of tholin or nitrogen.

Another find is "spots" of water ice that rise to the surface in some places, although they are usually covered with nitrogen or methane ice. They have a bright red hue that scientists cannot yet explain, so more and more mysteries arise. One of the scientists from the New Horizons team heated up the scientific atmosphere even more. During a lecture at the University of Alberta in Canada, he said of Pluto, "This world is alive." He meant weather, atmospheric and geological changes, but added intriguingly: "NASA will not let me say what I want to say ...". The last proposal has caused a wave of speculation on the subject. possible life forms on Pluto.

The mission's scientists found that layers of fog in Pluto's nitrogenous atmosphere vary in brightness depending on lighting and vantage point. They are best seen in photographs taken by the New Horizons spacecraft after it flew past Pluto as it moved away from it. She then photographed the atmosphere illuminated by solar radiation. In the photographs taken by the LORRI camera, several times, with an interval of up to 5 hours, it recorded fogs hovering over a certain geographical area. The brightness of the layers varied by 30%, although the height of the layers above the surface remained the same.

Spring 2016, incl. New Scientist magazine suggested that some of these structures, visible in Pluto's hazy atmosphere, could be clouds. This is evidenced by a photograph attached to an email from Southwestern Research Institute scientist John Spencer, in which he noted particularly bright areas of the atmosphere. “The first photo shows an exceptionally bright arc low over the southeastern Sputnik Plateau and a faint cloud against the sunlit surface. Krun Makula“, he wrote in an email (12).

12. Clouds on Pluto? Who knows…

Unlike the clouds on Earth, the clouds on Pluto will not be made up of water — they will most likely be formed by particles of nitrogen ice, methane ice, and other similar compounds. Clouds differ from fogs in that, unlike very fuzzy and extensive layers of floating particles, they are more concentrated, limited in size, and much shorter in duration. If the information is confirmed, this will mean that clouds have been detected for the first time on Pluto.

The moons are amazing too

Since July 2015, we have met not only Pluto. We also looked at some of his space company. Shortly after the flyby, NASA released detailed images of Pluto's largest moon, Charon (13). This moon is unusual in that it is relatively very large compared to the size of the body it orbits. Its diameter is 1214 km, or about half the diameter of Pluto. Both celestial bodies are actually double planet Two objects of comparable size revolving around a common center of mass.

Pluto's largest moon also surprised variety of formations on the surfaceThe most notable of these are the reddish "specks" at the North Pole. The color of this area is due to the presence of the aforementioned tholins. “Unlike Pluto, Charon's surface is quite old and uniform. Most of it is covered with water ice with a small admixture of ammonia. Charon is not as geologically active as Pluto,” Christina Dalle Ore, a SETI scientist, told the media.

Attention is drawn to a huge canyon in the equatorial zone, with a length of 1800 km - about the same as the famous Grand Canyon in the United States. According to scientists, this is the remnant of a rupture in Charon's crust, which, in turn, signals dramatic events in the geological past of the cosmic body. More precisely, scientists have identified two main canyons - the first has a depth of up to 7,5 km (the Grand Canyon in the deepest places does not even reach 2 km) and the second is 1,6 km deep.

The tectonic landscape of Charon indicates that it was stretched out in some way in the past. As a result, its outer shell cracked. Charon's outer layer is made up mostly of water ice. In the youth of the Moon, this layer had a relatively high temperature - heat was provided by the decay of radioactive elements and the internal heat of the formation of this celestial body. Scientists believe that Charon could have been warm enough to liquidize water deep below the surface. When the Moon cools, the inner ocean can freeze, expanding in volume (as when water in a bottle freezes) and thus lifting the outer layers of the Moon, resulting in the massive cracks seen today.

Four lesser moons - Styx, Knicks, Cerberus and Hydra (14) - probably arose simultaneously with Charon, as a result of a powerful collision. The small, elongated 45×30 km Hydra satellite reflects 45% of the light that hits it, so it could just be a huge chunk of water ice. "We thought the small satellites would resemble Charon," Mark Showalter, senior fellow at the SETI Institute, said in a media statement. "Contrary to our expectations, it turned out that their surface is much brighter and older than that of their older brother."

Researchers are amazed at the unusual rotation pattern of these satellites, which rotate rapidly around their highly tilted axes. “Pluto's gravitational influence should decrease the rate of rotation and change the orientation of the axis of rotation. But it wasn’t like that,” Showalter notes. The New Horizons mission team suggests that collisions with objects outside the system are responsible for the unusual rotation.

We're flying on!

New Horizons is part of a NASA program called New Frontiers, operated by the NASA Space Flight Center. Marshall in Huntsville, Alabama. The New Horizons probe was designed, built and operated, like the entire mission, by APL (Applied Physics Laboratory) on behalf of NASA's Science Mission Directorate. The Southwest Research Institute is responsible for the science mission and science planning when the spacecraft passes through the Pluto system.

In the March 18, 2016 issue of Science magazine, you can find many articles on the study of Pluto and its moons. So far, the New Horizons spacecraft has sent back to Earth about half of the data collected during last year's Pluto flyby. Scientists expect that much more amazing information is still waiting to arrive on Earth.

New Horizons set off on this long journey on January 19, 2006 and traveled over 4,8 billion kilometers to get close to Pluto. This is the most important, but not the last stop on his way. The probe is traveling at almost 14 km/s, so instead of slowing it down (which would have been rather impossible anyway) and trying to orbit the dwarf planet, it was decided that the spacecraft would go further. Already in September last year, NASA indicated another goal of the study. This will be the object known as 2014 MU69, located in the Kuiper belt. Counting from Pluto, it is a little more than one and a half billion kilometers from the probe.