The New Horizons Pluto probe has 3 new discoveries in the outer solar system

Pluto as seen by NASA’s New Horizons spacecraft during its flyby of the dwarf planet in July 2015.

NASA’s New Horizons probe flew by Pluto nearly eight years ago, but the epic encounter is still bearing scientific fruit.

New Horizons gave humanity its first look at Pluto on July 14, 2015, when the probe zoomed just 7,800 miles (12,500 kilometers) above the dwarf planet’s frigid surface. The mission team is still analyzing the trove of data New Horizons collected during the flyby — and is still making exciting discoveries, as new results show.

New Horizons scientists shared their latest findings Tuesday (March 14) at the Lunar and Planetary Science Conference (LPSC) being held in Texas and nearby. Among the discoveries presented was one bound Plutoits puzzling turn to its ice-filled basin, another found interesting but confusing landscapes on the dwarf planet’s surface, and a third revealed the building blocks that formed the snowman-like object Arrokothwhich New Horizons flew by on January 1, 2019.

Related: NASA’s New Horizons mission in pictures

Pluto’s flip tied to Sputnik Planitia

While scientists know that Pluto, like the earth, flipped on its side sometime in its past, Pluto’s orientation before the flip and the degree to which it reoriented has not been well understood. Scientists using New Horizons data to study Pluto’s geological past hope to find clues that explain this event.

Now a group of scientists have attributed Pluto’s flip to the formation of Sputnik Planitia, a 620-mile-wide (1,000 km) basin that makes up half of the iconic heart-shaped region on Pluto. Scientists previously knew that Sputnik, which is filled with nitrogen ice, played a profound role in shaping the dwarf planet’s surface.

Using images that New Horizons sent home from the flyby in 2015, they are now trying to trace the path to Pluto’s flip. In doing so, they found parallel mountain ranges and deep valleys that form what they believe is a global tectonic system. These features are more than 186 miles (300 km) wide and span a similar distance from Pluto’s north pole.

But the fact that Pluto changed its orientation in the past reveals that none of the terrains that scientists now see are in its original location.

“We can’t really explain it in Pluto’s current configuration,” said Oliver White, a New Horizons co-investigator at the SETI (Search for Extraterrestrial Intelligence) Institute in California, during a presentation Tuesday at LPSC. Instead, these features likely existed along Plutos equator early and migrated to their current locations closer to the poles because of the flip, he said.

White’s team found that too Pluto’s subterranean ocean likely gave a boost to Sputnik and helped shift much of the dwarf planet’s mass toward its equator.

Related: Why isn’t Pluto a planet?

The red line reflects the system of valleys and mountain ranges that scientists believe migrated from Pluto's equator to their current positions near its poles.

The red line reflects the system of valleys and mountain ranges that scientists believe migrated from Pluto’s equator to their current positions near its poles.

Massive knife-like deposits of methane ice extend to Pluto’s far side

In addition to helping scientists study ancient landscapes on Pluto, New Horizons data provide clues about its more recent features.

The spacecraft had previously spotted massive methane deposits near Pluto’s equator, many as tall as Earth’s skyscrapers. Scientists announced Tuesday that they had a new line of evidence suggesting that these knife-like landforms also extend to the far side of Pluto — beyond what New Horizons was able to see during its 2015 flyby.

“The discovery of these features only adds to our understanding of the processes that shape Pluto and other icy planets in our solar system and highlights the complexity, dynamic nature and diversity of planetary surfaces like Pluto’s,” Ishan Mishra, a postdoctoral fellow at NASA’s Jet. Propulsion Laboratory in California, said in a announcement.

On Earth, such pillars are called repentant; they are made of water ice and extend only a few meters. On Pluto, however, these features exist primarily at the highest points on its surface, hovering for hundreds of meters. At such altitudes, methane freezes out of Pluto’s ragged atmosphere in cold weather and evaporates back to its gaseous state during warmer periods.

The team behind the latest study used images taken by the Long Range Reconnaissance Imager (LORRI) aboard New Horizons and examined how the light reflected from surfaces changes with different viewing angles.

In doing so, they found similar methane absorption features on the other side of Pluto, thanks to the surfaces being “rougher than Pluto’s average roughness,” Mishra said during his presentation. Such “leafy” terrains are likely one of the most common landforms on Pluto, he added.

Related: Far beyond Pluto: What’s next for NASA’s New Horizons probe?

New Horizons researchers see evidence that so-called leaf terrain—a direct landscape response to Pluto's changing climate, marked in red on this map—extends across large parts of the planet.

New Horizons researchers see evidence that so-called leaf terrain—a direct landscape response to Pluto’s changing climate, marked in red on this map—extends across large parts of the planet.

Amalgamation of Arrokoth’s long ago fusion

On January 1, 2019, New Horizons passed a small object in the Kuiper Belt called Arrokoththat looks like one partially flattened snowman. Located 4 billion miles (6.6 billion km) from Earth, it became the most distant object ever explored by a spacecraft. It is also the most primitive, thanks to its distance from the sun, which lasts in a “deep freeze”.

Arrokoth is a gentle fusion of two objects that once orbited each other. The larger of the two lobes, called Wenu, is itself a pile of 12 rocks gathered around a larger plate, scientists announced Tuesday. The latest findings show that Wenu is not formed as a whole, but from pieces of rock that already existed in the outer reaches of the solar system.

“This is surprising and a new piece of the puzzle of how planetesimals — the building blocks of planets — like Arrokoth and other Kuiper Belt objects come together,” said New Horizons principal investigator Alan Stern of the Southwest Research Institute in Colorado. -one announcement.

Early in the solar system’s history, millions of kilometer-sized icy objects formed a large, donut-shaped region at its edge called the Kuiper Belt. A few of them merged to form Wenu, Stern said, but these small objects did not merge at high speeds, which explains why Wenu is elongated as it is. (When objects merge at high speeds, their spin throws material away and forms circular bodies.) Since the rocks have retained their shape even after merging, Stern’s team estimates that they would have been traveling less than 1 meter per second when they merged .

Previous research showed that the Wenu tide interacted with the smaller of the two objects; both lost some angular momentum by ejecting material and eventually merged to form present-day Arrokoth.

The individual rocks look like “Lego pieces” and have similar sizes, compositions and colors, all of which tell us “something very important about the formation of Arrokoth,” Stern said during his presentation at the conference.

Stern’s team found that each of Arrokoth’s 12 rocks is more than 5 km wide. Given that Wenu is only 10 km thick, scientists believe that the 12 rocks clustered around Venus’ equator make up a major part of its body and also extend to its other side, which was not seen by New Horizons.

Related: The icy ‘space snowman’ Arrokoth has just been named for his best qualities

Related stories:

— New Horizons: Exploring Pluto and Beyond

— NASA celebrates New Horizons’ historic 2015 Pluto flyby with stunning new videos

— Planets of the Solar System, Order and Formation: A Guide

Looking Inward: A unique view of Uranus and Neptune

Scientists also announced Tuesday that future New Horizons observations will include clicking color images of both Uranus and Neptune. From its distinct vantage point in the Kuiper Belt, the spacecraft will be well-placed for observations that “can only be done by a spacecraft well beyond Uranus and Neptune,” Stern said.

Spacecraft in the solar system can only see light reflected from the ice giants inward or from their sides facing Earth. However, New Horizons will be able to collect data on the light scattered from the far sides of the planets.

Unlike the test images it clicked in 2019, future observations will be taken as the planets rotate, scientists announced on Tuesday. They say the new images, despite being low-resolution, showing the two ice giants no more clearly than pale blue dots, will help scientists understand more about how cloud structures develop on the two ice giants.

On June 1, 2022, scientists put New Horizons “to sleep” to conserve fuel, and the spacecraft awoke from its 10-month hibernation on March 1. From the third week of April, scientists expect the spacecraft to begin studying the distant Kuiper belt objects as well as the two outer gas giants.

That observations about Uranus and Neptune will “be very exciting when they come along,” said Will Grundy, a New Horizons co-investigator from the Lowell Observatory in Arizona. New Horizons researchers will collaborate with those working with Hubble Space Telescopehe added.

“The science return is better than either spacecraft can deliver alone,” Grundy said in a announcement. “It also sets the stage for observations of similar ice giant planets around other stars.”

Follow Sharmila Kuthunur on Twitter @Sharmilakg. Follow us on Twitter @Spacedotcom or on Facebook.

The New Horizons Pluto probe has 3 new discoveries in the outer solar system

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