New Horizons: A mission to Pluto and the Kuiper Belt

[Rick]

How Big Is Pluto? New Horizons Settles Decades-Long Debate

NASA's New Horizons mission has answered one of the most basic questions about Pluto—its size.

Mission scientists have found Pluto to be 1,473 miles (2,370 kilometers) in diameter, somewhat larger than many prior estimates. Images acquired with the Long Range Reconnaissance Imager (LORRI) were used to make this determination. This result confirms what was already suspected: Pluto is larger than all other known solar system objects beyond the orbit of Neptune.

"The size of Pluto has been debated since its discovery in 1930. We are excited to finally lay this question to rest," said mission scientist Bill McKinnon, Washington University, St. Louis.

Pluto's newly estimated size means that its density is slightly lower than previously thought, and the fraction of ice in its interior is slightly higher. Also, the lowest layer of Pluto's atmosphere, called the troposphere, is shallower than previously believed.

Measuring Pluto's size has been a decades-long challenge due to complicating factors from its atmosphere. Its largest moon Charon lacks a substantial atmosphere, and its diameter was easier to determine using ground-based telescopes. New Horizons observations of Charon confirm previous estimates of 751 miles (1208 km) kilometers) across.

More: http://pluto.jhuapl.edu/News-Center/News-Article.php?page=20150713

[Mike]

Just 3 hours to go !!!

[Rick]

NASA's Three-Billion-Mile Journey to Pluto Reaches Historic Encounter

NASA's New Horizons spacecraft is at Pluto.

After a decade-long journey through our solar system, New Horizons made its closest approach to Pluto Tuesday, about 7,750 miles above the surface -- roughly the same distance from New York to Mumbai, India – making it the first-ever space mission to explore a world so far from Earth.

"I'm delighted at this latest accomplishment by NASA, another first that demonstrates once again how the United States leads the world in space," said John Holdren, assistant to the President for Science and Technology and director of the White House Office of Science and Technology Policy. "New Horizons is the latest in a long line of scientific accomplishments at NASA, including multiple missions orbiting and exploring the surface of Mars in advance of human visits still to come; the remarkable Kepler mission to identify Earth-like planets around stars other than our own; and the DSCOVR satellite that soon will be beaming back images of the whole Earth in near real-time from a vantage point a million miles away. As New Horizons completes its flyby of Pluto and continues deeper into the Kuiper Belt, NASA's multifaceted journey of discovery continues."

More from NASA

[Mike]

Those latest images will keep the geologists busy for quite some time.

[JohnP]

Assuming your ability to be impressed has not been completely sated, here's a killer stat: after travelling for 4.88bn km and nine-and-a-half years, New Horizons carried out its Pluto flyby within 72 seconds of its expected time..

That's 99.999976% accurate...

[Rick]

NASA's New Horizons 'Phones Home' Safe after Pluto Flyby

The call everyone was waiting for is in. NASA's New Horizons spacecraft phoned home just before 9 p.m. EDT Tuesday to tell the mission team and the world it had accomplished the historic first-ever flyby of Pluto.

"I know today we've inspired a whole new generation of explorers with this great success, and we look forward to the discoveries yet to come," NASA Administrator Charles Bolden said. "This is a historic win for science and for exploration. We've truly, once again raised the bar of human potential."

The preprogrammed "phone call" -- a 15-minute series of status messages beamed back to mission operations at the Johns Hopkins University Applied Physics Laboratory in Maryland through NASA's Deep Space Network -- ended a very suspenseful 21-hour waiting period. New Horizons had been instructed to spend the day gathering the maximum amount of data, and not communicating with Earth until it was beyond the Pluto system.

More from NASA

[Rick]

Charon's Surprising Youthful and Varied Terrain

A swath of cliffs and troughs stretches about 600 miles (1,000 kilometers) from left to right, suggesting widespread fracturing of Charon's crust, likely a result of internal processes. At upper right, along the moon's curving edge, is a canyon estimated to be 4 to 6 miles (7 to 9 kilometers) deep.

Mission scientists are surprised by the apparent lack of craters on Charon. South of the moon's equator, at the bottom of this image, terrain is lit by the slanting rays of the sun, creating shadows that make it easier to distinguish topography. Even here, however, relatively few craters are visible, indicating a relatively young surface that has been reshaped by geologic activity.

More: http://www.nasa.gov/image-feature/charon-s-surprising-youthful-and-varied-terrain

[Rick]

The Icy Mountains of Pluto

New close-up images of a region near Pluto's equator reveal a giant surprise: a range of youthful mountains rising as high as 11,000 feet (3,500 meters) above the surface of the icy body.

The mountains likely formed no more than 100 million years ago -- mere youngsters relative to the 4.56-billion-year age of the solar system -- and may still be in the process of building, says Jeff Moore of New Horizons' Geology, Geophysics and Imaging Team (GGI). That suggests the close-up region, which covers less than one percent of Pluto's surface, may still be geologically active today.

Moore and his colleagues base the youthful age estimate on the lack of craters in this scene. Like the rest of Pluto, this region would presumably have been pummeled by space debris for billions of years and would have once been heavily cratered -- unless recent activity had given the region a facelift, erasing those pockmarks.

"This is one of the youngest surfaces we've ever seen in the solar system," says Moore.

More: http://www.nasa.gov/image-feature/the-icy-mountains-of-pluto

[Rick]

From Mountains to Moons: Multiple Discoveries from NASA's New Horizons Pluto Mission

Icy mountains on Pluto and a new, crisp view of its largest moon, Charon, are among the several discoveries announced Wednesday by NASA's New Horizons team, just one day after the spacecraft's first ever Pluto flyby.

"Pluto New Horizons is a true mission of exploration showing us why basic scientific research is so important," said John Grunsfeld, associate administrator for NASA's Science Mission Directorate in Washington. "The mission has had nine years to build expectations about what we would see during closest approach to Pluto and Charon. Today, we get the first sampling of the scientific treasure collected during those critical moments, and I can tell you it dramatically surpasses those high expectations."

"Home run!" said Alan Stern, principal investigator for New Horizons at the Southwest Research Institute (SwRI) in Boulder, Colorado. "New Horizons is returning amazing results already. The data look absolutely gorgeous, and Pluto and Charon are just mind blowing."

More from NASA

[Rick]

Here are some other New Horizons Pluto stories. Click on the titles to read the stories and see the pictures...

Hydra Emerges from the Shadows

Since its discovery in 2005, Pluto's moon Hydra has been known only as a fuzzy dot of uncertain shape, size, and reflectivity. Imaging obtained during New Horizons' historic transit of the Pluto-Charon system and transmitted to Earth early this morning has definitively resolved these fundamental properties of Pluto's outermost moon. Long Range Reconnaissance Imager (LORRI) observations revealed an irregularly shaped body characterized by significant brightness variations over the surface. With a resolution of 2 miles (3 kilometers) per pixel, the LORRI image shows the tiny potato-shaped moon measures 27 miles (43 kilometers) by 20 miles (33 kilometers).

Views of Pluto Through the Years

This animation combines various observations of Pluto over the course of several decades. The first frame is a digital zoom-in on Pluto as it appeared upon its discovery by Clyde Tombaugh in 1930 (image courtesy Lowell Observatory Archives). The other images show various views of Pluto as seen by NASA's Hubble Space Telescope beginning in the 1990s and NASA's New Horizons spacecraft in 2015. The final sequence zooms in to a close-up frame of Pluto released on July 15, 2015.

Life Imitates Art: Pluto's Face Predicted in 1979

I talk a lot about how entwined art and science are, but I don't think I've ever seen as good an example as this: Space Artist Don Dixon predicted what Pluto looked like back in 1979 ... and he nailed it.

Pluto By Moonlight

It's Antarctic winter on Pluto. The sun has not been visible for twenty years in this frigid south polar region; it will not shine again for another 80 years. The only source of natural light is starlight and moonlight from Pluto's largest moon, Charon.

[Rick]

Pluto: The Ice Plot Thickens

The latest spectra from New Horizons Ralph instrument reveal an abundance of methane ice, but with striking differences from place to place across the frozen surface of Pluto.

"We just learned that in the north polar cap, methane ice is diluted in a thick, transparent slab of nitrogen ice resulting in strong absorption of infrared light," said New Horizons co-investigator Will Grundy, Lowell Observatory, Flagstaff, Arizona.  In one of the visually dark equatorial patches, the methane ice has shallower infrared absorptions indicative of a very different texture.  "The spectrum appears as if the ice is less diluted in nitrogen," Grundy speculated "or that it has a different texture in that area."

An Earthly example of different textures of a frozen substance:  a fluffy bank of clean snow is bright white, but compacted polar ice looks blue.  New Horizons' surface composition team, led by Grundy, has begun the intricate process of analyzing Ralph data to determine the detailed compositions of the distinct regions on Pluto.

More: http://www.nasa.gov/image-feature/pluto-the-ice-plot-thickens

[Rick]

New Horizons Close-Up of Charon's 'Mountain in a Moat'

This new image of an area on Pluto's largest moon Charon has a captivating feature—a depression with a peak in the middle, shown here in the upper left corner of the inset.

The image shows an area approximately 240 miles (390 kilometers) from top to bottom, including few visible craters. "The most intriguing feature is a large mountain sitting in a moat," said Jeff Moore with NASA's Ames Research Center, Moffett Field, California, who leads New Horizons' Geology, Geophysics and Imaging team. "This is a feature that has geologists stunned and stumped."

See it here: http://www.nasa.gov/image-feature/new-horizons-close-up-of-charon-s-mountain-in-a-moat

[Mike]

I'm pretty sure that inset rectangle is in the wrong place.

[ApophisAstros]

Amazing feature... Not looking at the inset though!
   Roger

[Rick]

More stories. Click the titles to see the pictures and read the detail:

NASA's New Horizons Discovers Frozen Plains in the Heart of Pluto's 'Heart'

In the latest data from NASA's New Horizons spacecraft, a new close-up image of Pluto reveals a vast, craterless plain that appears to be no more than 100 million years old, and is possibly still being shaped by geologic processes. This frozen region is north of Pluto's icy mountains, in the center-left of the heart feature, informally named "Tombaugh Regio" (Tombaugh Region) after Clyde Tombaugh, who discovered Pluto in 1930.

Frozen Carbon Monoxide in Pluto's 'Heart'

Peering closely at the "heart of Pluto," in the western half of what mission scientists have informally named Tombaugh Regio  (Tombaugh Region), New Horizons' Ralph instrument revealed evidence of carbon monoxide ice.

Pluto Wags its Tail: New Horizons Discovers a Cold, Dense Region of Atmospheric Ions Behind Pluto

New Horizons has discovered a region of cold, dense ionized gas tens of thousands of miles beyond Pluto -- the planet's atmosphere being stripped away by the solar wind and lost to space. Beginning an hour and half after closest approach, the Solar Wind Around Pluto (SWAP) instrument observed a cavity in the solar wind -- the outflow of electrically charged particles from the Sun -- between 48,000 miles (77,000 km) and 68,000 miles (109,000 km) downstream of Pluto. SWAP data revealed this cavity to be populated with nitrogen ions forming a "plasma tail" of undetermined structure and length extending behind the planet.

New Horizons Reveals Pluto's Extended Atmosphere

Scientists working with NASA's New Horizons spacecraft have observed Pluto's atmosphere as far as 1,000 miles (1,600 kilometers) above the surface of the planet, demonstrating that Pluto's nitrogen-rich atmosphere is quite extended. This is the first observation of Pluto's atmosphere at altitudes higher than 170 miles above the planet's surface (270 kilometers).

The new information was gathered by New Horizon's Alice imaging spectrograph during a carefully designed alignment of the sun, Pluto, and the spacecraft starting about an hour after the craft's closest approach to the planet on July 14. During the event known as a solar occultation, New Horizons passed through Pluto's shadow while the sun backlit Pluto's atmosphere.