New Horizons' Last Portrait of Pluto's Puzzling Spots: (July 11, 2015)
Three billion miles from Earth and just two and a half million miles from Pluto, NASA's New Horizons spacecraft has taken its best image of four dark spots that continue to captivate.
The spots appear on the side of Pluto that always faces its largest moon, Charon - the face that will be invisible to New Horizons when the spacecraft makes its close flyby the morning of July 14. New Horizons principal investigator Alan Stern of the Southwest Research Institute, Boulder, Colorado, describes this image as "the last, best look that anyone will have of Pluto's far side for decades to come".
The spots are connected to a dark belt that circles Pluto's equatorial region. What continues to pique the interest of scientists is their similar size and even spacing. "It's weird that they're spaced so regularly", says New Horizons program scientist Curt Niebur at NASA Headquarters in Washington. Jeff Moore of NASA's Ames Research Center, Mountain View, California, is equally intrigued. "We can't tell whether they're plateaus or plains, or whether they're brightness variations on a completely smooth surface".
In addition to solving the mystery of the spots, the New Horizons Geology, Geophysics and Imaging team is interested in identifying other surface features such as impact craters, formed when smaller objects struck the dwarf planet. Moore notes, "When we combine images like this of the far side with composition and color data the spacecraft has already acquired but not yet sent to Earth, we expect to be able to read the history of this face of Pluto".
When New Horizons makes its closest approach to Pluto in just three days, it will focus on the opposing or "encounter hemisphere" of the dwarf planet. On the morning of July 14, New Horizons will pass about 7,800 miles (12,500 kilometers) from the face with a large heart-shaped feature that's captured the imagination of people around the world.
At 7:49 AM EDT on Tuesday, July 14, New Horizons will zip past Pluto at 30,800 miles per hour (49,600 kilometers per hour), with a suite of seven science instruments busily gathering data. The mission will complete the initial reconnaissance of the solar system with the first-ever look at the icy dwarf planet.
From New Horizons' Last Portrait of Pluto's Puzzling Spots (July 11, 2015).
See also Charon's Chasms and Craters (July 12, 2015).
See also One Million Miles to Go; Pluto is More Intriguing than Ever (July 12, 2015).
Mission scientists have found Pluto to be 2,370 kilometers (1,473 miles) in diameter. Pluto is larger than all other known Solar System objects beyond the orbit of Neptune.
New Horizons observations of Charon confirm previous estimates of 1,208 km (751 miles) kilometers) across. Nix and Hydra were discovered using the Hubble Space Telescope in 2005. Nix is estimated to be about 35 kilometers (about 20 miles) across, while Hydra is roughly 45 kilometers (roughly 30 miles) across.
From How Big Is Pluto? New Horizons Settles Decades-Long Debate (July 13, 2015).
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.
The Pluto story began only a generation ago when young Clyde Tombaugh was tasked to look for Planet X, theorized to exist beyond the orbit of Neptune. He discovered a faint point of light that we now see as a complex and fascinating world.
From NASA's Three-Billion-Mile Journey to Pluto Reaches Historic Encounter (July 14, 2015).
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.
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.
Pluto is the first Kuiper Belt object visited by a mission from Earth. New Horizons will continue on its adventure deeper into the Kuiper Belt, where thousands of objects hold frozen clues as to how the solar system formed.
New Horizons is collecting so much data it will take 16 months to send it all back to Earth.
From NASA's New Horizons 'Phones Home' Safe after Pluto Flyby (July 15, 2015).
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 the NASA's New Horizons team, just one day after the spacecraft's first ever Pluto flyby.
A new close-up image of an equatorial region near the base of Pluto's bright heart-shaped feature shows a mountain range with peaks jutting as high as 3,500 meters (11,000 feet) above the surface of the icy body.
The mountains on Pluto likely formed no more than 100 million years ago -- mere youngsters in a 4.56-billion-year-old solar system. This suggests the close-up region, which covers about one percent of Pluto's surface, may still be geologically active today.
Unlike the icy moons of giant planets, Pluto cannot be heated by gravitational interactions with a much larger planetary body. Some other process must be generating the mountainous landscape.
The new view of Charon reveals a youthful and varied terrain. Scientists are surprised by the apparent lack of craters. A swath of cliffs and troughs stretching about 1,000 kilometers (600 miles) suggests widespread fracturing of Charon's crust, likely the result of internal geological processes. The image also shows a canyon estimated to be 7 to 9 kilometers (4 to 6 miles) deep. In Charon's north polar region, the dark surface markings have a diffuse boundary, suggesting a thin deposit or stain on the surface.
New Horizons also observed the smaller members of the Pluto system, which includes four other moons: Nix, Hydra, Styx and Kerberos. A new sneak-peak image of Hydra is the first to reveal its apparent irregular shape and its size, estimated to be about 43 by 33 kilometers (27 by 20 miles).
The observations also indicate Hydra's surface is probably coated with water ice. Future images will reveal more clues about the formation of this and the other moon billions of years ago. Spectroscopic data from New Horizons' Ralph instruments reveal an abundance of methane ice, but with striking differences among regions across the frozen surface of Pluto.
From From Mountains to Moons: Multiple Discoveries from NASA's New Horizons Pluto Mission (July 15, 2015).
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.
This fascinating icy plains region - resembling frozen mud cracks on Earth - has been informally named "Sputnik Planum" (Sputnik Plain) after the Earth's first artificial satellite. It has a broken surface of irregularly-shaped segments, roughly 12 miles (20 kilometers) across, bordered by what appear to be shallow troughs. Some of these troughs have darker material within them, while others are traced by clumps of hills that appear to rise above the surrounding terrain. Elsewhere, the surface appears to be etched by fields of small pits that may have formed by a process called sublimation, in which ice turns directly from solid to gas, just as dry ice does on Earth.
Pluto's icy plains also display dark streaks that are a few miles long. These streaks appear to be aligned in the same direction and may have been produced by winds blowing across the frozen surface.
The Tuesday 14 "heart of the heart" image was taken when New Horizons was 77,000 kilometers (48,000 miles) from Pluto, and shows features as small as 1 kilometer (one-half mile) across. Mission scientists will learn more about these mysterious terrains from higher-resolution and stereo images that New Horizons will pull from its digital recorders and send back to Earth during the next year.
The New Horizons Atmospheres team observed Pluto's atmosphere as far as 1,600 kilometers (1,000 miles) above the surface, demonstrating that Pluto's nitrogen-rich atmosphere is quite extended. This is the first observation of Pluto's atmosphere at altitudes higher than 270 kilometers above the surface (170 miles).
The New Horizons Particles and Plasma team 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.
From NASA's New Horizons Discovers Frozen Plains in the Heart of Pluto's 'Heart' (July 17, 2015).
See also New Horizons Finds Second Mountain Range in Pluto's 'Heart' (July 21, 2015).
New Horizons Mission to Pluto and Charon - Kuiper Belt Objects. The first reconnaissance of Pluto and Charon - a "double planet" and the last planet in our solar system to be visited by spacecraft. Later, as part of an extended mission to 2020, New Horizons will visit one or more objects in the Kuiper Belt region beyond Neptune. Launched on January 19, 2006.
Jupiter Encounter: Closest approach occurred on February 28, 2007. New Horizons flew about 3 to 4 times closer to Jupiter than the Cassini spacecraft. New Horizons has also crossed the orbits of Saturn, on June 8, 2008, Uranus on March 18, 2011, and Neptune on August 2014. It transitioned from hibernation to active mode on Dec. 6, 2014, in preparation for the Pluto-System Encounter close approach on July 14, 2015 (11:49:59 UTC), about 12,500 kilometers (7,750 miles) from Pluto.
See New Horizons - The Flyby.
What color is Pluto?
The answer, revealed in the first maps made from New Horizons data, turns out to be shades of reddish brown.
Although this is reminiscent of Mars, the cause is almost certainly very different. On Mars the coloring agent is iron oxide, commonly known as rust. On the dwarf planet Pluto, the reddish color is likely caused by hydrocarbon molecules that are formed when cosmic rays and solar ultraviolet light interact with methane in Pluto's atmosphere and on its surface.
From The 'Other' Red Planet (July 3, 2015).
New Horizons will pass by Pluto so quickly that only one hemisphere will be photographed in detail.
New Horizons will get an excellent look at the boundary between the bright features and nearby regions covered in pitch-black surface material.
Pluto is now a "dwarf planet" by the IAU definition of "planet" and "dwarf planets".
See IAU 2006 General Assembly: Result of the IAU Resolution votes (IAU Press Releases, 24 August 2006, Prague).
See Observatorio ARVAL: Solar System Data.
On 13 September '06 the IAU Minor Planet Center assigned to Pluto the asteroid number 134340.
See IAU Minor Planet Center Circular 8747 (.pdf).
See Clyde Tombaugh, 1906 - 1997 (Discoverer of dwarf planet Pluto on February 18, 1930). [in ARVAL]
Updated: July 17 '15
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