New Horizons (spacecraft)
New Horizons is a NASA spacecraft launched on January 19, 2006, with the mission to explore Pluto and its moons. After a nine-year journey that included a gravity assist from Jupiter, New Horizons made history on July 14, 2015, by becoming the first spacecraft to fly by Pluto, coming within 7,750 miles of its surface. The mission revealed Pluto as a geologically diverse world, featuring nitrogen glaciers, young mountains, and signs of atmospheric activity, vastly changing prior scientific understanding of the dwarf planet. New Horizons also analyzed Pluto's moons, including Charon, where evidence of a potential frozen ocean and cryovolcanoes was discovered.
Following the Pluto encounter, NASA extended the mission to explore other celestial bodies, including a flyby of the Kuiper Belt Object Arrokoth on January 1, 2019. This made Arrokoth the most distant object ever visited by a spacecraft, revealing its unique two-lobed shape. Although New Horizons was put into hibernation mode in 2022 to conserve power, it remained operational into 2024, continuing to send valuable data back to Earth. The mission has significantly contributed to our understanding of the outer solar system and the formation of planetary bodies.
New Horizons (spacecraft)
New Horizons is a spacecraft launched in 2006 by the National Aeronautics and Space Administration (NASA) on a mission to explore the dwarf planet Pluto. The spacecraft's nine-year journey to the ice-covered world first took it past Jupiter, where it observed the giant planet and one of its volcanic moons. In July 2015, New Horizons became the first human-made object to visit Pluto and sent back hundreds of photographs and valuable data—information that changed the way scientists view planetary geology. The probe found a world covered in different kinds of ice, an atmosphere being blown away into space, and a giant heart-shaped pattern on Pluto's surface. As New Horizons headed toward interstellar space, NASA extended the mission to include a 2019 flyby of a mysterious deep-space object that orbits the sun near the edge of the solar system.
Background
The 1,054-pound New Horizons spacecraft began its nine-year, $700 million mission on January 19, 2006. When it was launched from Cape Canaveral, Florida, its destination was considered the ninth planet in the solar system. Seven months later, however, the International Astronomical Union voted to change Pluto's classification, "demoting" it to the status of dwarf planet—a decision that upset some members of the New Horizons team. About a year after launch, the craft flew by the planet Jupiter, where it used the 43,440-mile-wide gas giant's gravity to boost it on the way to Pluto. During the encounter, New Horizons observed a stream of electrically charged particles behind the planet and photographed its moon, Io, the most volcanically active body in the solar system. The assist from Jupiter saved three years of flight time for the craft, which spent most of the next eight years in hibernation, with occasional check-ins with Earth to test its equipment.
In December 2014, NASA woke the spacecraft up to get it ready for its encounter with Pluto. A high-resolution telescope began monitoring the dwarf planet and sending photographs of the approach back to Earth. Among the equipment on the craft was an ultraviolet spectrometer to analyze Pluto's atmosphere, optical and infrared instrumentation to provide color maps of the surface, and instruments designed to detect charged particles from the sun known as the solar wind. Also included aboard New Horizons was a small amount of the ashes of Clyde Tombaugh, the astronomer who discovered Pluto in 1930.
Overview
On July 14, 2015, New Horizons began its flyby of Pluto. At its closest approach, the craft came within 7,750 miles of the dwarf planet and 17,900 miles of its moon, Charon. During this period, the probe remained out of contact with Earth while it focused on gathering photographs and data. Because of the vast distances involved, scientists had to wait four and a half hours for the spacecraft's signals to travel the three billion miles from Pluto. Just before the information arrived, New Horizons contacted mission control to let it know the data was on the way.
The spacecraft sent back pictures of a world with surface mountains that were estimated to be about one hundred million years old—relatively young from a geological standpoint. With the warmest temperatures on Pluto only reaching about -360 degrees Fahrenheit, scientists expected to find a frozen ball covered in craters. What they discovered, however, was a diverse landscape of slow-moving nitrogen glaciers, bladed and grooved terrain, and immense mountains of water ice. The dwarf planet was far more geologically active than scientists had expected, showing evidence of past liquids on its surface and changes in atmospheric pressure. In addition to nitrogen and water ice, scientists also detected methane and carbon monoxide ice—all of which were present in a giant heart-shaped glacier that dominated Pluto's Southern Hemisphere.
New Horizons also found a trail of ionized gas streaming away from Pluto for tens of thousands of miles. This is a sign that the dwarf planet's atmosphere is being pushed out to space by interaction with the solar wind. It is not escaping at a rate as fast as scientists expected, however, leading them to believe that the frigid cold of the upper atmosphere is somehow slowing the process. Another unexpected find were signs of possible haze and clouds in Pluto's skies. When New Horizons turned its attention to Charon, it discovered evidence of a possible frozen ocean of water ice inside the moon and cryovolcanoes on its surface that spew water. The spacecraft also photographed Pluto's four other moons—Styx, Nix, Kerberos, and Hydra—which surprised scientists by how much light they reflected.
As New Horizons sped away from Pluto, it continued to send data back to Earth. The transmission and examination of that data were expected to take years. The spacecraft's distance from its home world makes it only the fifth human-made object to journey so far away. Pioneer 10, Pioneer 11, and Voyager 2, all launched in the 1970s, are still traveling near the edge of the solar system. Voyager 1, which left Earth in 1977, passed the outer boundary of the solar system in 2012 and traveled into interstellar space. NASA expected Voyager 1 to continue to return scientific data to Earth until at least 2025.
In July 2016, the mission team received the go-ahead to send New Horizons on a flyby of a mysterious red object about one billion miles past the orbit of Pluto. On January 1, 2019, New Horizons came within 2,220 miles (3,538 kilometers) of the object 2014 MU69, which was later given the name Arrokoth. Arrokoth is a Kuiper Belt Object, one of billions of comets, asteroids, and other icy bodies beyond the orbit of Pluto that were left over from the formation of the solar system. The spacecraft found the object is actually made of two flattened lobe-like sections, with the largest about 13.5 miles (22 kilometers) long. The flyby of Arrokoth made it the most distant object ever explored by a human spacecraft. New Horizons remained operational into 2024, although the craft was put into hibernation mode in 2022 to save power for future observations.
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