New Horizons at 50 (AU)

On April 17, 2021, NASA's New Horizons reached a rare deep-space milepost -- 50 astronomical units from the Sun, or 50 times farther from the Sun than Earth is. New Horizons is just the fifth spacecraft to reach this great distance, following the legendary Voyagers 1 and 2 and Pioneers 10 and 11. It’s almost 5 billion miles (7.5 billion kilometers) away; a remote region where a signal radioed from NASA's largest antennas on Earth, even traveling at the speed of light, needs seven hours to reach the far-flung spacecraft.

To celebrate reaching 50 AU, the New Horizons team compiled a list of 50 facts about this historic mission.

1 New Horizons' Ralph camera actually works like a photocopier; a line of pixels scans across a scene to build a rectangular image.

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2 The "Pluto Not Yet Explored" U.S. stamp that New Horizons carries holds the Guinness World Record for the farthest traveled postage stamp.

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3 Arrokoth -- the official name the New Horizons team proposed for its main Kuiper Belt flyby target -- is a Native American term that means "sky" in the Powhatan/Algonquin language.

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4 Talk about reliability: Not a single prime system has failed at any time during New Horizons' 15-plus years in flight.

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5 The mission name was mainly inspired by the "new horizons" the team sought to explore at Pluto, in the Kuiper Belt, and beyond.

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6 New Horizons flew past Pluto exactly 10 years after NASA's Cassini spacecraft made its first flight through the active geysers of Saturn's moon Enceladus.

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7 New Horizons is one of only five spacecraft sent on trajectories to escape the solar system. The others are Voyagers 1 and 2, and Pioneers 10 and 11.

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8 New Horizons conducted the farthest flyby ever, of Kuiper Belt object Arrokoth, some 4.1 billion miles from Earth.

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9 New Horizons is the first -and so far, only -spacecraft to visit Pluto

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10 New Horizons has its own theme song, written and performed by legendary Queen guitarist, astrophysicist and mission contributing scientist Brian May.

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11 In 2020, New Horizons found that the universe is twice as bright as predicted - a major extragalactic astronomy discovery!

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12 New Horizons' radioisotope thermoelectric generator (RTG) - its nuclear battery - will provide enough power to keep the spacecraft operating until the late-2030s.

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13 New Horizons data is distributed from the Clyde Tombaugh Science Operations Center at Southwest Research Institute in Colorado.

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14 New Horizons is carrying some of the ashes of Pluto's discoverer, American astronomer Clyde Tombaugh.

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15 New Horizons' Venetia Burney Student Dust Counter is the first student-built instrument on any NASA planetary mission.

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16 New Horizons was the first launch on an Atlas V 551 -- the most powerful version of the Atlas V.

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17 More than 250 science and engineering papers have been papers published about New Horizons data

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18 New Horizons inspired a set of postage stamps after the Pluto flyby.

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19 New Horizons launched from the same Cape Canaveral Air Force Station pad (Launch Complex 41) as the storied Voyager missions.

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20 New Horizons gets its power from the heat released by the decay of an isotope of plutonium.

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21 New Horizons team members used ground-based telescopes only 16 inches in diameter to measure the size and unusual shape of Arrokoth 18 months before the flyby.

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22 Like Voyager - in fact, next to Voyager -- a full-scale model of New Horizons hung in the National Air and Space Museum.

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23 New Horizons was the first outer planets mission led by Southwest Research Institute and the Johns Hopkins Applied Physics Lab.

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24 New Horizons is built like a thermos bottle: its interior is kept near room temperature by "waste" heat from its nuclear battery, the radioisotope thermoelectric generator (RTG).

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25 New Horizons is so far away, that even the positons of the stars look different than what we see from Earth.

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26 The New Horizons spacecraft carries a CD with the names of more than 435,000 individuals.

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27 New Horizons captured the first detailed movie of a volcano erupting anywhere in the solar system except Earth, on Jupiter's moon Io.

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28 At the moment, the closest spacecraft to New Horizons is Juno, currently orbiting Jupiter.

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29 New Horizons has made long-range observations of about 30 Kuiper Belt objects in addition to its close-up flyby KBO target, Arrokoth.

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30 New Horizons obtained the best-ever pictures of Jupiter's faint ring during its flyby in 2007.

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31 New Horizons is about the size of a baby grand piano.

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32 New Horizons crossed the orbit of Neptune on August 25, 2014 - exactly 25 years to the day after Voyager 2 made the first (and so far, only) flyby of Neptune.

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33 At its current location (50 AU), the power of the signal sent by New Horizons when received by a Deep Space Network antenna on Earth is less than a billionth of a billionth of a watt.

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34 New Horizons flew by Pluto exactly 50 years to the day after the first spacecraft (Mariner 4) flew by Mars.

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35 New Horizons uses NASA's largest Deep Space Network antennas - located in Australia, Spain and the United States - to communicate with operators on Earth.

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36 New Horizons observed an asteroid in 2006; that asteroid was later named APL, after the institution that built and operates the spacecraft.

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37 There are 10 Eagle Scouts on the New Horizons team.

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38 At 50 astronomical units from the Sun, New Horizons is beyond even the farthest reaches of Pluto's elliptical orbit (which, over 248 years, ranges from 30 to 49.3 AU).

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39 With the amount of propellant it has used in flight, New Horizons is about 150 pounds lighter now than at launch.

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40 New Horizons is the first mission to visit to an object - in this case, the Kuiper Belt object Arrokoth -- that hadn't even been discovered when the spacecraft was launched.

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41 New Horizons' gold color comes from its protective coat of multi-layer thermal insulation.

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42 The New Horizons spacecraft is operated from the Johns Hopkins Applied Physics Laboratory in Maryland - where it was also built.

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43 It took about 16 months for New Horizons to send all the data from the Pluto encounter back to Earth.

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44 Of Pluto's five moons, four were discovered with the Hubble Space Telescope -- by teams led by New Horizons scientists.

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45 New Horizons is carrying nine mementos on its voyage to the "ninth planet" and beyond.

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46 The New Horizons spacecraft has spent 2,037 days of its flight - about 37% of the time since launch -- in power- and resource-saving hibernation mode.

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47 New Horizons team members used the Hubble Space Telescope to discover Arrokoth (MU69), the mission's Kuiper Belt flyby target.

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48 New Horizons' Jupiter flyby in February 2007 added speed that shaved about three years from its trip to Pluto.

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49 The seven instruments in New Horizons' science payload operate on less than 30 combined watts.

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50 Dispatched at 36,400 miles per hour (58, 500 kilometers per hour) on January 19, 2006, New Horizons is still the fastest human-made object ever launched from Earth.

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