Artist conception of New Horizons spacecraft at the Solar System's ninth planet Pluto and its moon Charon (JHUAPL/SwRI)
New Horizons over Mysterious Pluto
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Probe to arrive in 2015:
New Horizons On the Way to Pluto

The nuclear powered New Horizons interplanetary probe designed to study Pluto, the Solar System's farthest known planet, was blasted off on an Atlas 5 rocket from Cape Canaveral Air Force Station, Florida, on January 19, 2006.

New Horizons passes Jupiter
On its way to Pluto, the New Horizons spacecraft flies by the planet Jupiter in this artist's rendering by the Southwest Research Institute and Johns Hopkins University Applied Physics Laboratory. Tiny specks of light near the distant Sun are Earth, Venus and Mercury. The dim crescent shape at the upper right of the Sun is Callisto, the outermost of Jupiter's four largest moons. Just left of Jupiter is its moon Europa.

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The flight will take New Horizons across more than three billion miles of deep space to Pluto by 2015 because flight controllers are able to use a time-saving slingshot effect gained from a Jupiter flyby. The spacecraft will pass the planet Jupiter in February 2007, just 13 months after launch. The assist from the big planet's gravity will speed up the probe on its way out to Pluto.

The piano-sized spacecraft is about 8 feet wide and weighs half a ton – 1,025 pounds – at the outset with a full load of fuel.

New Horizons is on the fastest spacecraft trip ever to the outer Solar System. It reached the orbit of Earth's Moon in fewer than 9 hours, then hustled off toward Jupiter. It will be passing by Jupiter from February 25 and March 2, 2007.

The interplanetary cruise then will extend through June 2015 when New Horizons will arrive at the Pluto system for a five-month-long reconnaissance flyby of the planet, its moon Charon and two other unnamed moons just discovered in 2005.    MOONS »

Double planet no more. In 2015, what once was called the "double planet" will be about 3.1 billion miles from Earth. The double planet actually was Pluto and its moon Charon.

Now, astronomers using the Hubble Space Telescope have observed two additional moons around Pluto. The new moons announced in 2005 are said to be 5,000 times fainter than Pluto. Including the planet, the total number of objects known to be in that vicinity is four.

Beyond Pluto. After touring the Pluto system, New Horizons will fly on out, farther away from the Sun, into the zone of space known as the Kuiper Belt to examine one or two of the ancient, icy mini-worlds in that vast region a billion or more miles beyond Pluto's orbit. That journey will span 2016-2020.

New Horizons at Pluto
New Horizons flies by a Kuiper Belt object in this artist's rendering by Johns Hopkins University Applied Physics Laboratory and Southwest Research Institute. More than 4 billion miles away, the Sun shines as a bright star embedded in the glow of the zodiacal dust cloud. Jupiter and Neptune look like orange and blue stars at the right of the Sun. Kuiper Belt objects actually are much farther apart in a disk of icy worlds circling the Sun.

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Far, far away. A radio signal moving at the speed of light takes about four hours to reach Pluto from Earth, or to reach Earth from Pluto.

Data from New Horizons will be received by radio on Earth using NASA's Deep Space Network antennas. It then will be sent to the spacecraft's Mission Operations Center at Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Maryland. APL built the New Horizons spacecraft for NASA and manages the mission.

Electrical power. The spacecraft has a nuclear power supply to generate electricity over its many years of life.

Plutonium-238 fuel is used to power a radioisotope thermal generator (RTG), which is the probe's long-life battery. An RTG converts heat from naturally decaying plutonium into electricity.

The RTG uses plutonium dioxide ceramic pellets as a heat source and solid-state thermocouples that convert the plutonium's heat energy to electricity.

Half of the plutonium for New Horizons was on hand when the U.S. Department of Energy (DoE) stopped work at the nuclear weapons plant in July 2004. A total of 36 of the 72 fuel units ordered had been left over from a spare RTG built earlier for NASA's Galileo and Cassini missions. When the lab shut down, it had 18 more units in the works. The launch went ahead with as few as 61 fuel units.

More plutonium dioxide ceramic could be made at Los Alamos scientists by converting plutonium bought from Russia into pellets packaged in hockey-puck-sized containers. The Argonne National Laboratory at Idaho Falls could put the pellet containers into an RTG.

An RTG with a full load of 72 fuel units can deliver 200 watts of electricity. With only half of its fuel, 36 fuel units, it could deliver about 100 watts. With 61 fuel units, the RTG could provide 170 watts of electrical power. Such a quantity of electricity could power seven science instruments and spacecraft systems aboard New Horizons.

Pluto rings? Astronomers are wondering if they will see rings around Pluto when New Horizons arrives on the scene. Fine debris kicked up by objects hitting Pluto may have been captured in orbit around the planet.

Each of the four giant gas planets in the outer Solar System – Jupiter, Saturn, Uranus, Neptune – is orbited by rings of dust and small particles of matter. Saturn is most famous for its rings.

The astronomer Galileo saw Saturn's rings first in 1610. The interplanetary probe Voyager 1 found Jupiter's ring in 1974. The Uranian ring system was discovered in 1977 during observations from Earth. Suspected since the 1980s, The probe Voyager 2 verified rings around Neptune in 1989.

New Horizons at Pluto
New Horizons encounters Pluto and Charon in this artist's rendering by Johns Hopkins University Applied Physics Laboratory and Southwest Research Institute. The largest structure on the spacecraft is the 7-foot dish antenna through which it communicates with Earth from more than 3 billion miles or farther away. The miniature cameras, radio science experiment, ultraviolet and infrared spectrometers and space plasma experiments measure the global geology and geomorphology of Pluto and its moons, mapping surface compositions and temperatures, and examining Pluto's atmosphere.

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Science tools. New Horizon has seven scientific instruments with cute acronym names made up by their designers: Solar wind is a stream of charged particles leaving the Sun and traveling outward across the Solar System at high speed.

Searching for more moons. As evidenced by the Hubble discovery of two additional moons around Pluto, New Horizons astronomers have been using telescopes on Earth and in Earth-orbit to hunt for other moons orbiting Pluto.

The Hubble Space Telescope orbiting Earth is able to see natural satellites of Pluto as small as 6.2 miles in diameter. As it approaches the planet, the New Horizons spacecraft should be able to detect moons around Pluto only one-tenth that size — 0.62 miles in diameter.

The artist's conception at the top of this page – the New Horizons spacecraft passing over Pluto with the moon Charon behind and the bright Sun in the far distance – is from Johns Hopkins University Applied Physics Laboratory and Southwest Research Institute.
Pluto at last. Pluto is the only planet in our Solar System never visited by a spacecraft from Earth. A successful New Horizons trip will change that.

Believe it or not, NASA actually argued against sending a probe to the distant world, but planetary scientists across the country said it was important to go now while Pluto remains in a favorable position and before its surface becomes more frozen as it moves farther away on its long orbit around the Sun.

After a political struggle, Congress gave NASA money for a mission to Pluto over the space agency's objection. The bill, signed by President George W. Bush, placed $110 million in NASA's 2003 budget for the New Horizons project. The money allowed the spacecraft design team to start on the final design of the interplanetary probe. Construction began in Summer 2004. The entire project will have cost $300-$400 million.

Some astronomers have suggested Pluto should not be considered a planet, but a Kuiper Belt Object instead.

Project scientists. Johns Hopkins University's Applied Physics Laboratory at Laurel, Maryland, built the spacecraft and manages the flight for NASA. The New Horizons mission is part of NASA's New Frontiers program.

The team includes scientists is from more than a dozen institutions, including the Southwest Research Institute's (SwRI) Department of Space Studies at Boulder, Colorado, and Ball Aerospace, Stanford University, NASA's Goddard Space Flight Center and NASA's Jet Propulsion Laboratory.

Behind the scenes. New Horizons is the first mission in NASA's New Frontiers program of medium-class, high-priority Solar System exploration projects.

It is the 62nd spacecraft built at the Johns Hopkins University Applied Physics Laboratory (JHU/APL) in Laurel, Maryland.

Also involved in the project are NASA's Goddard Space Flight Center, NASA's Jet Propulsion Laboratory, Ball Aerospace Corporation, the Boeing Company, Stanford University, KinetX, Inc., Lockheed Martin Corporation, University of Colorado, the U.S. Department of Energy and a number of other firms, NASA centers and university partners.

JHU/APL says, " New Horizons is the first mission to the last planet – the initial reconnaissance of Pluto-Charon and the Kuiper Belt – sent out to explore the mysterious worlds at the edge of our Solar System."

About Pluto...
SOURCE: JHU/APL About Charon...
SOURCE: JHU/APL About the Kuiper Belt...
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