New Horizons is a mission designed to fly by Pluto and its moon Charon and transmit images and data back to Earth.
The satellite will then continue on into the Kuiper Belt where it will fly by a one or more Kuiper Belt Objects and return further data.
The primary objectives are to characterize the global geology and morphology and map the surface composition of Pluto and Charon and characterize the neutral atmosphere of Pluto and its escape rate.
Other objectives include studying the time variability of Plutos surface and atmosphere, imaging Pluto and Charon in stereo, mapping the terminators and composition of selected areas of Pluto and Charon at high-resolution, characterizing Plutos upper atmosphere, ionosphere, energetic particle environment, and solar wind interaction, searching for an atmosphere around Charon and characterizing its energetic particle environment, refining bulk parameters, orbits, and bolometric Bond albedos of Pluto and Charon, searching for additional satellites and rings, and characterizing one or more Kuiper Belt Objects.
New Horizons reached Jupiter for a gravity assist on February 28, 2007. The flyby came within about 32 Jovian radii of Jupiter at 21 km/s and was the center of a 4 month intensive Jupiter system observation campaign. The flyby put the spacecraft on a trajectory towards Pluto, about 2.5 degrees out of the plane of the solar system.
On June 8, 2008, New Horizons crossed the orbit of Saturn. During the cruise to Pluto, New Horizons may be targeted to fly by a Centaur object (an escaped Kuiper Belt Body) if a suitable target can be identified.
The flyby of Pluto will occur nominally on July 14, 2015. The encounter period starts 6 months prior to closest approach. Long range imaging will include 40 km mapping of Pluto and Charon, 3.2 days out. This is half the rotation period of Pluto-Charon and will allow imaging of the side of both bodies which will be facing away from the spacecraft at closest approach.
The flyby will take place at a distance of about 33 AU from Earth with a round-trip light time of 9 hours. Encounter data will be transmitted to Earth at 600 bps over a 9-month period. After passing by Pluto, New Horizons will be headed out to the Kuiper Belt where one to three Kuiper Belt Objects with diameters exceeding 35 km are expected to be targeted for encounter and similar measurements to those made at Pluto. This phase of the mission will last from 5 to 10 years.
The spacecraft has the shape of a thick triangle (0.68 x 2.11 x 2.74 m) with a cylindrical radiothermal generator (RTG) protruding from one vertex in the plane of the triangle and a 2.1 m high-gain radio dish antenna affixed to one flank side.
There are also two low gain antennas for communications within 5 AU and a medium gain antenna with uplink capability to 50 AU. The RTG will provide approximately 228 W at encounter in 2015. Hydrazine monopropellant is used for propulsion via four 4.4 N thrusters and twelve 0.8 N thrusters, a delta-V capability of 290 m/s will be available after launch. The hydrazine is stored in a titanium tank separated from the gaseous nitrogen pressurant by a girth-mounted diaphragm. The spacecraft has both 3-axis stabilized and spin-stabilized modes. Star cameras are mounted on the side of the spacecraft for navigation.
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All New Horizon images presented in this article are courtesy of NASA/Johns Hopkins University, Applied Physics Laboratory.