New Horizons

Launch data: Designation  28928 / 06001A Launch date  19 Jan 2006 - 19:00 UT Launch site  CC, SLC-41 Launch vehicle  Atlas-V 551 (AV-10) Mission  Pluto flyby Heliocentric orbit Perihelion / Aphelion   Incl. to ecliptic   ° Period   min

Spacecraft data: Prime contractor  Johns Hopkins University Applied Physics Laboratory (APL) Operator  NASA Platform   Mass at launch  478 kg (without kick motor) Dry Mass  401 kg Basic shape   Dimensions   Equipment  LORRI, MVIC, LEISA, ALICE, SWAP, PEPSSI, REX Configuration  spin or 3-axis stabilized body, high gain antenna, RTG Propulsion  STar-48B kick motor (jetisonable Design lifetime  10-15 years

Description:

• First spacecraft to be launched to fly by Pluto and its moon Charon and transmit images and data back to Earth. It will then continue on into the Kuiper Belt where it will fly by a number of Kuiper Belt Objects and return further data. The primary objectives are to characterize the global geology and morphology of Pluto and Charon, map the surface composition of Pluto and Charon, and characterize the neutral atmosphere of Pluto and its escape rate. Other objectives include studying time variability of Pluto's surface and atmosphere, imaging and mapping areas of Pluto and Charon at high-resolution, characterizing Pluto's upper atmosphere, ionosphere, and energetic particle environment, search for an atmosphere around Charon, refine bulk parameters of Pluto and Charon, search for additional satellites and rings, and characterize one or more Kuiper Belt Objects.

• New Horizons will fly around 2.3 million km from Jupiter on 2007 Feb 28, and will proceed to a Jupiter gravity assist in March 2007. The flyby will come within about 43 (+-5) Jovian radii of Jupiter and will be the center of a 4 month intensive Jupiter system observation campaign. The flyby will put the spacecraft on a trajectory towards Pluto, about 2.5 degrees out of the plane of the solar systems. During 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. Flyby of Pluto is expected in the summer 2016. The encounter period begins 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. New Horizons will fly within 9600 km of Pluto at a relative velocity of 11 km/s at closest approach and will come as close as 27,000 km to Charon. During the flyby the instruments should be able to obtain images with resolution as high as 25 m/pixel, 4-color global dayside maps at 1.6 km resolution, hyper-spectral near infrared maps at 7 km/pixel globally and 0.6 km/pixel for selected areas, characterization of the atmosphere, and radio science results. After passing by Pluto, New Horizons will be headed out to the Kuiper Belt where multiple Kuiper Belt Objects on the order of 50-100 km in diameter 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 with a cyclindrical radioisotope thermoelectric generator (RTG) which uses the heat of 11 kg of decaying Pu(238)O2 to provide 240 W of electrical power. This particular model of RTG is the GPHS-RTG, also used on Cassini; and a 2.5 m radio dish antenna affixed to one flat side. Communication will be via X-band at a rate of 768 bps from Pluto to a 70-m DSN dish. The RTG will provide 174 W at encounter in 2016. Hydrazine monopropellant is used for propulsion, a delta-V capability of 290 m/s will be available after launch. The spacecraft has both 3-axis stabilized and spin-stabilized modes. Star cameras are mounted on the side of the spacecraft for navigation.
• New Horizons has the following science instruments:
  • - Ralph, the high resolution imager, with a 0.08m telescope and a suite of detectors: MVIC (Multispectral Visible Imaging Camera), which has three black-and-white and four color CCD detectors, and LEISA (Linear Etalon Imaging Spectral Array), a 1.25-2.5 micron IR spectrometer. MVIC should reach 0.25 km/pixel at closest approach.
  • - Alice, the UV spectrometer covering the 500-1800A range.
  • - LORRI, the long range imager with a 0.21m aperture telescope and visible CCD detector.
  • - SWAP (Solar Wind at Pluto), low energy particle spectrometer
  • - PEPSSI (Pluto energetic particle spectrometer science investigation), high energy ion mass/energy spectrometer
  • - SDC (Student Dust Counter), measuring particle impacts.
  • - REX (Radio experiment), using the main dish to study radio propagation through the Plutonian atmosphere.

Mission details:

• The New Horizons probe to Pluto was launched at 19:00 UTC on Jan 19 from pad 41 at Cape Canaveral by Atlas V flight AV-010.
• The powerful Atlas 551 rocket, with five solid boosters, roared off the Florida pad after two days of delays. The solids separated at 1 min 45s into launch, arcing into the mesosphere before falling to Earth. The 5-meter-diameter fairing separated at 3min 23s, followed seconds afterwards by the two pieces of the CFLR (Centaur Forward Load Reactor), a contraption that connects the smaller 3.1m-diameter Centaur to the fairing for structural stiffness. By this time Atlas was in space, with the fairing probably reaching an apogee of 150 km or so. Atlas shut down at 4min 27s, falling away 6s later, and the Centaur second stage ignited at 4min 33s as the trajectory flattened out, reaching orbit insertion at 1910:08 UTC with a 167 x 213 km parking orbit. The vehicle coasted for 20 minutes and restarted over South Africa, with a 9-min burn taking the Centaur to 800 km altitude at a velocity of 12.4 km/s, a hyperbolic Earth orbit which will take the Centaur out to the asteroid belt. At 19:39 UTC the spin-table on the forward end of the Centaur began to rotate, and the injection stage with the payload separated. The injection stage is an Alliant (Thiokol) Star 48B solid motor, the same motor used on Delta 2 third stages and on the old Shuttle PAM-D flights. Solid kick motors like to be spinning when they fire to even out any misalignment of the thrust direction, hence the spin table - although the Star 48B also has a set of small hydrazine rockets to correct any unwanted nutation. After the Star 48B burn, the payload had reached escape velocity not only with respect to the Earth but also relative to the Sun (The velocity was 16.2 km/s relative to the Earth and I estimate an asymptotic velocity of 12.3 km/s, corresponding to 42.6 km/s relative to the Sun and leading to a heliocentric eccentricity of around 1.05). New Horizons separated from the Star 48B at 19:44 UTC and released two `yo-yo weights' on long wires; as NH spun around, the wires unwound and then were released, taking angular momentum with them and leaving the probe spinning much more slowly, around 5 rpm. NH now must depend on its own propulsion system, four small 4.4N thrusters, to adjust its course, with the first trajectory correction maneuvers coming over the next several weeks.
• New Horizons made its first pair of trajectory corrections, TCM-1A and 1B, on Jan 28 and 30, 2006; TCM-3 is scheduled for March.
• NH is now in a solar escape orbit with a perihelion of 0.98 AU, an ecliptic inclination of 0.87 deg and an eccentricity of 1.03. After the February 2007 Jupiter encounter it will have a perihelion of 2.2 AU, an inclination of 2.3 deg and an eccentricity of 1.40. On 2015 Jul 14 the probe passes Pluto, 1.1AU above the ecliptic plane and 32.9 AU from the Sun. As seen from Earth, NH and Pluto will be near the star Xi Sgr.
• New Horizons makes its closest approach to Jupiter on Feb 28, 2007 at 05:41 UTC, at a distance of 2.305 million km just outside the orbit of Callisto; the inert Star 48 third stage of the New Horizons launch flies past Jupiter at 2.8 million km at 0144 UTC the same day. New Horizons' Centaur AV-010 second stage has been left far behind, meandering through the asteroid belt 2.8 AU from the Sun.
• On 2010 Jan 1 New Horizons is 15.5 AU from the Sun, between the orbits of Saturn and Uranus.