New Horizons

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{{Spacecraft | Name =New Horizons | Image = Image:Encounter 01 lg.jpg | Caption = Artist's impression of New Horizons at Pluto | Organization = NASA | Major_Contractors = JHU APL, SwRI | Mission_Type = Fly-by | Satellite_Of = Jupiter and Pluto | Launch = 19 January 2006 | Launch_Vehicle = Atlas V-551 | Decay = N/A | Mission_Duration = Fly-by Planet Pluto | Mass = >470 kg | NSSDC_ID = 2006-001A | Webpage = New Horizons Home | Semimajor_Axis = N/A | Eccentricity = >1 | Inclination = currently negligible (2006) | Orbital_Period = N/A | Aphelion = .98 AU | Perihelion = N/A (infinity) | Orbits = N/A }}

New Horizons is a NASA unmanned mission to fly by Pluto and its moons. NASA may also approve flybys of one or more Kuiper Belt Objects. The craft was built primarily by Southwest Research Institute (SwRI) and the Johns Hopkins Applied Physics Laboratory (APL). The mission's principal investigator is S. Alan Stern of the Southwest Research Institute. New Horizons was successfully launched on 19 January 2006. It is expected to arrive at Pluto in 2015.

The New Horizons spacecraft was launched directly into an Earth- and solar-escape trajectory. It had an Earth-relative velocity of about 16.21 km/s (36,300 mph) just after its last engine shut down, making it the fastest spacecraft launch ever.

New Horizons is the first mission in NASA's New Frontiers mission category, larger and more expensive than Discovery missions but smaller than "flagship" programs.

Contents 1 Mission profile 1.1 Jupiter gravity assist 1.2 Pluto approach 1.3 Kuiper Belt mission 1.4 Current status 1.5 Key mission dates 2 Spacecraft subsystems 2.1 Structural overview 2.2 Structural 2.3 Propulsion/Attitude Control 2.4 Power/Thermal 2.5 Telecommunications 2.6 Data Handling 2.7 Flight Computer 3 Mission Science 3.1 Instrument suite 3.2 Science Objectives and Observation Plan 3.2.1 Jupiter Observations 3.2.1.1 Jupiter 3.2.1.2 Jovian Moons 3.2.2 Pluto Flyby 3.2.2.1 Primary Objectives (Required) 3.2.2.2 Secondary Objectives (Expected) 3.2.2.3 Tertiary Objectives (Desired) 3.2.3 Kuiper-Belt Objects 4 Hurricane Wilma 5 Cost 6 Trivia 7 Notes 8 See also 9 Media 10 External links

Mission profile

An Atlas V 551 rocket launched the spacecraft, with a Boeing Star 48B third stage added to increase the heliocentric (escape) speed. Launch of New Horizons was scheduled for 11 January 2006, but was delayed until 17 January to allow for borescope inspections of the Atlas's kerosene tank. Further delays related to high winds and technical difficulties unrelated to the rocket itself prevented launch until 14:00 EST on 19 January.

KinetX, Inc. of Tempe, AZ is the lead on the New Horizons' navigation team and is responsible for planning trajectory adjustments as the spacecraft speeds toward the outer solar system.

Jupiter gravity assist

Image:NewHorizons@Jupiter.jpg New Horizons is now proceeding to a Jupiter gravity assist in February 2007. It will pass through the Jupiter system at 21 km/s (47,000 mph), with closest approach to Jupiter occurring at approximately 6 UTC 28 February 2007. New Horizons was the first probe launched directly towards Jupiter since the Ulysses probe in 1990. Although there were backup launch opportunities in February 2006 and February 2007, only the first 23 days of the 2006 window permitted the Jupiter flyby. Any launch outside that period would have forced the spacecraft to fly a slower trajectory directly to Pluto, delaying its encounter by 2–4 years.

The flyby will increase New Horizons' speed away from the Sun by nearly 4 km/s (9,000 mph), putting the spacecraft on a faster trajectory to Pluto, about 2.5 degrees out of the plane of the solar system (the "ecliptic"). Template:Clear

Pluto approach

It is planned for New Horizons to fly within 10,000 km (6,213.7 mi) of Pluto. New Horizons will have a relative velocity of 13.78 km/s at closest approach, and will come as close as 27,000 km (16,800 mi) to Charon, although these parameters may be changed during flight.

Kuiper Belt mission

Image:Atlas V 551 with New Horizons on Lauch Pad 41.jpg

After passing by Pluto, New Horizons will continue further into the Kuiper Belt. Mission planners are now searching for one or more Kuiper Belt Objects on the order of 50–100 km (30–60 mi) in diameter for flybys similar to the spacecraft's Plutonian encounter. As maneuvering capability is limited, this phase of the mission is contingent on finding suitable KBOs close to New Horizons' flight path.

Current status

Overall control, after separation from the launch vehicle, is performed at Mission Operations Center (MOC) at APL. The science instruments are operated at the Clyde Tombaugh Science Operations Center (T-SOC) in Boulder, Colorado. Navigation is not realtime, and performed at various contractor facilities.

The New Horizons probe and its Atlas V launcher lifted off from Pad 41 at Cape Canaveral Air Force Station, Florida, directly south of Space Shuttle Launch Complex 39, at 2:00 pm EST (1900 UTC) on January 19, 2006. The launch time was slightly delayed due to low cloud ceiling conditions downrange. The Centaur second stage reignited at 2:30 pm EST (1930 UTC), successfully sending the probe out of Earth orbit. New Horizons passed Lunar orbit before midnight EST on the same day, and is scheduled to reach Jupiter in February 2007.

On January 28 and January 30, mission controllers guided the probe through its first trajectory correction maneuver (TCM), which was divided into two parts called TCM-1A and TCM-1B. The total velocity change of these two corrections was about 18 meters per second. TCM-1 was accurate enough to permit the cancellation of TCM-2, the second of three originally scheduled corrections. [1]

During the week of February 20, controllers conducted initial in-flight tests of three onboard scientific instruments, the Alice ultraviolet imaging spectrometer, the PEPSSI plasma-sensor, and the LORRI long-range visible-spectrum camera. No scientific measurements or images were taken, but instrument electronics (and in the case of Alice, some electromechanical systems) were shown to be functioning correctly. [2]

On March 9 at 1700 UTC, controllers performed TCM-3, the last of three scheduled course corrections. The engines burned for 76 seconds, adjusting the spacecraft's velocity by about 1.16 meters per second. [3]

On April 7, 2006 at about 1000 UTC, the spacecraft passed the orbit of Mars, moving at roughly 21 km/s away from the Sun at a solar distance of 243 million kilometers. [4]

Key mission dates

Image:New Horizons launch.jpgImage:New Horizons Liftoff.jpg

• 8 June 2001 — New Horizons picked by NASA over a competing design, POSSE (Pluto and Outer Solar System Explorer)
• 13 June 2005 — Spacecraft departs APL for final testing at Goddard Space Flight Center (GSFC)
• 24 September 2005 — Spacecraft shipped to Cape Canaveral, through Andrews Air Force Base, aboard a C-17 Globemaster III cargo aircraft
• 17 December 2005 — Transported from Hazardous Servicing Facility to Vertical Integration Facility at Launch Complex 41
• 11 January 2006 — Primary launch window opens. Launch delayed for further testing.
• 16 January 2006 — Atlas V rocket launcher, serial number AV-010, rolled out onto pad
• 17 January 2006 — First day launch attempts scrubbed because of unacceptable weather conditions (high winds).
• 18 January 2006 — Second launch attempt scrubbed because of morning power outage at the Applied Physics Laboratory.
• 19 January 2006 — Successful launch at 14:00 EST (1900 UTC) after brief delay due to cloud cover.
• 7 April 2006 — the probe passed Mars' orbit.
• 28 February 2007 — Jupiter flyby. Closest approach will be around 05:41 UTC at 2.305 million km, 21.219 km/s.
• 9 June 2008 - The probe will pass Saturn's orbit.
• 5 March 2011 - The probe will pass Uranus' orbit.
• 1 August 2014 - The probe will pass Neptune's orbit.
• 14 July 2015 — Flyby of Pluto around 11:59 UTC at 11096 km, 13.780 km/s
• 14 July 2015 — Flyby of Charon around 12:13 UTC at 26927 km, 13.875 km/s
• 2015-2020 - possible flyby of one or more Kuiper Belt objects (KBOs).

Spacecraft subsystems

Structural overview

The spacecraft is comparable in size and general shape to a grand piano and has been compared to a "piano glued to a sports-bar-sized satellite dish". Its simplicity in design mimicks that of the design of the Pioneer 10 and Pioneer 11 probes of the early 1970's, but it benefits from 30+ years of technology refinements and low-power electronics. Many subsystems and components have flight heritage from APL's CONTOUR spacecraft, which in turn had heritage from APL's TIMED spacecraft.

Structural

The spacecraft's body forms a triangle, almost 2.5 feet (0.75 m) thick. (The Pioneers had hexagonal [6-sided] bodies, while the Voyagers, Galileo, and Cassini-Huygens had decagonal [10-sided], hollow bodies.) An aluminum tube forms the main structural column, between the launch vehicle adapter ring at the "rear," and the 2.1 m radio dish antenna affixed to the "front" flat side. The titanium fuel tank is in this tube. The RTG attaches with a 4-sided titanium mount resembling a gray pyramid or stepstool. Titanium provides strength and thermal isolation. The rest of the triangle is primarily sandwich panels of thin aluminum facesheet (less than 1/64" or 0.4 mm) bonded to aluminum honeycomb core.Image:New Horizons 1.jpg

Propulsion/Attitude Control

The spacecraft has both spin-stabilized (cruise) and three-axis stabilized (science) modes, controlled entirely with hydrazine monopropellant. Seventy-seven kilograms of hydrazine provides a delta-V capability of over 290 m/s after launch. The spacecraft's on-orbit mass including fuel will be over 470 kg for a Jupiter flyby trajectory, but would have been only 445 kg for a direct flight to Pluto. This would have meant less fuel for later Kuiper Belt operations and is caused by the launch vehicle performance limitations for a direct-to-Pluto flight.

There are 16 thrusters, in large (1 lbf or 4.4 N) and small (0.18 lbf or 0.8 N) thruster circuits, with two redundant fuel routings. The large thrusters are primarily for course corrections, the small ones are primarily for attitude. Two star cameras are used for fine attitude control. They are mounted on the face of the spacecraft and provide attitude information while in spinning or in 3-axis mode. Between star camera readings, knowledge is provided by dual redundant IMUs (inertial measurement units). Electronically redundant Sun sensors can provide coarse attitude control in spin mode in the event of an anomaly.

Power/Thermal

A cylindrical RTG protrudes from one vertex in the plane of the triangle. The radioisotope thermoelectric generator (RTG) will provide about 240 W, 30 VDC at launch, decaying to 200 W at encounter in 2015. The RTG, model "GPHS-RTG," was originally a spare from the Cassini mission. The RTG contains 24 pounds (11 kg) of plutonium-238 oxide pellets. Each pellet is clad in iridium, then encased in a graphite shell.

It was developed by the Department of Energy Template:Ref at the Materials and Fuels Complex (formerly Argonne West), a part of the Idaho National Laboratory north of Idaho Falls, Idaho, near Arco, Idaho [5]. The plutonium was produced at Los Alamos National Laboratory in New Mexico. Less than the original design goal was produced, due to delays at the Department of Energy, including security activities, which held up production. The mission parameters and observation sequence had to be modified for the reduced wattage; still, not all instruments can operate simultaneously. The Department of Energy transferred the space battery program from Ohio to Argonne in 2002 because of security concerns. Image:Thermalbattery.jpg

Overall, the spacecraft is thoroughly blanketed to retain heat. Unlike the Pioneers and Voyagers, the radio dish is also enclosed in blankets, blankets that extend to the body. The heat from the RTG also adds warmth to the spacecraft in the outer solar system. In the inner solar system, the spacecraft limits its activity, and opens louvers to radiate excess heat. Then, when the spacecraft is cruising inactively in the outer solar system, the louvers are closed, and the shunt regulator reroutes power to electric heaters.

Telecommunications

Image:New Horizons - REX.jpeg Communication will be via X band, at a rate of 768 bit/s from Pluto (38 kbit/s at Jupiter) to a 70 m Deep Space Network dish. The spacecraft uses dual redundant transmitters and receivers, and either right- or left-hand circular polarization. The downlink signal is amplified by dual redundant 12-watt TWTAs (traveling wave tube amplifiers) mounted on the body under the dish.

In addition to the composite, high-gain dish (with well over 40 dB of gain and a half-power beam width of about a degree), there are two low-gain antennas and a medium-gain dish. The medium-gain antenna, with a 10-degree half-power beamwidth, is mounted to the back of the high-gain antenna's secondary reflector. The forward low-gain antenna is stacked atop the feed of the medium-gain antenna. The aft low-gain antenna is mounted within the launch adapter at the rear of the spacecraft. This antenna is only used for early mission phases near Earth, and later emergencies if the spacecraft loses attitude control.

To save mission costs, the spacecraft will be in "hibernation" between Jupiter and Pluto. It will awaken once per year, for 50 days, for equipment checkout and trajectory tracking. The rest of the time, the spacecraft will be in a slow spin, sending a beacon tone once per week. Depending on frequency, the beacon indicates normal operation, or one of seven fault modes. New Horizons is the first mission to use the DSN's beacon tone system operationally, the system having been flight-tested by the DS1 mission.

Data Handling

New Horizons will record scientific instrument data to its solid-state buffer at each encounter, then transmit the data to Earth. Data storage is done on two low-power solid-state recorders (one primary, one backup) holding up to 8 gigabytes (64 gigabits) each. Because of the extreme distance from Pluto and the Kuiper Belt, only one buffer load at those encounters can be saved. This is due to the fact that New Horizons will have exited the vicinity of Pluto (or future target object) by the time it takes to transmit the buffer load back to Earth.

Part of the reason that there will be a delay between the gathering and transmission of data is because all of the New Horizons instrumentation is body-mounted. In order for the cameras to record data, the entire probe must turn, and the high-gain antenna may not be pointing toward Earth. This design was implemented to save weight and cost. Previous spacecraft, such as the Voyager program probes, had a rotatable instrumentation platform that could take measurements from virtually any angle without losing radio contact with Earth.

Flight Computer

The spacecraft carries two computer systems, the Command and Data Handling system and the Guidance and Control processor. Each of the two systems is duplicated for redundancy, making for a total of four computers. The processor used is the Mongoose-V, a 12 MHz radiation-hardened version of the MIPS R3000 CPU.

To conserve heat and mass, spacecraft and instrument electronics are housed together in IEMs (Integrated Electronics Modules). There are two redundant IEMs.

Mission Science

Instrument suite

The spacecraft carries seven scientific instruments.

Long Range Reconnaissance Imager (LORRI) 

LOng Range Reconnaissance Imager -- a visible-light, high-resolution CCD Imager with an 8.2 inch aperture and 1024x1024 CCD. The CCD is chilled to tens of degrees below freezing by a passive radiator. The Ritchey-Chretien telescope is made of silicon carbide, to reduce weight and prevent warping at low temperatures. Resolution is 5 microradians (approximately one arcsecond).

Pluto Exploration Remote Sensing Investigation (PERSI) 

This consists of two instruments: The Ralph telescope, 6 centimeters in aperture, with two separate channels: a visible-light CCD imager (MVIC- Multispectral Visible Imaging Camera) with broadband and color channels, and a near-infrared imaging spectrometer, LEISA (Linear Etalon Imaging Spectral Array). LEISA is derived from a similar instrument on the EO-1 mission. The second instrument is an ultraviolet imaging spectrometer, Alice. Alice resolves 1,024 wavelength bands in the far and extreme ultraviolet (from 180 to 50 nanometers or 1800 to 500 angstroms), over 32 view fields. This Alice is derived from an Alice on the Rosetta mission, where it stood for 'A Lightweight Imaging spectrometer for Cometary Exploration.' Ralph, designed afterward, was named after Alice's husband on The Honeymooners.

Plasma and high energy particle spectrometer suite (PAM) 

Two instruments, consisting of SWAP (Solar Wind Analyzer around Pluto), a toroidal electrostatic analyzer and retarding potential analyzer, and PEPSI (Pluto Energetic Particle Spectrometer Investigation), a time-of-flight ion and electron sensor. SWAP measures particles of up to 6.5 keV, PEPSSI goes up to 1 MeV.

Radio Science Experiment (REX) 

REX will use an ultrastable oscillator and some additional electronics to conduct radio science investigations using the communications channels. These are small enough to fit on a single card. Since there are two redundant communications subsystems, there are two, identical REX circuit boards.

Student Dust Counter (SDC) 

Built by students at the University of Colorado, the Student Dust Counter will operate continuously to make dust measurements. Consists of a detector panel, about 18 inches x 12 inches (460 mm by 300 mm), mounted on the antisolar face of the spacecraft (the ram direction), and an electronics box within the spacecraft. The detector contains twelve PVDF panels which generate voltage when impacted. No dust counter has operated past the orbit of Uranus; models of dust in the outer solar system, especially the Kuiper Belt, are speculative.

Ralph

LORRI

SWAP

SDC

Science Objectives and Observation Plan

Jupiter Observations

The flyby will come within about 32 Jovian radii (3 Gm) of Jupiter and will be the center of a 4-month intensive observation campaign. Jupiter is an interesting, ever-changing target, observed intermittently since the end of the Galileo mission. New Horizons also has instruments built ten to twenty years after Galileo's- particularly Galileo's cameras and spectrometers, which were evolved versions of Voyager cameras. The Jupiter encounter will also serve as a shakedown and dress rehearsal. Because of the much shorter distance from Jupiter to Earth, the communications link can transmit multiple loadings of the memory buffer. The mission will actually return more data from Jupiter than Pluto.

Jupiter

Primary encounter goals will include Jovian cloud dynamics, which were greatly reduced from the Galileo observation program, and particle readings from the magnetotail of the Jovian magnetosphere. The spacecraft trajectory coincidentally flies down the magnetotail for months. New Horizons will also examine the Jovian nightside for aurorae and lightning.

Jovian Moons

The major (Galilean) moons will be in poor position. The aim point of the gravity-assist maneuver means the spacecraft will pass millions of kilometers from any of the Galilean moons. Still, the New Horizons instruments were intended for small, dim targets, so they will be scientifically useful on large, distant moons. LORRI will search for volcanos and plumes on Io. The infrared capabilities of LEISA will search for chemical compositions, and nightside temperatures (including hotspots on Io). The ultraviolet resolution of Alice will search for aurorae and atmospheres, including the Io torus.

Minor moons such as Amalthea will have their orbit solutions refined. The cameras will determine their position, acting as 'reverse optical navigation.'

Pluto Flyby

Observations of Pluto, with LORRI plus Ralph, will begin about 6 months prior to closest approach. The targets will be only a few pixels across. This should detect any rings or any additional moons (eventually down to 2 kilometers diameter), for avoidance and targeting maneuvers, and observation scheduling. 150 days out, resolution will exceed the Hubble Space Telescope's resolution, lasting another two weeks after the flyby. Long-range imaging will include 40 km (25 mi) 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 that will be facing away from the spacecraft at closest approach. Coverage will repeat twice per day, to search for changes due to snows or cryovolcanism. Still, due to Pluto's tilt and rotation, a portion of the north pole will be in shadow at all times. At some point REX will perform radiometry of the dayside, from which temperatures will be derived.

During the flyby, LORRI should be able to obtain select images with resolution as high as 25 m/px, and MVIC should obtain 4-color global dayside maps at 1.6 km resolution. LORRI and MVIC will attempt to overlap their respective coverage areas to form stereo pairs. LEISA will obtain hyperspectral near-infrared maps at 7 km/px globally and 0.6 km/pixel for selected areas. Meanwhile, Alice will characterize the atmosphere, both by emissions of atmospheric molecules (airglow), and by dimming of background stars as they pass behind Pluto (occultation).

During and after closest approach, SWAP and PEPSSI will sample the high atmosphere and its effects on the solar wind. REX will perform active and passive radio science. Ground stations on Earth will transmit a powerful radio signal as New Horizons passes behind Pluto's disk, then emerges on the other side. The communications dish will measure the disappearance and reappearance of the signal. The results will resolve Pluto's diameter (by their timing) and atmospheric density and composition (by their weakening and strengthening pattern). (Alice can perform similar occultations, using sunlight instead of radio beacons.) Previous missions had the spacecraft transmit through the atmosphere, to Earth ("downlink"). Low power and extreme distance means New Horizons will be the first such "uplink" mission. Pluto's mass and mass distribution will be evaluated by their tug on the spacecraft. As the spacecraft speeds up and slows down, the radio signal will experience a Doppler shift. The Doppler shift will be measured by comparison with the ultrastable oscillator in the communications electronics.

Reflected sunlight from Charon will allow some imaging observations of the nightside. Backlighting by the Sun will highlight any rings or atmospheric hazes. At some point, REX will perform radiometry of the nightside.

Initial, highly-compressed images will be transmitted within days. The science team will select the best images for public release. Uncompressed images will take about nine months to transmit, depending on Deep Space Network traffic. It may turn out, however, that fewer months will be needed. The spacecraft link is proving stronger than expected, and it is possible that both downlink channels may be ganged together to boost performance even further.

After analysis, publication of results will start after approximately one year. It must be noted that Deepspace Network @ Home [6] has not been funded -- a possible help with respect to maximizing return science. One ongoing problem: the Deep Space Network globally lacks 2 extra ~70m dishes, particularly in the Southern Hemisphere, to aid in the intercept of Voyager program and other outer solar system craft telemetry.

Primary Objectives (Required)

• Characterize the global geology and morphology of Pluto and Charon
• Map chemical compositions of Pluto and Charon surfaces
• Characterize the neutral (non-ionized) atmosphere of Pluto and its escape rate

Loss of any of these objectives will constitute a failure of the mission.

Secondary Objectives (Expected)

• Characterize the time variability of Pluto's surface and atmosphere
• Image select Pluto and Charon areas in stereo
• Map the terminators (day/night border) of Pluto and Charon with high resolution
• Map the chemical compositions of select Pluto and Charon areas with high resolution
• Characterize Pluto's ionosphere, and its interaction with the solar wind
• Search for neutral species such as H₂, HCN, hydrocarbons, and other nitriles in the atmosphere
• Search for any Charon atmosphere
• Determine bolometric bond albedos for Pluto and Charon
• Map surface temperatures of Pluto and Charon

It is expected, but not demanded, that most of these objectives will be met.

Tertiary Objectives (Desired)

• Characterize the energetic particle environment at Pluto and Charon
• Refine bulk parameters (radii, masses) and orbits of Pluto and Charon
• Search for additional moons, and any rings

These objectives may be attempted, though they may be skipped in favor of the above objectives. An objective to measure any magnetic field of Pluto was dropped. A magnetometer instrument could not be implemented within a reasonable mass budget, and SWAP and PEPPSI could do an indirect job detecting some magnetic field around Pluto.

Kuiper-Belt Objects

New Horizons is awaiting funds for an extended mission, as fuel usage appears to be well within predictions. Assuming the money for continued operations is found, the spacecraft will fly past one or more Kuiper-belt objects. Because the flight path is determined by the Pluto flyby, with only minimal hydrazine remaining, objects must be found along that path- a cone, extending from Pluto, of less than a degree's width, within 55 AU. Past 55 AU, the communications link becomes too weak, and the RTG wattage will have decayed too far to perform much science. Desirable KBOs will be well over 50 km in diameter, neutral in color (to compare with the reddish Pluto), and if possible, with a moon. Because the population of KBOs appears quite large, multiple objects may qualify. Large ground telescopes will find suitable objects up till the Pluto flyby; the Pluto aim point, plus some thruster firing, will then determine the subsequent trajectory. KBO flyby observations will be similar to those at Pluto, but reduced due to lower light, power, and bandwidth.

Hurricane Wilma

The Lockheed Martin Atlas V rocket that was being prepared to carry New Horizons into space was slightly damaged when Hurricane Wilma swept across Florida on October 24, 2005. One of the solid rocket boosters was hit by a door. Julie Andrews, spokeswoman for the Lockheed Martin Corp., stated, "We're pretty confident this isn't going to be a reason to hold up the launch". The booster was replaced with an identical unit, versus inspecting and requalifying the original. [7]

Cost

The cost of the mission (including spacecraft and instrument development, launch vehicle, mission operations, data analysis, and education/public outreach) is approximately $650 million over 15 years (from 2001 to 2016).

Trivia

• The craft includes a payload of 430,000 names (on a compact disc)[8], a piece of Scaled Composites SpaceShipOne[9], and an American flag, among other mementos.
• Principal investigator Alan Stern confirmed that some of the ashes of Pluto discoverer Clyde Tombaugh were aboard the spacecraft.
• This was the first launch of the 551 configuration of the Atlas V. Previous flights had used none, two, or three solid boosters, but never five. This puts the Atlas V 551 takeoff thrust, at well over 2 million pounds (8.9 MN), past the Delta IV-Heavy, of under 2 million lbf. The Delta IVH remains the larger vehicle, at over 1,600,000 lb (725 Mg) versus AV-010's 1,260,000 lb (570 Mg).
• The spacecraft only took nine hours to reach the Moon's orbit, compared to the three day trip the Project Apollo Apollo 11 spacecraft needed to reach the Moon in 1969.
• It was the fastest spacecraft ever launched, having achieved the highest Earth-relative velocity and thus leaving Earth faster than any other spacecraft to date. It was also the first spacecraft launched directly into a solar escape trajectory. However, it will not be the fastest spacecraft to leave the solar system; this record is held by Voyager 1, currently traveling at 17.145 km/s (38,350 mph) relative to the Sun, which attained greater hyperbolic excess velocity by Jupiter and Saturn gravitational slingshots than New Horizons will. Other spacecraft, such as Helios 1&2, can also be measured as the "fastest" objects, due to their orbital velocity relative to the Sun at perihelion. But, because they remain in solar orbit, their orbital energy relative to the Sun is lower than the five probes, including New Horizons, that achieved solar escape velocity (and overcame a far more massive gravity well than Earth's).
• The Star 48 third stage will beat the New Horizons spacecraft to Jupiter. So will two small despin weights, the "yo-yo weights," released from the stage. However, since they will not be in controlled flight, they will not receive the optimal gravity assist, and will pass Pluto after New Horizons.
• Because of the tenuous solar wind at Pluto's distance, the SWAP instrument has the largest aperture of any such instrument ever flown.

Notes

Image:New Horizons trajectory.svg

1. Template:Note The use of a plutonium RTG battery resulted in minor demonstrations some days before launch by about 30 anti-nuclear protestors. The amount of radioactive plutonium in the RTG is 10.9 kg, about one-third the amount on-board the Cassini-Huygens probe when it launched in 1997. That launch was protested by over 300 people. The United States Department of Energy estimated the chances of a launch accident that would release radiation into the atmosphere at 1 in 350 and monitored the launch as it always does when RTGs are involved. It was believed that a worst-case scenario of total dispersal of on-board plutonium would spread the equivalent radiation of 80% the average annual dosage in North America from background radiation over an area with a radius of 65 miles (~110 km), with cleanup costing anywhere from $241 million – $1.2 billion USD per square mile. [10][11]

See also

• Timeline of solar system exploration
• Outer solar system

Media

Template:Commons Template:Multi-video start Template:Multi-video item Template:Multi-video end Template:-

Video stream of mission (requires Java)

A paper model of the New Horizons spacecraft can be built from the sheets below. [12]

Paper cutouts (requires Adobe Acrobat Reader) [13]

Instructions: [14]

A paper model of Pluto, and a dynamic model of the Pluto-Charon system, can be built by visiting: [15]

External links

• Deep Space Network @ Home a proposal that could increase the data return at Pluto-Charon.
• New Horizons APOD
• Official New Horizons mission website
• The New Horizons spacecraft – Spaceflight Now, 8 January 2006 (from the NASA mission press kit)
• How the mission got its name
• NSSDC page
• Johns Hopkins Magazine - Mission: Pluto
• New Horizons Set To Launch With Minimum Amount of Plutonium
• Unmanned Spaceflight.com: Discussions on New Horizons including the plutonium problem
• NASA's New Horizons mission also a new horizon for INL
• Unofficial "Where is New Horizons Now?"
• Keep tracking New Horizons on your Dashboard (Mac OS X Tiger)bs:New Horizons

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