This material has been adapted from the New Horizons web site.


Mission Overview
================
The primary science goals of the NEW HORIZONS mission are to characterize the global geology and morphology of Pluto and Charon, to map the surface composition of Pluto and Charon, and to characterize the neutral atmosphere of Pluto and its escape rate (NASA AO, 2001 [NASAAO2001]; Stern & Spencer, 2004 [STERN&SPENCER2004A]).


Mission Design
==============
The New Horizons spacecraft trajectory was designed to have as early an arrival time at Pluto as practicable.

There are two reasons why the New Horizons science team wanted to reach Pluto and Charon quickly. The first has to do with the Pluto atmosphere: Since 1989, Pluto has been moving farther from the Sun, getting less heat every year [LUNINEETAL1995]. As Pluto gets colder scientists expect its atmosphere will freeze out, so the team wanted to arrive while there is a chance to see a thicker atmosphere.

The second reason is to map as much of Pluto and Charon as possible.
As New Horizons approaches and flies by the Pluto system, parts of Pluto or Charon will be in constant darkness, and, the later the flyby, the more of Pluto and Charon that will be unlit.

In addition, the trajectory was designed to enable all of the science goals, including Solar and Earth occultations by Pluto and Charon.


Prime Opportunity: Jupiter
---------------------------
By launching in January 2006, New Horizons took advantage of a gravity assist from Jupiter. In February 2007, New Horizons passed through the Jupiter system at about 80,000 kmph, ending up on a path that gets it to Pluto on July 14, 2015.

Science Opportunities at Jupiter included meteorology, aurora studies, magnetospheric sampling, and dust sampling and ultraviolet mapping of the torus around Io. Surface mapping, compositional mapping and atmospheric studies of the Jovian moons were possible, as was a close encounter with a small Jovian satellite.


Cruise from Jupiter to Pluto
----------------------------
During the PLUTOCRUISE mission phase from Jupiter to Pluto, the mission team monitored the health of the spacecraft while planning and practicing for the encounter with Pluto and Charon. At the same time, observers used telescopes on Earth and in Earth orbit to search for Kuiper Belt Objects (KBOs) the spacecraft can fly by after Pluto and Charon (as part of an extended mission). The KBOs are ancient, icy bodies that orbit beyond Neptune.


Closing In: Pluto
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The cameras on New Horizons started taking data on Pluto and Charon months before the spacecraft arrived. Pluto and Charon will first appear as unresolved bright dots, but the planet and its moon appear larger as the encounter date approaches. About three months from the closest approach - when Pluto and Charon are about 105 million kilometers away - the cameras on the spacecraft can make the first maps. For those three months, the mission team took pictures and spectral measurements.

Pluto and Charon each rotate once every 6.4 Earth days. For the last three Pluto days before encounter (21 Earth days), the team compiled maps and gathered spectral measurements of Pluto and Charon every half-day. The team then compared these maps to look for changes over a Pluto day, at a scale of about 48 kilometers.


The Encounter
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The busiest part of the Pluto-Charon flyby lasted a full Earth day, from a half-day before closest approach to a half-day after. On the way in, the spacecraft looked for ultraviolet emission from the Pluto atmosphere and made the best global maps of Pluto and Charon in green, blue, red and a special wavelength detector that is sensitive to methane frost on the surface. It also made spectral maps in the near infrared, telling the science team about the Pluto and Charon surface compositions and locations and temperatures of these materials.

In current mission designs, the spacecraft comes as close as about 9,600 kilometers from Pluto and about 27,000 kilometers from Charon.
During the half-hour when the spacecraft is closest to Pluto or its largest moon, it will take close-up pictures in both visible and near-infrared wavelengths. The best pictures of Pluto depict surface features as small as about 60 meters across.

Even after the spacecraft passed Pluto and its moons, its work is far from done. Looking back at the mostly dark side of Pluto or Charon is the best way to spot haze in the atmosphere, to look for rings, and to figure out whether their surfaces are smooth or rough.
Also, the spacecraft flew through the shadows cast by Pluto and Charon. It looked back at the Sun and Earth, and watched the light from the Sun or the radio waves from transmitters on Earth. A unique time to measure the atmosphere occurs as the spacecraft watches the Sun and Earth set behind Pluto and Charon.


Launch: January 19, 2006
Launch Vehicle: Atlas V 551 first stage; Centaur second stage; STAR 48B solid rocket third stage
Location: Cape Canaveral Air Force Station, Florida
Trajectory: To Pluto via Jupiter Gravity Assist

Mission Phases
==============

Summary of mission phases
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Mission phases provide convenient handles and approximate time boundaries to
1) partition the data into very broad categories of mission activity
2) provide approximate time boundaries for PDS archive data sets
The mission is continuous, so the boundaries are very soft i.e. in an operational sense they do not exist in a noticeable way.

That being the case, the user should not expect the actual range of times covered by data in this data set to exactly agree with the boundaries of the corresponding mission phase described below; the data set time range may be far less or it may overlap the boundaries. This is intentional and will not be changed.

For example, during the New Horizons mission it was decided to deliver data sets for the first three years of the 7.5-year Pluto Cruise mission phase before that mission phase was complete. As such, the time range of those data sets was from 2007 until mid- to late-2010, while the mission phase described below extends through the end of 2014. The intention was to deliver the balance of the Pluto Cruise at a later date. Once all Pluto Cruise data are delivered this paragraph will become obsolete; nonetheless this paragraph may be left in place as an example of the intentional flexibility of the boundaries between the mission phases defined in the dates below.


Full MISSION_PHASE_NAME, Short name Start(1,3) Stop(2,3) plus optional Description
---------- ---------- --------- -------------------------


LAUNCH 2006-01-19 2006-12-31 POST-LAUNCH CHECKOUT

JUPITER 2007-01-01 2007-06-26 JUPITER ENCOUNTER

PLUTOCRUISE 2007-06-27 2014-12-31 PLUTO CRUISE, Jupiter-Pluto/Charon Interplanetary Cruise

PLUTO_CHARON 2015-01-01 2016-04-30 PLUTO ENCOUNTER, Pluto/Charon approach, flyby, post-encounter

KBO1CRUISE 2016-05-01 TBD KBO1 CRUISE, Pluto-KBO1 Cruise (4)

KBO1 TBD TBD KBO1 ENCOUNTER KBO1 approach, flyby, post-encounter (4)

KBO2CRUISE TBD TBD KBO2 CRUISE, KBO1-KBO2 Cruise (4)


KBO2 TBD TBD KBO2 ENCOUNTER KBO2 approach, flyby, post-encounter (4) Notes:
1 Start at 00:00:00 UTC on the spacecraft that day 2 End before 00:00:00 UTC on the spacecraft next day 3 Start and end dates are not exact and identical for all instruments; some instruments take single observations over several days which span these mission phase boundaries.
4 All mission phases after PLUTO ENCOUNTER assume an extended mission for NH; as of early 2016, no extension to the mission has been approved.


The Voyage
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Post-Launch Checkout:
Short phase name (in DATA_SET_ID; DSID): LAUNCH Formal mission phase name: POST-LAUNCH CHECKOUT Mission Phase Start Time - 2006-01-19 Mission Phase Stop Time - 2006-12-31
The first 13 months include spacecraft and instrument checkouts, instrument calibrations, trajectory correction maneuvers, and rehearsals for the Jupiter encounter.


Jupiter Encounter:
Short phase name (in DSID): JUPITER Formal mission phase name: JUPITER ENCOUNTER Mission Phase Start Time - 2007-01-01 Mission Phase Stop Time - 2007-06-26
Closest approach occurred on Feb. 28, 2007. Moving about 21 kilometers per second, New Horizons flew 3 to 4 times closer to Jupiter than the Cassini spacecraft, coming within 32 Jupiter radii of Jupiter.


Pluto Cruise:
Short phase name (in DSID): PLUTOCRUISE Formal mission phase name: PLUTO CRUISE Mission Phase Start Time - 2007-06-27 Mission Phase Stop Time - 2015-01-15
Activities during the approximately 8-year PLUTOCRUISE mission phase to Pluto include annual spacecraft and instrument checkouts (ACOs), trajectory corrections, instrument calibrations and Pluto encounter rehearsals.


Pluto-Charon Encounter
----------------------
Short phase name (in DSID): PLUTO_CHARON Formal mission phase name: PLUTO ENCOUNTER Mission Phase Start Time - 2015-01-15 Mission Phase Stop Time - 2016-04-30
This phase will be broken down into three sub-phases:
Approach:
Mission Sub-phase Start Time - 2015-01-15 Mission Sub-phase Stop Time - 2015-07-14
Ten weeks before encounter, image resolution will exceed that of the best Hubble Space Telescope images. Four weeks before encounter, daily studies will begin. New Horizon will acquire maps and spectra throughout this period.


Near Encounter Phase (NEP, or Flyby):
Mission Sub-phase Start Time - 2015-07-14 Mission Sub-phase Stop Time - 2015-07-14
Activities include taking the highest resolution visible and spectral imaging at closest approach to Pluto and Charon. The time near occultations (Pluto/Sun, Pluto/Earth, Charon/Sun and Charon/Earth) will be used for atmospheric studies.


Departure (Post-Encounter):
Mission Sub-phase Start Time - 2015-07-14 Mission Sub-phase Stop Time - 2016-04-30
Four weeks of post-encounter studies and nine months of downloading data.


KBO 1 Cruise:
Short phase name (in DSID): KBO1CRUISE Formal mission phase name: KBO1 CRUISE Mission Phase Start Time - 2016-05-01 Mission Phase Stop Time - TBD
Activities during the KBO1CRUISE mission phase to the first KBO encounter will be similar to those for Pluto Cruise phase.


KBO 1 Encounter
Short phase name (in DSID): KBO1 Formal mission phase name: KBO1 ENCOUNTER Mission Phase Start Time - TBD Mission Phase Stop Time - TBD
Activities during this encounter are TBD, but will be similar to the Pluto Encounter phases.


KBO 2 Cruise:
Short phase name (in DSID): KBO2CRUISE Formal mission phase name: KBO2 CRUISE Mission Phase Start Time - TBD Mission Phase Stop Time - TBD
Activities during the KBO2CRUISE mission phase to the first KBO encounter will be similar to those for Pluto and KBO 1 Cruise phases.


KBO 2 Encounter
Short phase name (in DSID): KBO2 Formal mission phase name: KBO2 ENCOUNTER Mission Phase Start Time - TBD Mission Phase Stop Time - TBD
Activities during this encounter are TBD, but will be similar to the Pluto and KBO Encounter phases.