Just a year after it was dispatched on the first
mission to Pluto and the Kuiper Belt, the APL-built
spacecraft is on the doorstep of the solar system's largest
planet, about to swing past Jupiter and pick up even more
speed on its voyage toward the unexplored regions of the
The fastest spacecraft ever launched, New Horizons
will make its closest pass to Jupiter on Feb. 28, threading
its path through an "aim point" 1.4 million miles from the
center of Jupiter. Jupiter's gravity will accelerate New
Horizons away from the sun by an additional 9,000 miles per
hour — half the speed of a space shuttle in orbit
— pushing it past 52,000 mph and hurling it toward a
pass through the Pluto system in July 2015.
At the same time, the New Horizons mission team is
taking the spacecraft on the ultimate test drive: using the
flyby to put the probe's systems and seven science
instruments through the paces of a planetary encounter.
More than 700 observations of Jupiter and its four largest
moons are planned from January through June, including
scans of Jupiter's turbulent stormy atmosphere and dynamic
magnetic cocoon (called a magnetosphere); the most detailed
survey yet of its gossamer ring system; maps of the
composition and topography of the large moons Io, Europa,
Ganymede and Callisto; and an unprecedented look at
volcanic activity on Io.
The flight plan also calls for the first-ever trip
down the long "tail" of Jupiter's magnetosphere, a wide
stream of charged particles that extends tens of millions
of miles beyond the planet, and the first close-up look at
the Little Red Spot, a nascent storm south of Jupiter's
famous Great Red Spot.
"Our highest priority is to get the spacecraft safely
through the gravity assist and on its way to Pluto," said
the mission's principal investigator, Alan Stern of the
Southwest Research Institute. "But we also have an
incredible opportunity to conduct a real-world-encounter
stress test to wring out our procedures and techniques for
Pluto, and to collect some valuable science data."
The Jupiter test matches or exceeds the mission's
Pluto study in duration, data volume sent back to Earth and
operational intensity. Much of the data from the Jupiter
flyby won't be sent back to Earth until after closest
approach, because the spacecraft's main priority is to
observe the planet and store data on its recorders before
transmitting information home.
Glen Fountain, New Horizons project manager at APL,
which built and operates the spacecraft, said, "We designed
the Jupiter encounter to prove out our planning tools, our
simulation capabilities, our spacecraft and our instrument
sensors on a real planetary target, well before the Pluto
encounter. If the team needs to adjust anything before
Pluto, we'll find out about it now," he said.
The mission team at APL, SwRI and other institutions
has learned much in a hectic year since New Horizons lifted
off on Jan. 19, 2006, from Cape Canaveral Air Force
Station, Fla. The spacecraft has undergone a full range of
system and instrument checkouts, instrument calibrations
and commissioning, some flight software enhancements and
three small propulsive maneuvers to adjust its trajectory.
Operational highlights included long-distance snapshots of
both Jupiter and Pluto, and a flyby of asteroid 2002 JF56,
which was recently named "APL" by the International
With closest approach to Jupiter coming 13 months
after launch, New Horizons will reach the planet faster
than any of its seven previous visitors. Pioneers 10 and
11, Voyagers 1 and 2, Ulysses and Cassini all used
Jupiter's gravity to reach other destinations; NASA's
Galileo orbited the planet from 1995 to 2003.
New Horizons also provides the first close-up look at
the Jovian system since Galileo — and the last look
until NASA's Juno mission arrives in 2016. Jeff Moore, of
NASA Ames Research Center, who heads the mission's Jupiter
Encounter Science Team, said, "The Jupiter system is
incredibly dynamic. From constant changes in Jupiter's
magnetosphere and atmosphere, to the evolving surfaces of
moons such as Io, you get a new snapshot every time you go
After an eight-year cruise from Jupiter across the
expanse of the solar system, New Horizons will conduct a
five-month-long study of Pluto and its three moons in 2015,
characterizing their global geology and geomorphology,
mapping their surface compositions and temperatures, and
examining Pluto's atmospheric composition and structure.
Then, as part of a potential extended mission, New Horizons
would conduct similar studies of one or more smaller worlds
in the Kuiper Belt, the region of ancient, rocky and icy
bodies far beyond Neptune's orbit.
The New Horizons science payload includes imaging
infrared and ultraviolet spectrometers, a multicolor
camera, a long-range telescopic camera, two particle
spectrometers, a space-dust detector and a radio science
experiment. The compact 1,050-pound spacecraft, drawing
electricity from a single radioisotope thermoelectric
generator, currently operates on slightly more power than a
pair of 100-watt light bulbs.
New Horizons is the first mission in NASA's New
Frontiers Program of medium-class spacecraft exploration
projects. Stern leads the mission and science team as
principal investigator; APL manages the mission for NASA's
Science Mission Directorate.
For more information on New Horizons, go to