National Aeronautics and Space Administration

NASA

www.nasa.gov

Launch Period  

August 2011

(Launch from Cape Canaveral) 

Earth Flyby  

October 2013

(Earth Gravity Assist)

 
Arrival at Jupiter 

August 2016

End of Mission (Deorbit) 

October 2017

Spacecraft Mass 

3625 kg

Solar Arrays (3)   2.65 m x 8.9 m (435 W total at end of mission)

Juno Mission to Jupiter 

Juno’s primary goal is to reveal the story of the forma-
tion and evolution of the giant planet Jupiter. Using a 
microwave observational technique for the first time, 
Juno detects the thermal radiation from several layers 
deep below the clouds simultaneously. This allows Juno 
to determine the all-important water abundance. The 
motion of the spacecraft near Jupiter provides informa-
tion on Jupiter’s gravity field, whether a solid core exists 
and how the giant planet rotates. Multiple orbits provide 
Juno the ability to precisely measure the magnetic field 
and investigate its auroras—the strongest in the solar 
system. An understanding of the origin and evolution of 
Jupiter, as the archetype of giant planets, can provide 
the knowledge needed to understand the origin of our 
solar system and planetary systems around other stars.

Science Objectives   

 

 

 

 

 

             Instrument

Atmospheric Composition
and Dynamics

Magnetic Field

Gravity Field

Polar Magnetosphere

Visible Imaging Camera

Measure the water and ammonia
abundance in Jupiter’s atmosphere 

Determine magnetic field and time  
variability

Measure the gravity field to explore how 
mass is distributed inside the planet

Explore and characterize the three- 
dimensional magnetosphere and auroras

Public processing of unprecedented close-
up images of Jupiter and the first views of 
its poles

Microwave Radiometer (MWR) and  
Infrared Spectrometer/Imager (JIRAM)   

Fluxgate Magnetometer (MAG) 

X- & Ka-band uplink and downlink

Juno Energetic Particle Detector Instru-
ment (JEDI), Jovian Auroral Distributions 
Experiment (JADE), Ultraviolet Spectrom-
eter (UVS), Radio and Plasma Waves Ex-
periment (WAVES), Infrared Spectrometer/
Imager (JIRAM)

JunoCam

NASA

National Aeronautics and Space Administration

Jet Propulsion Laboratory
California Institute of Technology 
Pasadena, California 

JPL 400-1382  4/09

Jupiter

 

The largest planet in our solar system, Jupiter is  
more massive than all of the other planets combined. 
Composed mostly of hydrogen and helium, Jupiter 
resembles a star in composition. There are hundreds 
of Jupiter-like planets now being discovered in orbits 
around other stars, and the study of this strange and 
mysterious world will help us understand the formation 
of these planetary systems throughout our galaxy and 
beyond.

Jupiter’s appearance is a tapestry of beautiful colors 
and atmospheric features. Most of the visible clouds  
are composed of ammonia. Water clouds exist deep  
below. Jupiter’s “stripes” are created by strong east–
west winds in the planet’s upper atmosphere. Within 
these belts and zones are storm systems that can rage 
for decades. The Great Red Spot, a giant spinning 
storm, has been observed for more than 300 years.

The composition of Jupiter’s atmosphere is similar to 
that of the Sun—mostly hydrogen and helium. Deep in 
the atmosphere, pressure and temperature increase, 
compressing the hydrogen gas into a liquid. At depths 
about a third of the way down, the liquid hydrogen 
becomes electrically conducting, like a metal. In this 
conducting layer, Jupiter’s powerful magnetic field is 
generated by electrical currents driven by the planet’s 
fast rotation in ways that we don’t yet understand. At the 
center, the immense pressure may support a solid core 
more than ten times the mass of Earth.

Jupiter’s enormous magnetic field traps swarms of 
charged particles (electrons and ions) whose high-
speed motion around the planet creates immense cur-
rents that drive Jupiter’s powerful auroras. The Jovian 
magnetosphere, comprising these particles and fields, 
balloons 1 million to 3 million kilometers (600,000 to  
2 million miles) toward the Sun and tapers into a wind-

For more information about Juno, go to:  

http://www.nasa.gov/juno

http://newfrontiers.nasa.gov/missions_juno.html

sock-shaped tail extending more than 1 billion kilome-
ters (600 million miles) behind Jupiter as far as Saturn’s 
orbit. Jupiter’s magnetosphere is thus the largest struc-
ture in the solar system, even larger than our Sun.

Jupiter has three thin rings around its equator that are 
fainter than the rings of Saturn. The rings appear to 
consist mostly of fine dust particles and may be formed 
by dust associated with the giant planet’s four small  
inner moons.

Jupiter’s four largest moons—Io, Europa, Ganymede, 
and Callisto—were discovered by Galileo in 1610. Io is 
the most volcanically active body in our solar system.  
Ganymede is the largest planetary moon and is the only 
moon in the solar system known to have its own mag-
netic field. Europa appears to possess a liquid water 
ocean beneath its frozen crust, and similar oceans may 
also lie within Callisto and Ganymede. Astronomers 
have discovered more than 60 moons orbiting the giant 
planet in total. Numerous small, outer moons may be 
asteroids captured by Jupiter’s gravity.

A Cassini view of Jupiter in 2000.