Juno is a NASA New Frontiers mission to the planet
It was originally proposed
at a cost of approximately US$
700 million (FY03) for a June 2009
launch. NASA budgetary restrictions resulted in Juno being
re-scheduled to an August 2011 launch. The Atlas
rocket has been chosen to launch Juno in the Atlas V-551
The spacecraft will be placed in a polar
to study the planet's composition, gravity field
, magnetic field
, and polar magnetosphere
. Juno will also
search for clues about how Jupiter formed, including whether the
planet has a rocky core, the amount of water present within the
deep atmosphere, and how the mass is distributed within the planet.
Juno will also study Jupiter's deep winds, which can reach speeds
of 600 km/h.
Juno's trajectory will use a gravity
speed boost from Earth
accomplished through an Earth flyby
after its 2011 launch. In 2016, the spacecraft will perform an
orbit insertion burn to slow the spacecraft enough to allow capture
into an 11-day polar orbit.Once Juno enters into its orbit,
instruments will begin to measure the
thermal radiation emanating from deep within Jupiter's atmosphere
observations will complement previous studies of the planet's
composition by assessing the abundance and distribution of water,
and therefore oxygen. While filling missing pieces of the puzzle of
Jupiter's composition, this data also provides insight into the
planet's origins. Juno will also investigate the convection that
drives general circulation patterns in Jupiter's atmosphere.
Meanwhile, other instruments aboard Juno will gather data about the
planet's gravitational field and polar magnetosphere.
The Juno mission will conclude in 2018, after 32 orbits around
Jupiter. Data analysis may continue beyond 2018.
The Juno spacecraft's suite of seven science instruments will
- The ratio of oxygen to hydrogen, effectively measuring the abundance of
water in Jupiter, which will help distinguish
among prevailing theories linking the gas giant's formation to the
- Obtain a better estimate of Jupiter's core mass, which will
also help distinguish among prevailing theories linking the gas
giant's formation to the solar system.
- Precisely map Jupiter's gravity to
assess the distribution of mass in Jupiter's interior, including
properties of the planet's structure and dynamics.
- Precisely map Jupiter's magnetic
field to assess the origin and structure of the field and how
deep in Jupiter the magnetic field is created. This experiment also
will help scientists understand the fundamental physics of dynamo theory.
- Map the variation in atmospheric composition, temperature,
structure, cloud opacity and dynamics to depths far greater than
100 bars at all latitudes.
- Characterize and explore the three dimensional structure of
Jupiter's polar magnetosphere and its
Scott Bolton of the Southwest
Research Institute in San Antonio, Texas is the
Principal Investigator and is responsible for all aspects of the
mission. The Jet Propulsion Laboratory in California manages the mission and Lockheed Martin Corporation is
responsible for the spacecraft development.
The mission is
being carried out with the participation of several institutional
Proposed scientific instruments
Zones, belts and vortices on
The Juno mission's science objectives will be achieved with a
payload of eight instruments onboard the spacecraft:
- Microwave radiometer
- Jovian Infrared Auroral Mapper
- Fluxgate Magnetometer (FGM) and Advanced Stellar Compass
- Jovian Auroral Distribution Experiment (JADE)
- Jovian Energetic Particle Detector Instrument (JEDI)
- Radio and Plasma Wave Sensor
- Ultraviolet Imaging Spectrograph
Juno will be the first mission to Jupiter using solar panel
instead of the radioisotope
(RTGs) used by Pioneer 10
, Pioneer 11
the Voyager program
, and the Galileo orbiter
. Advances made in both
solar cell technology and efficiency over the past several decades
makes it economically feasible to use solar panels of practical
size to provide power 5 Astronomical
from the Sun
. In addition, RTGs are in
short supply, limiting their availability for space missions. NASA
plans several more projects involving RTGs, and the decision to use
alternate technology on this mission is more practical and
economical than political.
The Juno spacecraft uses three solar arrays symmetrically arranged
around the spacecraft, which are stowed against the sides of the
spacecraft for launch. Immediately after launch the arrays deploy.
Two of the arrays have 4 panels each, and the third array has 3
panels with a magnetometer experiment in place of the fourth panel.
The total area of the arrays is over . This is enough to produce
over while in Earth orbit, and just over while on Jupiter orbit.
The solar panels will remain in sunlight continuously from launch
through end of mission, except for short periods during the
operation of the main engine.