Jupiter, the third brightest object in our night sky.
This distant point of light has beckoned humanity for millennia in our quest for knowledge and our place in the universe.
Our fascination with the largest planet in the solar system has continued from antiquity
and into the renaissance when, for the first time, humans looked up through a telescope.
In 1610, using a telescope only one and a half inches in diameter, Galileo Galilei observed
through this tiny telescope wonders that would fundamentally change our views of the universe forever.
Visible in this small telescope, and magnified about 20 times, tiny worlds were seen circling
around this giant planet. What became known as the Galilean satellites, Io, Europa, Ganymede,
Callisto, their existence provided a powerful argument that Earth may not be the center
of the Universe, instead, the Earth may actually circle the Sun.
Much, much later, when humans started venturing into space, we sent missions to study the
solar system’s colossus. First there was the arrival of Pioneer 10 in 1973, followed
a year later by Pioneer 11; Voyagers I and II visited the planet in 1979; Ulysses studied
Jupiter’s magnetosphere in 1992 and again in 2000; the Galileo spacecraft studied the
planet in intricate detail in from 1995 until 2003, and it even launched a probe into the
atmosphere of Jupiter itself; The Cassini probe approached the planet in 2000 and took
very detailed images of its atmosphere; and, most recently, Jupiter was used for the New
Horizons mission to accelerate the probe to Pluto in 2007.
Since that flyby of New Horizon almost a decade ago, we’ve had no orbiters or probes studying
the largest planet in our solar system, until now.
Finally, a new mission is on its final approach to Jupiter.
Built by Lockheed Martin, Juno launched on August 5th 2011 atop an Atlas Five rocket
and will enter into Jupiter’s orbit on July 4th 2016. This mission to Jupiter is a collaboration
of many agencies: flight operations will be controlled from the Flight Control Center
in Pasadena California at NASA JPL; The Goddard Space Flight Center handles the instrumentation
The Universities of Hawaii, California Institute of Technology, the University of Colorado
at Boulder, and the Planetary Science Institute all make up the primary science investigators.
Juno is very large, it is 11 feet tall and 11 feet wide its three large solar panels
have a total surface area of 650 square feet. It is this large for a reason, this is the
first time a spacecraft has been sent beyond the asteroid belt using solar cells as its
primary power supply - made possible by advances in solar cell efficiency.
After its launch and two years hurtling through the solar system Juno returned for a swing
by Earth for a gravity assist. By firing its maneuvering thrusters at its greatest distance
from Earth, this gave the spacecraft an added push as it flew past, using Earth’s gravity
to exponentially increase its speed when it flew by, accelerating Juno to a speed of 87,000
miles per hour - the required velocity to reach Jupiter..
After five years, the spacecraft will finally arrive at its destination on July 4th 2016.
As it enters into Jupiter’s gravitational influence it will begin to speed up to 160,000
mile per hour making Juno the fastest human made object in history. And now it must slow
down or it will be lost in the depths of the solar system.
Its LEROS 1b main engine will ignite at the lowest point in Juno’s pass of Jupiter,
slowing the spacecraft down and allowing it to be captured by Jupiter’s immense gravity.
After two deceleration orbital maneuvers Juno will be in its eccentric 14 day polar orbit.
From this unique orbit, Juno will circle the planet 37 times over 20 months and will allow
the on board instruments to study the atmosphere and interior of Jupiter. It also will protect
Juno from the harmful radiation of the planet. Orbiting up high then ducking low to just
31,000 miles above the cloud tops means the spacecraft spends a short amount of time within
the radiation belts of Jupiter. The main computer and other critical systems are further protected
in a one centimeter thick titanium compartment within the main structure of Juno.
The design of the orbit and the spacecraft are meant to enable the 29 sensors and nine
science instruments to study the planet Jupiter like never before. Juno will look inside the
planet using magnetometers to Earth to measure the magnetic fields of Jupiter and its aurorae,
infrared and Microwave sensors will look deep into the atmosphere to assess the abundance
and distribution of water, and therefore oxygen, and provide insight into Jupiter's origins
as well as the solar system’s formation.
By peering inside Jupiter’s core scientists hope to answer whether or not it has a condensed
Hydrogen center which due to pressure and magnetism behaves like a metal.
By understanding the magnetosphere of the planet and taking measurements of the charged
particles that Jupiter emits and absorbs in giant aurora, we will unlock not only the
mystery of how the planet is structured but also how it sustains the energy to generate
the storms that move throughout its atmosphere, including: the Great Red Spot.
The answer to this grand mystery of our solar neighborhood maybe just around the corner.
Using microwaves and spectroscopy, Juno will look for how much water and thus oxygen Jupiter
has. Understanding the amount of water will also tell scientist the conditions in which
the heavy elements collapsed to help form Jupiter and how the rest of its gaseous structure
formed together due to the effects if gravity.
How and when Jupiter formed may hold clues to the process the rest of the solar system
underwent during its formation. Including hints to where Earth’s water came from and
why the inner planets are rocky.
When it’s mission is complete in February 2018, after two years and 37 orbits, Juno
will be ordered to de-orbit and burn up in Jupiter’s outer atmosphere, this precaution
will avoid any possibility of biological contamination of any of Jupiter’s moons, including Europa.
The probe will send back data of the environment of Jupiter until its final breakup.
Right now, Juno hurtles through space towards our largest planet, preparing for it’s arrival
in just a few short months, its science instruments primed to unlock the mysteries of a world
unimagined by Galileo when he first glimpsed its wonder through a telescope a little over
400 years ago.