A Whole New Jupiter: First Science Results from NASA's Juno Mission

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A Whole New Jupiter: First Science Results from NASA's Juno Mission
Jet Propulsion Laboratory
May 25, 2017

Early science results from NASA's Juno mission to Jupiter portray the
largest planet in our solar system as a complex, gigantic, turbulent world,
with Earth-sized polar cyclones, plunging storm systems that travel deep
into the heart of the gas giant, and a mammoth, lumpy magnetic field that
may indicate it was generated closer to the planet's surface than previously
thought.

"We are excited to share these early discoveries, which help us better
understand what makes Jupiter so fascinating," said Diane Brown, Juno
program executive at NASA Headquarters in Washington. "It was a long trip
to get to Jupiter, but these first results already demonstrate it was
well worth the journey."

Juno launched on Aug. 5, 2011, entering Jupiter's orbit on July 4, 2016.
The findings from the first data-collection pass, which flew within about
2,600 miles (4,200 kilometers) of Jupiter's swirling cloud tops on Aug.
27, are being published this week in two papers in the journal Science,
as well as 44 papers in Geophysical Research Letters.

"We knew, going in, that Jupiter would throw us some curves," said Scott
Bolton, Juno principal investigator from the Southwest Research Institute
in San Antonio. "But now that we are here we are finding that Jupiter
can throw the heat, as well as knuckleballs and sliders. There is so much
going on here that we didn't expect that we have had to take a step back
and begin to rethink of this as a whole new Jupiter."

Among the findings that challenge assumptions are those provided by Juno's
imager, JunoCam. The images show both of Jupiter's poles are covered in
Earth-sized swirling storms that are densely clustered and rubbing together.

"We're puzzled as to how they could be formed, how stable the configuration
is, and why Jupiter's north pole doesn't look like the south pole," said
Bolton. "We're questioning whether this is a dynamic system, and are we
seeing just one stage, and over the next year, we're going to watch it
disappear, or is this a stable configuration and these storms are circulating
around one another?"

Another surprise comes from Juno's Microwave Radiometer (MWR), which samples
the thermal microwave radiation from Jupiter's atmosphere, from the top
of the ammonia clouds to deep within its atmosphere. The MWR data indicates
that Jupiter's iconic belts and zones are mysterious, with the belt near
the equator penetrating all the way down, while the belts and zones at
other latitudes seem to evolve to other structures. The data suggest the
ammonia is quite variable and continues to increase as far down as we
can see with MWR, which is a few hundred miles or kilometers.

Prior to the Juno mission, it was known that Jupiter had the most intense
magnetic field in the solar system. Measurements of the massive planet's
magnetosphere, from Juno's magnetometer investigation (MAG), indicate
that Jupiter's magnetic field is even stronger than models expected, and
more irregular in shape. MAG data indicates the magnetic field greatly
exceeded expectations at 7.766 Gauss, about 10 times stronger than the
strongest magnetic field found on Earth.

"Juno is giving us a view of the magnetic field close to Jupiter that
we've never had before," said Jack Connerney, Juno deputy principal investigator
and the lead for the mission's magnetic field investigation at NASA's
Goddard Space Flight Center in Greenbelt, Maryland. "Already we see that
the magnetic field looks lumpy: it is stronger in some places and weaker
in others. This uneven distribution suggests that the field might be generated
by dynamo action closer to the surface, above the layer of metallic hydrogen.
Every flyby we execute gets us closer to determining where and how Jupiter's
dynamo works."

Juno also is designed to study the polar magnetosphere and the origin
of Jupiter's powerful auroras -- its northern and southern lights. These
auroral emissions are caused by particles that pick up energy, slamming
into atmospheric molecules. Juno's initial observations indicate that
the process seems to work differently at Jupiter than at Earth.

Juno is in a polar orbit around Jupiter, and the majority of each orbit
is spent well away from the gas giant. But, once every 53 days, its trajectory
approaches Jupiter from above its north pole, where it begins a two-hour
transit (from pole to pole) flying north to south with its eight science
instruments collecting data and its JunoCam public outreach camera snapping
pictures. The download of six megabytes of data collected during the transit
can take 1.5 days.

"Every 53 days, we go screaming by Jupiter, get doused by a fire hose
of Jovian science, and there is always something new," said Bolton. "On
our next flyby on July 11, we will fly directly over one of the most iconic
features in the entire solar system -- one that every school kid knows
-- Jupiter's Great Red Spot. If anybody is going to get to the bottom
of what is going on below those mammoth swirling crimson cloud tops, it's
Juno and her cloud-piercing science instruments."

NASA's Jet Propulsion Laboratory in Pasadena, California, manages the
Juno mission for NASA. The principal investigator is Scott Bolton of the
Southwest Research Institute in San Antonio. The Juno mission is part
of the New Frontiers Program managed by NASA's Marshall Space Flight Center
in Huntsville, Alabama, for the agency's Science Mission Directorate.
Lockheed Martin Space Systems, in Denver, built the spacecraft.

More information on the Juno mission is available at:

https://www.nasa.gov/juno

http://missionjuno.org

Follow the mission on Facebook and Twitter at:

http://www.facebook.com/NASAJuno

http://www.twitter.com/NASAJuno

News Media Contact
DC Agle
Jet Propulsion Laboratory, Pasadena, Calif.
818-393-9011
ag...@jpl.nasa.gov

Dwayne Brown / Laurie Cantillo
NASA Headquarters, Washington
202-358-1726 / 202-358-1077
dwayne....@nasa.gov / laura.l....@nasa.gov

Nancy Neal Jones
Goddard Space Flight Center, Greenbelt, Md.
301-286-0039
nancy....@nasa.gov

Deb Schmid
Southwest Research Institute, San Antonio
210-522-2254
dsc...@swri.org

2017-153