This image shows Jupiter’s south pole, as seen by NASA’s Juno
spacecraft from an altitude of 32,000 miles (52,000 kilometers). The oval
features are cyclones, up to 600 miles (1,000 kilometers) in diameter.
Multiple images taken with the JunoCam
instrument on three separate orbits were combined to show all areas in
daylight, enhanced color, and stereographic
projection.
Credits: NASA/JPL-Caltech/SwRI/MSSS/Betsy
Asher Hall/Gervasio Robles
|
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:
Follow the mission on Facebook and Twitter at:
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