This infrared 3-D image of Jupiter's north pole was derived from data collected by the Jovian Infrared Auroral Mapper (JIRAM) instrument aboard NASA's Juno spacecraft. Image credit: NASA/JPL-Caltech/SwRI/ASI/INAF/JIRAM. › Larger view
Scientists working on NASA's Juno mission to Jupiter shared a 3-D infrared movie depicting densely packed cyclones and anticyclones that permeate the planet's polar regions, and the first detailed view of a dynamo, or engine, powering the magnetic field for any planet beyond Earth. Those are among the items unveiled during the European Geosciences Union General Assembly in Vienna, Austria, on Wednesday, April 11.
Juno mission scientists have taken data collected by the spacecraft's Jovian InfraRed Auroral Mapper (JIRAM) instrument and generated the 3-D fly-around of the Jovian world's north pole. Imaging in the infrared part of the spectrum, JIRAM captures light emerging from deep inside Jupiter equally well, night or day. The instrument probes the weather layer down to 30 to 45 miles (50 to 70 kilometers) below Jupiter's cloud tops. The imagery will help the team understand the forces at work in the animation - a north pole dominated by a central cyclone surrounded by eight circumpolar cyclones with diameters ranging from 2,500 to 2,900 miles (4,000 to 4,600 kilometers).
"Before Juno, we could only guess what Jupiter's poles would
look like," said
Alberto Adriani, Juno co-investigator from the Institute for Space Astrophysics
and Planetology, Rome. "Now, with Juno flying over the poles at a
close distance it permits the collection of infrared imagery on Jupiter's polar
weather patterns and its massive cyclones in unprecedented spatial resolution."
Another
Juno investigation discussed during the media briefing was the team's latest
pursuit of the interior composition of the gas giant. One of the biggest pieces
in its discovery has been understanding how Jupiter's deep interior rotates.
"Prior
to Juno, we could not distinguish between extreme models of Jupiter's interior
rotation, which all fitted the data collected by Earth-based observations and
other deep space missions," said Tristan Guillot, a Juno co-investigator from the Université Côte
d'Azur, Nice, France. "But Juno is different -- it orbits the planet from pole-to-pole
and gets closer to Jupiter than any spacecraft ever before.
Thanks to the
amazing increase in accuracy brought by Juno's gravity data, we have
essentially solved the issue of how Jupiter's interior rotates: The zones and
belts that we see in the atmosphere rotating at different speeds extend to
about 1,900 miles (3,000 kilometers).
An infrared view of Jupiter's North Pole. The movie utilizes imagery
derived from data collected by the Jovian Infrared Auroral Mapper
(JIRAM) instrument aboard NASA's Juno mission. The images were obtained
during Juno's fourth pass over Jupiter. Infrared cameras are used to
sense the temperature of Jupiter's atmosphere and provide insight into
how the powerful cyclones at Jupiter's poles work. In the animation, the
yellow areas are warmer (or deeper into Jupiter's atmosphere) and the
dark areas are colder (or higher up in Jupiter's atmosphere). In this
picture the highest "brightness temperature" is around 260K (about
-13°C) and the lowest around 190K (about -83°C). The "brightness
temperature" is a measurement of the radiance, at 5 µm, traveling upward
from the top of the atmosphere towards Juno, expressed in units of
temperature.
"At
this point, hydrogen becomes conductive enough to be dragged into near-uniform
rotation by the planet's powerful magnetic field."
The
same data used to analyze Jupiter's rotation contain information on the
planet's interior structure and composition. Not knowing the interior rotation
was severely limiting the ability to probe the deep interior. "Now our work can
really begin in earnest -- determining the interior composition of the solar system's
largest planet," said Guillot.
At the meeting,
the mission's deputy-principal investigator, Jack Connerney of the Space
Research Corporation, Annapolis, Maryland, presented the
first detailed view of the dynamo, or engine, powering the magnetic
field of
Jupiter.
Connerney
and colleagues produced the new magnetic field model from measurements made
during eight orbits of Jupiter. From those, they derived maps of the magnetic
field at the surface and in the region
below the surface where the dynamo is thought to originate. Because Jupiter is
a gas giant, "surface" is defined as one Jupiter radius, which is about 44,400
miles (71,450 kilometers).
These maps provide an extraordinary
advancement in current knowledge and will guide the science team in planning
the spacecraft's remaining observations.
"We're finding that Jupiter's magnetic field is unlike
anything previously imagined,"said
Connerney. "Juno's investigations of the magnetic environment at Jupiter represent the
beginning of a new era in the studies of planetary dynamos."
The map Connerney's team made of the
dynamo source region revealed unexpected irregularities, regions of surprising
magnetic field intensity, and that Jupiter's magnetic field is more complex in
the northern hemisphere than in the southern hemisphere. About halfway between
the equator and the north pole lies an area where the magnetic field is intense
and positive. It is flanked by areas that are less intense and negative. In the
southern hemisphere, however, the magnetic field is consistently
negative, becoming more and more intense from the equator to the pole.
The researchers
are still figuring out why they would see these differences in a rotating
planet that's generally thought of as more-or-less fluid.
"Juno is only about one third the way through its planed
mapping mission and already we are beginning to discover hints on how Jupiter's
dynamo works," said Connerney. "The team is really anxious to see the data from
our remaining orbits."
Juno has logged nearly 122 million miles (200 million
kilometers) to complete those 11 science passes since entering Jupiter's orbit
on July 4, 2016. Juno's 12th science pass will be on May 24.
NASA's Jet Propulsion Laboratory, Pasadena, California, manages
the Juno mission for the principal investigator, Scott Bolton, of the Southwest
Research Institute in San Antonio. Juno is part of NASA's New Frontiers
Program, which is managed at NASA's Marshall Space Flight Center in Huntsville,
Alabama, for NASA's Science Mission Directorate. The Italian Space Agency
(ASI), contributed two instruments, a Ka-band frequency translator (KaT) and
the Jovian Infrared Auroral Mapper (JIRAM). Lockheed Martin Space, Denver,
built the spacecraft.
https://www.missionjuno.swri.edu
The public can follow the mission on Facebook and Twitter at:
https://www.facebook.com/NASAJuno
https://www.twitter.com/NASAJuno
More information on Jupiter can be found at: https://www.nasa.gov/jupiter
News Media Contact
DC Agle
Jet Propulsion Laboratory, Pasadena, Calif.
818-393-9011
agle@jpl.nasa.gov
JoAnna Wendel
NASA Headquarters, Washington
202-358-1003
joanna.r.wendel@nasa.gov
Source: JPL-Caltech/News
