This
is a reconstructed view of Jupiter's northern lights through the
filters of the Juno Ultraviolet Imaging Spectrograph instrument on Dec.
11, 2016, as the Juno spacecraft approached Jupiter, passed over its
poles, and plunged towards the equator. Image Credit:
NASA/JPL-Caltech/Bertrand Bonfond. › Full image and caption
This image,
created with data from Juno's Ultraviolet Imaging Spectrograph, marks
the path of Juno's readings of Jupiter's aurora, highlighting the
electron measurements that show the discovery of the so-called discrete
auroral acceleration processes indicated by the "inverted Vs" in the
lower panel. Image Credit: NASA/JPL-Caltech/SwRI/Randy Gladstone. › Full image and caption
Scientists on NASA's Juno mission have observed massive amounts of
energy swirling over Jupiter's polar regions that contribute to the
giant planet's powerful auroras - only not in ways the researchers
expected.
Examining data collected by the ultraviolet spectrograph and
energetic-particle detector instruments aboard the Jupiter-orbiting Juno
spacecraft, a team led by Barry Mauk of the Johns Hopkins University
Applied Physics Laboratory, Laurel, Maryland, observed signatures of
powerful electric potentials, aligned with Jupiter's magnetic field,
that accelerate electrons toward the Jovian atmosphere at energies up to
400,000 electron volts. This is 10 to 30 times higher than the largest
auroral potentials observed at Earth, where only several thousands of
volts are typically needed to generate the most intense auroras -- known
as discrete auroras -- the dazzling, twisting, snake-like northern and
southern lights seen in places like Alaska and Canada, northern Europe,
and many other northern and southern polar regions.
Jupiter has the most powerful auroras in the solar system, so the
team was not surprised that electric potentials play a role in their
generation. What's puzzling the researchers, Mauk said, is that despite
the magnitudes of these potentials at Jupiter, they are observed only
sometimes and are not the source of the most intense auroras, as they
are at Earth.
"At Jupiter, the brightest auroras are caused by some kind of
turbulent acceleration process that we do not understand very well,"
said Mauk, who leads the investigation team for the APL-built Jupiter
Energetic Particle Detector Instrument (JEDI).
"There are hints in our latest data indicating that as the power
density of the auroral generation becomes stronger and stronger, the
process becomes unstable and a new acceleration process takes over. But
we'll have to keep looking at the data."
Scientists consider Jupiter to be a physics lab of sorts for worlds
beyond our solar system, saying the ability of Jupiter to accelerate
charged particles to immense energies has implications for how more
distant astrophysical systems accelerate particles. But what they learn
about the forces driving Jupiter's auroras and shaping its space weather
environment also has practical implications in our own planetary
backyard.
"The highest energies that we are observing within Jupiter's auroral
regions are formidable. These energetic particles that create the
auroras are part of the story in understanding Jupiter's radiation
belts, which pose such a challenge to Juno and to upcoming spacecraft
missions to Jupiter under development," said Mauk. "Engineering around
the debilitating effects of radiation has always been a challenge to
spacecraft engineers for missions at Earth and elsewhere in the solar
system. What we learn here, and from spacecraft like NASA's Van Allen Probes
and Magnetospheric Multiscale mission (MMS) that are exploring Earth's
magnetosphere, will teach us a lot about space weather and protecting
spacecraft and astronauts in harsh space environments. Comparing the
processes at Jupiter and Earth is incredibly valuable in testing our
ideas of how planetary physics works."
Mauk and colleagues present their findings in the Sept. 7 issue of the journal Nature.
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.
Lockheed Martin Space Systems, Denver, built the spacecraft.
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 / 818-354-6278
agle@jpl.nasa.gov
Michael Buckley
Johns Hopkins University Applied Physics Laboratory
443-778-7536
Michael.Buckley@jhuapl.edu
Dwayne Brown / Laurie Cantillo
NASA Headquarters, Washington
202-358-1726 / 202-358-1077
dwayne.c.brown@nasa.govo / laura.l.cantillo@nasa.gov
