A massive hotspot — larger the Earth’s Lake Superior —
can be seen just to the right of Io’s south pole in this annotated image taken
by the JIRAM infrared imager aboard NASA’s Juno on Dec. 27, 2024, during the
spacecraft’s flyby of the Jovian moon.
NASA/JPL-Caltech/SwRI/ASI/INAF/JIRAM
Even by the standards of Io, the most volcanic celestial body in the solar
system, recent events observed on the Jovian moon are extreme.
Scientists with NASA’s Juno mission
have discovered a volcanic hot spot in the southern hemisphere of Jupiter’s
moon Io. The hot spot is not only larger than Earth’s Lake Superior, but it
also belches out eruptions six times the total energy of all the world’s power
plants. The discovery of this massive feature comes courtesy of Juno’s Jovian
Infrared Auroral Mapper (JIRAM) instrument, contributed by the Italian Space
Agency.
“Juno had two really close flybys
of Io during Juno’s extended mission,” said the mission’s principal investigator, Scott
Bolton of the Southwest Research Institute in San Antonio. “And while each
flyby provided data on the tormented moon that exceeded our expectations, the
data from this latest — and more distant — flyby really blew our minds. This is
the most powerful volcanic event ever recorded on the most volcanic world in
our solar system — so that’s really saying something.”
The source of Io’s torment:
Jupiter. About the size of Earth’s Moon, Io is extremely close to the mammoth
gas giant, and its elliptical orbit whips it around Jupiter once every 42.5
hours. As the distance varies, so does the planet’s gravitational pull, which
leads to the moon being relentlessly squeezed. The result: immense energy from
frictional heating that melts portions of Io’s interior, resulting in a
seemingly endless series of lava plumes and ash venting into its atmosphere
from the estimated 400 volcanoes that riddle its surface.
Close Flybys
Designed to capture the infrared light (which isn’t visible to the human eye) emerging from deep inside Jupiter, JIRAM probes the gas giant’s weather layer, peering 30 to 45 miles (50 to 70 kilometers) below its cloud tops. But since NASA extended Juno’s mission, the team has also used the instrument to study the moons Io, Europa, Ganymede, and Callisto.
Images of Io captured in 2024 by the JunoCam imager
aboard NASA’s Juno show signif-icant and visible surface changes (indicated by
the arrows) near the Jovian moon’s south pole. These changes occurred between
the 66th and 68th perijove, or the point during Juno’s orbit when it is closest
to Jupiter.
Image data: NASA/JPL-Caltech/SwRI/MSSS Image
processing by Jason Perry
During its extended mission, Juno’s trajectory passes by Io every other
orbit, flying over the same part of the moon each time. Previously, the
spacecraft made close flybys of Io in December 2023 and February
2024, getting
within about 930 miles (1,500 kilometers) of its surface. The latest flyby took
place on Dec. 27, 2024, bringing the spacecraft within about 46,200 miles
(74,400 kilometers) of the moon, with the infrared instrument trained on Io’s
southern hemisphere.
Io Brings the
Heat
“JIRAM detected an event of extreme
infrared radiance — a massive hot spot — in Io’s southern hemisphere so strong
that it saturated our detector,” said Alessandro Mura, a Juno co-investigator
from the National Institute for Astrophysics in Rome. “However, we have
evidence what we detected is actually a few closely spaced hot spots that
emitted at the same time, suggestive of a subsurface vast magma chamber system.
The data supports that this is the most intense volcanic eruption ever recorded
on Io.”
The JIRAM science team estimates
the as-yet-unnamed feature spans 40,000 square miles (100,000 square
kilometers). The previous record holder was Io’s Loki Patera, a lava lake of about 7,700 square miles (20,000 square kilometers). The
total power value of the new hot spot’s radiance measured well above 80
trillion watts.
Picture This
The feature was also captured by
the mission’s JunoCam visible light camera. The team compared JunoCam images
from the two previous Io flybys with those the instrument collected on Dec. 27.
And while these most recent images are of lower resolution since Juno was
farther away, the relative changes in surface coloring around the newly
discovered hot spot were clear. Such changes in Io’s surface are known in the
planetary science community to be associated with hot spots and volcanic
activity.
An eruption of this magnitude is
likely to leave long-lived signatures. Other large eruptions on Io have created
varied features, such as pyroclastic deposits (composed rock fragments spewed
out by a volcano), small lava flows that may be fed by fissures, and
volcanic-plume deposits rich in sulfur and sulfur dioxide.
Juno will use an upcoming, more
distant flyby of Io on March 3 to look at the hot spot again and search for
changes in the landscape. Earth-based observations of this region of the moon
may also be possible.
“While it is always great to
witness events that rewrite the record books, this new hot spot can potentially
do much more,” said Bolton. “The intriguing feature could improve our
understanding of volcanism not only on Io but on other worlds as well.”
More About
Juno
NASA’s Jet Propulsion Laboratory, a
division of Caltech in 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 the agency’s
Science Mission Directorate in Washington. The Italian Space Agency (ASI)
funded the Jovian InfraRed Auroral Mapper. Lockheed Martin Space in Denver
built and operates the spacecraft. Various other institutions around the U.S.
provided several of the other scientific instruments on Juno.
More information about Juno is
available at:
Source: NASA Juno Mission Spots Most Powerful Volcanic Activity on Io to Date - NASA
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