Extended Mission

Artist’s impression of lightning in Jupiter’s northern hemisphere. Credits: NASA/JPL-Caltech/SwRI/JunoCam.

Jul 10, 2019

Juno will circle Jupiter for another four years.

Jupiter is the largest planet. It is so large that all of the other planets could fit comfortably inside its 1.77 X 10^15 cubic kilometer volume. Jupiter rotates in 9.925 hours, causing its diameter to be 9275 kilometers more than the distance between its poles. Jupiter reveals an electrical connection between its polar regions and its four largest moons: all of them leave trails in Jupiter’s polar aurorae. As discussed in previous Pictures of the Day, electric charge flow creates lightning in the planet’s upper atmosphere, as well as intense aurorae at the poles.

Juno began observations of Jupiter on July 4, 2016 after an August 5, 2011 launch. Since there are radiation belts around Jupiter similar to the Van Allen radiation belts that surround Earth, but thousands of times greater in strength and extent, Juno’s electronics are housed within a titanium shell, so that the energetic particles trapped around Jupiter will not interfere with its systems.

Jupiter is an even more electrically active world than their models predicted. Instead of a 5 gauss magnetic field, Juno detected a 9 gauss field, compared to Earth at .5 gauss. The field is also quite irregular, suggesting to astrophysicists that there is a nonconformity in Jupiter’s core.

According to a recent press release, NASA extended funding for the Juno mission until 2022. As it stands, spacecraft operations will end in July 2021 with incineration taking place sometime in 2022. The extension is largely due to a concern with its fuel delivery system. Instead of orbiting Jupiter every 14 days, Juno is in a 53 day orbit.

Scott Bolton from the Southwest Research Institute said:

“… the larger orbits allow us to further explore the far reaches of the Jovian magnetosphere — the region of space dominated by Jupiter’s magnetic field — including the far magnetotail, the southern magnetosphere, and the magnetospheric boundary region called the magnetopause. We have also found Jupiter’s radiation environment in this orbit to be less extreme than expected, which has been beneficial to not only our spacecraft, but our instruments and the continued quality of science data collected.”

One of Juno’s more interesting discoveries is the way that lightning occurs on Jupiter. Data from the Microwave Radiometer Instrument (MWR) detects electromagnetic emissions across a wide frequency range. However, there are differences between lightning’s behavior on Jupiter compared to Earth.

Shannon Brown from JPL said:

“In the data from our first eight flybys, Juno’s MWR detected 377 lightning discharges. They were recorded in the megahertz as well as gigahertz range…Jupiter lightning distribution is inside out relative to Earth. There is a lot of activity near Jupiter’s poles but none near the equator. You can ask anybody who lives in the tropics — this doesn’t hold true for our planet.”

The Galileo spacecraft discovered electric charges flowing around Jupiter, just as Electric Universe theorists predicted. As the moon Io revolves through Jupiter’s electromagnetic fields, trillions of watts are dissipated between them. This electric charge flow travels along Jupiter’s magnetic field, creating the lightning and polar aurorae.

It is not convection that drives lightning on Jupiter, or on Earth, it is electricity and plasma dynamics.

Stephen Smith

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