IOWA CITY — Nearly a decade ago, NASA’s $1.13 billion Juno mission began what was expected to be a seven-year endeavor to Jupiter in hopes of better understanding the Giant Planet’s origin and evolution, potentially unlocking answers to mysteries of the solar system.
Once Juno entered the massive planet’s orbit in 2016, scientists — including those at the University of Iowa — determined the mission should extend beyond 2018 to July 2021. And this month, NASA announced plans to keep Juno in Jupiter’s orbit even longer — through September 2025 — thanks to the mission’s scientific success and potential.
Among its achievements, a UI-developed “Waves” instrument aboard Juno has provided insights into distribution of lightning on Jupiter, understanding of its intense auroras, and novel detection of small dust grains between Jupiter’s ring system and its atmosphere.
Juno has answered scientist questions about whether its core is firm — like Earth’s — or not.
“We found that, instead of there being a small compact core, there’s a very diffused or fuzzy core, which no one had anticipated,” said William “Bill” Kurth, UI research scientist in the Department of Physics and Astronomy and lead investigator for the Waves instrument aboard Juno.
Because Juno’s evolving orbit over the years has shifted nearer Jupiter’s northern pole, the spacecraft has achieved an improved vantage point for closer investigation into the physics behind that planet’s magnificent auroras, according to Kurth.
“One of the primary objectives of the original mission was to do the first exploration of the polar magnetosphere — this is a region of magnetized plasma consisting of charged particles that exists over the poles,” he said. “They are involved in the generation of (Jupiter’s) Northern and Southern lights, which are the most intense in the solar system.”
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No spacecraft previously had gone through that region until Juno — equipped with nine instruments, including the UI Waves technology designed to study radio and plasma waves.
“The Iowa Waves instrument actually made measurements in the source of those radio emissions,” Kurth said. “We were able to understand the nature of the energetic electrons that provide the energy for the radio emissions. This is groundbreaking territory for us.”
The spot in Juno’s orbit where it crosses Jupiter’s equator as it approaches the planet also has progressed closer — allowing nearer flybys of the planet’s moons.
“That’s something that the prime mission just physically could not accomplish,” he said. “So now we’ll be expanding the science objectives of the mission to look more at how those moons interact with Jupiter through its magnetic field.”
Having already traveled 2.98 billion miles — including its five-year journey from Earth to Jupiter — Juno aims to add 42 additional orbits with the extension, including close passes by moons Ganymede, Europa and Io, and with the planet’s north polar cyclones.
Juno also will embark on the first “extensive exploration of the faint rings encircling” Jupiter, the fifth planet from the sun and 2.5 times bigger than the other planets combined — containing 70 percent of the solar system’s mass, excluding the sun.
“Jupiter is such an extraordinary place,” Kurth said. “Only superlatives can describe it. So it is extremely exciting to be able to continue to follow Juno as it orbits in the Jovian system for another four years.”
Kurth said he is certain extending the mission will require more NASA funding, although those discussions have yet to occur.
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UI’s extensive and historic physics and astronomy research endeavors annually earn it millions in NASA funding, including $9.5 million in the 2020 budget year that ended June 30. That was up over recent NASA funding totals for UI-based science, including $6.7 million in fiscal 2019, $8.8 million in fiscal 2018 and $6.3 million in fiscal 2017.
UI’s NASA funding, while significant, accounts for a fraction of the external research funding it generates annually. In the last budget year, UI obtained $187.3 million from the National Institutes of Health; $61.6 million from the Department of Health and Human Services; and $39.3 million from the Department of Education.
Juno’s new end date in 2025 is logical, according to Kurth, in that researchers expect it will have spent its fuel stores by that time. The plan is to dispose of the spacecraft in Jupiter’s atmosphere — avoiding possible collision with the moon Europa and potential contamination of the planetary body.
The ongoing data Juno collects is expected to contribute to the next generation of Jovian system missions.
In addition to Kurth, Iowa’s Waves team includes co-investigator George Hospodarsky; research scientist Ali Sulaiman; postdoctoral scholar Sadie Elliott; and famed astrophysicist Donald Gurnett.
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