Iowa scientists excited for Jupiter ‘Great Red Spot’ flyby

Astronomers and the like have been observing Jupiter's 'Great Red Spot” almost continuously for more than 180 years.

But they've never seen it like this.

On Monday, NASA's Juno mission is expected to pass directly over the 10,000-mile-wide storm, coming unprecedentedly close - about the distance from New York to Egypt - of the iconic tempest that remains, in many ways, a mystery. NASA, supporting the mission that includes a University of Iowa instrument, is heralding the flyby as 'humanity's first up-close and personal view” of the phenomenon.

'We'll be about 5,600 miles above the cloud tops when we're over the Great Red Spot,” said Bill Kurth, a UI space researcher and lead investigator for the Waves instrument aboard Juno. 'Given that the Great Red Spot is maybe 10,000 miles across, that's pretty close.”

Data collected from Juno's encounter could shed light on how deep into the atmosphere the storm extends and why, unlike Earth's storms that come and go, it possibly has persisted for more than 350 years - since Giovanni Cassini first observed it in 1665.

'That's precisely why we're interested in taking these measurements,” said Kurth, who has been working with dozens of UI researchers on the mission for years. 'People have been studying the generation of storms like the Great Red Spot in gas giant planets for a number of years. ... But since we don't know how deep into the atmosphere this feature exists, it's hard to have a complete model.”

When Juno began its 1.74 billion-mile journey to Jupiter in 2011, researchers didn't necessarily plan to pass over the spot. The mission, which entered Jupiter's orbit last summer, aimed to make at least 30 science orbits and lay down a network of observations in hopes of, among other things, determining the amount of water in its atmosphere, gauging its atmospheric composition, mapping its magnetic and gravitational fields, and exploring its poles - specifically its auroras, like Earth's northern lights.

That last aspect, the auroras, is where UI's Waves instrument comes in. It will measure the solar system's most powerful auroras by flying through the electrical current systems and tracking radio and plasma waves.

All that, Kurth said, is a higher priority than flying over the red spot.

'But it just so happened that the spot is under where we're flying over Monday,” he said. 'It's certainly something that we looked forward to doing, we simply didn't drive the mission to make that measurement.”

Now that it's happening, Kurth said, 'We're all very excited about the possibility of the images that will come back and the other measurements.”

Scientists involved in the Juno mission realized the likelihood of a red spot flyby within the last several months. And, despite the potentially massive payoff, the encounter is expected to last only a few minutes. Due to the spacecraft's position, data will take days to transfer back to Earth. Measurements and readings could take much longer to process, Kurth said.

'But I'm certain you will see some great images of the red spot from this upcoming flyby as soon as they're available,” he said.