Artist illustration of Juno as it approaches Jupiter. (NASA)

It took a while — almost five years since launch — but the Juno spacecraft is now at Jupiter and orbiting the giant planet. A 35-minute rocket burn to slow Juno down from its record-breaking 130,000 mph entry speed led to a successful insertion into orbit just minutes before midnight, making it another July 4th NASA spectacular.

During its mission, Juno will orbit the planet 37 times, dipping as low as 2,600 miles above the planet’s upper clouds of ammonia and water.  Primary goals of the mission are to determine whether Jupiter has a solid rocky core or is made up of gases all the way through, to learn about its extraordinarily powerful magnetic forces, and to determine better the components of those upper clouds and what might lie beneath them.

The overriding purpose is to better understand how Jupiter — the first planet formed in our solar system — came to be, and consequently how our solar system was formed. Considering that Jupiter contains more matter than the rest of the solar system planets, moons, asteroids and comets combined, it clearly is the place to look to understand the origins of the solar system.

But another goal, and a significant one at that, is to learn about the big gas giant as a way to learn about similar planets orbiting other stars.  Woven into the Juno mission from the beginning was a requirement that the two years of orbiting be designed and operated with distant solar systems and exo-Jupiters in mind.

I had the opportunity to speak with Juno principal investigator Scott Bolton just the day before Juno’s arrival, and he made clear that providing information and insights that will help understand exo-Jupiters is a high priority, indeed.

Scott Bolton, principal investigator of the Juno mission. (NASA)

“We know that our Jupiter is quite different from many of the other Jupiter-sized planets found, and so there will be differences,” he said.  “But the dynamics we find, the presence of a rocky core or not, the water abundances, the structure of the planet — I think that will all be extremely useful to exoplanet modelers and theorists.”

He also made the intriguing observation that there may well be links between Juno discoveries and the search for Earth-size planets around other stars.

“It may be that finding a system with a Jupiter of a size like ours,  and in  a location {in its solar system} similar to ours, would be a strong signal that there is also an Earth-sized planet in the system.”… Read more