Rick Robinson

Jan 22nd 2021

Juno Spacecraft May Extend Jupiter Mission


NASA mission planners are weighing the possibility of a new Jupiter mission to further explore the atmosphere of the solar system’s largest planet, its moons, and the little-studied rings of Jupiter, as Space News reports.

If the four-year mission is approved, no giant booster rocket will thunder up from Cape Canaveral or anywhere else on Earth. None will be needed. The probe that will carry out the mission, the Juno spacecraft, is already orbiting Jupiter and has been since 2016. But it will be assigned new tasks and new objectives.

In effect, Juno will become a new exploratory mission: a spaceship with a second act and a second life.

A Space Explorer Recycled

Mission extensions are nothing new for NASA. From Mars rovers to outer-planet probes, many spacecraft have turned out to be more rugged and reliable than their designers dared hope for, allowing their missions to be extended for years or even decades.

Sometimes, like the Mars rovers, they continued their original missions much longer than expected. Other times, like with outer planet fly-bys, they left their initial objectives billions of miles behind them but are still making measurements and reporting back to us from the fringes of interstellar space.

However, the Juno spacecraft will take this mission extension capability to a new level, exploring Jupiter and its environs in ways not anticipated when it launched from Earth in 2015.

Mysteries of Mighty Jove

The original Juno mission, according to Astronomy magazine, was intended to study the origin and evolution of Jupiter, a world more massive than all other solar planets, moons, asteroids and comets combined.

Juno’s elongated orbit brings it within a thousand miles of Jupiter’s cloud tops, per Astronomy, while allowing it to almost entirely avoid the planet’s intense, spacecraft-frying radiation belt. The greatest-hits list from its original (and currently still-continuing) mission features spectacular, surreal close-ups of the Jovian atmosphere, including neatly arranged clusters of monster storms, each the size of the United States, grouped around Jupiter’s north and south poles.

Other instruments aboard the Juno spacecraft have allowed us to examine Jupiter’s deep interior, finding hints that enormous protoplanetary collisions early in its history may have dramatically reshaped its interior structure.

A Full System Explorer

In a sense, the proposed extension of the Juno mission will be not Act II in the story of the Juno spacecraft, but Act III. The mission was already extended once, according to NASA. As Space News explains, possible problems with the spacecraft’s main rocket engine forced cancellation of a planned shift to a closer, more frequent orbit. The change meant it took longer for Juno to complete its initial tasks, and the spacecraft checked out for a mission extension.

But the new Juno extension will be a bigger deal — less an extension than an entirely new mission. Says mission principal investigator Scott Bolton, “It really becomes a full system explorer, not as focused as the prime mission was.”

Juno’s orbit is gradually shifting and will continue to shift, and the new, extended mission will take full advantage of this shift. As it passes near Jupiter itself, Juno will be able to closely examine auroras in the Jovian upper atmosphere. But its shifting orbit will also allow close passes over three of Jupiter’s four giant moons: Ganymede, Europa and Io.

Another objective of the new Juno mission will be Jupiter’s rings, which Bolton notes have received little study. That Jupiter — not just Saturn — had rings was one of the most startling discoveries made by the early Jupiter missions. But with so much else to explore, there has been little opportunity for follow-up.

As notes, we now know that all four of the solar system’s giant planets have rings. And astronomers have seen tantalizing hints that planets far beyond the solar system, exoplanets, may have vast ring systems even more spectacular than Saturn’s. All of this makes Juno’s extended Jupiter mission an excellent opportunity to learn more about Jupiter itself, its giant moons and its remarkable (if visually subdued) rings.