NASA extends Juno, turning spacecraft into an Io, Europa, and Ganymede explorer


NASA’s Juno spacecraft soared directly over Jupiter’s south pole when JunoCam acquired this image on February 2, 2017.
Enlarge / NASA’s Juno spacecraft soared directly over Jupiter’s south pole when JunoCam acquired this image on February 2, 2017.

NASA has announced that it will extend the missions for two of its interplanetary explorers launching during the last decade—the Juno spacecraft orbiting Jupiter and the InSight lander on the surface of Mars.

The Juno extension means the spacecraft will now operate in the Jovian system through 2025. This will effectively transform the spacecraft from a mission to study Jupiter into a full-fledged Jovian system explorer, complete with close flybys of several of Jupiter's moons as well as its system of rings.

Back in the inner Solar System on the surface of Mars, the InSight mission will now run through December 2022. During these additional two years, the lander will continue to operate its seismometer to identify Marsquakes, as well as continue to collect detailed information about weather at the surface.

After determining that both missions had done exceptional science to date, an independent review panel recommended extensions of both to NASA. "The Senior Review has validated that these two planetary science missions are likely to continue to bring new discoveries and produce new questions about our solar system," said Lori Glaze, director of the planetary science division at NASA Headquarters in Washington.

Excited about Juno

For us, the extended Juno mission is most tantalizing. After its launch in 2011, Juno entered into a polar orbit around Jupiter in July 2016. Since that time, it has completed more than 30 orbits around the largest planet in the Solar System, studying Jupiter's composition and magnetic field. It has also survived an exceptionally harsh radiation environment.

The extension indicates that scientists and engineers believe the spacecraft is healthy enough to continue working and will be able to more than double its number of orbits in the Jupiter system to 76. Over the next five years, the spacecraft will adjust its orbit such that Juno will be able to fly much closer to some of Jupiter's most intriguing moons.

As part of a research plan submitted by Scott Bolton, Juno's principal investigator, the spacecraft will fly to within 1,000km of the surface of Ganymede this summer to within 320km of Europa in late 2022 and to within 1,500km of the volcanically active Io twice in 2024.

With these flybys, Juno will be able to study surface changes on Ganymede since the Voyager and Galileo missions and investigate the 3-D structure of Ganymede's magnetosphere. In coming so close to Europa, Juno should be able to identify regions where the moon's ice shell is thick or thin and confirm the presence of subsurface liquid water. In making multiple close flybys of Io, Juno will monitor short-term changes in volcanic activity, which evolved dramatically between Voyager and Galileo over a matter of months.

Extended missions cost a fraction of actually building and launching large interplanetary spacecraft—which often exceed $1 billion—so they're like a bonus for Solar System exploration.