Orbiting, NASA’s streaked previous Ganymede on Monday, beaming back the first close-up views of the biggest moon within the photo voltaic system for the reason that Galileo orbiter final flew previous in 2000.
“This is the closest any spacecraft has come to this mammoth moon in a generation,” Scott Bolton, the Juno principal investigator on the Southwest Research Institute, stated in an announcement. “We are going to take our time before we draw any scientific conclusions, but until then we can simply marvel at this celestial wonder, the only moon in our solar system bigger than the planet Mercury.”
Juno raced by Ganymede at 1:35 p.m. EDT Monday, passing inside about 645 miles of the moon and capturing a razor-sharp view of the cratered world, thought to harbor a sub-surface sea beneath an icy crust. Along with capturing recent photos, Juno’s suite of science devices additionally collected knowledge.
“Ganymede’s ice shell has some light and dark regions, suggesting that some areas may be pure ice while other areas contain dirty ice,” Bolton stated earlier than the flyby. Juno “will provide the first in-depth investigation of how the composition and structure of the ice varies with depth, leading to a better understanding of how the ice shell forms and the ongoing processes that resurface the ice over time.”
Juno was launched from Cape Canaveral in 2011 and braked intoon July 4, 2016. Still going robust on the finish of its preliminary two-year main mission, NASA has now permitted two extensions, the most recent operating from this summer season to mid-2025.
Built to check Jupiter’s deep inside, its environment, magnetic discipline and aurorae, Juno has made repeated shut passes over the planet’s north polar areas, offering startling views of never-before-seen polar storms, detecting indicators of a considerably diffuse core and accumulating gigabytes of knowledge to higher perceive the planet’s total conduct.
The probe’s 53-day polar orbit was set as much as slowly transfer the purpose of closest method northward because the flight progresses. On the far aspect of the orbit, the spacecraft initially crossed the equatorial airplane effectively past the orbit of Ganymede.
But the purpose of closest method has moved inward all through the mission and the most recent extension supplied a golden alternative to make shut flybys of Ganymede, Europa and volcanic Io.
“We’re going to cross the orbital plane near Ganymede and as the orbit keeps progressing farther and farther north, the (equatorial) crossing moves farther and farther in,” Bolton stated in an earlier interview. “So first, we cross near Ganymede and then we keep moving in and we cross near Europa. Eventually we cross near Io, and then we’re even inside of Io.”
The Ganymede encounter Monday was arrange to make use of the moon’s gravity to bend the trajectory barely, decreasing Juno’s orbital interval by about 10 days. That, in flip, units up a flyby of icy Europa on September 29, 2022, and two shut flybys of Io on December 30, 2023, and February 3, 2024.
“So we have these close flybys of the satellites that are going to allow us to now point our instruments at the satellites, get the first close-up analysis and look for changes since the days of Galileo and Voyager,” Bolton stated.
Juno will not be outfitted with a telescope for close-up, narrow-angle observations. Instead, its “Junocam” imager was meant primarily for wide-angle, contextual observations and public outreach, offering spectacular hemispheric views of Jupiter’s turbulent environment.
Bolton expects equally gorgeous views from the Ganymede, Europa and Io flybys.
“When we’re really far away, we can’t make a high-resolution shot,” he stated. “But when we’re close up, we get a wide field of view at high resolution.” That large discipline of view, he stated, “makes all the difference when you’re looking at it, saying do I understand the context?”
Junocam captured nearly a whole aspect of Ganymede in the course of the probe’s flyby Monday. Shots utilizing completely different filters might be mixed later to offer coloration views, resolving floor options as small as six-tenths of a mile throughout.
Juno’s navigation digital camera captured a extra zoomed-in view of Ganymede’s darkish aspect, illuminated by daylight mirrored from Jupiter. Additional photos saved on board the spacecraft might be beamed back later.