The spacecraft flew closer to Jupiter’s largest moon than at any time in more than two decades, providing a dramatic glimpse of the icy orb.
The first two images from NASA’s Juno’s June 7, 2121 flyby of Jupiter’s giant moon Ganymede’s have been received on Earth. The photos – one from Jupiter Orbiter’s Junocam imager and the other from his Steller Reference Unit Star camera – are notched, clearly distinct dark and bright regions, and long structural features are probably associated with tectonic faults.
Scott Bolton, Juno Principal Investigator at the Southwest Research Institute in San Antonio, said ” this is closest any spacecraft has come to this large moon in a generation.” “We’ll take our time before we reach a scientific conclusion, but until then we can simply marvel at this celestial wonder.”
Using its green filter, the visible-light image of the spacecraft’s Juno cam captured almost the entire side of the water-ice-encrusted moon. Later, when versions of the same image come down including the camera’s red and blue filters, imaging experts will be able to provide a color portrait of Ganymede. The resolution of the image is about 0.6 miles (1 kilometer) per pixel.
Also, Juno’s Stellar Reference Unit, a navigation camera that must keep the spacecraft, provided a black-and-white image of the dark side of Ganymede (the opposite side of the Sun) bathed in dim light scattered off Jupiter. Image resolution ranges from 0.37 to 0.56 miles (600 to 900 meters) per pixel.
Heidi Baker, Juno’s radiation monitoring lead at JPL, said, “The situation in which we collected the image of the dark side of the Ganymede was ideal for a low-light camera like our Stellar reference unit.” “So it is a different part of the surface than seen by Junocam in direct sunlight. It will be fun to see what pieces the two teams can do together. ”
The solar-powered spacecraft’s encounter with the Jovian moon is expected to yield insights into its composition, ionosphere, magnetosphere, and ice shell while also providing measurements of the radiation environment that will benefit future missions to the Jovian system.
About the mission
JPL, Caltech’s division in Pasadena, California, conducted the Juno mission for chief investigator Scott J. Bolton, at the Southwest Research Institute in San Antonio. Juno is part of NASA’s new Frontiers program, which is conducted for the agency’s science mission department at the NASA Marshall Space Flight Center in Huntsville, Alabama. The Lockheed Martin space in Denver was built and operated the spacecraft.
Overview of Jupiter’s moon Ganymede
Jupiter’s moon Ganymede (“GAN uh meed”) is the largest moon in our solar system and the only moon in its own magnetic field. The magnetic field causes auroras, which are ribbons of glowing, electrified gas, in regions circling the moon’s north and south poles. As Jupiter’s magnetic field changes, the aurorae on Ganymede also change, “rocking” back and forth.
Ganymede has larger, brighter areas and notched areas that break into older, darker terrain. These grooved regions are a formula that the moon experienced dramatic rise in the distant past.
In 2015, NASA’s Hubble Space Telescope found the best evidence to date for an underground saltwater sea on Ganymede. The subterranean ocean is thought to contain more water than all of the earth’s surface.
Ganymede has three main levels. In the center is a sphere of metallic iron (the core, which creates a magnetic field), a spherical shell of rock (mantle) surrounding the core, and a spherical shell of ice mostly around the rock shell and core. The outer ice shell is very dense and about 500 miles (800 kilometers) thick.
The surface is at the very top of the ice shells. Although it is mostly ice, the ice shell may contain some rock. Scientists believe that there must be enough rock in the ice near the surface. Ganymede’s magnetic field is embedded in Jupiter’s vast magnetic field.
Astronomers using Hubble space telescope found evidence of a thin oxygen atmosphere in Ganymede in 1996. The life environment is so thin that we know it to support life.
In 2004, scientists discovered irregular lobes beneath the ice surface of Ganymede. Irregular masses can form rock formations supported by Ganymede’s ice shell for billions of years. It tells scientists that the ice is probably strong enough, at least near the surface, to help keep these potential rock masses from sinking to the bottom of the ice. However, this anomaly can also be caused by piles of rocks at the under of the ice.
Pictures of Ganymede spacecraft show the moon has a complex geological history. The surface of Ganymede is a mixture of two types of terrain. 40% of the surface of Ganymede is covered by extremely cratered dark regions and the remaining 60% is covered by a light grooved terrain, which creates complex structures across Ganymede.
On June 7, 2021, NASA’s the Juno spacecraft built a flyby of Ganymede. The photos – one from Jupiter Orbiter’s Junocam painter and the other from his Stellar Reference Unit Star camera – show the surface in remarkable detail, including craters, clearly distinct dark and bright terrain, and long structural features possibly linked to tectonic faults.
This is the only moon in our solar system is bigger than Mercury.”
The grooved area of the Ganymede is probably the result of excitatory defects or the release of water from below the surface. Grooves up to 2,000 feet (700 m) high have been observed and the grooves run thousands of miles across the surface of the Ganymede. The grooves have relatively few craters and probably developed at the expense of the crust.
The dark regions of Ganymede are old and the rough and dark cratered terrain is believed to be the main crust of the satellite. The light regions are young and smooth (as opposed to the Earth’s moon). The largest region of Ganymede is called Galileo Regio.
The large craters in Ganymede have almost no vertical relief and are quite flat. They lack central depressions common to craters often found on the rocky surface of the moon. This is probably due to the slow and gradual adjustment on the soft ice surface. This larger phantom crater, called the Palimpsets, was originally applied to reusable ancient writing materials on which the old writing was still visible beneath more new writing. Polympsets range in diameter from 30 to 250 miles (50 to 400 kilometers). Ejector bright and dark rays both exist around Ganymede’s craters – rays tend to be bright from craters in the grooved terrain and dark from the dark cratered terrain.
Ganymede was discovered by Galileo Galilei on Jan. 7, 1610. The discovery, along with three other Jovian moons, was the first time a moon was discovered orbiting a planet other than Earth. The discovery of four Galilean satellites led us to understand that the planets in our solar system orbit the sun instead of our solar system revolving around Earth.
Simon Marius probably made an independent discovery of the moons at about the same time as Galileo, and he probably saw them unknowingly a month ago, but Galileo made the first discovery.
How Ganymede got its name
Ganymede is named after a boy who was made cupbearer for the ancient Greek gods by Zeus – Jupiter to the Romans.
Galileo first called the Jupiter’s moons the Medicean planets, after his patrons, the Medici family. He numbered the individual moons as I, II, III and IV. Galileo’s naming system has been used for a couple of centuries.
It wasn’t until the mid-1800s that the Galilean moon, Io, Europa, Ganymede, and Callisto names would be officially adopted, and only after it became apparent that naming moons by number would be very confusing as new additional moons were being discovered.