Ganymede, the solar system's largest satellite, looks amazing in the photos sent back by NASA's Juno's epic flyby
This is the spacecraft's most recent contact with Ganymede since May 2000.
This image of Jupiter's largest moon, Europa, was taken by Juno's camera's imager as it flew by the icy moon on June 7, 2021, UTC. (Image source: NASA/JPL-Caltech/SwRI/MSSS)
A wave of photos of the solar system's largest satellite in history is about to hit us
On Monday (June 7), NASA's Juno probe was just 645 miles (1,023 kilometers) larger than Mercury, Jupiter's largest moon, Europa. It was the closest of all the probes to Europa since May 2000, after NASA's Galileo spacecraft flew about 620 miles (1,000 kilometers) from the satellite's ice surface.
It will take some time to receive and process the data from Monday's contact, but we've already tasted it: The first two photos have been sent back to Earth, and NASA uploaded them to the web on Tuesday (June 8).
One of the images, taken by Juno's camera equipment, shows almost the entire side of the crater-ridden Ganymede, which is thought to have a huge ocean of liquid water beneath its ice shell. (That ocean, however, is likely sandwiched between two layers of ice, so it's not as much of an astrobis interest to astrobis as Europa and Enceladus, which have underground seas.) Scientists believe that for satellites that exist in the underground sea, the contact between the underground sea and the rocks inside may undergo a variety of complex chemical reactions.
This photo taken by Juno's camera has a resolution of about 0.6 miles (1 kilometer) per pixel and was taken using the device's green filter. NASA officials said the image was black and white, but once the version of the photo taken using Juno's red and blue filters was transmitted back to the ground, the project team would be able to create a color effect for it.
The second image was provided by the StellarReference Unit, a monochrome camera used by Juno for navigation. With a resolution of 0.37 miles to 0.56 miles (0.6 to 0.9 kilometers) per pixel, this image shows Ganymede's opposite side to the Sun, which is dimly illuminated by jupiter's reflected light.
"Low-light cameras like the stellar reference unit capture the dark side of the satellite perfectly under the conditions we took the second Ganymede photo above," Hedi Becker, juno's radiation monitoring lead at the Jet Propulsion Laboratory in Southern California, said in a statement.
"It's going to be different from the surface that Juno's camera captures in direct sunlight," Becker adds, "and it would be interesting to put the two parts together." ”
This dark-sided image of Ganymede was taken by Juno's stellar reference unit navigation camera as it flew over the moon on June 7, 2021 (Credit: Credit: NASA/JPL-Caltech/SwRI)
Juno was launched in August 2011 and arrived on Jupiter in July 2016. The solar probe is studying Jupiter's composition, internal structure, and magnetic and gravitational fields, collecting data to help scientists better understand how Jupiter and our solar system formed and evolved.
Juno occasionally turns its keen eye to other objects in Jupiter's system — such as Ganymede, which is 3,273 miles (5,268 kilometers) in diameter. NASA officials say observations made during Monday's flyby could reveal key insights into characteristics such as the moon's composition, ice crust and radiation environment.
The data could provide valuable information and guidance for future missions to the Jupiter galaxy, including Europe's Jupiter Ice Moon Explorer (JUICE) spacecraft, which is scheduled to launch in 2022 to study Ganymede, Ganymede and Ganymede, which are also Galileo moons.
Related knowledge
Ganymede, also known as Ganymede, is the moon of Jupiter and is the largest and most massive moon in the solar system. It is the ninth largest object in the solar system and the largest without a substantial atmosphere. It has a diameter of 5,268 kilometers (3,273 miles) and is 26 percent larger than Mercury, although it has only 45 percent of Mercury's mass. [16] With a metal core, Ganymede is the smallest solid object of inertia in the Solar System and the only known moon with a magnetic field. Sorted by distance jupiter from nearest to farthest, it ranks seventh of all moons of Jupiter and third among the Galileo moons, and it is the first group of discovered celestial bodies orbiting another planet. [17] Ganymede has an orbital resonant relationship of approximately seven days and maintains a 1:2:4 orbital resonance relationship with Europa and Ganymede, respectively.
Ganymede consists of nearly equal amounts of silicate rock and water. It is a fully differentiated structure with an iron-rich liquid core and an inner ocean that may contain more water than all the oceans on Earth combined. [18] [19] [20] [21] Its surface consists of two main types of terrain. One is a very old dark area that dates back 4 billion years and is densely packed with impact craters, accounting for about one-third of the total area of the sphere. The other is slightly younger than the former, with bright areas covered with a large number of grooves and ridges, occupying the remaining spheres. The reasons for the destruction of the geology of the Ming Area are not fully understood, but are likely the result of tectonic activity caused by tidal heating.
Ganymede's magnetic field may have been generated by convection of its liquid iron core. [22] Its weak magnetic field is wrapped around Jupiter's powerful magnetic field, so that only faint interfering field lines are revealed during detection. Ganymede has a thin atmospheric oxygen atmosphere consisting of oxygen atoms, oxygen, and trace amounts of ozone that may exist. [15] The minor atmospheric component is the hydrogen atom, but it is not yet known whether Europa's atmosphere contains an ionosphere of its atmospheric component. [23]
Ganymede's discovery is attributed to Galileo Galilei, who first observed it on January 7, 1610. [1] [g] Astronomer Simon Marius was soon named after zeus's lover in Greek mythology, Prince Troy (corresponding to the Greek Jupiter), and ganemides, the drinker of the gods. [25] Starting with Pioneer 10, several spacecraft have detected Ganymede. [26] Voyager 1 and Voyager 2 made precise measurements of its size, while Galileo discovered its subsurface sea and magnetic field. The Jupiter Ice Moon Explorer (JUICE), the next Jupiter mission planned by the European Space Agency, is scheduled to launch in 2022. It will plan to enter orbit around Ganymede after flying over three icy Galilean satellites.
BY： MikeWall
FY：Astronomicalvolunteer team
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