From the left to the right: The mosaic and geologic maps of Ganymede, Jupiter's moon, were created using the finest available photos from NASA's Voyager 1 and 2 spacecraft, as well as NASA's Galileo spacecraft.
Credit: USGS Astrogeology Science Center/Wheaton/NASA/JPL-Caltech/USGS Astrogeology Science Center/Wheaton/NASA/JPL-Caltech
After more than 20 years, the first of the gas-giant orbiter's back-to-back flybys will deliver a close encounter with the gigantic moon.
NASA's Juno spacecraft will pass within 645 miles (1,038 kilometers) of Jupiter's biggest moon, Ganymede, on Monday, June 7 at 1:35 p.m. EDT (10:35 a.m. PDT). Since NASA's Galileo spacecraft made its last near approach to the solar system's largest natural satellite on May 20, 2000, the flyby will be the closest a spacecraft has gotten near the solar system's greatest natural satellite.
The solar-powered spacecraft's flyby will provide insights about the moon's composition, ionosphere, magnetosphere, and ice shell, in addition to stunning photographs. Future missions to the Jovian system will benefit from Juno's studies of the radiation environment around the moon.
Ganymede is the only moon in the solar system with its own magnetosphere, a bubble-shaped area of charged particles around the celestial body that is larger than Mercury. “Juno contains a suite of sensitive equipment capable of observing Ganymede in ways never previously possible,” stated Southwest Research Institute in San Antonio Principal Investigator Scott Bolton.
“By flying so close, we will bring Ganymede exploration into the twenty-first century, complementing future missions with our unique sensors and assisting in the preparation of the next generation of missions to the Jovian system, including NASA's Europa Clipper and ESA's Jupiter ICy moons Explorer [JUICE] mission.”
About three hours before the spacecraft's closest approach, Juno's science equipment will begin gathering data. Juno's Microwave Radiometer (MWR) will gaze through Ganymede's water-ice crust, gathering data on its composition and temperature, alongside the Ultraviolet Spectrograph (UVS) and Jovian Infrared Auroral Mapper (JIRAM) sensors.
A spinning Ganymede globe with a geologic chart placed over a global color mosaic is animated. Credit: USGS Astrogeology Science Center/Wheaton/ASU/NASA/JPL-Caltech/USGS Astrogeology Science Center/Wheaton/ASU/NASA/JPL-Caltech
“The ice shell of Ganymede contains some light and dark parts, implying that certain parts may be pure ice while others include filthy ice,” Bolton explained.
“MWR will conduct the first comprehensive study of how ice composition and structure change with depth, leading to a deeper understanding of how the ice shell originates and the mechanisms that resurface the ice over time.”
The findings will be used to supplement those from ESA's upcoming JUICE mission, which will study ice using radar at various wavelengths when it launches in 2032 to become the first spacecraft to circle a moon other than Earth's Moon.
Juno's X-band and Ka-band radio frequencies will be utilized in a radio occultation experiment to study the moon's fragile ionosphere (the outer layer of an atmosphere where gases are excited by solar radiation to form ions, which have an electrical charge).
“As Juno travels behind Ganymede, radio signals will travel over Ganymede's ionosphere, generating modest variations in frequency that should be picked up by two antennas at the Deep Space Network's Canberra complex in Australia,” said Dustin Buccino, a Juno mission signal analysis engineer at JPL. “We might be able to grasp the relationship between Ganymede's ionosphere, its intrinsic magnetic field, and Jupiter's magnetosphere if we can monitor this change.”
With NASA's interactive Eyes on the Solar System, you can see where Juno is right now.
The Juno spacecraft is a dynamic technical wonder, with three huge blades reaching out 66 feet (20 meters) from its cylindrical, six-sided body, spinning to keep itself steady as it executes oval-shaped orbits around Jupiter.
Juno's Stellar Reference Unit (SRU) navigation camera is normally responsible for keeping the Jupiter spacecraft on track, but it will perform double duty during the flyby.
Along with its navigational functions, the camera will collect information on the high-energy radiation environment in the region surrounding Ganymede by capturing a particular collection of photos.
The camera is adequately insulated against radiation that may otherwise harm it. “In Jupiter's harsh radiation environment, the traces from penetrating high-energy particles appear in the photos as dots, squiggles, and streaks — like static on a television screen.
According to Heidi Becker, Juno's radiation monitoring lead at JPL, "we extract these radiation-induced noise patterns from SRU photos to obtain diagnostic pictures of the radiation levels encountered by Juno."
Meanwhile, the Advanced Stellar Compass camera, developed by the Technical University of Denmark, will count very intense electrons that pass through its shielding at a quarter-second interval. The JunoCam imager has also been enlisted.
The camera was designed to transmit the thrill and beauty of Jupiter exploration to the public, but it has also given a wealth of essential research throughout the mission's almost five-year stay there. JunoCam will capture photographs at a resolution comparable to the best from Voyager and Galileo for the Ganymede flyby.
The Juno research team will examine the photographs and compare them to those taken by earlier missions, seeking for changes in surface characteristics that may have happened over four decades or more.
Any changes in the pattern of craters on the surface might aid astronomers in better understanding the present population of objects that collide with moons in the outer solar system.
Due to the speed of the flyby, the frozen moon will change from a point of light to a visible disk and back to a point of light in roughly 25 minutes from JunoCam's perspective.
There's just enough time for five photographs in that amount of time. “Things move quickly in the area of flybys, and we have two back-to-back flybys coming up next week. As a result, every second counts,” stated Juno Mission Manager Matt Johnson of the Jet Propulsion Laboratory.
“On Monday, we'll fly through Ganymede at about 12 miles per second (19 kilometers per second). We're making our 33rd scientific flyby of Jupiter in less than 24 hours, swooping low over the cloud tops at around 36 miles per second (58 kilometers per second). It's going to be a roller coaster.” even more Concerning the Mission.
The Juno mission is managed by JPL, a subsidiary of Caltech in Pasadena, California, for the principle investigator, Scott J. Bolton of the Southwest Research Institute in San Antonio. Juno is part of NASA's New Frontiers Program, which is administered for the agency's Science Mission Directorate in Washington by NASA's Marshall Space Flight Center in Huntsville, Alabama.
The spacecraft was manufactured and is operated by Lockheed Martin Space in Denver.
courtesy www.nasa.com
Posted by Jai Krishna Ponnappan
More data on Juno may be found at,
https://www.nasa.gov/juno for further details.
https://www.missionjuno.swri.edu
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