On Monday, June 7 at 1:35 p.m. EDT (7:35 p.m. EDT), NASA’s Juno spacecraft will zoom within just 1038 kilometers of the surface of Jupiter’s largest moon, Ganymede. This flyby will be the closest a spacecraft has been to the solar system’s largest natural satellite since NASA’s Galileo spacecraft made its penultimate close approach on May 20, 2000.
The spacecraft will collect shocking images, but also the flyby of the solar powered spacecraft will shed key information about this moon: composition, ionosphere, magnetosphere and ice sheet. Juno’s measurements of the radiation environment near the moon will also favor future missions to the Jovian system.
The orbiter will travel at 19 kilometers per second in what project scientists have called “a wild ride.”
Ganymede, the most massive moon in the solar system
Ganymede is larger than the planet Mercury and is the only moon in the solar system that has its own magnetosphere, a bubble-shaped region of charged particles that surround the celestial body.
According to Juno Principal Investigator Scott Bolton of the Southwest Research Institute in San Antonio: “Juno carries a suite of sensitive instruments capable of seeing Ganymede in ways never before possible. By flying so close, we will bring Ganymede exploration into the 21st century. , complementing future missions with our unique sensors and helping to prepare for the next generation of missions to the Jovian system, such as NASA’s and ESA’s Europa Clipper, or the Jupiter Icy moons Explorer or JUICE Mission. “
Juno’s science instruments will begin collecting data about three hours before the spacecraft’s closest approach. Together with the Ultraviolet Spectrograph (UVS) and Jovian Infrared Aurora Mapper (JIRAM) instruments, Juno’s Microwave Radiometer (MWR) will observe Ganymede’s water ice crust, obtaining unique data on its composition and temperature.
” The Ganymede ice sheet has some light and dark regions , suggesting that some areas may be pure ice while others contain dirty ice,” according to Bolton. “MWR will provide the first rigorous investigation of how the composition and structure of ice varies with depth, leading to a better understanding of how the ice sheet forms and the processes that resurface ice over time.”
The results will complement those of ESA’s upcoming JUICE mission, which will observe ice using radar at different wavelengths when it becomes the first spacecraft to orbit a moon other than Earth’s in 2032.
Juno’s X-band and Ka-band radio wavelength signals will be used to conduct a radio cloaking experiment to probe the moon’s faint ionosphere (the outer layer of an atmosphere where gases are excited by solar radiation to form ions, which have an electrical charge).
“When Juno passes behind Ganymede, the radio signals will pass through Ganymede’s ionosphere, causing small changes in frequency that should be picked up by two antennas at the Canberra complex of the Deep Space Network in Australia,” in words from Dustin Buccino, Mission Juno signal analysis engineer at JPL. “If we can measure this change, we could understand the connection between Ganymede’s ionosphere, its intrinsic magnetic field, and Jupiter’s magnetosphere.”
