NASA’ss Juno spacecraft will fly close to Jupiter’s moon Ganymede today, offering scientists their closest encounter with it in more than 20 years.
Ganymede is the largest moon in the solar system and is actually larger in volume than the planet Mercury.
It is thought to contain an internal ocean beneath its crust that could hold more water than all of the Earth’s oceans combined. Later in the evening, Juno will come within 1038 km of its surface — the closest a spacecraft has come to the satellite since NASA’s Galileo spacecraft made its penultimate approach on May 20, 2000.
Along with striking images, the flyby of the solar-powered spacecraft will provide insight into the composition of the moon, ionosphere, magnetosphere and ice shell.
Juno’s measurements of the lunar radiation environment will also benefit future missions to the Jupiter system.
“Juno carries a set of sensitive instruments capable of seeing Ganymede in a way that has never been possible before,” said Juno’s lead researcher Scott Bolton.
“By flying so close, we are bringing Ganymede’s exploration into the 21st century, both to complement future missions with our unique sensors and in preparation for the next generation of missions to the Jovian system – NASA’s Europa Clipper and ESA’s [European Space Agency’s] JUpiter ICy moons Explorer [JUICE] mission.
” Juno’s science instruments will begin collecting data about three hours before the spacecraft’s closest approach, and the microwave radiometer (MWR) will be used to look inside Ganymede’s water ice crust and obtain data on its composition and temperature.
” Ganymede’s ice shell has some light and dark areas, suggesting that some areas may be pure ice, while others contain dirty ice,” Bolton said.
“MWR will provide the first in-depth study of how ice composition and structure varies with depth, leading to a better understanding of how the ice shell forms and the ongoing processes that return the ice to the ice over time. surface.
” The results will complement those of ESA’s upcoming JUICE mission, which will look at the ice using radar at different wavelengths when it becomes the first spacecraft to orbit a moon other than the Earth in 2032.
Earth’s moon rotates. As Juno passes behind Ganymede, radio signals will pass through the ionosphere, causing small changes in frequency that should be picked up by two antennas in the Canberra complex of the Deep Space Network in Australia.
Dustin Buccino, a signal analysis engineer for the Juno mission, said: “If we can measure this change, perhaps we can understand the connection between Ganymede’s ionosphere, its intrinsic magnetic field, and Jupiter’s magnetosphere.
” Juno’s built-in imager will be used to take some photos with resolutions equal to the best of Voyager and Galileo.
Juno’s scientific team will search the images and compare them with those from previous missions, looking for changes in surface features that have occurred over the course of more than four decades.
Any change in the distribution of the crater’s surface could help astronomers better understand the current population of objects impacting on moons in the outer solar system.
Due to the speed of the flyby, Juno only has about 25 minutes to take about five photos. In 2017, Juno was forced to make long orbits around Jupiter due to sticky valves.
This meant it took longer to collect the data needed to complete the mission of surveying Jupiter and its moons. The extension of the mission cost NASA ten million dollars.