According to project scientist Olivier Witasse who is working on the upcoming Jupiter Icy Moon Explorer for ESA, “The Ganymede Ocean is believed to hold more water than the Europa’s Ocean” (JUICE).
“Ganymede’s ocean contains three times as much water as Europa and six times as much as the ocean on Earth combined.” The best proof of a subsurface saltwater ocean on Ganymede, Jupiter’s largest moon, which is bigger than Mercury and not much smaller than Mars, was discovered in March 2020 by N.A.S.A’s Hubble Space Telescope.
Finding liquid water is essential for both the hunt for extraterrestrial habitable worlds and the quest for life as we know it. The now-retired assistant administrator of N.A.S.A’s Science Mission Directorate at N.A.S.A Headquarters, John Grunsfeld, noted that this discovery was an important milestone that showed off what only Hubble could do. “Hubble has produced numerous scientific discoveries in our own solar system throughout its 25 years in orbit. The discovery of a deep ocean beneath Ganymede’s frozen shell creates new and exciting opportunities for life beyond Earth.
Ganymede is the largest moon in our solar system and the only moon with its own magnetic field. The magnetic field causes aurorae, which are ribbons of glowing, hot electrified gas, in regions circling the north and south poles of the moon. Because Ganymede is close to Jupiter, it is also embedded in Jupiter’s magnetic field. When Jupiter’s magnetic field changes, the aurorae on Ganymede also change, “rocking” back and forth.
Similar to how Enceladus and Titan perpetually shade Dione, Saturn’s moon, Ganymede’s fame is overshadowed by Europa, its sister ocean planet, which N.A.S.A’s Europa Clipper mission is scheduled to flyby in the 2020s.
The Hubble Space Telescope’s observations of Ganymede’s surface auroral activity cycles show that the internal heat-generating tidal churning of a vast ocean hundreds of kilometers below the surface is the best explanation for the moon’s magnetic field oscillations. JUICE will orbit Ganymede for nine months, with the final four months spent at an altitude of roughly 500 km, passing by the moons at distances ranging from 1000 to 200 kilometers. Radar will be able to piece together the oceans of Jupiter’s moons, even though they are probably buried at a large depth below their icy crusts together clues as to their complex evolution.
For example, it will explore Europa’s potentially active regions and be able to distinguish where the composition changes, such as if there are local, shallow reservoirs of water sandwiched between icy layers. It will be able to find ‘deflected’ subsurface layers, which will help to determine the tectonic history of Ganymede in particular.
Soucre: fancy4work.com
