NASA Announces New Evidence Suggesting Jupiter's Moon Ganymede Has a Subsurface Ocean
There's a lot of talk about various moons throughout our solar system having the potential to support life. Europa and Enceladus have, for the most part, been the satellites attracting the most attention, but NASA today announced new evidence, which suggests another of Jupiter's moons, Ganymede, may also be joining the party.
Using the Hubble Space Telescope, researchers were able to study Ganymede's auroras, detecting changes in their movements which resembled a subtle rocking motion in the process. The results not only provides strong evidence that Ganymede possesses a vast ocean of liquid water, but also proves that Hubble can be used for such indirect detection tasks in the future. Who says you can't teach an old dog new tricks?
"This discovery marks a significant milestone, highlighting what only Hubble can accomplish," said NASA's John Grunsfeld. "In its 25 years in orbit, Hubble has made many scientific discoveries in our own solar system. A deep ocean under the icy crust of Ganymede opens up further exciting possibilities for life beyond Earth."
Ganymede is the largest of Jupiter's moons, so large in fact that it's bigger than the planet Mercury. The subterranean ocean on Ganymede is thought to contain more water than all of Earth's combined, and at approximately 60 miles deep, is likely 10 times deeper than Earth's darkest ocean depths.
Like Jupiter's other moons, Ganymede is witness to significant gravitational forces both from its host planet and its fellow satellites. This gravitational tug of war creates enough heat to sufficiently warm the moon's iron core and create a magnetic field. Another side-effect of this heating is the potential for the presence of liquid water. Ganymede's surface is covered in a layer of ice approximately 95 miles thick, which may serve to help insulate a potentially massive body of liquid water below it.
The canny utilization of Hubble to detect these changes in Ganymede's aurorae came about thanks to a team led by Joachim Saur of the University of Cologne.
"I was always brainstorming how we could use a telescope in other ways," said Saur. "Is there a way you could use a telescope to look inside a planetary body? Then I thought, the aurorae! Because aurorae are controlled by the magnetic field, if you observe the aurorae in an appropriate way, you learn something about the magnetic field. If you know the magnetic field, then you know something about the moon's interior."
(Credit: NASA/ESA/A. Field)
The presence of Ganymede's magnetic field as well as the pull of Jupiter's would allow for a significant oscillation in the moon's aurora, but when this movement was observed at far lower levels than expected, it led to the conclusion that something inside the moon was countering the force of the various magnetic fields. That something, it would seem, is almost certainly a significant body of liquid water, and where there is water, there is the chance for life.
These Ganymede findings are the latest in a string of exciting new evidence, all of which suggests that liquid water is far from a rarity in our solar system. It now looks more than likely that both Jupiter and Saturn play host to at least two moons with bodies of liquid water, while we also know that at least two planets (Earth and Mars) possess or possessed it, which means that the chances of finding alien life in our solar system have taken a huge boost in recent years.