In About Three Hours, Long Serving Juno (5+ Years At Jupiter!) Will Dip Close To The Solar System's Largest Moon... What Will We Learn, About Potential Life?

It is getting increasingly difficult to pretend that there is not life, beyond Earth (and no, I do not mean the US Navy's latest footage -- as released). I mean to refer to the numerous ways that warm water seems to turn up -- in all sorts of previously unexpected places, churned and fueled with either tidal forces, or sub-surface volcanic action. . . . So it is easy to imagine that microbial life might exist there, as well -- just as likely occurred on Earth, over a billion years ago.

In any event, we may well learn more -- about whether magnetospheres might act as protectors, for nascent life -- over the course of the coming weeks, as Juno beams data back from Ganymede. Here's a bit of it all, from the capable science reporters at NPR:

. . .Jupiter's moon Ganymede will have a visitor from Earth on Monday. At 1:35 p.m. ET, NASA's Juno spacecraft will zoom by, just 645 miles above the surface of the solar system's largest moon.

It's the first time a probe has made a close-up visit to Ganymede since the Galileo mission flew by in 2000.

Ganymede is an icy moon, and icy moons are attracting a lot of attention from planetary scientists these days. Ice is not unusual on moons, there's even some on the Earth's moon. But some of the large moons around the outer planets have significant amounts of water, and some are thought to have liquid oceans under their icy surfaces.

Researchers have come to understand that these watery worlds could be home to some kind of life, even though they are far from the sun. Gravitational tugging from the giant planets they orbit may help explain how the ice is able to melt. . . .

Ganymede has one feature the other icy moons lack.

"Ganymede is the only one that has its own magnetic field," says Katherine de Kleer, a planetary scientist at Caltech. . . .

A very large moon, with its own magnetic field -- and subsurface water oceans, some of which may well be heated like the volcanic ocean vents on early Earth. . . that is certainly a tantalizing mix, for the potential of. . . biological life. Onward, grinning into the Loop. . . .

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