Features

PASADENA— NASA’s Galileo will swoop within 124 miles of the north pole of Io on Sunday, a close shave that may take the aging robotic spacecraft through a giant plume of volcanic gases erupting from the moon of Jupiter. 

The probe will make its closest approach to Io – the most volcanic body in the solar system – at 9:59 p.m. PDT on Sunday. Just seconds later, the spacecraft’s path should take it through an area where a giant volcanic plume was seen belching as high as 239 miles from the volcano Tvashtar in December. 

If the plume has persisted, the glitch-prone Galileo will fly through the top quarter of the column of gas. While volcanic ash can gum up jetliner engines here on Earth, the tenuous plume of gas should not damage Galileo. 

During the flyby, scientists expect Galileo to take readings of the moon to determine whether it produces its own magnetic field or if it is induced by Jupiter’s field. It will be two months before images and data from the flyby will be returned to Earth. 

It will mark the first of Galileo’s three passes by Io. Others are scheduled in October and January. After that, the $1.4 billion probe will swing past the tiny moon Amalthea before plunging to a fiery death in the crushing atmosphere of Jupiter in 2003. 

Galileo, launched in 1989, has orbited Jupiter since 1995. 

Io is the innermost of Jupiter’s four largest moons, discovered by Italian astronomer Galileo Galilei – the Galileo spacecraft’s namesake – in 1610. 

The gravitational pull of nearby Jupiter tugs on the moon with tidal regularity, heating the moon and causing its tremendous volcanism. NASA scientists estimate as many as 300 volcanoes pock the surface of the moon, which is just slightly larger than the Earth’s moon. 

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On the Net: http://www.jpl.nasa.gov/galileo/