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Galileo gathers views of Earth and moon.

The Galileo spacecraft swung by Earth last month, receiving from the planet a second and final gravitational kick on its way to orbit Jupiter in 1995. Flying over the moon and recording images of the lunar north pole at several different wavelength -- a feat never before accomplished -- Galileo found evidence that the moon was more volcanically active during its early history than researchers had thought.

On Dec. 7, the craft gathered a variety of infrared and visible-light fingerprints that indicate the chemical composition of the moon's polar region. In the false-color image at top right, which NASA released Dec. 22, pink denotes highlands; blue and orange indicate volcanic lava flows; and light blue indicates thin, mineral-rich soils associated with relatively recent meteorite impacts.

The picture suggests that these and other impacts on the moon have exposed lava flows more than 3 billion years old. The size of the lava flows indicates that the moon had even more frequent and extensive volcanic disturbances during its youth than suspected, says Jay Bergstralh, Galileo program scientist at NASA in Washington, D.C. In an image taken eight days later (bottom right), the craft captured the Earth and the far side of the moon.

Because Galileo's main antenna remains jammed, researchers have only just received the final data from the craft's encounter with the asteroid Gaspra in October 1991. Near its closest approach, the craft found indirect evidence of a magnetic field surrounding Gaspra: The solar wind changed direction a few hundred kilometers from the asteroid, as if it had slammed into a magnetic region. The magnitude of the inferred magnetic field appears similar to that associated with iron-rich meteorites -- possible fragments of asteroids like Gaspra -- that have fallen to Earth, reports Margaret G. Kivelson of the University of California, Los Angeles.
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Title Annotation:images from satellite suggest volcanos on moon more active than previously believed
Publication:Science News
Article Type:Brief Article
Date:Jan 2, 1993
Words:298
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