EP-95 ON THE MOON WITH APOLLO 16

FIGURE 71.-Lunar Gravity.

FIGURE 71.-Lunar Gravity. These lines, called contour lines, show the departures from "normal" gravity on the front side of the Moon. The units are 100 milligals. The difference between adjacent lines, termed contour interval, is 200 milligals. To obtain total gravity, you must add the usual l/6 of the Earth's gravitational field to these values. Mueller and Sjogren, working at the Jet propulsion Laboratory, first found these very large variations in the Moon's gravitational field by measuring the very small changes in the velocity of orbiting spacecraft. Notice the excellent correlation between the gravitational feature and the surface features of the Moon. The discovery of these variations in the gravitational field surely ranks as one of the most important in Lunar Science. NASA PHOTO S-72-1634O.

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