Word: earths
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Dates: during 1960-1969
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Using the same distance-measuring technique, with the moon as a reference point, scientists will, during the next several years, also be able to make precise measurements of the wobbling of the earth on its axis. This motion, called Chandler's Wobble, should tend to damp out with the passage of time, but is periodically reinforced by unknown forces?possibly earthquakes. More accurate measurements of the wobble with the aid of the laser reflector might someday lead to a technique for earthquake prediction...
Other scientific benefits will flow immediately from the instruments that the astronauts will leave behind on the moon. As soon as Astronaut Aldrin sets up a seismometer on the lunar surface, for example, a command radioed from earth will activate it by releasing four suspended weights. In the future, whenever a quake or a meteor disturbs the lunar surface, the seismometer's frame will vibrate, while the suspended weights remain immobile. The seismometer, sensing the relative motion between the frame and the weights, will express it as digital data and transmit it to earth. The instrument is so sensitive that...
...astronauts will also leave behind a laser reflector pointed toward the earth. The reflector actually consists of an array of 100 quartz corner reflectors, so called because they are shaped like the corner of a cube or a room. Each reflector has a valuable characteristic: it will reflect a beam of light directly back to the source. Thus light aimed at the lunar reflector from a laser located in Los Angeles, for instance, will bounce directly back to Los Angeles...
...timing the round trip of the laser beam, scientists will be able to fix the distance between the earth and the moon at any time to within 6 in. of the exact figure. This precise measuring rod should help answer a number of vexing scientific questions. By revealing previously unmeasurable variations in the orbit of the moon, for example, it should provide a better understanding of the nature of gravity. For if scientists can determine precisely how much the moon's orbit is increasing each year, they may finally be able to confirm?or disprove?the theory that the force...
...after emerging from Eagle, they will place on the lunar surface a sheet of aluminum foil suspended from a stand. It will be exposed to the constant stream of particles expelled by the sun and should trap rare gases such as argon, krypton, xenon, neon and helium. Returned to earth in a vacuum box, the captive gases will be analyzed to give scientists new insights into the sun and the "wind" that it blows through the solar system...