• Short Summary

    Man is slowly unravelling the moon's mysteries. But many remain.

    The two missions that landed men?

  • Description

    Man is slowly unravelling the moon's mysteries. But many remain.

    The two missions that landed men on the moon in 1969 - Apollo 11 and 12 - emplaced instruments on the surface that have contributed to our knowledge...and our questions.

    One of them is the Passive Seismometer left by Apollo 12 to detect and report data on seismic waves from meteoroid hits and other sources.

    On the Apollo 14 mission, for the second tie, a spent Saturn V launch vehicle's third stage will be sent crashing into the moon in order to study the impact waves.

    Called the S-IVB, the stage will first inject the spacecraft on its flight path to the moon. The S-IVB will then separate and by ground command will perform an evasive manoeuvre, blow out its surplus oxygen, and be thrust toward the moon.

    Its Auxiliary Propulsion system will be fired to guide the missile to impact on a target area near the Apollo 12 site.

    At the Manned Spacecraft Center in Houston, scientists will again be able to analyze the results of a man-made moon quake.

    The S-IVB impact on the moon was the only successful lunar experiment completed by the aborted Apollo 13 mission in 1970.

    Before that, the Apollo. 12 Lunar Module Ascent Stage was also guided to strike the moon.

    The after-effects of both man-made impacts were surprising. They caused the moon to reverberate for almost an hour, with the volume of sound rising to a peak about seven minutes after impact, then slowly subsiding.

    There has been nothing in our experience with seismic waves through the earth's crust that yields vibrations so prolonged and increasing in intensity following the sharp impact.

    The resonance resembles the sound waves of a bell ringing, or possibly a spoon tapping a crystal glass.

    Analysis of the Apollo 14 S-IVB impact will add to our understanding of lunar structure and the moon's interior; for instance, the huge mascons - mass concentrations - believed to lie beneath the surface of the lunar seas.

    Other studies of sound waves in lunar material have confirmed that they travel at a slow rate. Compared to rates up to five miles per second for waves through the earth's crust, the top speed of moon waves is about one and a half miles per second.

    For what it's worth, this is about the rate of sound waves travelling through green cheese.

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    Film ID:
    Media URN:
    Reuters - Source to be Verified
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    Available on request
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