Scientists have speculated for years if the moon actually had a moving molten core, due to the strong gravitational pull of the Earth. Recent analysis of 30-year-old data supplies solid information about the layering of the core, and indicates like Earth, the moon has an inner core of rock, enveloped by a molten outer core. Apollo astronauts planted seismic sensors on the surface in the 1970s, signals from these instruments have received a fresh look using the power of present day computers.
Four seismometers positioned on the moon by astronauts from 1969 to 1972 during the six manned moon landings provided the data currently being analyzed. The instruments recorded data and relayed it back to Earth until 1977. Renee Weber of NASA’s Marshall Flight Space Center in Huntsville, Alabama stated the seismic data was too noisy to confidently image the moon. A new unprecedented technique used to examine earthquake data provided direct information about the core of the moon.
Apollo rocket stages of Saturn moon rockets, and moon landers were crashed unto the surface to calibrate the network of seismometers. Information from the seismometers continued until 1977, when the instruments were shut down. Meteoroid impacts and moonquakes supplied most of the data. Deep moonquakes, occurring about 435 miles below the surface, accounted for more than 6,000 seismic signals. Each specific region where the moonquakes occurred produced repeatable seismic waveform signals.
It is easy to see different waveforms and seismic phases on Earth, but the moon has a more fractured surface, seismic energy reaching the surface is blurred and smeared. Using computing techniques to clear up the signals and rearrange stacks of data renders a clearer measurement of the interior of the moon.
The time it takes for a moonquake to travel through the moon is affected by density and size of the moon’s core, using the stacked data and a clear measurement, Weber’s team could predict when a theoretical wave would reach a certain place and allow them to compute the structure and size of the core with precision.
Meanwhile, other scientists are speculating about recent evidence of water within the moving molten core of the moon. These scientists are using data detected with NASA’s Moon Mineralogy Mapper (M3), describing it as “magmatic water,” using analysis conducted on moon rocks from four decades ago.
Using NASA’s M3 images of an impact crater containing measurable amounts of hydroxyl, hints of water that once existed beneath the lunar surface. The find is significant because this information is garnered from deep within a crater and not on the surface. Solar winds can impact the moon and create molecules of water when striking the surface.
More evidence of unusual happenings on the moon, and in conjunction with the earth, are also being declared. NASA has announced measurable bulging, using satellites, on the moon and the Earth due to the strong gravitational pull between the two planets. On the earth it is obvious, as those living near any ocean can attest to, as they observe the tides moving in and out. On the moon the effect is called a lunar body tide, is more difficult to observe as the moon is solid, excepting the molten core. Earth’s strong pull on the life-less satellite causes a bulge, raising the surface about 20 inches both on the far side and the near side of the moon.
The accurate measurement was recorded with the Lunar Reconnaissance Orbiter Satellite. NASA is using this instrument to map the features on the surface of the moon and their various heights, together with another of NASA’s satellites, the Gravity Recovery and Interior Laboratory satellite, mapping the gravitational field of the moon. Measuring the height of 350,000 locations around areas of the moon closest to Earth and areas on the opposite side from Earth. Passing over the moon several times, the satellites provide varying data on the heights and compare which places with height differences, enabling an accurate measurement of the lunar tide.
Molten moving moon cores, lunar tides and magmatic water are new information streams about a silent, lonely satellite still giving release new secrets through modern instruments and some not so new. Most of the scientific studies of the moon have been from the ground we all call home, now satellite instrumentation is confirming theories and suppositions previously constructed from the big blue marble.
By Andy Towle