Published: Tue, May 14, 2019
Global News | By Blake Casey

Space shocker: Earth's moon is shrinking, experiencing seismic activities

Space shocker: Earth's moon is shrinking, experiencing seismic activities

Astronaut James Irwin, lunar module pilot, gives a military salute while standing beside the USA flag during Apollo 15 lunar surface extravehicular activity (EVA) at the Hadley-Apennine landing site on the moon, August 1, 1971.

"We've always assumed that a lot of the little bodies were very boring, very small, maybe a volcano back in the distant past but that's about it", said Dr O'Neill, who was not involved in the study. "Not often do you get somewhere outside of the earth, active tectonics to see, therefore, it is very exciting to ponder that these fractions produce, perhaps, still moon quakes". The Apollo 11 seismometer operated only for three weeks, but the four remaining instruments recorded 28 shallow moonquakes-the type produced by tectonic faults-from 1969 to 1977. These are cliffs caused by the Moon's surface shearing away from itself, thanks to long-term shrinking and contracting of the surface.

NASA says the moon isn't the only part of our solar system that is "shrinking with age", as planet Mercury has shrank more than the moon has.

Despite the apparent intensity felt by those stood on the lunar surface when the waves rippled beneath their feet, the epicentre locations of these quakes were poorly constrained by data collected at the time.

But unlike the flexible skin on a grape the moon's crust is brittle - causing it to break as the interior shrinks.

Authors of the latest study plan to continue analyzing seismic data from the Apollo seismometers, as well as images of the moon's faults, in hopes of uncovering additional evidence of recent moonquakes. Researchers believe that these quakes would have measured between 2 and 5 in the "Moment Magnitude scale" if they had been on earth.

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Another Nasa project, the Lunar Reconnaissance Orbitor (LRO) spacecraft, has snapped thousands of images of the fault scarps on the moon since 2009, showing various landslides on the Moon's surface. These faults resemble small stair-shaped cliffs, or scarps, when seen from the lunar surface; each is roughly tens of yards high and a few miles long.

NASA hopes that more exploration of the moon will help the United States establish a strategic presence in space and grow their worldwide partnerships.

Those that appear brighter indicate freshly exposed rock, suggesting an event like a "moonquake". "Such a young age raises the intriguing possibility that these thrust faults are now active", says Watters and colleagues in their paper. Such tracks would be erased relatively quickly, in terms of geologic time, by the constant rain of micrometeoroid impacts on the moon. This is close enough to tentatively attribute the quakes to the faults, since modeling by the team shows that this is the distance over which strong shaking is expected to occur, given the size of these fault scarps.

The researchers also found that six of the eight quakes happened when the Moon was at or near the apogee of its orbit, the farthest point from the Earth.

Future cash boosts will need to be higher than $1.6 billion, he added, comparing the funding requirements to a bell curve: Needs will start out low, get higher and higher, and then come back down again.

It turns out, that a large proportion of the quakes coincide with young fault scarps; a displacement of the land caused by a shortening, or contraction, of the crust.

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