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geophysics (2)

Our Shrinking Moon...

New surface features of the Moon have been discovered in a region called Mare Frigoris, outlined here in teal. NASA
Image: New Republic

 

Topics: Astrophysics, Geophysics, Moon, NASA, Planetary Science


The Moon is shrinking as its interior cools, getting more than about 150 feet (50 meters) skinnier over the last several hundred million years. Just as a grape wrinkles as it shrinks down to a raisin, the Moon gets wrinkles as it shrinks. Unlike the flexible skin on a grape, the Moon’s surface crust is brittle, so it breaks as the Moon shrinks, forming “thrust faults” where one section of crust is pushed up over a neighboring part.

“Our analysis gives the first evidence that these faults are still active and likely producing moonquakes today as the Moon continues to gradually cool and shrink,” said Thomas Watters, senior scientist in the Center for Earth and Planetary Studies at the Smithsonian’s National Air and Space Museum in Washington. “Some of these quakes can be fairly strong, around five on the Richter scale.”

Watters is lead author of a study that analyzed data from four seismometers placed on the Moon by the Apollo astronauts using an algorithm, or mathematical program, developed to pinpoint quake locations detected by a sparse seismic network. The algorithm gave a better estimate of moonquake locations. Seismometers are instruments that measure the shaking produced by quakes, recording the arrival time and strength of various quake waves to get a location estimate, called an epicenter. The study was published May 13 in Nature Geoscience.



Shrinking Moon May Be Generating Moonquakes, NASA

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Mars Quake...

Model of the spaceship Insight, NASA's first robotic lander, dedicated to study the deep interior of Mars. REUTERS/Mike Blake/File Photo

 

Topics: Geophysics, Mars, NASA, Planetary Exploration


Finals are over. I'll be with our new granddaughter and her parents next week, along with working on my thesis, following up on my PhD application and changing diapers. My posts will be sporadic since I'll be on the road. I'll catch up.

The breakthrough came nearly five months after InSight, the first spacecraft designed specifically to study the deep interior of a distant world, touched down on the surface of Mars to begin its two-year seismological mission on the red planet.

The faint rumble characterized by JPL scientists as a likely marsquake, roughly equal to a 2.5 magnitude earthquake, was recorded on April 6 - the lander’s 128th Martian day, or sol.

It was detected by InSight’s French-built seismometer, an instrument sensitive enough to measure a seismic wave just one-half the radius of a hydrogen atom.

The lunar and Martian surfaces are extremely quiet compared with Earth, which experiences constant low-level seismic noise from oceans and weather as well as quakes that occur along subterranean fault lines created by shifting tectonic plates in the planet’s crust.

Mars and the moon lack tectonic plates. Their seismic activity is instead driven by a cooling and contracting process that causes stress to build up and become strong enough to rupture the crust.

Three other apparent seismic signals were picked up by InSight on March 14, April 10 and April 11 but were even smaller and more ambiguous in origin, leaving scientists less certain they were actual marsquakes.

 

NASA probe detects likely 'marsquake' - an interplanetary first
Joey Roulette, Reuters Science

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