Earth’s moon is shrinking and quaking, study says

Shrinking Moon may be experiencing powerful quakes to this day

The moon is quaking as it shrinks

The researchers in the new study wanted to see if the shallow moonquakes that the Apollo missions detected were linked with faults on the lunar surface, and thus ongoing tectonic activity on the moon.

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

The ultra-HD image is 9000px by 9000px. These dramatic features, which are similar in appearance to cliffs found on Earth, can be miles long and tens of feet high. A team of researchers have now reanalyzed the data along with detailed images captured by the Lunar Reconnaissance Orbiter, which was launched in 2009.

In 1972, Apollo 17 astronauts Eugene Cernan and Harrison Schmitt had to ascend one of these cliffs, the Lee-Lincoln fault scarp, by zig-zagging the lunar rover over it.

"It's really remarkable to see how data from almost 50 years ago and from the LRO mission has been combined to advance our understanding of the moon while suggesting where future missions intent on studying the moon's interior processes should go", said Lunar Reconnaissance Orbiter (LRO) Project Scientist John Keller.

And as it shrinks, the moon actively produces moonquakes along the faults.

In a study published in Nature Geoscience on Monday, a team of scientists examined data from the LRO and compared it to the location of moonquakes recorded during the Apollo program in the 1960s and 1970s.

Astronauts placed five seismometers on the moon's surface during the Apollo 11, 12, 14, 15 and 16 missions.

The discovery of young faults less than 50 million years old by the LSO's camera in 2010 has been interpreted as evidence of lunar tectonic activity.

Although the Apollo instruments recorded their last quake shortly before the instruments were retired in 1977, the researchers suggest that the moon is likely still experiencing quakes to this day.

"It's really remarkable to see how data from almost 50 years ago and from the [orbiter] mission has been combined to advance our understanding of the Moon while suggesting where future missions intent on studying the Moon's interior processes should go", said John Keller in a statement, study author and Lunar Reconnaissance Orbiter project scientist at NASA's Goddard Space Flight Center.

The recent research has been all about drawing a direct connection between the quakes and the "staircase on the Moon".

According to Thomas Watters, a scientist at the Smithsonian's National Air and Space Museum in Washington, these lunar quakes can be incredibly powerful.

"Some of these quakes can be fairly strong, around five on the Richter Scale".

"For me, these findings emphasize that we need to go back to the Moon", said Nicholas Schmerr, an assistant professor of geology at the University of Maryland and co-author of the paper.

The researchers believe the quakes are still occurring on the moon.

"We found that a number of the quakes recorded in the Apollo data happened very close to the faults seen in the LRO imagery", Schmerr said, noting that the LRO imagery also shows physical evidence of geologically recent fault movement, such as landslides and tumbled boulders. Because weathering gradually darkens material on the lunar surface, brighter areas indicate regions that are freshly exposed by an event such as a moonquake.

"It is truly wonderful that the datasets collected by the astronauts so many years ago are still yielding new scientific findings about our moon", Schmerr said. For example, the Apollo missions detected about 11,000 moonquakes happening about 500 to 680 miles (800 to 1100 kilometers) beneath the lunar surface.

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