Wednesday, 24 July, 2019

The Moon is shrinking: NASA study

Apollo 11 Moon landing Apollo 11 Moon landing
Deanna Wagner | 14 May, 2019, 20:12

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. The Apollo 11 seismic instrument listened for rumbles in the moon's crust for only three weeks, but subsequent missions recorded 28 moonquakes.

Now though, researchers in the U.S. and Canada, have used a problem-solving computer program called a relocation algorithm to help determine whereabouts the waves may have struck from.

Instead of going directly to the surface of the moon, as NASA did during the Apollo missions of the late 1960s and early 70s, it is instead looking to build a more permanent presence by building an orbiting outpost known as the Gateway.

Professor Nicholas Schmerr, a geologist at Maryland University, said: "We found a number of the quakes recorded in the Apollo data happened very close to the faults seen in the LRO imagery". "Such a young age raises the intriguing possibility that these thrust faults are now active", says Watters and colleagues in their paper. Each of the magnitudes of the 28 moonquakes would register as somewhere between two and five on the Richter scale if they had been carried out on Earth.

What's more, most of the Moonquakes occurred during times of the month when the tidal stresses between the Moon and Earth were at their greatest, which would make those faults more likely to slip and thus cause a quake. Mercury has enormous thrust faults - up to about 600 miles (1,000 kilometers) long and over a mile (3 kilometers) high - that are significantly larger relative to its size than those on the Moon, indicating it shrank much more than the Moon.

As the moon shrinks, it gets wrinkled, which then forms "thrust faults" and results in one section of the surface crust pushing up over another crust. The space agency has also recorded evidence of fault lines in a series of images. Normally, weathering darkens material on the moon's surface in time. Researchers re-analyzed seismic data they had from the moon to compare with the images gathered by the orbiter.

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"It (also) means that the moon has somehow managed to remain tectonically active after 4.51 billion years", Thomas Watters, lead author of the study, from the Smithsonian Institution, said in a statement. What's more, the constant rain of micrometeoroids should have erased these tracks, suggesting that they are relatively fresh.

Additionally, "Establishing a new network of seismometers on the lunar surface should be a priority for human exploration of the Moon, both to learn more about the Moon's interior and to determine how much of a hazard moonquakes present", said co-author Renee Weber, a planetary seismologist at NASA's Marshall Space Flight Center in Huntsville, Alabama.

A new analysis suggests that the moon may still be shrinking today and actively producing moonquakes along these thrust faults.

According to the budget amendment, another $650 million of the additional funding would help NASA to develop the next-generation Space Launch System (SLS)-the most powerful rocket in the world-and Orion, the agency's new spacecraft, which will ultimately take astronauts to the Gateway.

Prof Schmerr said: "For me, these findings emphasise we need to go back to the Moon". "We learned a lot from the Apollo missions, but they really only scratched the surface. This provides some very promising low-hanging fruit for science on a future mission to the Moon".