麻豆传媒

NASA scientists and astronauts say that moonquakes 鈥� some with magnitudes as high as five on the Richter scale 鈥� may be caused by the moon shrinking as its interior cools.

鈥淥bjects expand when they heat up and shrink as they cool,鈥� said Bill Steigerwald, science writer at NASA鈥檚 Goddard Space Flight Centre, in an email to 麻豆传媒. 鈥淭he moon鈥檚 formation generated a lot of heat, and it has been gradually cooling off ever since.鈥�

Using data generated by the Apollo missions and scans by the Lunar Reconnaissance Orbiter (LRO) spacecraft, NASA has been able to monitor the faults that form due to the moon鈥檚 brittle crust breaking as it shrinks.

鈥淥ur 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,鈥� Thomas Watters, senior scientist at the Center for Earth and Planetary Studies at the Smithsonian鈥檚 National Air and Space Museum in Washington, said in a press .

Although the Apollo missions occurred decades ago, 鈥渢he Apollo seismometers are the only ones deployed on the Moon,鈥� Watters said in an email to 麻豆传媒.

Those seismometers (instruments used to measure the shaking produced by quakes) recorded the moonquakes that occurred between 1969 and 1977, which allowed Watters and his team to analyze their data using an algorithm to pinpoint the quake locations.

Their study found that the locations of the quakes were close enough to the faults 鈥渢o tentatively attribute them鈥� as the cause.

Neither the moonquakes nor the moon shrinking is dangerous to us on Earth, said Steigerwald.

In fact, Watters and his team attribute the moon鈥檚 interaction with the Earth as part of the reasons the lunar crust is compressing.

鈥淭idal forces exerted on the Moon by the Earth, those from the flow recessions of the Moon away from the Earth and diurnal (daily) forces that arise because of the Moon is鈥�in orbit around Earth, contribute to the global contraction forces from interior cooling of the Moon鈥檚 still hot interior,鈥� said Watters.

Future space projects, such as the (in which Canada is a major partner), 鈥渨on鈥檛 be affected鈥� as the space station is to be in orbit around the moon and not on its surface.

However, NASA believes that 鈥渆stablishing a new network of seismometers on the lunar surface should be a priority for human exploration of the Moon,鈥� which will allow scientists 鈥渢o learn more about the Moon鈥檚 interior and to determine how much of a hazard moonquakes present,鈥� said Renee Weber, a planetary seismologist at NASA's Marshall Space Flight Center in Huntsville, Ala., in the release.

NASA plans on sending 鈥渢he first woman鈥� and 鈥渘ext man鈥� to the moon by 2024, via the Lunar Gateway.

The space agency wants to establish 鈥渟ustainable missions by 2028鈥� 鈥� taking what they learn from the moon and applying it to reaching Mars.