Looking up in the night sky, you might not realise it.
But our moon is actually shrinking – and it could be disastrous for NASA.
According to a new study, the moon is shrinking because its dense, metallic core is gradually cooling down.
As a result, the lunar surface is contracting and becoming more brittle – and in turn more prone to seismic tremors known as ‘moonquakes’.
If these tremors cause landslides, they could be a danger to NASA’s Artemis astronauts after they eventually land on the moon, scientists from the University of Maryland warn.
Earth’s moon shrank more than 150 feet in circumference as its core gradually cooled over the last few hundred million years. Pictured is the moon’s south region with blue boxes denoting proposed locations of the upcoming Artemis III moon landing. Magenta dots indicate possible epicentres of a very strong moonquake in the early 1970s
The moon has been shrinking very gradually in the 4.4 billion years since it formed, according to the team of experts.
It has shrunk more than 150 feet in circumference as its core has cooled over the last few hundred million years.
In much the same way a grape wrinkles when it shrinks down to a raisin, the moon also develops creases as it shrinks.
But unlike the flexible skin on a grape, the moon’s surface is brittle, causing faults to form where sections of crust push against one another.
This is causing the moonquakes – and could lead to landslides that put any moon dwellers in danger.
‘As we get closer to the crewed Artemis mission’s launch date, it’s important to keep our astronauts, our equipment and infrastructure as safe as possible,’ said study author Nicholas Schmerr, a geologist at the University of Maryland.
‘This work is helping us prepare for what awaits us on the moon – whether that’s engineering structures that can better withstand lunar seismic activity or protecting people from really dangerous zones.’
For their study, the scientists linked a group of faults located in the moon’s south polar region to one of the most powerful moonquakes recorded by Apollo seismometers, back on March 13, 1973, dubbed the N9 event.
Using models to simulate the stability of surface slopes in the region, the team found that some areas were particularly vulnerable to landslides from seismic shaking.
Scientists say moonquakes have happened before and could happen again. Here, arrows point to ‘scarps’ – long structures interpreted to be tectonic in nature and the result of a thrust fault – on the moon’s south pole
Pictured, a portion of the interior wall and floor of Shackleton crater at the lunar south pole. Boulder falls (white arrows) suggest that recent seismic shaking events were experienced in the crater
Space agencies are generally interested in landing at the southern region of the moon (pictured) due to the rich reserves of water ice there
The experts say the continuing shrinkage of the moon has led to notable surface warping in its south polar region.
As it happens, the lunar south is where the Artemis III mission – the first mission to put people on the moon in over 50 years – aims to land.
Later in the Artemis programme, likely after 2030, NASA aims to set up a base camp in the lunar south.
Space agencies are generally interested in landing at the southern region of the moon due to the rich reserves of water ice there.
It could be a source of drinking water for moon explorers and could help cool equipment, or be broken down to produce hydrogen for fuel and oxygen to breathe.
But moonquakes and the resulting landslides have the potential to destroy the Artemis base camp, including buildings and infrastructure.
The study authors are concerned about shallow moonquakes (SMQs), which occur near the surface of the moon, just a hundred or so miles deep into the crust.
Artemis Base Camp: By the end of this decade, NASA aims to set up a base camp in the lunar south region (artist’s impression)
Artemis is the successor to NASA’s Apollo programme of the 1960s and 1970s. In this famous NASA photo, astronaut Buzz Aldrin Jr. poses for a photograph beside the US flag on the moon during the Apollo 11 mission on July 20, 1969
Similar to quakes on Earth, they can be strong enough to damage buildings, equipment and other human-made structures.
But unlike earthquakes, which tend to last only a few seconds or minutes, shallow moonquakes can last for hours and even a whole afternoon.
The researchers will continue to map out the moon and its seismic activity, hoping to identify more locations that may be dangerous for human exploration.
Although the next moon landing has recently been delayed to 2026, this is still relatively soon, especially considering we’re still learning about our lunar neighbour.
‘Light seismic shaking may be all that is necessary to trigger regolith landslides,’ the team warn in their paper, published in The Planetary Science Journal.
‘The potential of strong seismic events from active thrust faults should be considered when preparing and locating permanent outposts and pose a possible hazard to future robotic and human exploration of the south polar region.’
NASA plans to send a manned mission to Mars in the 2030s after first landing on the Moon
Mars has become the next giant leap for mankind’s exploration of space.
But before humans get to the red planet, astronauts will take a series of small steps by returning to the moon for a year-long mission.
Details of a the mission in lunar orbit have been unveiled as part of a timeline of events leading to missions to Mars in the 2030s.
Nasa has outlined its four stage plan (pictured) which it hopes will one day allow humans to visit Mars at he Humans to Mars Summit held in Washington DC yesterday. This will entail multiple missions to the moon over coming decades
In May 2017, Greg Williams, deputy associate administrator for policy and plans at Nasa, outlined the space agency’s four stage plan that it hopes will one day allow humans to visit Mars, as well as its expected time-frame.
Phase one and two will involve multiple trips to lunar space, to allow for construction of a habitat which will provide a staging area for the journey.
The last piece of delivered hardware would be the actual Deep Space Transport vehicle that would later be used to carry a crew to Mars.
And a year-long simulation of life on Mars will be conducted in 2027.
Phase three and and four will begin after 2030 and will involve sustained crew expeditions to the Martian system and surface of Mars.
