Scientists Find Deep Structure Hidden Beneath The Moon’s Surface

The Moon is about as mysterious as the human brain, but like the brain, we continue to learn more about it every year – and the more we learn about it, the more amazed we become. In 2019, scientists discovered something about the Moon they had never noticed before – and it was located at the South Pole-Aitken Basin. 

What Is The South Pole-Aitken Basin? 

The South Pole-Aitken Basin is the largest crater in our solar system (to our knowledge), and it’s located on the far side of the Moon – that’s why we can’t see it from Earth. Scientists say it’s as wide as 2,500 km and between six and eight km deep. 

Current estimations suggest it was formed between 4.2 and 4.3 billion years ago, during the Pre-Nectarian epoch. Not much is known about the basin, but scientists have been interested in it for several decades – it was discovered as early as 1962.

Scientists Discover A Large Structure

In 2019, scientists discovered a large mass hidden underneath the crater – and when we say large, we mean massive. They said it weighs approximately 2.18 billion kilograms, is more than 300 kilometers deep, and is more than 2,000 kilometers long.

“Imagine taking a pile of metal five times larger than the Big Island of Hawaii and burying it underground. That’s roughly how much-unexpected mass we detected,” Peter B. James (lead author) from Baylor University said back in 2019. 

Used Data From NASA’s GRAIL Mission

The scientists were using data from a pair of spacecraft that were active between September 2011 and December 2012 – as part of NASA’s Gravity Recovery and Interior Laboratory (GRAIL) mission.  

The laboratory used high-quality gravitational mapping to determine the Moon’s interior and composition. The two spacecraft, GRAIL A (Ebb) and GRAIL B (Flow), impacted the Moon on December 17, 2012 – effectively ending the mission. 

Combined With Lunar Topography Data

Scientists also used data from the Lunar Reconnaissance Orbiter (LRO), which was originally launched in 2009 and is currently orbiting the Moon. It is equipped with seven different technologies that produce more than 155 GB per day of data. 

“When we combined that with lunar topography data from the Lunar Reconnaissance Orbiter, we discovered the unexpectedly large amount of mass hundreds of miles underneath the South Pole-Aitken basin,” James said, according to IFLScience. 

Explanation #1: Metal From Impact

Scientists aren’t 100% sure where the structure came from, what it’s made of, and how long it has been there, but they certainly have their theories. One of those theories is that ‘the metal from the asteroid that formed this crater is still embedded in the Moon’s mantle.’ 

“We did the math and showed that a sufficiently dispersed core of the asteroid that made the impact could remain suspended in the Moon’s mantle until the present day, rather than sinking to the Moon’s core,” James added.

Explanation #2: Collection Of Dense Oxides

A second theory, which is also possible, is that the large structure is made of a concentration of dense oxides from the crystallization of a magma ocean. Let’s not forget – the Moon used to have active volcanoes several billions of years ago.

Scientists might not know what the structure is or where it came from, but they do know one thing – it’s weighing the basin floor downward by more than half a mile, according to James.

The South Pole Has Been A Hot Ticket For Years

Wanting to explore the Moon’s South Pole-Aitken Basin is nothing new. It’s one of the least explored parts of the Moon and we know very little about what that side of the Moon has to offer, so it’s only natural for scientists and researchers to want to learn more.

“[It’s] one of the best natural laboratories for studying catastrophic impact events, an ancient process that shaped all of the rocky planets and moons we see today,” James said of the basin – a testament to how priceless and valuable that data could be.

India Wins Race To Moon’s South Pole In 2023

On July 14, 2023, the Indian Space Research Organisation (ISRO) launched Chandrayaan 3 into space. The spacecraft, equipped with a lander and rover, was India’s third mission to the Moon, and the team hoped to land on the lunar South Pole. 

Chandrayaan 3 landed on the Moon’s surface on August 23, 2023 – a trip that lasted 1 month, 9 days – making India the fourth country to explore the Moon. This landing was a little extra special because it was the first time humans got to explore the Moon’s South Pole.

Russia Tried What India Tried, But Failed

A few days before India landed Chandrayaan on the moon, Russia launched a spacecraft of their own – called Luna 25. They had high hopes for the mission and were targeting a crater named Boguslawsky – in the lunar South Pole.

The spacecraft was launched on August 10 and reached lunar orbit six days later, but crashed into the Moon’s surface on August 19 after trying to attempt an orbital maneuver. Unfortunately, Russia never got the opportunity that India had.

NASA Has Plans To Send Humans To South Pole

All this talk about sending robots and rovers to Moon probably has you wondering when humans will get their opportunity to explore the lunar South Pole. It might sound farfetched to some, but we’re a lot closer than you’d think.

In fact, we’re already starting to plan out the best possible landing locations for when that day comes – which is currently scheduled for no earlier than September 2026, when the US launches their Artemis III mission.

Hope To Learn More About History Of The Moon

Artemis III will usher in a new era of space travel and will mark the first time since 1972 that the US will send humans to the Moon. The goal is to learn more about the history of the Moon, but to also learn more about how to make regular travel to the Moon a reality.

“Several of the proposed sites within the regions are located among some of the oldest parts of the Moon, and together with the permanently shadowed regions, provide the opportunity to learn about the history of the Moon through previously unstudied lunar materials,” said Sarah Noble, an Artemis lunar science lead for NASA.

Scientists Discover Large Mass Of Granite

For now, scientists will have to make do with what they have. The good news is they have a world of data to sift through, and it’s leading to a number of incredible discoveries that we didn’t know before – including one discovery made on the far side of the Moon last year. 

Hidden underneath the Compton and Belkovich craters on the Moon, scientists discovered a massive, unexplained source of heat – which they believe to be a large mass of granite. The problem is the volcano hasn’t erupted in 3.5 billion years – so where is the heat coming from?

Compton-Belkovich Has Unknown Heat Source

According to co-lead researcher Dr Matt Siegler, of the Planetary Science Institute, the ‘heat flux’ is a result of the ‘radiogenic-rich granite body below the caldera.’ Temperatures are roughly 18 degrees Fahrenheit warmer in this area.

To tell the truth, we were a bit puzzled when we found it: fortunately, my wife, Dr Rita Economos, is the geochemist in the family, so with her guidance, we were able to piece together the probable geologic cause of the heat anomaly,” said Dr. Siegler.