The Moon holds secrets spanning billions of years, but a recent study has revealed that one of our most fundamental beliefs about its surface was wrong. This unexpected correction isn't a setback—it’s a massive win for future lunar exploration, particularly NASA's Artemis III mission, which aims to return humans to the lunar surface.
KREEP discovery: New research shows the asteroid impact that formed the Moon's largest crater, the South Pole-Aitken (SPA) basin (blue), splashed valuable radioactive KREEP material (red) onto the southwestern rim. This region is a prime science target for the Artemis III mission. (Image credit: Jeff Andrews-Hanna/University of Arizona/NASA/NAOJ)
The South Pole-Aitken Basin: A Case of Back-to-Front Thinking
The South Pole-Aitken (SPA) basin is a behemoth: the Moon's largest and oldest confirmed impact feature, stretching 1,550 miles wide. Formed about 4.3 billion years ago by a colossal asteroid impact, scientists have long theorized about the direction of the strike and where the resulting debris landed.
The Major Discovery
For years, the prevailing belief suggested the asteroid slammed into the Moon from the south, splashing radioactive material onto the crater's northern rim.
However, a new study published in the journal Nature has completely flipped this theory. By comparing the SPA basin's unique, teardrop-like shape to other known impact craters like Mars’ Hellas basin, researchers concluded the impact actually came from the north.
This single change in direction has a powerful implication: the ejected material was plastered around the southern edge of the crater. This material is an ancient, scientifically valuable compound, and it’s now sitting exactly where NASA is planning its next crewed mission.
Artemis III’s Unexpected Treasure: A KREEP Goldmine
The corrected impact direction means the Artemis III astronauts are now positioned for a once-in-a-lifetime scientific opportunity.
What is KREEP?
The key material ejected by the SPA impact is known as KREEP, an acronym for K (potassium), Rare Earth Elements, and Phosphorus. KREEP is a radioactive residue left over from the Moon’s early evolution when its global magma ocean cooled and solidified. Studying KREEP is critical because these elements are believed to hold the answers to major lunar mysteries, such as why the crust on the far side of the Moon is significantly thicker than the near side.
The Great News for NASA
The new research, which used historical data from NASA’s Lunar Prospector spacecraft to confirm high concentrations of thorium (a component of KREEP) at the southwestern rim, places this valuable ejecta right into the flight path.
Artemis III is scheduled to land near the lunar south pole, within the newly-confirmed KREEP splash zone. As study lead author Jeffrey Andrews-Hanna stated, the astronauts will be landing on the "down-range rim of the basin—the best place to study the largest and oldest impact basin on the moon."
This means the first samples collected by astronauts since 1972 will likely include ancient, deep-seated lunar material, offering an unprecedented window into the Moon's 4.5-billion-year history. The correction of a 4-billion-year-old error has turned the Artemis III lunar landing from a monumental achievement into a guaranteed scientific jackpot.
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