A research team led by Johns Hopkins University Applied Physics Laboratory scientists, examining images captured by NASA’s Lunar Reconnaissance Orbiter Camera (LROC), has identified a new impact crater on the Moon’s surface surrounded by a huge, mysterious cold spot that likely formed in the Spring of 2024.
The research team, which also includes scientists from UCLA, Intuitive Machines, and NASA’s Jet Propulsion Laboratory (JPL), said that the new lunar surface feature, dubbed McGetchin crater, offers scientists a unique opportunity to study its formation and shed new light on unexplained lunar cold spots that surround fresh impact craters.
Newly Identified “Pristine’ Moon Crater Offers Rare Opportunity
According to a study detailing the newly discovered lunar impact crater, initial estimates suggest it is about 222 meters in diameter. The study authors said crater production models predict that craters of McGetchin’s size occur on the Moon once every 132 years on average, “making it an event of century-scale rarity.”
The research team said the new crater is the largest since NASA’s LRO mission began in 2009. The previous record holder was 70 meters smaller than McGetchin.
The research team said the crater’s exceptional size and pristine state “make it an exceptional natural experiment” for measuring the lunar surface’s reaction to a relatively fresh impact. They also noted that the crater’s recent formation offers researchers a chance to study it before it is permanently changed by “space weathering, impact gardening, and other surface processes.”
“Discovered in repeat Lunar Reconnaissance Orbiter Camera images, it provides a unique opportunity to study surface modification by a pristine impact, prior to subsequent fading,” they explained.
Shedding Light on A Lunar Cold Spot Mystery
Beyond fresh surface details, the researchers said the newly formed crater “provides the best opportunity yet to observe a large, virtually unaltered cold spot with well-characterized pre-impact conditions.”
First discovered in nighttime temperature data from the LRO’s Diviner Lunar Radiometer, cold spots are mysterious regions around fresh impact craters that are cooler than the surrounding regolith.
“Cold spots are extensive regions of reduced nighttime temperature relative to surrounding terrain that have been observed around young impact craters between ∼30 m and ∼2 km in diameter,” the research team explained.
These lunar cold spots are also much larger than the actual craters they encompass. According to the study authors, some cold spots extend “tens to, in some cases, hundreds of crater radii.”
Regolith Decompaction Could Explain Temperature Difference
While more research is needed to explain their existence, the research team said most theories suggest that lunar cold spots result from a “decompaction” of the upper layer of regolith during the impact event.
“Thermal modeling shows that the observed nighttime cooling is consistent with reduced density in the upper centimeters of the regolith, resulting in lower thermal inertia,” they explained.
The team notes that the Apollo 16 mission landed on a ‘faint’ cold spot associated with the South Bay crater, and measurements taken there by that mission’s astronauts support the decompaction theory. For example, Astronauts’ footprints left in the South Bay cold spot were measurably deeper than similar prints at other lunar landing sites.
When measuring the temperature around the newly formed McGetchin crater, the researchers found it was 8 to 9 kelvin cooler than its surrounding area. The team said this measurement is “consistent with decompaction of the upper centimeters to decimeters of regolith.”
The team also found that cold spot anomalies increased with crater size. This supports the idea that larger impacts result in more regolith decompaction.
Providing Calibration for Fading Timescale Cold Spots
When discussing the significance of their findings, the Johns Hopkins-led research team noted that cold spots fade extremely slowly, “on ∼100 ka to ∼2 Ma timescales.” This makes these natural formations reliable dating markers of some of the Moon’s youngest impact craters.
For example, when investigating all newly formed craters over 20 meters in diameter, the team found that all those that were larger than 30 meters produced detectable cold spots. The team said this suggests that cold spot formation is a “common consequence of fresh lunar impacts.”
The study authors said that finding relatively young lunar impact craters “has enabled their use in investigations of regolith thickness, the recent impact cratering rate, and as potential source craters for lunar meteorites.”
“This will improve our understanding of cold spot formation and provide a calibration for the fading timescale of cold spots, potentially enabling age estimates for some of the youngest craters on the Moon using cold spot properties,” they explained.
The study “New lunar crater reveals extensive distal regolith modification” was published in Science Advances.
Christopher Plain has spent the last six years as Associate News Editor and Head Science Reporter at The Debrief. Follow and connect with him on X, learn about his novels at plainfiction.com, or email him at christopher@thedebrief.org.