New Lunar Crater Offers Keys To The Moon's Shallow Subsurface
In a remarkable stroke of scientific fortune, NASA's Lunar Reconnaissance Orbiter (LRO) has made what experts are calling a once-in-a-generation discovery: a newly formed impact crater on the Moon's near side, located approximately 330 kilometers from the edge of the Mare Crisium. The crater — now formally designated McGetchin Crater — stretches an impressive 728 feet (roughly 222 meters) in diameter, spanning the equivalent of two American football fields end-to-end. For planetary scientists, it represents an extraordinary natural laboratory, offering an unparalleled window into the Moon's shallow subsurface geology and the violent mechanics of cosmic impacts.
The crater is believed to have been carved out by a bolide — a large, brilliantly luminous meteor or small asteroid — that slammed into the lunar surface in the spring of 2024. Despite the dramatic nature of the event, it was not detected until LRO cameras captured telltale changes in late 2024. The discovery has since been detailed in two peer-reviewed papers published in the journal Science Advances, sending ripples of excitement through the planetary science community.
"It's going to be a treasure trove for geology in terms of the immediate effects of impacts capable of excavating deep beneath the Moon's outer surface." — Erik Asphaug, Professor of Planetary Sciences, Lunar and Planetary Laboratory, University of Arizona
A Record-Breaking Find for the Lunar Reconnaissance Orbiter
Since entering lunar orbit in 2009, NASA's Lunar Reconnaissance Orbiter has been the workhorse of modern lunar science, mapping the Moon's surface in extraordinary detail and monitoring it continuously for changes. In that time, the Lunar Reconnaissance Orbiter Camera (LROC) has catalogued dozens of newly formed craters — but none have come close to the scale of McGetchin Crater. The previous record-holder detected by LROC measured only about 70 meters across, making this new discovery more than three times larger and representing a quantum leap in what scientists can study about fresh impact dynamics.
The rarity of such an event underscores just how significant this discovery is. According to Timothy Glotch, Professor and Chair of Geosciences at Stony Brook University in New York, a crater of this size forms on the Moon only once every century or so on average.
"On average, we'll get a new crater this size forming on the Moon every 132 years. But we can't say when the last crater of this size formed because the LRO has only been continuously monitoring the lunar surface since 2009." — Timothy Glotch, Stony Brook University
This statistical rarity makes the timing of LRO's active surveillance all the more fortunate, and it raises pressing questions about what craters of similar vintage may have formed in the centuries before continuous orbital monitoring began.
The Dangers of Fast-Moving Ejecta
One of the most striking features of McGetchin Crater is the extraordinary extent of its ejecta blanket — the field of debris blasted outward from the impact site. Visible imagery from LROC reveals that ejecta extends for perhaps hundreds of crater radii beyond the crater rim itself, painting a dramatic picture of the violent energies involved.
This has immediate and sobering implications for future human and robotic presence on the Moon. As Glotch explains, understanding ejecta dispersal is not merely an academic exercise — it is a critical engineering challenge for sustainable lunar infrastructure. Fast-moving ejecta, traveling at velocities that can exceed several kilometers per second, poses a serious threat to equipment, solar panels, and pressurized habitats left on the surface. NASA's Artemis program, which aims to establish a long-term human presence at the lunar south pole, must account for such risks when siting and designing surface assets.
- Ejecta from even moderately sized impacts can travel hundreds of crater radii from the source
- High-velocity ejecta fragments can sandblast and degrade sensitive optical and electronic equipment
- Crater formation frequency data helps engineers calculate probabilistic risk exposure over mission lifetimes
- McGetchin Crater's ejecta field provides the best-resolved dataset yet for validating impact ejecta dispersion models
The Importance of Cold Spots: A Thermal Fingerprint of Youth
Perhaps the most scientifically evocative signature of a fresh lunar impact is what researchers call a "cold spot" — a thermally anomalous zone surrounding the crater that is detectably cooler at night than its surroundings. Using LRO's Diviner Lunar Radiometer Experiment, scientists identified a cold spot extending approximately 7 kilometers (about 4 miles) across around McGetchin Crater — roughly 16 degrees Fahrenheit (about 9 degrees Celsius) cooler at night than the surrounding terrain.
This thermal signature is not merely cosmetic. It reflects a profound physical change in the lunar regolith — the thin, fragmented layer of pulverized rock, dust, and micrometeorite debris that blankets the entire Moon. Under normal circumstances, the regolith is a remarkably efficient insulator, trapping daytime heat and releasing it slowly through the long lunar night. But when a large impact decompacts and disturbs the regolith, its thermal properties change dramatically, causing it to cool more rapidly after sunset.
The phenomenon is not new to science. Researchers have been aware of cold spots for decades, and the Apollo program provided direct observational evidence of their physical reality. During the Apollo 16 mission, astronauts landed within a faint cold spot associated with the nearby South Ray Crater, and mission crew members noticed that their bootprints in the cold spot region were noticeably deeper than at other sites — direct physical evidence that the regolith had been decompacted by the seismic energy of the ancient impact.
"Such cold spots fade on timescales of up to two million years, making them reliable markers of some of the youngest impact craters on the Moon." — Science Advances authors
The longevity of cold spots — persisting for up to two million years — gives them extraordinary scientific utility. They serve as chronological breadcrumbs, helping scientists:
- Estimate regolith thickness across different regions of the lunar surface
- Refine models of the recent impact cratering rate in the inner Solar System
- Identify potential source craters for lunar meteorites found on Earth
- Understand how seismic energy from impacts propagates through the shallow subsurface
Lunar Fluff: Impact Seismology by Proxy
One of the most intellectually exciting implications of McGetchin Crater's cold spot concerns what Asphaug memorably calls "lunar fluff" — the phenomenon by which powerful stress waves radiate outward from an impact site and physically loosen, or fluff up, the lunar regolith to depths of centimeters or more.
"LRO's Diviner instrument showed us that we can do a kind of seismology by proxy, by understanding how powerful stress waves radiating from this event would fluff up lunar regolith to a depth of centimeters or more. This tells us about transmission of stress waves with distance, which modelers will use in decades to come to figure out how impacts couple their energy into the lunar surface." — Erik Asphaug
This idea — using the thermal imprint of regolith disturbance as a proxy for seismic wave propagation — is a creative scientific workaround born of necessity. In the absence of an active seismic network on the Moon, the Diviner data allows researchers to reverse-engineer the mechanical properties of the shallow lunar subsurface. It is, in essence, reading the Moon's geological memory written in heat.
The Need for a New Lunar Seismic Network
The discovery of McGetchin Crater has reignited long-standing calls within the planetary science community for a comprehensive lunar seismic network. The original Apollo Passive Seismic Experiment, which operated between 1969 and 1977, provided the first seismological data from another world and revealed a surprisingly complex lunar interior. But that network was shut down in 1977 due to budget constraints, leaving the Moon seismically silent for nearly five decades.
Had a seismic network been operational in the spring of 2024, the impact that created McGetchin Crater would have produced seismic signals of immense scientific value, potentially illuminating the structure of the deep lunar interior — its core size, mantle properties, and internal layering — with a precision that orbital remote sensing simply cannot match.
"It's a shame that there was no seismic network in place at the time of this crater's formation. But a seismic recording of an impact of this size would be of great global significance in terms of understanding the deep Moon." — Erik Asphaug
Plans for a new lunar seismic network have circulated in the scientific literature and NASA planning documents for decades. The Farside Seismic Suite, delivered to the lunar farside aboard a commercial lander in early 2024, represents a modest step forward, but a globally distributed network of sensitive seismometers remains a priority for the next era of lunar science.
McGetchin Crater as a Future Mission Target
Beyond its value as a remote-sensing target, McGetchin Crater has attracted attention as a compelling destination for a future surface mission. Its location on the near side — within line of sight of Earth — makes it ideal for high-bandwidth communications, eliminating the need for relay satellites. Its relatively young age means the impact-disturbed geology is pristine and uncontaminated by billions of years of subsequent micrometeorite gardening.
"This would be a fantastic mission target for someone doing relatively inexpensive fundamental lunar science in an area where operations could be relatively simple. You would be able to find out directly whether lunar melt was created and if so, how thick it was, and whether it stayed as a lens inside the crater or was widely distributed." — Erik Asphaug
The question of impact melt — molten rock created by the extreme heat and pressure of the impact event — is particularly tantalizing. On Earth, impact melt sheets are well-documented features of large craters, but their behavior in the low-gravity, vacuum environment of the Moon is not fully understood. A robotic lander or rover visiting McGetchin Crater could collect samples of impact melt glass, measure in-situ regolith properties within the cold spot, and deploy local seismic sensors to characterize subsurface structure — all at a fraction of the cost of flagship missions.
The Broader Scientific Context: Mare Crisium and Lunar History
The region surrounding McGetchin Crater is itself scientifically rich. Approximately 330 kilometers away lies Mare Crisium, an ancient and roughly 560-kilometer-diameter (350-mile) impact basin that formed in the Moon's early history, during the period of heavy bombardment known as the Late Heavy Bombardment, and subsequently flooded with dark basaltic lava. Like other lunar maria — from the Latin for "seas," a name bestowed by early astronomers who mistook these dark plains for bodies of water — Mare Crisium is a testament to the Moon's violent geological past.
The juxtaposition of ancient and brand-new impact structures in the same region offers scientists a rare opportunity to study impact processes across billion-year timescales, comparing the preserved geology of ancient craters with the fresh, pristine record offered by McGetchin Crater. For more on the Moon's geological history, the Lunar and Planetary Institute's lunar mission archive provides extensive resources.
Looking Ahead: The Case for a Next-Generation Lunar Orbiter
The Lunar Reconnaissance Orbiter, now operating well into its second decade, has been nothing short of transformational for lunar science. But it was designed and launched in a different era, and its instruments — while still performing admirably — have inherent limitations in spatial resolution and spectral coverage. As the discovery of McGetchin Crater demonstrates, the Moon still has profound secrets to reveal, and the tools to reveal them must evolve accordingly.
Glotch argues persuasively that NASA needs a next-generation lunar orbiter to eventually succeed LRO when it exhausts its remaining fuel reserves. Such a spacecraft, equipped with modern hyperspectral imagers, higher-resolution cameras, and advanced radar systems capable of probing the subsurface to greater depths, could observe the lunar surface at significantly higher spatial resolution than is currently possible. It could monitor impact-generated changes in near-real time, track the evolution of cold spots, and map the distribution of volatiles critical to future human exploration.
For the latest updates on LRO's ongoing scientific mission and its future successors, readers can explore NASA's official LRO mission page and the European Space Agency's lunar science portal.
Key Takeaways
- McGetchin Crater is the largest new crater detected by LROC since the mission began in 2009, measuring approximately 222 meters (728 feet) in diameter
- It was formed by a bolide impact in spring 2024 and discovered in late 2024 through analysis of before-and-after LROC imagery
- A crater of this size forms on the Moon approximately once every 132 years on average
- The crater's 7-kilometer cold spot reveals how far the impact decompacted and disturbed the surrounding regolith
- Ejecta extending hundreds of crater radii from the impact site has direct implications for designing safe lunar infrastructure
- The discovery underscores the urgent scientific need for a new lunar seismic network and a next-generation lunar orbiter
- McGetchin Crater is a compelling target for a future robotic surface mission to study fresh impact geology at close range
