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Mons Hadley
Mons Hadley
Mons Hadley
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Oblique view of Mons Hadley, including Hadley Rille (lower right), from orbit

Key Information

Hadley C crater, with ejecta filling in part of Hadley Rille

Mons Hadley is a massif in the northern portion of the Montes Apenninus, a range in the northern hemisphere of the Moon. It has a height of 4.5 km (2.8 mi) 14,764 ft (4,500 m) above the adjacent plain and a maximum diameter of 25 km at the base.[1]

To the southwest of this mountain is a valley that served as the landing site for the Apollo 15 expedition. To the southwest of this same valley is the slightly smaller Mons Hadley Delta (δ) peak with a height of about 3.5 km above the valley floor. Mons Hadley Delta was visited and sampled by the astronauts, but Mons Hadley itself was only photographed from the surface. To the west of these peaks is the sinuous Rima Hadley rille.

These features were named after the English mathematician John Hadley (1682–1744).[3]

Rima Hadley

[edit]
Main article: Hadley–Apennine § Rima Hadley

This sinuous lunar rille follows a course generally to the northeast, toward the Mons Hadley peak, for which it is named. This feature is centered at selenographic coordinates 25.0° N, 3.0° E, and lies within a diameter of 80 km. It begins at the crater Béla, an elongated formation with the long axis oriented to the northwest.

Nearby craters

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Selenographic features of Rima Hadley and its small craters

Four small craters near this rille have been assigned names by the IAU. These are listed in the table below.

Crater Coordinates Diameter Name source
Béla 24°42′N 2°18′E / 24.7°N 2.3°E / 24.7; 2.3 11 × 2 km Hungarian masculine name
Carlos 24°54′N 2°18′E / 24.9°N 2.3°E / 24.9; 2.3 4 km Spanish masculine name
Jomo 24°24′N 2°24′E / 24.4°N 2.4°E / 24.4; 2.4 7 km African masculine name
Taizo 24°42′N 2°12′E / 24.7°N 2.2°E / 24.7; 2.2 6 km Japanese masculine name

Satellite craters

[edit]

By convention these features are identified on lunar maps by placing the letter on the side of the crater midpoint that is closest to Mons Hadley.

Hadley Latitude Longitude Diameter
C 25.5° N 2.8° E 6 km

The crater Joy was formerly known as Hadley A, prior to being renamed by the IAU in 1973.[4]

See also

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References

[edit]
[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

Mons Hadley

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Mons Hadley is a prominent lunar mountain located on the , rising approximately 4 kilometers above the surrounding plains and forming part of the range near the border with . It measures about 26 kilometers in diameter at its base and is situated at coordinates 26.7° N, 4.1° E, overlooking the Palus Putredinis plain and adjacent to the sinuous Hadley Rille. Named after John Hadley (1682–1744), the British inventor of the , the feature was officially recognized by the in 1935. Geologically, Mons Hadley is composed primarily of ancient highland materials ejected during the formation of the Imbrium Basin approximately 3.85 billion years ago, with its rugged terrain reflecting the impact's massive ring structure and subsequent mare volcanism. The mountain's slopes include from the lunar crust, as evidenced by samples like the "" (anorthosite 15415), dated to about 4.0–4.5 billion years old, providing key insights into the Moon's early magmatic history. The surrounding region mixes highland breccias, KREEP-rich basalts, and mare basalts aged 3.3–3.6 billion years, highlighting the transition between highland and basaltic lowlands shaped by impacts, lava flows, and erosion. Mons Hadley gained historical significance as part of the mission's Hadley-Apennine landing site in July 1971, where astronauts and explored its lower slopes and nearby features using the . The mission, the first "J-type" extended lunar surface stay, covered nearly 28 kilometers across three extravehicular activities totaling 18.5 hours, collecting 77 kilograms of samples from stations near the mountain's base, including volcanic glasses and highland fragments that advanced understanding of lunar stratigraphy. Exploration focused on Mons Hadley Delta, a southern spur rising about 3.5 kilometers, where the ascended slopes up to 95 meters above the landing site to document bedrock exposures and gather diverse geologic materials.

Physical Characteristics

Location and Regional Context

Mons Hadley is situated on the at coordinates 26.69°N 4.12°E. This position places it at the northern end of the , a major highland mountain range that forms the southeastern rim of the vast Imbrium impact basin. The feature is part of the arcuate Apennine Front, representing the basin's most prominent topographic ring, and exposes materials related to the Imbrium event in this geologically dynamic region. Adjacent to Mons Hadley lies Palus Putredinis, a lowland marshy plain filled with basaltic material, which serves as an inlet extending from the broader to the west. This proximity highlights the transitional nature of the area between rugged highlands and smoother mare terrains, with Mons Hadley marking the boundary along the eastern edge of . The mountain is approximately 20 km northeast of the Apollo 15 Hadley-Apennine landing site, located at 26.13°N 3.63°E within Palus Putredinis. This close association made Mons Hadley a prominent backdrop for the mission, influencing site selection for its scientific value in studying basin rim dynamics. Detailed mapping of Mons Hadley first appeared in the Lunar Topographic Orthophotomaps (LTO) series, specifically quadrangle LTO-41B4, which provides orthophotographic coverage of the Hadley region at a scale of 1:250,000. These maps, produced by the U.S. Defense Mapping Agency and , integrated photographic and topographic data to delineate the feature's context within the lunar nearside highlands.

Dimensions and Morphology

Mons Hadley is an isolated lunar massif rising approximately 4.5 km (14,764 ft) above the surrounding mare plains of Palus Putredinis. Its base measures about 25 km in diameter, forming a prominent topographic feature within the range. The morphology of Mons Hadley exemplifies a rugged, blocky terrain characteristic of lunar highland , with steep slopes exceeding 20 degrees in places and irregular, jagged peaks resulting from and processes. The surface displays hummocky outcrops, talus-covered lower flanks, and scalloped landslide scars, contributing to its uneven, fractured appearance visible in high-resolution orbital imagery. Adjacent to the massif's base lies Mons Hadley Delta, a related fan-shaped approximately 3.5 km wide, extending southward and characterized by similar steep slopes and debris accumulations of highland material. This delta rises about 3.5 km above the plains, presenting a more subdued but still irregular profile compared to the main peak.

Geological Features

Formation and Composition

Mons Hadley represents uplifted highland terrain originating from the Imbrium approximately 3.9 billion years ago, which formed the vast Imbrium Basin and associated blanket, thrusting pre-existing lunar crust into the prominent Apennine scarp system. This tectonic uplift created Mons Hadley as a fault-bounded along the southeastern rim of the basin, with the mountain's structure reflecting both the initial crustal disruption and subsequent modifications from basin deposition. The feature consists of pre-Imbrium highland material, dating back to the early lunar crust formation, overlaid by later Imbrium-sourced layers that altered its surface through impact-related processes. In terms of composition, Mons Hadley is primarily made up of anorthositic rocks characteristic of the ancient lunar highlands, including plagioclase-rich materials from the differentiated crust, interspersed with breccias formed during impact events and possible impact melt sheets. The surface is blanketed by mature , a fine-grained layer developed over billions of years through bombardment, which has comminuted particles, produced agglutinates, and homogenized the to depths of several meters. This exhibits indicators of high maturity, such as increased metallic iron content and finer grain sizes, reflecting prolonged exposure in the highland environment. Geologically, Mons Hadley is classified as a highland massif within the Apennine-Hadley region on USGS maps, distinguishing it as a structural block of elevated, ancient crust amid the basin's ejecta-dominated bench formation.

Rima Hadley

Rima Hadley is a prominent sinuous rille on the , characterized as a narrow, winding depression formed by volcanic processes, serving as a lava channel with sections suggestive of collapsed lava tubes. It originates at the elongated crater Béla and extends northward along the eastern margin of the , meandering through the basaltic plains of Palus Putredinis while bordering the landing site. Centered at approximately 25.7°N 3.2°E, the rille measures about 116 km in length, with widths reaching up to 1.2 km and depths of up to 300 m in its southern segments. Its morphology includes a V-shaped cross-section with a rounded , steep walls that rise 30-40 m higher on the eastern side near the landing site, and outcrops exposing layered mare basalts up to 60 m thick. The formation of Rima Hadley is attributed to effusive volcanic activity during the Imbrian period, where fluid basaltic lavas flowed downslope from a source near Béla, eroding and channeling into the underlying deposits while influenced by pre-existing . Alternative mechanisms include partial collapse along a fault line, potentially creating roofed-over sections that later subsided to form the observed depressions, though evidence favors a primary volcanic erosion model over tectonic fracturing or aqueous processes due to the absence of tributaries or alluvial features. This rille incises Imbrium basin ejecta and Eratosthenian basalts, highlighting the transition from highland to terrains. As a key topographic boundary, Rima Hadley delineates the rugged slopes of Mons Hadley to the west from the smoother plains of Palus Putredinis to the east, influencing local drainage and providing a natural corridor for geological sampling during the mission.

Impact Features

Nearby Craters

Béla crater is an impact feature measuring 10 km in diameter, situated at the head (southwestern end) of Rima Hadley at coordinates 24.67° N, 2.27° E. Carlos crater, approximately 4.7 km in diameter, lies southwest of Mons Hadley in the Palus Putredinis plain at 24.91° N, 2.28° E. Southwest of the massif is Jomo crater, a 7 km-wide depression at 24.41° N, 2.44° E. Adjacent to the southwestern slopes of Mons Hadley is Taizo crater, with a diameter of 6 km at 24.7° N, 2.12° E. These nearby craters are predominantly secondary impact structures generated by ejecta from the Imbrium basin event, which scattered debris across the region and produced chains and clusters of subordinate craters along the Apennine scarp. Their formation ages range from the period, associated with the widespread deposition of Imbrium ejecta, to the younger Copernican era, reflecting ongoing cratering processes in the lunar highlands.

Satellite Craters

Hadley C is the primary satellite officially designated for Mons Hadley under IAU , with a of 5.8 km and centered at 25.48° N, 2.80° E, approximately 50 km southwest of the main peak. This location places it within the broader highland terrain of the , where it intersects partially with Rima Hadley. The formed as a secondary impact, consistent with the regional history of from larger nearby craters, resulting in a shallow, eroded bowl morphology typical of highland secondaries. The nomenclature for satellite features around Mons Hadley originated in the 1935 catalog Named Lunar Formations by Mary A. Blagg and K. Müller, which assigned letter designations like Hadley A and Hadley B to nearby s associated with the mountain. Subsequent IAU updates refined these, with Hadley A renamed in 1973 to honor American astronomer Alfred Harrison Joy (1882–1973); is a small 5.12 km diameter at 25.01° N, 6.56° E on the southeastern flanks of the region. Hadley C itself received formal IAU approval as a in 2006, reflecting ongoing standardization of lunar features. These designations emphasize the craters' affiliation with the parent massif while accounting for erosion and impact dynamics in the Apennine highlands.

Exploration and Significance

Apollo 15 Mission

, launched on July 26, 1971, at 9:34 a.m. EDT from Kennedy Space Center's Launch Complex 39A, marked the fourth crewed lunar landing and the first of the extended "J-type" missions designed for longer surface stays and enhanced mobility. The crew consisted of Commander David R. Scott, Lunar Module Pilot James B. Irwin, and Command Module Pilot Alfred M. Worden. On July 30, 1971, at 6:16 p.m. EDT, Scott and Irwin piloted the to a landing on the mare plains of Palus Putredinis, approximately 1.5 km north of Hadley Rille and near the base of Mons Hadley, at coordinates 26°07'56" N, 3°38'02" E. This site was selected pre-mission for its diverse geological features, including the Apennine mountain front, rille, and mare basalts. The mission featured the debut of the (LRV), enabling extended extravehicular activities (EVAs) and covering a total traverse distance of 27.9 km over three EVAs. During EVA-1 on July 31, Scott and Irwin drove 10.3 km southwest to the edge of Rima Hadley, visiting Elbow and St. George craters. EVA-2 on August 1 extended 12.5 km southeast to the base of Mons Hadley Delta, ascending its lower slopes to Spur Crater and returning via Dune Crater, providing close-up views of the massif's rugged terrain. The shorter EVA-3 on August 2 covered 5.1 km westward along Rima Hadley to Scarp and Rim craters, allowing sampling along the rille's margins. These traverses represented the farthest exploration yet from a , facilitated by the LRV's top speed of 13 km/h and 90 km range capability. Surface operations focused on geological documentation and sample collection around Mons Hadley and Hadley, yielding approximately 77 kg (170 pounds) of lunar material overall, including rocks from the delta's base. At stations near the mountain front, such as Spur Crater on Mons Hadley Delta, the astronauts gathered comprehensive samples of breccias and conducted tests, while photographing the massif's layered outcrops with 500-mm telephoto lenses for detailed mapping. Along Hadley, they documented sinuous walls and collected rake samples of at multiple stations, supplemented by panoramic imagery totaling 1,152 frames across the EVAs. The Apollo Lunar Surface Experiments Package (ALSEP) was also deployed near the landing site for ongoing scientific monitoring. Key moments included Irwin's tentative first steps down the about two hours after , where he nearly stumbled due to the low and stiff suit, expressing awe at the view of . During EVA-3's conclusion, Scott performed a demonstration of Galileo's by simultaneously dropping a and a falcon feather, both hitting the lunar surface at the same time, broadcast live to . The ascent stage liftoff occurred on August 2, 1971, at 5:11 p.m. EDT, after 66 hours and 55 minutes on the surface, rendezvousing with Worden's Endeavour for the return journey.

Scientific Contributions

The Apollo 15 mission collected a diverse array of rock samples from the Mons Hadley Delta and surrounding areas, including anorthosite fragments, mare basalts, and impact breccias, which have provided critical data on lunar geological processes. Anorthosite samples, such as specimen 15415 from Spur Crater, consist primarily of plagioclase-rich material (An95-An98 composition) with high aluminum content, indicating differentiation of the early lunar crust. Mare basalts, including boulder 15555 from the edge of Hadley Rille, have been dated to approximately 3.3 billion years old via Rb-Sr isochron methods, revealing low-titanium, olivine-phyric and pyroxene-rich varieties that formed from primitive volcanic melts. Breccias, like those from Stations 2 and 7, contain shocked clasts showing evidence of the Imbrium impact event, including shock metamorphism and ejecta layers that predate mare flooding. These samples have yielded key insights into the region's volcanic and tectonic history. The mare basalts demonstrate extensive volcanic flooding in Palus Putredinis, with layered flows up to 90 meters thick exposed in Hadley Rille walls, suggesting successive eruptions that filled the Imbrium Basin's outer plains around 3.3 billion years ago. Faulting along the Apennine Front, as evidenced by lineations on Mons Hadley and displaced blocks, is linked to uplift from the Imbrium impact, creating a structural boundary that channeled later lava flows. Rille formation mechanisms are illuminated by the sinuous, 1.5-kilometer-wide Hadley Rille, interpreted as resulting from crustal fracturing, lava tube collapse, or erosional downcutting during early , with seismic data indicating a fractured subsurface up to 20 kilometers deep. The and feldspathic clasts have significantly contributed to the hypothesis, supporting the idea of an early global molten layer that differentiated into a plagioclase-rich crust through flotation of buoyant minerals. High Al/Si ratios (0.64-0.89) in these samples align with models of a 55-70 kilometer thick anorthositic crust formed around 4.4 billion years ago, predating the Imbrium event and subsequent mare basalts. This evidence underscores Mons Hadley's role in tracing the Moon's thermal evolution from initial accretion to prolonged volcanism. Subsequent observations by the (LRO), operational since 2009, have confirmed these findings through high-resolution imagery and , verifying the persistence of rover tracks across 28 kilometers of terrain and mapping the delta's composition as dominated by , , and in the mare basalts. No additional human or robotic landings have occurred at Mons Hadley as of 2025, preserving the site for future missions. Overall, the region remains a pivotal analog for studying the highland-mare boundary, where impact intersected with early lunar to shape the Moon's hemispheric .

References

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  6. https://www.lpi.usra.edu/resources/mapcatalog/LTO/lto41b4_2/
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  21. https://adsabs.harvard.edu/full/1986gpal.work..119W
  22. https://planetarynames.wr.usgs.gov/Feature/9628
  23. https://planetarynames.wr.usgs.gov/Feature/2851
  24. https://www.nasa.gov/history/alsj/a15/a15mr-1.htm
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  28. https://www.nasa.gov/wp-content/uploads/static/history/alsj/a15/as15psr.pdf
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  32. https://lroc.im-ldi.com/images/362
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