Hadley–Apennine is a region on the near side of Earth's Moon that served as the landing site for the American Apollo 15 mission, the fourth crewed landing on the Moon and the first of the "J-missions", in July 1971. The site is located on the eastern edge of Mare Imbrium on a lava plain known as Palus Putredinis. Hadley–Apennine is bordered by the Montes Apenninus (often referred to as "Apennine Front"), a mountain range, and Hadley Rille, a meandering channel, on the east and west, respectively. Data obtained from the composition of soil samples collected on Apollo 15 show that most (about 90%) of the samples from the Apennine Front are brown-glass breccias, and approximately 60–70% obtained from the mare surface are basalt. Although the basalts seem to vary in their texture, their ages appear to be approximately the same. Most of the samples obtained on the Apennine Front are KREEP (potassium, rare-earth elements, phosphorus) materials, anorthosites, recrystallized norite, or recrystallized breccia.
Geography and geology
Location
Hadley–Apennine is located west of the Montes Apenninus and east of Hadley Rille. The Apennine mountains form a 15,000 foot (4,600 m) escarpment that rises higher above the Hadley plain than the Himalayan front above the plains of India and Nepal. Hadley Rille (also referred to as Rima Hadley) is located to the west of the Apollo 15 landing site and was the subject of substantial investigation during that mission. The feature, named from nearby Mons Hadley, is a channel that was likely formed by volcanic processes earlier in the history of the Moon.
Apollo 15 landing site
The American Apollo 15 mission, the first of the J-series missions that featured both increased scientific capability and the use of the Lunar Roving Vehicle, landed in an area of the Hadley–Apennine region to the west of the Apennine Front situated between the mountains Mons Hadley and Mons Hadley Delta to the northeast and south, respectively. This landing site was selected with the objectives of exploring the Apennine Front, Hadley Rille, and other geologic features in the area. Apollo 15 was the first mission in which landing sites were not restricted to equatorial areas. The Hadley–Apennine site was chosen with the specific objectives of sampling material from deeper within the Moon than had been obtained from the Fra Mauro formation on Apollo 14 and investigating Hadley Rille, a sinuous rille possibly formed by volcanic activity. The site had been of interest to mission planners since early in the program. During the early stages of Apollo landing site planning, Apollo 19 (which was originally planned to be the fourth and penultimate J-mission of the initial exploration portion of the Apollo program) was tentatively set to land in the Hadley–Apennine region, albeit at a point south of the eventual Apollo 15 site and west of Hadley Rille—near the Carlos pit at the southwestern terminus of the rille. The Marius Hills area in Oceanus Procellarum was also considered for Apollo 15, but mission planners determined that a landing on the edge of Mare Imbrium at the Hadley–Apennine site would be more scientifically fruitful than the Marius Hills alternative, and placing a seismometer at Hadley–Apennine, given the locations of seismic packages from previous Apollo expeditions, would create a more optimal configuration for seismic study.
Apennine Front
The Apennine mountains are hypothesized to be fault-block mountains displaced upward and segmented by the impact that formed Mare Imbrium. The frontal escarpment of Mons Hadley Delta is believed to be an exposed segment of the pre-Imbrium impact lunar crust. This made the mountain one of the mission's primary locations to visit, as doing so would allow the astronauts to obtain samples of the lunar crust as it was before the creation of Mare Imbrium. The area of the Apennine mountains between Mons Hadley and Silver Spur (a mountain just southeast of Mons Hadley Delta), although lacking an official designation on maps and other official mission literature, was informally referred to as the "Swann Range" by Apollo 15 astronauts David Scott and James Irwin, after mission geology team leader Gordon Swann. One of the mountains in the Swann Range was informally referred to by the astronauts as "Big Rock Mountain", after the Apollo Program Director at the time of the mission, Rocco Petrone. The composition of the samples collected by the Apollo 15 astronauts from the Apennine Front, other than KREEP (potassium, rare-earth elements, phosphorus) materials, included anorthosite, and recrystallized norite and breccia. Unknown before the Apollo 15 mission, there are parallel linear patterns on the faces of the mountains in the area. Although they appeared to be occurrences of fracturing or layering appearing through the regolith, determining this is made difficult by the lighting circumstances during the mission. A dark band on Mount Hadley, believed to be a marking left by lava after receding, was observed by the Apollo 15 crew. Additionally, a thick regolith layer on the lower slopes of the mountains and a thin cover of debris on the upper slopes are suggested by the relative absence of large boulders on the lower mountain flanks.
Rima Hadley
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