L67 Fra Mauro Formation
Unassuming hummocky highland south of Mare Imbrium, chosen as an Apollo landing site precisely because there was nothing to see on the surface — the significance of this ground lies almost entirely underfoot, in ejecta blasted up from deep within the crust.
L67 Fra Mauro Formation
Southern Highlands · Apollo 14 Landing Site📉 Vital Statistics
🔭 Field Notes
The Fra Mauro Formation is a hilly, unassuming stretch of highland south of Mare Imbrium — low ridges and undulating valleys that look, at first glance, like ordinary lunar terrain. There’s no dramatic crater or rille to anchor the view here; the significance of this ground lies almost entirely underfoot rather than on the surface. This is Imbrium’s own ejecta blanket, material blasted outward when the basin-forming impact struck nearly 3.9 billion years ago, and it was chosen as an Apollo landing site specifically because reaching it meant reaching ancient material excavated from deep within the lunar crust during that impact.
- ▶ A Second Chance at a Lost Landing: Fra Mauro was originally the target of Apollo 13, whose landing was aborted following the in-flight explosion that crippled the spacecraft. Apollo 14 returned to the same site less than a year later, landing on February 5, 1971, roughly midway between two small craters informally called Doublet and Triplet.
- ▶ Racing a Handcart Toward Cone Crater: The mission’s central goal was to sample ejecta from Cone Crater, a small, deep impact roughly 340 m across whose excavation was expected to have penetrated through the regolith and brought up genuine Fra Mauro Formation material. Commander Alan Shepard and Lunar Module Pilot Edgar Mitchell hauled a handcart toward the rim across increasingly steep, boulder-strewn ground, but disorientation among the hummocky terrain meant they turned back only 20–30 m short of the rim itself — a near miss confirmed only later by matching boulder positions in their photographs against orbital imagery.
- ▶ Samples That Dated a Basin: Despite falling short of Cone Crater’s rim, the 42 kg of rock and regolith Shepard and Mitchell did return were overwhelmingly breccias and impact-melt rocks, and radiometric dating of this material helped pin down the Imbrium impact itself to roughly 3.9 billion years ago — a foundational data point for the entire lunar geologic timescale.
📍 Nearby L100 Targets
- L5 Copernicus: The 93 km “Monarch of the Moon,” roughly 410 km north, its terraced walls and brilliant ray system offering a study in contrasts — one target is a young, dramatic impact scar, the other a quiet, ancient ejecta blanket from a basin four times its age.
- L74 Copernicus H: A small, roughly 5 km dark-halo crater roughly 320 km north, on Copernicus’s own southwestern rim. Once thought volcanic, Lunar Orbiter imagery showed it to be an impact crater excavating dark mare basalt from beneath the Copernicus ejecta — a reminder that even features far from Fra Mauro have their own layered, more-than-meets-the-eye histories.
- L69 Copernicus Secondary Craters: A chain of secondary craters and rays near the crater Pytheas, roughly 700 km north in southern Mare Imbrium, formed by debris thrown out when Copernicus struck. Where Fra Mauro is ejecta from the basin itself, this target is ejecta from a much younger, much smaller crater sitting on top of that same basin’s floor.
🚀 Mission Log
Target Acquisition
Find Fra Mauro crater, then look at the ground around it
Locate the crater Fra Mauro, part of a well-known trio with neighboring Parry and Bonpland in the southern highlands below Mare Imbrium. The formation named after it isn’t the crater itself but the hilly, undulating terrain surrounding it — Imbrium’s own ejecta blanket, hurled outward when the basin-forming impact struck nearly 3.9 billion years ago.
Wait for a low terminator — there’s nothing dramatic to anchor on
With no standout crater or rille to draw the eye, this target lives or dies on lighting. Best viewing falls around Day 9 waxing or roughly Day 24 waning, when a low Sun angle picks out the subtle hummocky ridges and shallow valleys of the ejecta blanket. Under higher Sun, the whole region can appear as relatively featureless highland terrain.
Sweep the terrain rather than hunting a single feature
At 100x–150x, scan the undulating ground rather than expecting a clean boundary — the ejecta blanket blends gradually into the surrounding highlands. Cone Crater, the small ~340 m impact Apollo 14’s astronauts trekked toward, is far too small to resolve in an amateur telescope; what you’re really doing here is taking in the broad, hummocky character of a basin’s ejecta rather than tracking down a single landmark.
From Fra Mauro’s ejecta to Copernicus, Copernicus H, and the Pytheas secondaries
Roughly 410 km north, Copernicus (L5) is the 93 km “Monarch of the Moon,” its terraced walls and brilliant ray system a study in contrasts — a young, dramatic impact scar versus Fra Mauro’s quiet, ancient ejecta blanket from a basin four times its age. About 320 km north on Copernicus’s own southwestern rim, Copernicus H (L74) is a small dark-halo crater once thought volcanic but shown by imaging to be an impact excavating dark mare basalt from beneath the ejecta. And roughly 700 km north near Pytheas, the Copernicus Secondary Craters (L69) are debris thrown out when Copernicus struck — where Fra Mauro preserves part of the Imbrium basin’s own ejecta blanket, this chain is ejecta from a much younger, much smaller crater sitting on that same basin’s floor.
📝 Observation Log — L67 Fra Mauro Formation
0/3 CompleteIs the Fra Mauro Formation visible tonight?
The Fra Mauro Formation sits in the southern highlands near 3.6°S, 17.5°W, around the crater Fra Mauro itself. Best viewing is around Waxing Gibbous (roughly Day 9) or Day 24 waning, since this hummocky ejecta blanket has no standout crater or rille and needs a low sun angle just to bring out its subtle relief. Libration is not a meaningful factor at this longitude.
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When to Observe Fra Mauro Formation
There’s no dramatic crater or rille to anchor the view here, so this target lives or dies on lighting. What matters isn’t the ground itself so much as what’s underfoot — Imbrium’s own ejecta blanket, hurled outward when the basin-forming impact struck.
- Wait for a Low Terminator: Best viewing falls around Day 9 waxing or roughly Day 24 waning, when a low Sun angle picks out the subtle hummocky ridges and shallow valleys of the ejecta blanket. Under higher Sun, the whole region can appear as relatively featureless highland terrain.
- Sweep the Terrain, Don’t Hunt a Landmark: At 100x–150x, scan the undulating ground rather than expecting a clean boundary — the ejecta blanket blends gradually into the surrounding highlands. Cone Crater, Apollo 14’s target, is far too small to resolve in an amateur telescope.
- For Orientation: Locate the crater Fra Mauro, part of a well-known trio with neighboring Parry and Bonpland in the southern highlands below Mare Imbrium. The formation is the hilly terrain surrounding it, not the crater itself.
What to Look For
Look for low ridges and undulating valleys south of Mare Imbrium that, at first glance, resemble ordinary lunar terrain — there’s nothing visually dramatic here, which is part of the point.
This is Imbrium’s own ejecta blanket, chosen as an Apollo landing site specifically because reaching it meant reaching ancient material excavated from the lunar crust during the basin-forming Imbrium impact.
Fra Mauro was originally the target of Apollo 13, whose landing was aborted following the in-flight explosion that crippled the spacecraft. Apollo 14 returned to the same site less than a year later, landing on February 5, 1971.
Commander Alan Shepard and Lunar Module Pilot Edgar Mitchell hauled a handcart toward Cone Crater’s rim across increasingly steep, boulder-strewn ground, but disorientation among the hummocky terrain meant they turned back only a few tens of meters short of the rim — a near miss confirmed only later by matching boulder positions in their photographs against orbital imagery.
The Science: Ground Chosen for What Lies Beneath It
Fra Mauro’s interest lies almost entirely in what the astronauts carried home, rather than in anything visible from Earth — a landing site picked precisely because the surface itself had little to offer the eye.
Vital Statistics
The Apollo 14 landing point sits at 3.6°S, 17.5°W, on Rükl chart 42. As a regional ejecta blanket rather than a discrete crater, the formation has no defined diameter or boundary. It’s named for the nearby crater Fra Mauro, honoring a fifteenth-century Italian monk and mapmaker. Its L100 distinction: the Apollo 14 landing site on Imbrium ejecta.
Samples That Helped Date a Basin
Despite falling short of Cone Crater’s rim, the 42 kg of rock and regolith Shepard and Mitchell did return were overwhelmingly breccias and impact-melt rocks. Radiometric dating of these samples became one of the key constraints on the age of the Imbrium impact, placing it at roughly 3.9 billion years — a foundational data point for the lunar geologic timescale.
Mission Record
Apollo 13 originally targeted Fra Mauro in April 1970, but the mission was aborted following an oxygen tank explosion en route to the Moon, leaving the site unvisited. Apollo 14 landed Antares in the Fra Mauro highlands in February 1971, with Shepard and Mitchell conducting two moonwalks and returning the samples used to help constrain the age of the Imbrium impact. Lunar Orbiter III’s 1967 photographic coverage of Cone Crater and the surrounding terrain was used in Apollo 14’s landing-site planning and traverse design.
Most Lunar 100 targets ask you to look for something. Fra Mauro asks you to look at ordinary-looking ground and remember what was carried out of it — samples that helped anchor the age of one of the Moon’s defining impacts.