Unassuming volcanic vent north of Aristarchus Plateau

This unassuming textured surface surrounding a smooth tongue of material is likely a volcanic vent. Field of view 1500 meters, from LROC Narrow Angle Camera (NAC) observation M181495512L, spacecraft orbit 11859, January 18, 2011; angle of incidence 66.53° and 1.46 meters resolution from 147.24 km altitude [NASA/GSFC/Arizona State University].

Drew Enns
LROC News System

Igneous rocks are common on the Moon, basalt makes up the darker mare, and anorthosite makes up the lighter highlands. Less common are the volcanic structures that might have produced the mare. But in today's Featured Image we might have one such structure!

The area highlighted looks similar to vents (the source point of lava) on terrestrial volcanoes. How strong a case can we make for this being volcanic in origin? Maybe a larger view will help give context.

UPDATE: The "unassuming extrusive dome" from the east, in an oblique LROC NAC observation (camera and spacecraft slew -67° from nadir), M177927436LR mosaic, orbit 11357, December 7, 2011; roughly 3.2 meters per pixel resolution from 41.93 km over 30.98°N, 314.73°E (more than 140 km from target) [NASA/GSFC/Arizona State University].

LROC Wide Angle Camera mosaic providing context for the area highlighted within the LROC NAC Featured Image released April 1, 2013 (red asterisk). South lay the volcanic shield Aristarchus Plateau complex Field of view 58 v 80 kilometers [NASA/GSFC/Arizona State University].

The small channel in the Featured Image does not have much depth, so it is difficult to make out. But in the high incidence angle (nearly 80°) context mosaic we see that a shallow channel superposes the center of a low relief pancake-like mound. This pancake feature is very similar to shallow shield volcanoes on Earth. These types of volcanoes have very low slopes and additionally, Aristarchus Plateau is just to the south with a number of volcanic features (rilles, flat floored craters, and massifs). Taken together these observations present a strong case that the smooth area in today's Featured Image is the vent for a shield volcano!

Explore more of the area in the full LROC NAC, HERE.

Related Posts:
New views of the Hollows of Rimae Sosigenes

Farside Highlands Volcanism
Bulls-Eye Crater or Volcanic Vent?
New Views of the Gruithuisen Domes

Floor of Schiaparelli E

Sharply defined contact zone between boulder and debris-strewn wall and ponded impact melt on the floor of Schiaparelli E in Oceanus Procellarum (27.126°N, 297.932°E). Resolution 0.49 meters per pixel. A roughly 290 meter wide field of view cropped from the LROC Featured Image released February 27, 2013. Narrow Angle Camera (NAC) observation M170965859R, orbit 10329, September 18, 2011; from 44.29 km, angle of incidence 29.33° [NASA/GSFC/Arizona State University].

James Ashley
LROC News System

Schiaparelli E, located in central Oceanus Procellarum, presents a floor made partly smooth by an accumulation of impact melt, and partly rugged by debris collected within or on the pooled melt. Low-reflectance boulders litter the surface like sprinkles on a chocolate cupcake.

A radial excavation pattern is also apparent on the slopes of this crater, particularly visible in the full NAC frame.

Notice the sharply defined contact between the margins of the melt and the surrounding crater walls. Note also how the melt has been fractured and fragmented where it thinly mantles the central debris mound.

Context for the full resolution close-up above (rectangle inset), a roughly 1.8 km-wide field of view of the impact melt ponded floor of Schiaparelli E -  LROC Featured Image released February 27, 2013, NAC frame M170965859R [NASA/GSFC/Arizona State University].

The Schiaparelli crater complex (consisting of Schiaparelli and Schiaparelli A, C and E) is named after Giovanni Virginio Schiaparelli (1835-1910), who is remembered primarily for his painstaking telescopic observations of Mars during its 1877 and 1879 oppositions. Schiaparelli's claim - to have seen and mapped a network of straight lines (which he termed "canali") on the Red Planet - sparked a debate about their existence, origin, and meaning.

Today we know these martian linear features to be purely illusory. Yet a public fervor (together with unbridled speculations on intelligent inhabitants) was fueled for many decades over them by the supporting observations of Bostonian amateur astronomer Percival Lowell, the science fiction of H.G. Wells, and the showmanship of Orson Welles. Schiaparelli himself (for whom craters have been named on both the Moon and Mars) never intended to imply anything more than a natural origin for the features he thought he saw. Although most professional astronomers disregarded Lowell's claims, not until the Mariner 9 orbiter mission in 1971 was the myth of the straight lines finally put to rest.

The wide expanse of Oceanus Procellarum, about 142 km-wide field of view, northwest of the Aristarchus Plateau seems featureless, on first glance. A closer look reveals secondary cratering rays and overlapping flows of lava. This zone is near the heart of the Moon's Procellarum KREEP terrain, of a unique composition of Potassium and Rare Earth elements. LROC Wide Angle Camera (WAC) mosaic, LROC WMS Image Map [NASA/GSFC/Arizona State University].

Notice how the few impact craters visible in the Schiaparelli E floor deposits are shallow with hummocky interiors. These are a special type of impact feature called a bench crater, formed when a hard rock surface is overlain by a thin veneer of regolith.

HERE is another example from a previous Featured Image post.

Other than these few small, bench craters, and the fresh rubble salting the floor, this crater appears to have changed little since it formed. Imagine that you are the first to observe this crater at high resolution. What additional lines of evidence would you cite to make yourself comfortable claiming recent impact before a panel of professional planetary scientists?

See the full NAC frame HERE. Other examples of crater floors have been discussed in (the LROC posts) Sunny-Side Up, Crater in 3D!, and Farside Impact!