Wednesday, March 21, 2012

Ina of the Meniscus Hollows

Joel Raupe
Lunar Pioneer

Before my daughter left for college I tried to pass along a little advice Kurt Vonnegut once tried to impress upon me. I paraphrase: "warn your little Grade A students whom they shall inevitably meet on campus, no matter how gifted they may be. His name is Wolfgang Amadeus Mozart."
Such was the case yesterday only a few hours after posting "Whale of a hollow," which became an excuse to post a perspective shot of an extrusion dome on the geologically interesting southwestern edge of Mare Serenitatis.

The hollows perched on this isolated, but otherwise typical, mare extrusion dome resemble similar features discovered early in the Messenger survey of Mercury. We had a lot of images left over after a thorough study of this one site on the Moon from five months ago. And after simply stumbling on the "whale" structure, while we were examining a newly-released LROC Narrow Angle Camera (NAC) frame showing the Ranger 6 impact, we jumped on an excuse to discuss the Aratus-Serenitatis dome in that context; with the Ina structure and its distant cousin that also happens to resemble a cave dweller's rendition of a whale, or perhaps something one might see from the air flying over the plains of Nazca.

One of the better images of the Aratus-Serenitatis extrusion dome (24.77°N, 7.98°E), before LRO, is this 1971 Mapping Camera view (AS15-M-0410) from the Apollo 15 Service Module, 104 kilometers overhead. For a 21st century look at this dome, and in relief, an animated image demonstrating changes in the landscape during the long lunar day can be seen HERE [NASA/GSFC/Arizona State University].
Which brings us to "Mozart," who manifested almost immediately, first in the form of Phil Stooke, of Western Ontario University, a selenographer well-known for startlingly accurate maps of the Apollo landing sites before these were photographed for the first time in four decades from LRO. He also shares our interest in using the new and deep reservoir of LROC imagery to document the artifacts of human activity on the Moon, and he Emailed us after presenting a fairly comprehensive paper on the topic of lunar "meniscular hollows" at the 43rd Lunar and Planetary Science Conference underway in The Woodlands, Texas. Stooke gently recommended his paper, presented that very evening,
LUNAR MENISCUS HOLLOWS. P. J. Stooke, Department of Geography and Centre for Planetary Science and Exploration, University of Western Ontario, London, Ontario, Canada; 43rd Lunar and Planetary Science Conference (2012), #1011.
My first impression was how ridiculous the context view shown in yesterday's post appeared, one showing the location in Mare Tranquillitatis of the "whale" structure in its "serendipitous" relation to a nearby crater created by the 1964 impact of Ranger 6. That part of the floor of western Tranquillitatis, around the Ross and Arago crater and dome groupings, is crowded with these out-gas-formed "hollows." It will require some revision, to say the least. 

Figure 1. from LUNAR MENISCUS HOLLOWS, P.J. Stooke, U. Western Ontario, #1011, 43rd Lunar and Planetary Science Conference (2012), "Twenty Lunar Meniscus Hollows. Scales vary, image widths are between 300 and 1000 m, approximately." View a full-sized version of the plate HERE [Phil Stooke].
Of course, that's what's being said of all the lunar maps and textbooks these days, and that's a good thing.

The second question is an unfair one. Are there any such "blow-outs" on the Moon's farside? Even the Lunar Reconnaissance Orbiter Camera hasn't photographed the entire Moon in high-resolution, but it's close.

While examining his impressive catalog of 27 nearside hollows, as we prepared to show it off beyond the narrow confines required by the conference, YouTube videographer jayem4646 , who's work has appeared in these pages before, followed up on Stooke's note by calling attention to perhaps the best attempt so far to digest what's been so recently learned about the Ina structure, the "D caldera," and most famous of the lunar meniscus hollows.

It's seen in the embedded video above, way ahead of the Scientific Visualization Studio (SVS) at Goddard, and definitely in their class. 

We missed attending the LPSC this year, but it's warmed more than one heart knowing someone attending that grand meeting found the website useful, or at least amusing!

No comments: