User sergsh posted some interesting images in the “Interesting Terrain” thread from the area around the Moore F crater on the farside, then Jules followed up with further images and then Tom128 posted the following:
from LROC strip: M128075293RE
What I find exciting is that I believe we are seeing an erosion/landslide starting on the rim with the expanding cracks on the edge.
[quote by Tom128]
Further informative comments were made by IreneAnt:
These are indeed spectacular images of crater rim slumping, presenting examples of differing size and morphology! The size of the slump blocks and the way they look at the top are related to fracture systems in the rim, consolidation status of the block, and presence/thickness of the melt/ejecta/regolith at the top of the slump block. However, the question of when these blocks began slumping (during cratering or more recently) can’t be answered with the data we have here.
[quote by IreneAnt]
The Moore F crater has many impressive debris flows caused in part by the steepness of the walls of the crater. The Lunar Orbiter Laser Altimetry (LOLA) instrument indicates that in some cases the walls exceed 38 degrees especially near the crater rim.
The floor of the crater contains impact melts, broad terraces and slumps. An interesting crater to explore and plenty of LROC strips cover this crater (some of them are listed at the end if you want to explore further).
Some odd looking debris flow:
LROC Strip: M125720601RC
Melt from the floor of the crater:
LROC Strip: M125720601RC
A 3-D debris flow, originally found by user Tom128
LROC Strip: M108019392RC
LROC Strip: M110383422LC
The following short PDF document contains some interesting information about Moore F crater:
LROC Strips – Latitude and Longitude relate to the centre of the strip:
Apollo 15 Image LROC Image
Apollo lunar missions 15 – 17 carried onboard the orbiting command service module a sophisticated array of camera systems used for mapping the lunar surface from orbit.
Apollo 15 and Apollo 16 system arrangement
While reading, “APOLLO OVER THE MOON: A VIEW FROM ORBIT (NASA SP-362)” on page 123, I found a crater similar to an example Forum moderator Geoff posted for our Transient Lunar Phenomena (TLP) thread on Boulder Repellent.
AS15-9287 Panoramic (P) High Resolution Click here for full image.
The interesting name was given to this type of crater because of the open space in its center marked by a ring of boulders. To date we have not come across an example as good as the one posted on the TLP thread until now- 22.5° N / 34° E” in the Taurus mountains. With help from Forum moderater Jules and Astrostu the Apollo 15 crater was tracked down on a LROC M126704350RE photo strip with a tantalizing partial view of the crater. Jules was especially helpful in moving this project forward.
When a LROC photo strip is made showing the entire crater we hope to do a comparison of the crater center looking for change between the two versions as well as surveying craters and boulders in the surrounding area. You are all invited to participate in the fun. Though not the superior resolution of LROC, the high resolution Apollo 15 version is very impressive. Once you begin comparing the two versions of the crater, details in the Apollo 15 photograph begin to appear more clearly and you can see the details as smaller patterns but noticeable. Downloading the Apollo 15 version and magnifying it with your photo viewer is a big help. Also enhancing the photograph using a free online photo editing tool such as Sumo Paint allows one to modify the photograph with warmer colors (tan) to enhance boulders and craters.
Below is an example of an enhancement of the Apollo 15 crater center. The annotated lines were made on Sumo Paint. The photograph resizing and hosting were performed at Photobucket. So, I moved the photograph back and forth as it was modified. The arrow points toward the large boulder on the crater rim (not shown). The white radial lines move out from the approximate center touching boulders and areas closest in to give one perspective. I also marked the circumference of the open center area. The red lines are possible alternative routes.
Visit the MZ Forum thread, “Crater matching – Apollo 15 v LROC” for more information on this project and how it evolved. You can also participate in the investigation of two recently added Apollo 16 versus LROC photographs.
Tom128 is a regular contributor to the Moon Zoo Forum.
Back in June Moon Zoo forum member Toban posted this unusual looking crater in the Alpine Valley east of Plato from the LRO strip M104497175LE. Toban wondered if what we were seeing was “old” lava. He asked:
“Was the impact so deep, that this has “opened” the ground a long time ago?! I think there is no liquid under the moon surface… so maybe it is very old or it’s not lava…”
It reminded me of another unusual crater posted by Geoff a week earlier
which IreneAnt identified as “an impact into a not-completely-solidified melt sheet” and she also provided a link to a paper showing experimental impacts into viscous targets and noted that there were more examples of this type of crater in the same area (Aristarchus – strip M111904494RE.)
Alternatively could Toban’s crater be a very eroded crater or a “ghost” crater? Eroded craters have been worn and eroded by a history of micrometeorite impacts so that their original form is hard to make out. Ghost craters are craters which have subsequently been filled with lava leaving only a “ghost” of a rim visible when the sun is at a sufficiently low angle. Here are a couple of examples of ghost craters:
Toban thought this unlikely because his crater has a very definite unbroken ring structure with a clear boundary which has captured some of the boulders that have rolled down into the ring area.
Close up of Toban’s crater – the section around 10 o’clock
IreneAnt confirmed that Toban’s crater was another impact into viscous material and provided a link to another paper which describes laboratory experiments to study the morphologies of craters produced by impacts into various viscous materials using different impact velocities. IreneAnt draws our attention to Figure 4b of this paper which shows an impact into a clay-oil mixture producing a crater with no central peak and poorly defined rim topography. A similar type of crater, known as a “splosh crater” is much more common on Mars where the geology, history, atmosphere and gravity produce craters which are multi-lobed with splashed rather than rubbly ejecta. This type of Martian crater was formed when a meteorite hit an area rich enough in water to turn the impact site into runny mud. The lunar version, however, did not involve water but was formed because the impact site rocks had melted enough to behave like a viscous liquid. IreneAnt, therefore, suggests the term “melt splosh crater” to describe the lunar version to avoid confusion with the Martian water based splosh craters.
Although not quite the same thing the lunar versions were still formed more from a splash than a crash. Geoff found more examples of lunar viscous impact craters around King Crater on LROC strip M115529715LE.
These craters were formed when parts of the Moon were covered in molten lava and the splashes have been “frozen” as the lava cooled. So we should be able to find craters in various stages depending on the consistency of the lava impacted. Look out for them and post your finds in Toban’s thread.
Jules is a volunteer moderator for the Moon Zoo Forum.
This crater lip — in the mare south of Apollo 14 — can only be called “awesome” – mercutin
# ID: AMZ4000b8o
# Latitude: -4.79051°
# Longitude: 342.43°
I downloaded the LRO strip containing the crater and extracted the following image:
from strip: M102265088LC
The crater is called Fra Mauro D and is “a thermal anomaly crater” according to Moore et al 1980 (not Patrick Moore). It is about 5 km in diameter.
There is some very well defined dendritic filament-like debris flow on the crater wall, just what we are looking for in the TLP Project – The Landslides of Birt / Gullies project.
Unfortunately I wasn’t able to find an adjoining strip so it appears we only have half of this crater in LRO.
This NASA article has a picture of the Fra Mauro D crater: Apollo 14 Landing Site