April's Pink Moon with a Hat. Thursday's Partial Eclipse

One of an excellent sequence of images of the Partial Lunar Eclipse, April 25, 2013, approximately seven minutes prior to maximum coverage. The face of the Moon is subdued in the penumbra of Earth's shadow, while the long and pointed umbra intersects the far north [Lupu Victor].

My Old Farmers Almanac (2013) reminds me the Full Moon of 25 April is traditionally called the "Pink Moon," but the transitory moment when the Moon was full, Thursday afternoon, came and went before moonrise, in the middle of the afternoon in North America.

Had I been in Romania, however, I might have been in Baia Mare, Maramures, with Lupu Victor, and the moment of "fullness" would have occurred simultaneous to the Moon's encounter with the edge of Earth's far-reaching shadow.

It appears projections of a dull eclipse made here the day prior might seem a bit of Aesop's "Sour Grapes," because from Lupu's well accomplished sequence published on his website, the Solar System's record cold temperature at Hermite crater may, if possible, have become colder still!

"On the evening of April 25, 2013, I prepared my 8 " telescope, and installed on the balcony at 21:00.

"It was a very beautiful and serene night, so I think I was very lucky as the weather was favorable for observations with, or without a telescope.

"I've photographed the event before, during and after till 11:29 p.m..

"I've replaced a few moments the Nikon camera, with the video camera Sony CX130 and I've filmed the Moon with zoom to see the shaded area and how craters looks in these conditions.

"By 00:30 I was able to put the first DSLR photos of the event. In this article, I've posted the same photos with Nikon D80,  Exposure 1/500, but with a lower ISO of only 200, compared to the previous article photos, made ​​with ISO 500.

"It was my choice to photograph all the event by these two ISO settings: 200 and 500.

"The images are in chronological order from 10:35 p.m. to 11:29 p.m."

View the images at Lupu's website, HERE.

The Monadnocks of Sinus Honoris

A northwest-southwest oriented groove between two inselbergs in Sinus Honoris (12.276°S; 18.712°E), an embayment near the northwest extreme of Mare Tranquillitatis. LROC Narrow Angle Camere (NAC) frame M181944849L, LRO orbit 11796, January 12, 2012. Illumination angle of incidence 67.94°from the west, field of view roughly 5.8 km across, resolution in the original 1.21 meters per pixel from 122.13  km [NASA/GSFC/Arizona State University].

James Ashley
LROC News System

Most of the physical sciences are instructive in the art of piecing together observations made at vastly different scales. Note, for example, how climatologists look at pollen in soil samples to assess climate change through time on a global scale. Geologists use microscopes to examine mm-scale crystals in order to understand magma chambers many cubic miles in volume.

Astronomers attempt to make sense of subatomic particles in the context of the entire visible Universe. With this in mind, try to explain the sculpted mountains in today's Featured Image, located at the northwestern margin of Mare Tranquillitatis.

Field of view shown at high-resolution in the LROC Featured Image released April 25, 2013 is outlined in yellow in this Wide Angle Camera (WAC) monochrome (566 nm) observation M165726769C, swept up in orbit 9557, July 19, 2011. Field of view 45.8 km, resolution 58 meters per pixel from 40.97 km [NASA/GSFC/Arizona State University].

You may find that adjusting the scale is necessary. Indeed; we will have to zoom out until we can see a good deal of the lunar nearside before the features have the context they need to be understood. (Examine the image above and below to pull back for increasingly smaller-scale, wider-field of view LROC WAC context images.)

A mosaic of the LROC WAC image immediately above, stitched together to observations of the same latitude from one orbit prior and after, July 19, 2011. Field of view roughly 145 km [NASA/GSFC/Arizona State University].

The WAC mosaic context image released with the LROC NAC Featured Image covers a more familiar 1,500 km wide field of view (one that happens also to include four of six successful Apollo landing sites; Apollo 11, 15, 16 and 17) [NASA/GSFC/Arizona State University].

These mountains are members of a group of mare-surrounded highland structures nestled between Mare Tranquillitatis and Mare Serenitatis. Examination of the region will quickly reveal a strong northwest to southeast trending orientation to most of the upland features that points directly back to the Apennine Mountains, which form the southeastern rim of the Imbrium basin. Now we can see that this whole region was sculpted by ground-hugging forces unleashed in the terrible cataclysm that formed that basin. Imagine witnessing this awesome event from the Earth over 3 billion years ago; it would have been clearly visible to the unaided eye!

Isolated mountains like these, which rise from a surrounding plain, are often referred to by geologists as monadnocks or inselbergs ("island mountains," or "sky islands"). On Earth such features might be erosional remnants, but here in the Bay of Honor (Sinus Honoris) we know them to be isolated by surrounding mare deposits.

Click HERE to see the full NAC frame. Additional examples of large-scale features on the Moon can be explored with Four of a Kind in Catena Davy, Nearside Spectacular!, and A Scar in the Highlands.

A Very Partial Eclipse, 25 April 20:08:36 UT

Apparitions like the Partial Lunar Eclipse April 25, 2013 demonstrate the miraculous improbability of lunar and solar eclipses on Earth actually are, because an exceptionally sensitive light meter will be needed to detect any apparition at all [NASA/GSFC].

They don't come more partial. In line of sight from Earth the Partial Lunar Eclipse of April 25 may serve to demonstrate the ephemeral depth of the umbra of Earth's long shadow.

As carefully mapped out in Espenak's schematic from Goddard Space Flight Center (PDF and HERE) The penumbral phase first contact (P1) occurs at 18:03:38 UT and terminates (P4) at 22:11:26 UT, totalling 4 hours, 7 minutes and 47 seconds.

The Umbral first contact (U1) occurs at 19:54:08 UT and ends (U4) at 20:21:02 UT, darkening the Moon's far north 26 minutes, 55 seconds. Maximum occurs at 20:08:36 UT.

The capstone of the International Year of Astronomy 2009, the Blue Moon Partial Eclipse New Years Eve, 31 December 2009 captured by Jean Paul Roux and featured as NASA's Astronomy Picture of the Day, 2 January 2011.

Getting Cracked at Weiner F

An impact crater is caught in the process of disintegration, barely visible today on the complex terrace of Weiner F crater (40.881°N; 150.608°E). LROC Narrow Angle Camera (NAC) frame M169574198L, spacecraft orbit 10124, September 2, 2011. Illumination angle of incidence 46.95° from the southwest, resolution reduced from the original 43 cm per pixel from 30.02 km [NASA/GSFC/Arizona State University].

James Ashley
LROC News System

This small impact crater happened to form just a little too close to the widening edge of the Wiener F crater. Fault-slumping of the upper wall of Wiener F has cracked it along a series of linear, subparallel fractures, and the whole area appears to be in the process of down-slope migration. Eventually, if the process were to continue, the disintegration would be complete and the small superposed crater would no longer be recognizable.

The context images above and below show the location of this feature -- nestled within the slumping and fault-bounded eastern crater wall that has produced an irregular protrusion into the surrounding highland terrain. The occurrence of Wiener F within a former, older and larger crater is a coincidence of nature. Who says impacts cannot occur in the same place twice? Here we see three nested craters!

Context image from NAC frame, 1.3 km across; downslope to lower left [NASA/GSFC/Arizona State University].

The WAC global mosaic context image field of view approximately 48 km from west to east [NASA/GSFC/Arizona State University].

Click HERE to examine the full NAC frame. Other examples of fault-terraced crater walls can be found with Top of the Landslide, Aristarchus Spectacular!, and Post-impact Modification of Klute W.

Center crop from HDTV still centered on Weiner F, view toward the south over the farside anorthositic highland terrain from an estimated 100 km altitude in 2007. From Japan's lunar orbiter SELENE-1 (Kaguya) [JAXA/NHK/SELENE].

Other related posts:
Impact melt outside Weiner F (October 27, 2012)
Secondary melt on the rim of Weiner F (October 2, 2012)

Thin Crust Moon

Map of the thickness of the Moon's crust from GRAIL mission gravity data. Mean thickness are estimated to be 34-43 km.

Paul D. Spudis
The Once and Future Moon
Smithsonian Air & Space

Imagine a system of molten silicate material, where low-density minerals float and higher density minerals sink.  Minerals rich in iron and magnesium (such as olivine and pyroxene) will settle toward the bottom of the magma body while those rich in the elements aluminum and calcium (such as plagioclase feldspar) will float.  Just such a scenario – on a global basis – is thought to have created the crust of the Moon.

Before Apollo, many believed that the Moon was a primitive, undifferentiated lump of cosmic debris.  By studying the samples returned by Apollo 11, scientists identified small fragments of white, plagioclase-rich rocks (anorthosite).  There are no known magma compositions corresponding to this rock type – anorthosite is created by removing low-density plagioclase from a crystallizing system and concentrating it by floatation.  From the evidence of fragments in the lunar soil, large amounts of anorthosite were inferred to be present in the nearby highlands of the Moon.  As the highlands make up more than 85% of the surface of the Moon, it was postulated that the crust of the Moon formed early in its history by global melting, an episode termed the “magma ocean.”

Expecting only minor volcanic activity and perhaps a local igneous intrusion, the concept of a global ocean of magma was surprising to most scientists.  Given its small size and consequent paucity of radioactive heat-producing elements, the idea that most of the Moon might have melted and differentiated was astounding.  The existence of an early magma ocean, which implied high-energy processes, provided us with clues to lunar origin.  Once it was recognized that the Moon had a crust, it was important to gain an understanding of its composition and physical nature.

On subsequent missions, Apollo astronauts were tasked with laying out a series of seismic stations across the near side.  These stations allowed us to measure “moonquakes” – both natural events as well as those created artificially by slamming spent rocket stages and satellites into the Moon.  Seismic recording allowed us to infer the speed at which seismic waves traveled through the lunar interior.  These estimated speeds indicated densities that implied composition, allowing us to deduce the probable chemical and mineral composition of the lunar interior.

The Apollo seismic network indicated that the crust of the Moon was about 50-60 km thick in the central near side, a surprisingly large value, especially compared to the thickness of the crust of the Earth (which varies from as thin as 5-10 km under the ocean basins to over 30 km in continental areas).  Such a thick crust for the Moon led to the postulation of a global magma ocean, as so much anorthosite could only be produced under the conditions of near global melting.  Subsequent studies incorporating gravity data from Lunar Orbiter and other missions suggested that the lunar crust is variable in thickness, with values exceeding 100 km in some regions of the far side highlands.

Re-analysis of the Apollo seismic data gave the first indication that those values might be overestimated.  Using modern techniques on these old data, new analysis revealed that the crust might be thinner than we had originally thought, on the order of 40-50 km thick.  This lower value of crustal thickness had some implications for estimating the bulk chemical composition of the Moon, but because it was considered to be a relatively minor adjustment, it caused no major difficulties for the rest of lunar science.

However, the recent GRAIL mission to the Moon (using high precision gravity mapping) ascertained the thickness of its crust to be 34-43 km.  Why should this new value worry some scientists?  Because we are now entering realms in which the new estimates of crustal thickness create consistency problems for other aspects of lunar science.  A crust as thin as 35 km on the near side of the Moon implies that the largest impacts – the multi-ring basins – should have excavated considerable amounts of material from the layer below the crust, the mantle of the Moon.  One might object that, as this region of the interior is inaccessible, we don’t know what the mantle would look like.  But in fact, the density constraints imposed by the seismic and gravity data dictate that it must be a rock type rich in iron and magnesium, made up mostly of the minerals olivine and pyroxene.  Such rocks are not unknown in the lunar collections, but they possess chemical and mineralogical characteristics indicating their origins at much shallower (crustal) depths.  In other words, there does not appear to be any material from the lunar mantle in the Apollo collections.  Given our obviously incomplete sampling of the Moon, should this be a problem?

Close view of a section of the central peak of Hausen crater (65.11°S, 271.5°E), among the few craters thought by some to have excavated more than 27 km and candidate for sampling below one of the thinner areas of the lunar crust. If the Moon's crust is as thin as GRAIL data indicate, however, why did basin-forming-impacts like Imbrium not appear to have excavated material from far deeper? LROC Narrow Angle Camera (NAC) mosaic M105100555LR, LRO orbit 643, August 16, 2009; angle of incidence 72.47° and 48 cm per pixel resolution, from 41.38 km [NASA/GSFC/Arizona State University].

Several Apollo landing sites (e.g., Apollo 14 and 15) were specifically chosen to maximize the chances of sampling ejecta from the enormous 1100 km diameter Imbrium basin (one of the biggest impact features on the Moon).  Virtually any reconstruction of the dimensions of the excavation cavity of this basin indicates that it should have dug up material from tens of kilometers depth, much deeper than the new value of crustal thickness implied by the GRAIL data.  So where is this debris from the mantle of the Moon?  True enough, it is possible that it may have been missed during the limited exploration time available to the Apollo crews, but the astronauts were trained to recognize such rocks and none were found.  Additionally, because we can map rock types by remote sensing (both from spacecraft and from Earth), we have an understanding of the regional distribution of rocks around these large impact features.  Despite a 30-year, exhaustively detailed search of the Imbrium impact basin (an area larger than Texas), we have found no convincing evidence for mantle material on the surface of the Moon.

So where does this leave us? In science, new data can solve some problems but at the same time, it may also create new ones.  Modern analyses of the old seismic data and new information on the Moon’s gravity field both suggest a relatively thin crust, with mantle material being very close to the surface (a few km) in some areas.  On the other hand, none of the ubiquitous impact basins and large craters of the Moon show evidence for mantle material in their ejecta, either in the Apollo collections or in remote sensing data.  Could our understanding of impact mechanics be completely wrong?  How could an event that formed an impact crater thousands of kilometers across excavate only a few kilometers deep?  Or are we misunderstanding the new gravity data?

Originally published April 24, 2013 at his Smithsonian Air & Space blog The Once and Future Moon, Dr. Spudis is a senior staff scientist at the Lunar and Planetary Institute. The opinions expressed are those of the author but are better informed than average.

The peculiar domes of Stevinus

A distinctive positive-relief feature on the floor of Stevinus crater (32.760°S; 53.739°E). LROC Narrow Angle Camera (NAC) frame M113603383L, spacecraft orbit 1875, illumination is from the east, angle of incidence 57.67° field of view 1.9 km at 58 cm resolution from 55.68 km [NASA/GSFC/Arizona State University].

James Ashley
LROC News System

Today's image explores a portion of the Stevinus crater floor (southern hemisphere, nearside highlands). Here we see a topographic feature that can be found by the dozens throughout the area in many shapes and sizes. These mounded forms show positive relief upon a flat surface of ponded impact melt deposits (now solid).

Some are circular, while others show more irregular outlines. Some occur in clusters that appear to have coalesced, and others superpose one another. Some have smooth upper surfaces and others appear deflated with depressed central portions. The featured dome likely superposes an extension crack, indicating that it occurred after the crack formed.

What caused these peculiar mounds on the floor of Stevinus crater?

Some perspective on the peculiar dome of interest near center of this LROC Wide Angle Camera (WAC) monochrome (643nm) mosaic of three observations gathered in sequential orbits, November 20, 2011. Field of view roughly 40 km across. Angle of incidence 69.83° at 70 meters resolution from 50.66 km [NASA/GSFC/Arizona State University].

While not entirely clear without a better understanding of melt pond dynamics for still-molten deposits, we note that moderately viscous materials can behave in odd ways. The isolated occurrence of individual domes suggests molten behavior with each dome forming in-situ from a local source just beneath its position. Since the phenomenon is occurring in impact melt, we would be wrong to call this behavior volcanic. But something similar to volcanism in the sense that molten rock is locally "erupting" from an accumulated, still-hot deposit, might be appropriate for conceptual purposes. Perhaps isostatic readjustment of the crater floor "squeezes up" these blobs through holes or cracks in crust as the melt mass cools and thickens. This mechanism might explain why today's mound is centered over a fracture.

Reduced view of the LROC WAC mosaic from which the image immediately above it was taken shows the entirety of 71 km-wide Stevinus [NAXA/GSFC/Arizona State University].

Perhaps experiments with analog melts would be a good way to study impact melt behavior. Of course collecting samples is always recommended for any geologic study. What kinds of samples would be helpful for determining the solution to this mystery? Where should they be collected from and why?

Click HERE to see the full NAC frame. Other examples of odd features in impact melt deposits can be found with the Melt Fractures in Jackson Crater, Rippled Pond, and Anomalous Mounds on the King Crater Floor LROC Featured Image posts.

New views of the lava terraces of Bowditch

A lava terrace rings the floor of farside crater Bowditch. LROC Narrow Angle Camera (NAC) observation M180493674L, LRO orbit 11718, January 12, 2012; a roughly 4 km-wide field of view at 1.74 meters per pixel resolution, angle of incidence 75.91° from 85.27 km [NASA/GSFC/Arizona State University].

Sarah Braden

LROC News System

Bowditch is a highly irregularly shaped farside crater partially filled with a mare basalt (25.0°S, 103.2°E).

Today's Featured Image is located along the inner wall of the crater, where the mare deposit meets the wall (24.935°S, 102.705°E). A section of the crater wall is visible in the upper left hand corner of the image, there is a step down in topography from left to right.

All along the inner wall of Bowditch there is a higher elevation ring, or terrace.

LROC WAC context image of mare-filled Bowditch crater. The yellow box outlines the field of view captured at high resolution in the LROC Featured Image released April 18, 2013. Field of view above roughly 38.3 km-wide. The LROC WAC context image accompanying the Featured Image released shows greater topographic relief at smaller scale HERE [NASA/GSFC/Arizona State University].

It is thought that this terrace is a marker of the highest level of liquid lava within the crater. As the lava cooled and solidified within the Bowditch depression it subsided into the center of the depression, causing a lower final elevation of mare basalt towards the center of the crater. Lava terraces such as this one provide important clues about the thickness, viscosity, composition, and cooling rate of lunar lavas and will help us better understand volcanism on the Moon.

View the entire LROC NAC frame to explore more of the Bowditch mare basalt deposit, HERE.

Related Images:
Bowditch Lava Terraces
A Lunar Dichotomy
The Mare-highlands Boundary in Tsiolkovskiy!

The Fourth Marian Dome

A volcanic dome in northeastern Oceanus Procellarum., west of Rima Sharp. LROC Narrow Angle Camera (NAC) observation M1119207667R, spacecraft orbit 17144, March 29, 2013, resolution 1.5 meters over a field of view 3.1 km across [NASA/GSFC/Arizona State University].

Sarah Braden
LROC News System

The volcanic dome in the Featured Image (located at 43.673°N, 310.145°E) rises above the mare basalt of Oceanus Procellarum. This dome is another example of silicic volcanism on the Moon, much like the nearby Mairan Domes, the Gruithuisen Domes, and the Lassell Massif.

Each of these features were originally identified as "red-spots," meaning they are spectrally anomalous compared to surrounding mare and highlands material, with strong ultraviolet absorptions that are responsible for their red color.

New data from the Diviner Lunar Radiometer Experiment instrument on the LRO spacecraft confirmed that all four domes (see the WAC context image below) are highly silicic compared to mare and highlands compositions. The Diviner team's work included this fourth dome as part of the Mairan Domes and dubbed it Mairan "northwest." In terms of size and shape, Mairan "northwest" has the most in common with the smallest Mairan dome, Mairan "south." Mairan "northwest" is ~3.2 km in diameter, just slightly smaller than Mairan "south" at ~4.2 km in diameter. However, Mairan "south" is about 400 meters in height (relative to the surrounding mare) while the structure in the Featured Image has a height of only ~180 meters (measurements taken from the WACGLD100 DTM). Regardless of their height relative to the mare, both domes may be greater in size that their surface expressions due to embayment by mare basalt.

LROC Wide Angle Camera (WAC) context image of northeastern Oceanus Procellarum shows the location of the area surrounding the LROC Featured Image field of view (white box) in relation to the more prominent named Mairan Domes. Field of view is about 120 km across [NASA/GSFC/Arizona State University].

The dome of interest (lower right) and its relation to points north and a lengthy segment of Rima Sharp. LROC WAC monochrome (643 nm) observation M117827780ME, orbit 2498, January 11, 2010; spacecraft and camera slew -11.15° resolution 59 meters per pixel from 40.72 km [NASA/GSFC/Arizona State University].

Oblique view south over Rima Sharp from the JAXA planetary camera on-board SELENE-1 (Kaguya) in 2007. The small dome of interest can be seen as small white blur, between the horizon and the bend region of Rima Sharp at lower center. The named Marian Domes and the crater Marian G are visible half way between the horizon and the small dome of interest [JAXA/SELENE].

The dome of interest (yellow arrow) as seen from Earth, photographed by Lunar Picture of the Day (LPOD) contributor Stephan Lammel, June 11, 2003. The massive Mons Rümker effusive dome is visible at high relief at left. The largest crater in the highlands at right is Marian, 40 km across.

Examples of extrusive silicic materials are rare in the collection of Apollo samples and the origins of these materials are not known. However, it is thought that silicic domes like the Mairan domes may be the source locations. Studies of the Compton-Belkovich region have shown that highly silicic lunar rocks are more volumetrically important in the lunar crust than would be implied by their near absence in the Apollo samples. A sample return mission to the region of today's Featured Image would finally answer questions about the origin of these highly silicic rocks - how they were created as part of the Moon's late stage magmatic evolution.

Explore the entire NAC frame, HERE.

Related Images:
New Views of the Gruithuisen Domes
Gruithuisen Domes Constellation Region of Interest
Marius Hills Constellation Region of Interest
Compton-Belkovich: Farside Highlands Volcanism!

Crater chain near Rima T Mayer

A small, rather unique crater chain, or catena, near Rima T Mayer, a geologically and observationally interesting region northwest of the central near side, between Copernicus and Kepler. LROC Narrow Angle Camera (NAC) M181373663R, a 2.6 km field of view captured at 1.29 meters per pixel resolution from 128.61 kilometers in spacecraft orbit 11842, January 16, 2012; angle of incidence 64.29° [NASA/GSFC/Arizona State University].

Sarah Braden
LROC News System

What sound do impacts make when they hit the lunar surface? If you were an astronaut standing on the lunar surface, you probably would not hear anything even if you were nearby since the lunar surface is a near-vacuum! However, you might feel the rumble of the impact through your boots perhaps giving you enough time to duck behind a nearby boulder. Today's Featured Image shows part of a ~3 km long crater chain, located at 13.360°N, 328.807°E.

The irregular shape of the crater rims and tapered appearance suggests that these are not primary but rather secondary craters, formed from material ejected from a larger primary impact.

LROC Wide Angle Camera (WAC) context image of the area surrounding the crater chain (located inside the white box). The sinuous rille Rima T Mayer winds its way through the region (denoted by white arrows). Image field of view 58 km across [NASA/GSFC/Arizona State University].

Secondary craters form many of the crater chains on the Moon, but not all. The term crater chain, or catena, describes any set of craters in a linear array. Crater chains can be formed not only by secondary craters but also by volcanic collapse (associated with graben) or primary impacts from a string of smaller objects which was observed during the Comet Shoemaker-Levy 9 impact with Jupiter.

A slightly closer look at the same region in "pushed" LROC WAC photography shows the catena bisects a contact zone between an effusive dome structure and the mare material of the surrounding area. Illustration from "New Pyroclasts identified using LROC data," February 18, 2011. LROC WAC observation M117691527ME (689 nm), orbit 2478, January 9, 2010 [NASA/GSFC/Arizona State University].

Can you find other areas with evidence of secondary crater ejecta in the full LROC NAC, HERE?

Related Images:
Tres Amicis
Four of a Kind in Catena Davy
Stream of Secondary Craters
Chain of Secondary Craters in Mare Orientale
New Pyroclasts identified using LROC data

Golden Spike, no longer 'Waiting for Godot'

Rather than continuing to wait on a traditional government space exploration program, Golden Spike believes it’s time to turn to commercial ventures to enable human space exploration. In their scenario, using the lunar orbit rendezvous and return method, a single stage lander would be launched separately from crews and remain in lunar orbit for future expeditions [Golden Spike].

S. Alan Stern and Homer Hickam
The Space Review

We’ve both had long careers in the space field. And almost all of that time, most people in our industry have been waiting for government space agencies to return humans to the Moon and to go on to Mars—boldly exploring new worlds, inspiring a new generation, and creating a robust future for space exploration.

It hasn’t happened.

 Why? The reasons are many, but after observing a long series of false starts and dashed attempts, we’ve concluded that relying on the 1950s and 1960s model of space exploration led primarily by central governments, is a little like Samuel Beckett’s play Waiting for Godot. In that story line, two characters, Vladimir and Estragon, endlessly wait in vain for the arrival of a character named Godot. Well, it’s not just in Beckett’s novel, because in space exploration the 1950s–1960s model, Godot isn’t coming either.

Fortunately, 21st century industry and entrepreneurs are stepping up to the plate, creating exciting new models for how human space explorations can be launched commercially.

Just read the papers, it sounds like science fiction—companies planning suborbital space lines, private space stations, and a private expedition to fly past Mars. In the case of our company, Golden Spike, privately mounted lunar surface expeditions to be sold primarily to foreign space and science agencies, but also to US and international corporations, and wealthy individuals.

And why not? Back in the heady days of Apollo’s Moon race, the hard part was the technologies that had to be invented to make it all possible. Today, those technologies are well in hand. The hard part of today’s Moon shots and other commercial space exploration is raising the capital for large ventures.

Read the full article, new this week at The Space Review, HERE

Crater on Crater Debris

Evidence of erosion and mass-wasting abound in lunar craters. Boulders and a variety of aggregate debris  intrude on the melt pool on the floor of a small crater which, in turn, is neatly nested on the rim of a larger and older crater in the Planck crater group on the southern far side (53.821°S, 139.639°E). Detail from LROC Featured Image released April 12, 2013. [NASA/GSFC/Arizona State University].

Mass-wasting abounds in lunar craters. LROC Featured Image, April 12, 2013; rescaled from LROC Narrow Angle Camera (NAC) mosaic  M18731958LR, LRO orbit 12673, March 25, 2012; original resolution 53 cm per pixel, angle of incidence 55.75° over a field of view approximately 810 meters across, from 51.01 kilometers [NASA/GSFC/Arizona State University].

Lillian Ostrach
LROC News System

The high resolution and stunning detail of LROC NAC images reveal evidence of recent erosion on the Moon, particularly within crater interiors. How do we know that the erosion is recent?

Boulder trails are one reason; micrometeorite bombardment of the lunar surface creates and churns up the regolith over millions of years resulting in erasure of surficial features. Absence of many superposed impact craters is another reason; over geologic time, craters accumulate on lunar surfaces and the absence of many superposed craters suggests that mass-wasting landslides in craters are young. Today's Featured Image highlights the southeastern portion of an unnamed 1.5 km diameter crater (53.819°S, 139.652°E) that shows evidence of mass-wasting.

Full 6.1 kilometers field of view covered by the footprint of the LROC NAC mosaic, source of the LROC Featured Image. From the full image browser exploration tool [NASA/GSFC/Arizona State University].

Just as on Earth, gravity promotes downhill movement and thus erosion of landforms. The crater floor (opening image, upper left) is a mix of pooled impact melt, fragmented blocks coated in melt, and boulders (>1 m diameter) that migrated downhill after the melt solidified. Piles of material (often called talus on Earth) are located at the change in slope between crater walls and floor. The piles of material have boulders of various sizes with smoother material in between. One might call this smoother material "fine-grained", but we are unable to quantitatively characterize the size distribution of the debris below the pixel size of the NAC images, here about 50 cm. Indeed, the term "fine-grained" is particular to a grouping of particle sizes when used in Earth-based sedimentary geology (1/16 to 1/256 mm).

LROC WAC monochrome mosaic centered on an unnamed crater on the farside that formed on the outside rim of another crater. Asterisk notes location of the crater in opening image [NASA/GSFC/Arizona State University].

Generally speaking, an object on a planetary surface is "detectable" when considering two or more pixels in a remotely sensed image. In today's NAC, two pixels represent 1.1 m on the lunar surface. However, simply because an object occupies two pixels does not mean that the object is "resolvable" so that scientists can confidentally determine the type of feature (is it a car or a boulder?). Thus, a good rule of thumb is to use at least three to five pixels when determining the true nature of a feature in an image. So, it is possible that the "fine-grained" material is not so "fine-grained" at all, and the material looks smooth because the individual particles are smaller than both a detectable and resolvable "grain".

The deepest material excavated by an impact crater usually ends up on its rim, which is also its highest elevation. Thus, as we see in this LROC Global Wide Angle Camera mosaic, the relatively fresh small crater (yellow arrow) is nested on the rim of a larger unnamed crater that is, itself in proximity to the rim of the ancient Planck impact and the rim of Planck C. It might be a good place to look for samples of the Moon originally excavated by Planck, if such samples are not shocked beyond usefulness. LROC Lunaserv tool [NASA/GSFC, Arizona State University].

Explore the erosive products in this crater for yourself in the full LROC NAC image, HERE.

Related Posts:
Physics is Fun!
Weaving boulder trails on the Moon
Sampling a Central Peak

Bigelow, NASA rumored contracted for the Moon

Robert Bigelow explains his moon base concept. Photograph by Bigelow Aerospace. HT: Astronwright ("Chronicles of someone trying to get off this rock.")

George Knapp
Las Vegas City Life

Business deals don’t get much bigger than this one. Have you ever read a contract that gives a governmental green light to a program to “place a base on the surface of the moon?” Ever see an agreement signed by the U.S. government that declares a specific goal “to extend and sustain human activities across the solar system?” Me, either.

Yet that is essence of an adventurous deal already reached between NASA and Las Vegas space entrepreneur Robert Bigelow. An official announcement is still a few days away and will likely happen during a news conference at NASA headquarters. In the meantime, I have a draft copy of what could be an historic contract, one that reads like a Kubrick screenplay or an Arthur C. Clarke story. It is flat-out otherworldly.

Bigelow made his fortune building apartment buildings and weekly-rental hotel rooms in Las Vegas. In 1999, he launched what must have seemed a pipe dream at the time — his own private space program. But within a few short years he stunned the aerospace world by launching two of his own locally built spacecraft, both of which still circle the Earth (and one of which contains my weightless, floating business card). The focus of Bigelow Aerospace is an expandable module, small and light enough to make for less expensive launches but so strong and durable when expanded to full size that it accomplishes what NASA has been unable to do on its own: It puts more space in space, that is, more room for companies and governments to work, live and conduct research.

Back in January, NASA bigwigs came to Bigelow’s main plant to announce a landmark deal that calls for one of Bigelow’s modules to be attached to the International Space Station (ISS) within two years. Bigelow used that occasion to let slip some even bigger news — the fact that he is spending $250 million of his own money to build a private space station, larger than the ISS, and that he plans to have it in low-Earth orbit by 2016. What few knew at the time was that he was secretly negotiating an even bigger deal with NASA, one that represents a fundamental, across-the-board change in our approach to space.

Read the full article HERE.

Bipartisan legislation sets NASA's focus on the Moon

George M. Cecala
Office of Representative Bill Posey
Cannon House Office Bldg.
U.S. House of Representatives

U.S. Representatives Bill Posey (R-FL), Sheila Jackson Lee (D-TX), Chairman Frank Wolf (R-VA), Robert Aderholt (R-AL), John Culberson (R-TX), Steve Stockman (R-TX), Pete Olson (R-TX), Rob Bishop (R-UT) and Ted Poe (R-TX) have once again reintroduced bipartisan legislation directing NASA to develop a plan for returning to the Moon and establishing a human presence there. The RE-asserting American Leadership in Space Act, or REAL Space Act (HR 1641), sets a clear course for NASA toward human space flight while keeping within current budgetary constraints.

“The Moon is our nearest celestial body, taking only a matter of days to reach,” said Rep. Bill Posey, who as a young man worked on the Apollo Program at the Kennedy Space Center. “In order to explore deeper into space—to Mars and beyond—a moon presence offers us the ability to develop and test technologies to cope with the realities of operating on an extraterrestrial surface.”

“Space is the world’s ultimate high ground, returning to the Moon and reinvigorating our human space flight program is a matter of national security. Returning to the moon would allow NASA to continue to develop technologies that have not only enhanced our exploration programs but have been applied across all disciplines of science,” said Rep. Sheila Jackson Lee.

“Last year, the National Research Council committee charged with reviewing NASA’s strategic direction found that there was no support within NASA or from our international partners for the administration’s proposed asteroid mission. However, there is broad support for NASA to lead a return to the Moon. So the U.S. can either lead that effort, or another country will step up and lead that effort in our absence -- which would be very unfortunate,” said Rep. Frank Wolf, Chairman of the House Commerce-Justice-Science Appropriations Subcommittee.

“Moon missions, both human and robotic, offer the United States true international cooperation, while ensuring that we lead from the front. Other nations, private industry, and government experts all regard the Moon as the right place for NASA to direct its resources. The time to reassert the United States as the leader in space is now and the REAL Space Act is the next step,” said Rep. Robert Aderholt.

“Congress should be committed to NASA and to expanding the frontiers of scientific progress. This bill is the correct path forward to get Americans to the Moon and expand human knowledge,” said Rep. Steve Stockman who represents the Johnson Space Center in Houston, Texas. “With a real destination and a realistic timetable, we can achieve our greatest dreams. Without it, we risk seeing our future plans perpetually delayed or cancelled, and only watching as other nations seize the lead in space exploration—and reap the benefits in jobs, inventions, investments, national pride and international respect. I urge my fellow Members of Congress to cosponsor this vital legislation, and I urge space advocates and organizations to join together in support of this bill and in support of the Moon being the stepping stone to Mars.”

Rep. Pete Olson said, “The REAL Space Act clarifies NASA's mission, something it has been lacking in recent years. Human space exploration is critically important to America's global future. President Kennedy understood that the real benefit of exploration to our nation was not landing men on the moon, but what it would take to get there — the technology, the initiative and the will to do it. He knew, as we know, that space exploration is both a scientific and national security priority. This legislation sets clear and achievable goals that will ensure America maintains global preeminence in both space exploration and scientific discovery.”

Rep. Rob Bishop said, “This legislation is not just about landing another human on the Moon. It is about restoring our nation’s now defunct human space flight program and setting clear and achievable goals that will lead to advancements in science and technology. If we are to be leaders in the exploration of the cosmos, to the Moon and beyond, we must have our own innovative resources to get there. It’s going to be next to impossible to maintain our preeminence in the exploration of space if we are having to hitch rides from other countries. Going back to the moon has always been an essential stepping stone for technology development for manned exploration to other parts of the galaxy. This legislation restores and clarifies NASA’s role in human space flight and sets the U.S. back on course to lead exploration of the cosmos.”

Specifically, the REAL Space Act directs NASA to plan to return to the Moon by 2022 and develop a sustained human presence there as a stepping stone for the future exploration of Mars and other destinations within our solar system. The legislation also emphasizes the importance of maintaining the United States’ preeminence in space, and underscores the necessity of preserving America’s independent access to space.

Returning to the Moon presents many scientific, technological and economic benefits for the United States and the world at large. The economic contribution of NASA’s space program is in the tens of billions of dollars. The technologies developed through and transferred from our nation's program have created advancements across all disciplines of science and advances in healthcare in particular have saved and enriched countless lives.

Aside from providing a training ground for space faring enabling technologies, humans still have much to learn from exploring the Moon. To date, twelve Americans have explored a section of our Moon smaller than the National Mall. There are many minerals, isotopes, and other natural resources that can be gleaned from the Moon’s surface such as ice deposits, which can be used to sustain an outpost or produce rocket propellant for deep space exploration.

Setting the Moon as the goal will reengage the public’s interest in the space program and inspire a new generation of American students to study science, technology, engineering, and mathematics (STEM) where they currently lag behind students in competitor nations.

Related:
General Bolden on the Moon (April 10, 2013)

Squished Crater

A lobate scarp cuts across and deforms an ancient impact scar on the floor of Seares crater in the far north of the farside highlands terrain. From a mosaic of LROC Narrow Angle Camera (NAC) frame M187315000L an R, field of view 1.95 km, angle of incidence 81.38° at 2.95 meters resolution from 143.54 kilometers [NASA/GSFC/Arizona State University].

Lillian Ostrach
LROC News System

Lobate scarps, found almost only in the highlands, represent the surface expression of thrust faulting within the lunar crust. In the opening image, several segments of a lobate scarp deformed the Seares crater (75.529°N, 146.385°E, approximately 105 kilometers in diameter) floor material, including an unnamed 1.1 km crater (72.964°N, 144.897°E).

Based on the northeast/southwest trend of the lobate scarp segments, this area was probably under compression in the approximate northwest to southeast direction (squeezed from top left toward bottom right), creating bulges on the surface and squishing the crater.

LROC WAC monochrome mosaic of Seares crater. An asterisk notes the location of the opening image's field of view [NASA/GSFC/Arizona State University].

The squished crater is degraded, without a well-defined sharp rim, and it is difficult to determine with a quick glance just how much deformation occurred. Drawing a best-fit circle around the probable rim of the crater to use as a guide for many measurements of crater diameter is one way to estimate the amount of crater deformation. Using this method, the crater diameter is ~1.06 km if the measurement is based on a circle fitting the rim in the east-west direction, while a fit based on the north-south direction provides a diameter of ~1.13 km. Furthermore, the crater shape is somewhat square, which may indicate that this region was affected by ancient episodes of faulting - perhaps resulting from the Seares crater impact formation - that affected today's crater formation, similar to the structural influences that influenced the formation of Meteor Crater.

Put your eyes to the test! Can you find other cross cutting relationships involving the lobate scarp segments in the full NAC image, HERE?

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Rim Slumping inside pre-Nectarian Gamov

Faulting of a crater rim. Downhill to lower right, LROC Narrow Angle Camera (NAC) M187307653L & R, LRO orbit 12672, March 25, 2012; field of view approximately 1.9 km across, resolution 1.79 meters per pixel from 189.55 km [NASA/GSFC/Arizona State University].

Lillian Ostrach
LROC News System

Post-impact modification is frequently observed in LROC NAC images, because post-impact modification begins as soon as the impact crater has formed and ejecta emplaced. Impact crater formation is a violent process, so it should be no surprise that the target rock surrounding the impact site may be fractured and faulted, especially near the crater rim.

Today's Featured Image of the northern rim of an unnamed about 8.5 km diameter crater (64.754°N, 145.546°E) focuses on the faulted nature of the crater rim and evidence for mass wasting.

12.2 km wide field of view from the LROC NAC mosaic showing the entirety of the left and right frames of observation M187307653. The area highlighted in the LROC Featured Image further up is outlined by the white square [NASA/GSFC/Arizona State University].

The upper portion of the opening image is the outer flank of the crater, the fractures represent the crater rim "edge" (the lower portion of the image is the steep interior wall). As time passes and materials (blocks, fine-grained material) are dislodged from the rim and crater wall, the crater rim erodes and degrades, expanding outward (the diameter of the crater actually increases, while its depth decreases).

LROC Wide Angle Camera (WAC) monochrome mosaic highlighting a bowl-shaped crater superposed in pre-Nectarian Gamow crater. An asterisk denotes location of the area seen at high resolution in opening image [NASA/GSFC/Arizona State University].

Some examples of this "slope retreat" of the crater rim are very obvious, whereas others, like today's example, are less so. Today's example shows small-scale slumping of the crater wall as opposed to larger-scale slumping of massive portions of rim material. Perhaps the smaller size of this crater compared to other examples is the reason the slope retreat does not appear well-developed, or maybe the failure of rim faults is less pronounced due to pre-existing target properties (e.g., highly fractured nature of the highlands, impact into floor material of a larger crater, etc.).

Explore this farside simple crater for yourself in the full LROC NAC image, HERE.

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