Second Conference on the Lunar Highlands

First Results: from Figure 2, "Preliminary results on the structure of lunar highland crust from GRAIL and LOLA altimetry," Zuber & Smith, et al, (#9015, Second Conference on the Lunar Highlands Crust, 2012) Preliminary GRAIL gravity field for the 86-km-diameter Tycho crater. Tycho is the prominent structure at upper left. In this GRAIL map reds correspond to mass excesses and blues to mass deficits. GRAIL gravity has a spatial resolution of 18 kilometers [NASA/JPL/MIT].

Clive Neal
Notre Dame

The first conference on the Lunar Highlands Crust was held in 1979. Since that seminal meeting, our knowledge of the lunar highlands has advanced enormously. Unimagined new data have become available, notably in orbital remote sensing of mineralogy, chemistry, topography, and gravity; geochronology; and geochemistry, especially isotopic constraints and the abundances and natures of lunar volatiles. These new data are paralleled by new concepts of solar system science, including the importance and timing of impact events (including the one that formed the Moon) and the nature of the early solar system disk and its dynamical instabilities. 

In light of these advances in the last 34 years, the time seems right for a synoptic reexamination of the lunar highlands crust. The Second Conference on the Lunar Highlands Crust is intended to bring members of the planetary science community together to share their specialized insights into the lunar highlands crust, exchange ideas freely, and perhaps develop new cross-disciplinary ideas and tests of those ideas.

A field trip to the Stillwater Mine will be held on Thursday, July 12, and a field trip to Picket Pin Mountain will be held on Monday, July 16 (departing Bozemanon Sunday, July 15, following the conclusion of the final oral session). More details about the field trips, along with information about registration, accommodations, transportation, and much more, are available in the final announcement.

For more information, visit the conference website, HERE.

"Preliminary results on the structure of lunar highland crust from GRAIL and LOLA altimetry," Zuber & Smith, et al, (#9015, Second Conference on the Lunar Highlands Crust, 2012)

Related: Lunar Picture of the Day (LPOD), "First Results," June 13, 2012, Charles Wood

The replicators have arrived

"Slide show" comparing an illumination model of the lunar north pole region, made using a three-dimensional printer and LRO laser altimetry by Howard Fink of New York University, with standard representations of LOLA data and one LROC WAC mosaic [Howard Fink/NYU/NASA/GSFC/ASU].

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

Of all the wonders depicted in science fiction books and movies, one of the most intriguing is the machine that makes anything that you need or desire.  Merely enter a detailed plan, or push the button for items programmed into the machine – dials twirl, the machine hums and out pops what you requested.  Technology gives us Aladdin’s Lamp.  A handy device that will find many uses.

We’re not quite there yet but crude versions of such imagined machines already exist.  These machines are called “rapid prototype” generators or three-dimensional printers.  They take digitized information about the dimensions and shape of an object and use that data to control a fabricator that re-creates the object using a variety of different materials.  Typically, these machines use easy to mold plastics and epoxy resins but in principle, any material could be used to create virtually any object.

3-D printers contribute to the advancement our understanding of lunar morphology, as LRO fills long-neglected gaps in lunar morphology. Malapert Massif (85.9°S, 0.42°E). From an 80 meter resolution image of the South Pole region of the Moon built from a 20 meter original supplied by the LRO/LOLA science team [Howard Fink/NYU].

For comparison nearly the same area modeled by laser altimetry (LOLA) above, Malapert from the LROC Wide Angle Camera (WAC) RDR 100 meter Global Mosaic [NASA/GSFC/Arizona State University].

What’s the relevance of this technology to spaceflight and to the Moon?  One of the key objects of lunar return is to learn how to use the material and energy resources of the Moon to create new capabilities.  To date, we have focused our attention on simple raw materials like bulk regolith (soil) and the water found at the poles.  It makes sense to initially limit our resource utilization ambitions to simple materials that are both useful and relatively massive, which currently have those killer transportation costs when delivered from Earth.  Bulk regolith has many different uses, such as shielding (e.g., rocket exhaust blast berms) as well as raw material for simple surface structures.

However, once we are on the Moon and have met the basic necessities of life, we can begin to experiment with making and using more complex products.  In effect, the inhabitants of the Moon will begin to create more complicated parts and items from what they find around them, just outside their door.  The techniques of three-dimensional printing will allow us to discover what makes life off-planet easier and more productive.  We will experiment by using the local materials to maintain and repair equipment, build new structures, and finally begin off-planet manufacturing.

To illustrate the obliquity of the view angle and the problem posed in gathering information about the tantalizing but permanently shadowed regions of the Moon, Shackleton crater, with the Moon's South Pole on its rim (upper left) together with Malapert Massif on the horizon, seen with Earth as a back drop. HDTV still from Japan's Kaguya orbiter released November 2007 [JAXA/NHK/SELENE].

During the early stages of lunar habitation, material and equipment will be brought from Earth.  With continued use, particularly in the harsh lunar surface environment, breakdowns will occur.  Although initially we will use spare parts from Earth, for simple uncomplicated structures that are needed quickly, a three-dimensional printer can make substitute parts using local resource materials found near the outpost.  Most existing 3-D printers on Earth use plastics and related materials (which are complex carbon-based compounds, mostly derived from petroleum) but some processing has used concrete, which can be made on the Moon from sieved regolith and water.  In addition, we also know that regolith can be fused into ceramic using microwaves, so rapid prototyping activities on the Moon may eventually find that partially melting particulate matter into glass is another way to create useful objects.

The lunar surface is a good source of material and energy useful in creating a wide variety of objects.  I mentioned simple ceramics and aggregates, but additionally, a variety of metals (including iron, aluminum and titanium) are available on the Moon.  Silicon for making electronic components and solar cells is abundant on the Moon.  Designs for robotic rovers that literally fuse the in-place upper surface of the lunar regolith into electricity-producing solar cells have already been imagined and prototyped.  We can outsource solar energy jobs to the Moon!

These technical developments lead to mind-boggling possibilities.  Back in the 1940s, the mathematician John von Neumann imagined what he called “self-replicating automata,” small machines that could process information to reproduce themselves at exponential rates.  Interestingly, von Neumann himself thought of the idea of using such automata in space, where both energy and materials are (quite literally) unlimited.  A machine that contains the information and the ability to reproduce itself may ultimately be the tool humanity needs to “conquer” space.  Hordes of reproducing robots could prepare a planet for colonization as well as providing safe havens and habitats.

We can experiment on the Moon with self-replicating machines because it contains the necessary material and energy resources.  Of course, in the near-term, we will simply use this new technology to create spare parts and perhaps simple objects that we find serve our immediate and utilitarian needs.  But things like this have a habit of evolving far beyond their initial envisioned use, and often in directions that we do not expect; we are not smart enough to imagine what we don’t know.  The technology of three-dimensional printing will make the habitation of the Moon – our nearest neighbor in space – easier and more productive.  Even now, creative former NASA workers have found a way to make this technology pay off.  In the future, perhaps their talents could be applied to making the Moon a second home to humanity.

Originally published October 24, 2011 at his Smithsonian Air & Space blog The Once and Future Moon, Dr. Spudis is a Senior Staff Scientist at the Lunar and Planetary Institute in Houston. The opinions expressed are those of the author and are better informed than average.

The thinking behind the GRAIL twins

A useful view of our heterogeneous Moon. A practical illustration of the thinking behind the GRAIL project. From several thousand kilometers above the southern hemisphere and just below the equator of the lunar Farside it’s easier to see our Moon is “lumpy;” perhaps like the asteroids, it's own mass isn't high enough to crush it into a unified solid. From the standpoint of gravity the Moon retains the the memory of the smaller solid and semi-solid bodies from both before and after it's original formation. So nothing stays in close orbit around the Moon for very long without getting a frequent boost, and such boosts need fuel and fuel eventually runs out. This false color map of the lunar surface shows, in low resolution, differences from average elevation, or datum. Mare Orientale is on the right, and just beyond, so a crescent of the Nearside’s is visible. The expanse of the Farside here is defined, by the ancient South Pole Aitken basin, with the Moon's thinnest crusts, below center left, and by the Moon’s highest elevations and thickest crusts in the Farside highlands spread above the SPA rim (yellow box shows field of view in the next illustration [NASA/GSFC/MSFC/LOLA/LMMP/LP].

The Lunar Reconnaissance Orbiter (LRO) has orbited the Moon over 10,000 times since June 2009, mostly in a low and circular polar orbit. It requires a monthly boost to keep its record-breaking mission going. A common demonstration of the Moon's mass concentration (MASCON) problem is a thought experiment. A future astronaut stands on the rim of the Nearside impact basin Mare Imbrium holding a weight suspended a meter below a gloved hand sees that it doesn't hang straight down. Instead it hangs angling slightly toward the center of the basin hundreds of kilometers away. Anything in orbit is alternately tugged or gains slack changing its speed, causing it to eventually crash. This inconvenience, when carefully recorded and studied, is also a good way of mapping the Moon's interior in 3D.

The elevation map above shows how radically different the Moon’s Farside is from the familiar Nearside. In a photographs the extent of the 4 billion year-old SPA basin and the higher ground and its rim don’t stand out nearly as well. The map is plotted from millions of laser points measured from LRO's orbit to and from the lunar surface by the LOLA instrument, shown here using the ILIADS program available from NASA Marshall Space Flight Center. The yellow rectangle shows the field of view shown in an August 2011 release of LOLA science from the Goddard Space Flight Center.

 

NASA/GSFC, August 15, 2011 - Twenty-five years have passed since seven brave astronauts lost their lives in the Challenger accident. As the Shuttle program comes to an end, we are reminded of those who lost their lives in the pursuit of human exploration. Shortly after the accident, the Challenger astronauts were memorialized by having lunar craters named after them. These seven craters, located on the far side of the Moon in the Apollo Basin, expose deep portions of the lunar crust.

This LOLA image reveals that the depths of McNair and Jarvis craters, in particular, reach nearly 7 km below the lunar datum (the Moon's equivalent of 'sea level'). The depth of McNair and Jarvis is due to their placement within the large Apollo Basin (an existing topographic low) as well as the Apollo Basins location in the even larger South Pole-Aitken Basin. When combined with data from other LRO instruments such as LROC and Diviner, and instruments aboard other spacecraft such as the Moon Mineralogy Mapper (M3) aboard Chandrayaan-1, the complex nature of the Challenger craters is revealed. Data from the M3 instrument reveal that Jarvis crater's composition may represents a deep portion of the lunar crust.

References: 

Steigerwald, B. (2010) "Biggest, Deepest Crater Exposes Hidden, Ancient Moon," June 2, 2011.

Robinson, M. (2011) "Challenger Astronauts Memorialized on the Moon," January 28, 2011, LROC

Petro, N., et al. (2010) "Lower Crustal Materials Exposed in the Apollo Basin Revealed Using Moon Mineralogy Mapper (M3) Data," 41st Lunar and Planetary Science Conference, #1802, March 2010.

LOLA original map: small | large 

Japan’s lunar orbiter Kaguya (SELENE-1, 2007-2009) vastly added to our knowledge about the “hidden Moon” originally gathered through the Apollo era and afterward, stitched together by 2005. Along with the first HDTV from lunar orbit, Kaguya was a platform for a variety of instruments, including laser altimetry, like LRO. The Kaguya LALT system itself built up an elevation map that is only very recently being surpassed by LOLA during the past two years.

Using their links with Kaguya, with its sub-satellite R-SAT, and in a manner very much like the mission plan for GRAIL-A and B, JAXA investigators delicately measured Doppler shift and subtle light-speed changes between each orbiting spacecraft and with the ground to built-up a detailed map of the Moon’s "gravimetric anomalies."

Together with the unprecedented detail of the Moon’s crustal thicknesses, seen in maps like the one below, Kaguya presented scientists with new and very much more detailed faces of the Moon. Kaguya investigators also helped refine the elusive center of the Moon, from within 20 to 2 kilometers, much more.

The relative thickness of the lunar crust as teased out by Japan's Kaguya orbiter and its sub-satellite R-SAT. The Moon's MASCONS and 'negative gravity anomalies' don't necessarily manifest themselves in surface features, like the one associated with Mare Imbrium.[JAXA].

GRAIL-A and B will join LRO and the recommissioned ARTEMIS twins for a grand total five American unmanned lunar missions, all orbiting the Moon at the same time by the end of the year. The skies above the Moon will become nearly as crowded as those of Mars.

The GRAIL twins will pick up the task of mapping our lumpy Moon’s mass, ARTEMIS the intricacies of the Moon’s plasma wake and its interaction with Solar wind as the Moon orbits through Earth’s magneto-tail with LRO continuing to map the lunar surface from more lasting, slightly higher polar orbit.

All this latter-day renewed interest in the Moon began as preparation for an eventual return, inspired by the loss of Columbia in 2003. That original timeline for renewed, extended human activity on the Moon may seem much further away once again, for the moment, but these unmanned “precursor missions” set into motion through the vagaries of reaction to tragedy or short-term public policy shifts are well along in the pipeline, on time and under budget.

LROC Wide Angle Camera (WAC) monochrome (604nm) mosaic of northeastern Apollo basin, from observations in LRO orbits 2068 and 2069, December 8, 2009; field of view roughly 120 km, resolution 78 meters per pixel, incidence 70° The depth of the interior floor of Jarvis and McNair, the larger and smaller of the two co-joined craters, respectively, and the largest feature seen above, are roughly 7,000 meters below lunar mean elevation. [NASA/GSFC/Arizona State University].

LOLA: refining impact basin dimensions

Laser altimetry by LOLA, now having traveled nearly 10,000 orbits of the Moon on-board the Lunar Reconnaissance Orbiter, has confirmed the existence of impact basins once believed "questionable" [NASA/GSFC].

GSFC - This image reveals the power LOLA data have in helping scientists refine sizes of impact basins on the Moon. By studying lunar impact basins, scientists refine their understanding of what happened in the earliest stages of the formation of our Solar System, including the size distribution of early impactors.

The Sikorsky-Rittenhouse impact basin, which is estimated to be between 3.9 and 3.5 billion years old, was originally estimated to be 310 km in diameter, and its existence was considered "questionable" in Wilhelms' lunar atlas.

The ghostly Sikorsky-Rittenhouse impact basin, northwest its more-recent doppelganger, the slightly larger and still well-defined Schrodinger basin, is also visible in this LROC Wide-Angle Camera (LROC WAC WMS) global mosaic [NASA/GSFC/Arizona State University].

This initial definition was based on low-resolution images from Lunar Orbiter missions. Later Earth-based radar estimates confirmed Sikorsky-Rittenhouse's status as a basin and placed the basin diameter at 319 km. However, the use of LOLA data have helped scientists to further define the diameter size to 275 km, which represents an 11% decrease in the original diameter estimate. LOLA's high density of measurements across the Moon allows its data to create the most accurate definition of lunar craters ever.

References:

1. Jones, N. and B. Steigerwald, (2010) "NASA's LRO Exposes Moon's Complex, Turbulent Youth," 03 June 2011.
2. Wilhelms, D.E, (1987) The Geologic History of the Moon, USGS Professional Paper 1348
3. Frey, H.V. (2010) Chapter 2, GSA Special Publication Recent Advances and Current Research Issues in Lunar Stratigraphy (in press).
4. Romine, G.C., and H.V. Frey, (2011) "Using LOLA Data to Test the Reality of Candidate Lunar Basins Derived from Older Data," 41st Lunar and Planetary Science Conference, Abstract 1188, March 1-5, The Woodlands, TX.

small | large | high-res [PDF]

Late in its mission, Japan's Kaguya captured this relatively low altitude HDTV view across 98 km-wide Sikorsky (66.1°S, 103.2°E), bisected by 310 km-long Vallis Schrodinger. The northern rim, where the horns of the Valley cross through, is also the broader and essentially invisible rim of the Sikorsky-Rittenhouse impact basin. View the full-sized Kaguya HDTV image HERE [JAXA/NHK/SELENE].

LOLA: Steepness of the Moon's polar slopes

The steepness of elevation changes, or slopes, in degrees rather than relative elevation heights, themselves are seen above north of the 75th parallel, as determined through millions of laser altimeter samples gathered in thousands of orbits of LRO since 2009 [NASA/GSFC].

The Lunar Orbiter Laser Altimeter (LOLA) aboard the Lunar Reconnaissance Orbiter (LRO) sends laser pulses down to the surface of the Moon from the orbiting spacecraft. These pulses bounce off of the Moon and return to LRO, providing scientists with measurements of the distance from the spacecraft to the lunar surface. As LRO orbits the Moon, LOLA measures the shape of the lunar surface, which includes information about the Moon's surface elevations and slopes.

LOLA's laser pulse is split into 5 separate beams that hit the lunar surface in a cross-shaped pattern. The reflected pulses from these beams provide 5 parallel profiles along the surface directly beneath LRO. This pattern allows scientists to calculate slopes on the surface of the Moon in a variety of directions on scales of approximately 25 meters.

This image shows the slopes found near the north pole of the Moon, poleward of 75 degrees North. The bright red to white areas have the highest slopes (25 degrees or more) while the dark blue to purple areas have the lowest slopes (5 degrees or less). The steepest slopes are found in impact crater rims, which appear as brightly colored circular features throughout the image.

References: [1] Smith, D. E., et al., 2010. The Lunar Orbiter Laser Altimeter Investigation on the Lunar Reconnaissance Orbiter Mission. Space Sci. Rev. 150: 209-241. [2] Rosenburg, M. A., et al., 2011. Global surface slopes and roughness of the Moon from the Lunar Orbiter Laser Altimeter. J. Geophys. Res., 116, E2, E02001.

>> small (South Pole) | large (South Pole) | high-res (North Pole) [PDF]

LOLA slope determinations in the vicinity of the lunar South Pole include sanctuaries of permanent shadow noted in the LROC Wide Angle Camera Global Mosaic at the bottom. Shackleton (1.) has a steeper inner rim to floor ratio than most simple craters nearby. The LCROSS impact in Cabeus (2.) seems surprisingly free of steeper inclinations at the resolution determined above, and Malapert Massif (3.) has wider slopes on its Earth-facing side (up) than its opposite side, facing south [NASA/GSFC/Arizona State University].

LOLA: Drygalski of the Far South

LOLA Featured Image - It is only fitting that Drygalski Crater (diameter 149 km), located near the lunar south pole, is named for German polar scientist and geophysicist Eric Von Drygalski. LOLA data are used to examine complex craters such as Drygalski to better constrain the shape of lunar craters. High resolution topographic data from LOLA are also used to refine crater depth-to-diameter relationships for the Moon [1]. Different types of craters (simple craters, complex craters, and multi-ringed basins) have diagnostic depth-to-diameter ratios. The ratios vary for each planetary body in the Solar System due to a number of factors, including crustal density and structure as well as other characteristics of the crust.

[Get high-res version]

References: Mazarico, et al (2010). Depth-Diameter Ratios of Small Craters from LOLA Multi-Beam Laser Altimeter Data. 41st LPSC, Abstract #2443

Traveling backward in available resolutions of Drygalski we don't lose much from the compiled LRO/LOLA laser altimetry to long polar shadow obscuring only some detail in this LROC monochrome mosaic. Note a difference in texture seen on a third of the ancient crater's floor, appearing on first glance to be an artifact of creating a mosaic of images swept up under differing sets of lighting conditions? Laser altimetry built up into the topography in the LOLA map reveals detail lost to shadow, particularly terraces within the north rim - but also that same division of landscapes on the crater floor. It's not any artifact of high latitude photography. Over the aeons, "things happened" close by and far away from Drygalski that left different traces on different parts of the crater. Note the lava pond on the south heights and the catena, a curved closely grouped chain of craters immediately to the north [NASA/GSFC/Arizona State University].

This mosaic of images in the ultraviolet (750 nm) was gathered by Clementine in 1994, swept up over a shorter period of time and from greater altitude than LRO travels today [NASA/DOD/ASU].

Priorities for the Lunar Orbiter series were scouting potential landing sites for the Apollo expeditions though the polar latitudes were photographed in unprecedented detail, providing what stood for decades as our best overhead surveys of Drygalski. Until well after the Apollo Era large areas of the Moon were undiscovered country [NASA/JPL/ASU].

LOLA data improves the crater count

Updated September 20, 2010 0051 UT

Another Gap. Following up on a global crater count and mean elevation study of LRO laser altimetry (LOLA), spotlighted by NASA, Sept. 16, another conspicuous, surprisingly oblong gap in the distribution of >20 km craters appears in and around Mare Orientale [NASA/GSFC/LOLA/Brown/SVS].

A study of 5,185 lunar craters of similar size, their global distribution and how their interior elevations deviate from the Moon's global average appears to confirm work by Wilhelms, El Baz and others, published a half-century ago.

Amazingly, those earlier investigators, who improved existing maps of the near side and mapped what was still being learned about the wildly different far side, did not have the benefit of laser altimetry streaming down from the LOLA instrument on board the Lunar Reconnaissance Orbiter (LRO).

More amazing, the Moon's mean elevation, its average radius of 1737.5 kilometers, was far from accurately understood. The LAT package on board JAXA's Kaguya (SELENE-1) isolated the Moon's elusive center further, from within 2 km to within about 200 meters.

In comparison, the Brown University study authored James W. Head is rather like modern lunar instrumentation rated against Apollo guidance computers.

Originally, grid by grid, with slide rule geometry and calculus, plugging time and illumination angles into formula, crater counts of extraordinary accuracy were weaved together by patient investigators. Their published conclusions continue to be confirmed in the mining of laser data from LRO. But questions raised by them stubbornly remain unanswered by 21st century remote sensing. The Ground Truth is still irreplaceable

James W. Head of Brown University has performed a global census 5,185 lunar craters >20 km. in diameter. The study, published in Science, includes a global color-coded tally of the crater's interior elevations, showing deviation from the Moon's global mean "sea level" of 1737.5 km. Not surprisingly, a thinner population of such craters are found in and around familiar near side basins, reconfirming conclusions from long ago that the huge plains represent younger surfaces. (Of craters included in the Brown University census, green = mean global elevation; bluer = below, yellower = above.) [NASA/GSFC/LOLA/Brown/SVS]

So what are these data telling us, confirming theories and restating questions asked by the Light and Shadow slide rule guys of the Apollo era?

Broadly speaking, the Moon holds a reliable record of the history of the Solar System, a record largely lost to water, dynamic weather and plate tectonics on Earth. The Moon's obvious proximity shows this history is also the history of Earth, particularly the history of conditions in that part of the Solar System simultaneously occupied by both bodies.

And the Moon's surface tells a story writ large in bombardment, beginning a very long time ago with the large impactors, like the 4 billion year-old event that formed the 2,100 km-wide South Pole-Aitken basin or the 1290 km-wide Imbrium event that probably happened less than a few hundred million years later. All through the course of the past 4,500 million years, smaller but also respectable kinds of interlopers that punched out the craters in the Head census have continued to "encounter" the Moon with decreasing frequency.

If our dating of features on the Moon's surface is close to being correct, the fall-off in this more common kind of bombardment must have been fairly rapid. Otherwise, the 3.9 billion year-old near side basins, "only" a half-billion years or so after the Moon's magma ocean solidified, would be more punctuated with craters.

The evidence, particularly after studies of the Moon's far side literally entered the picture in 1959, hints that between the formation of SPA and the more familiar near side basins, a gradual decline in these "mid-sized" impacts may have reversed for a 150 to 200 million years before resuming its decline. This is the strongest evidence we have for what's become known as the Grand Bombardment, possibly a juggling of material perturbed as the outer planets, for some unknown reason, waltzed for several million years until stabilizing into their present orbits.

The presentation of the LOLA data study, prepared by the Science Visualization Studio (SVS) at NASA Goddard, was atypical in not including the classic near and far side panels; the two hemispheres shown side by side, centered on the 0° and 180° meridians. The SVS illustrations do include the separate panel above, centered on 90° and 900 frames from their animation. And the animation presents the 5,185 color-coded craters in a way that fancifully builds up gong from east to west as Moon rotates once around. This method does not allow for a view centered over any areas of interest other than the two equatorial slides. If you want to see the census results over Mare Orientale, for example, as at the head of this post, the area of interest falls behind before becoming fully populated [NASA/GSFC/LOLA/Brown/SVS].

Nevertheless, as the the Moon rotates, another second gap appears in the crater count, this time arguably in the the lunar highlands but hardly typical in composition, an oblong gap 2000 kilometers north to south and 1200 km wide centered on Mare Orientale.

Orientale was a late comer, slightly smaller and perhaps more energetic than the great basin-forming impacts of a billion years earlier. If dating methods are reliable, then the fall-off in >20 km-wide impact events had fallen to a trickle by the time of Orientale's formation, 3.1 billion years ago. Some studies hint the Orientale event was energetic enough to have caused an upwelling of molten material in the near side basins, the many ponds of mare material within South Pole-Aitken and elsewhere.

Additional Reading:
The Moon through LRO's eyes
Kelly Beatty
Sky & Telescope

Lunar superlatives from LROC WAC

The 'Rooftop of the Moon' appears to be on the wide, flat northwest rim of 43 km-wide Engel'gard, the largest crater in this monochrome sample from the LROC Wide Angle Camera. The actual spot (5.44°N, 201.36°E) is not immediately distinct, as are Everest or Denali, for example. A future traveler standing there, 10.75 km above the global mean elevation might notice little beyond a close horizon. A brief 'bunny hop' may be necessary to get to an overlook, to see breathtaking views of astounding depths and distances. LROC WAC observation M103209735ME, field of view roughly 100 km; LRO orbit 379, July 26, 2009; alt. 112.88 km, res. 178.3 meters, phase angle 66.22° [NASA/GSFC/Arizona State University].

Barely 2400 km from the Moon's highest point is it's lowest point, invisible above, inside the shadows of the 12 km crater at middle-left, within the wide interior of 143 km-wide Antoniadi, not far from the center of 4 billion year old South Pole-Aitken basin. From Kaguya the smaller crater's interior (70.43°S, 187.42°E) was measured to a depth of 9.06 km below global mean (19.85 kilometers below the high point at Engle'hardt and 2 km more than the range gauged as recently as 2005). This image was processed using LROC WAC Previewer (v.1.2) from LROC WAC observation M103254154ME; field of view approximately 150 km; LRO orbit 385, July 26, 2009; alt. 42.68 km, res. 66.03 meters, phase angle 82.5° [NASA/GSFC/Arizona State University].

The bright, highest of the Moon's highlands as seen from Kaguya as the orbiter sailed under a late morning Sun. [JAXA/NHK/SELENE].

Also from Kaguya, the Moon's lowest place (70.43°S, 187.42°E) is briefly seen at the bottom of the bowl-shaped crater in wider Antoniadi. All the scenery in this late mission Terrain Camera image averages a few kilometers lower in lunar elevation than anything we can see of the Moon's near side from Earth. [JAXA/SELENE].

The global image of the Moon obtained by Chang’E-1: Data processing and lunar cartography

The digital elevation model (DEM) from the Chang'E-1 laser altimeter, used for geometric correction of the CCD photography [CNSA/CAS/CLEP].

LI ChunLai, et al.
Science China, Earth Sciences
August 2010 (Vol.53 No.8)

The global lunar image of the first phase of Chinese Lunar Exploration Program (CLEP) is the first image to cover all over the surface of the Moon. It will serve as a critical foundation for succeeding exploration and scientific research.

In this paper, the acquisition, characteristics, and data quality of Chang’E-1 Charged Coupled Device (CCD) image data are described in detail.

Also described are the methodology and procedure of data processing. According to rule of planetary cartography, the image data has been processed, geometrically corrected, and then (made into a mosaic) and merged to a scale of 1:2,500,000. The results of data processing and charting show the image data of Chang’E-1 CCD and its geometric precision meet the demands of charting a map in the scale of 1:2,500,000.

The relative geometric positioning precision of the global image is better than 240 meters, and the absolute geometric positioning precision is slightly better than that of the ULCN2005 and Clementine lunar basemap (v. 2.0). The plane positioning precision is approximately 100–1500 meters. The global image is proven to be the best global image of the Moon so far in terms of space coverage, image quality and positioning precision.

Download the RESEARCH PAPER (PDF), HERE.
Google Scholar, August 6, 2010

LOLA's Malapert Region

NASA/GSFC - 6.18.2010 - Located near the lunar South Pole, the Malapert region (85.99 S, 357.07 E) is of interest as a potential location for lunar exploration. In addition to revealing the elevation of different points on the lunar surface, such as the topographically high Malapert Massif, LOLA data can also be used to classify surface roughness and to model how much sunlight different areas on the lunar surface receive for given amounts of time. With these models, scientists can find places that never receive sunlight, commonly referred to as permanently shadowed regions, as well as those that are constantly illuminated. LOLA data can also be used to determine how easily an area on the Moon could communicate with Earth by switching the "light source" in illumination models to "Earth." Areas with high "illumination" in this situation have better visibility from Earth (people on Earth can see them most often), and therefore have better communication pathways between the Earth and the Moon.

LOLA data have found the rim of Malapert Massif to have high illumination. Malapert Massif also has exceptional Earth visibility, and because of its excellent communication potential (and interesting science potential!), the Malapert region has been suggested as a site for future lunar exploration. + View Image | + High Resolution

Turned on it's head, for the convenience of the Earth-bound, the now-iconic HDTV Earthset frames imaged by Japan's first lunar orbiter Kaguya (SELENE-1), released in 2008 [JAXA/SELENE].

LOLA: Moscoviense

Mare Moscoviense (GSFC - LOLA Image of the Week, June 14, 2010) is one of the few large maria located on the far side of the Moon.

LOLA data reveal the lowest point inside Titov crater to be about 2.7 km below the lunar datum. In contrast, the highest point on the rim of the basin rests about 3 km above lunar datum.

The total relief for the basin surrounding Mare Moscoviense is 5.7km. Although there are just as many impact basins on the lunar far side as the near, the extensive lunar volcanism seen on the near side is lacking on the far side of the Moon [NASA/GSFC/LOLA].

The spectacular Moscoviense Terrain Camera image from 2008, returned by Japan's first lunar orbiter Kaguya (SELENE-1). The yellow arrow indicates the location of a new and distinct kind of lunar rock discovered from data returned by India's first lunar orbiter Chandrayaan-1. The story from April 12 can be read here [JAXA/SELENE].

Figure 2, LROC News System Featured Image, January 8, 2010. LROC Wide Angle Camera color (Red=689, Green=566, Blue=415 nm) mosaic, with the location of the proposed Constellation Region of Interest (ROI) indicated with arrow [NASA/GSFC/Arizona State University].

Looking east over the Moscoviense Constellation ROI, LROC WAC M103531211, overlaid with LROC Narrow-Angle Camera image M105887165, atop the improving resolution of the lunar far side elevation map available in Google Moon. The arrow on the WAC image released by LROC is not completely covered, left center [NASA/GSFC/Arizona State University].

Stepping back from the false-color data in the LOLA Image of the Week, at the top, "bright is equal to relative height" in this look at Moscoviense in the global-scale, low-resolution LOLA data available through the Planetary Data System. Titov is just visible, and unlike visible imagery of the area, the multi-ringed nature of this impact basin is clearly visible along with a strong indication that the original inner ring may have been partially inundated with intrusive molten material, probably from within the Moon after it's original formation The obliquity of the "impact-forming event," retained in its present 'rectangular' shape also appears to have been a part of the formation from the instant it formed [NASA/GSFC/LOLA].

Some other postings related to Moscoviense:

Far Side was volcanically active
until 2.5 billion years ago
June 13, 2009

Far Side borderland landing site
October 6, 2009

Mare Moscoviense Constellation Landing Site
January 8, 2010

New spinel-rich lunar rock type
April 12, 2010

LROC/LOLA: Hunting for Ancient Impact Basins

Figure 1: The lesser-known impact basin Freundlich-Sharonov (centered ~ 18.5°N, 175°E) is revealed in this Digital Terrain Model (DTM) created using data from LROC Wide-Angle Camera stereo images. Darker shades represent lower elevations and higher elevations by increasingly brighter shades. The diameter of the orange-colored ring is 595 km. DTM images like these allow scientists to inventory and study the morphologies of lunar basins. (Most of the mare-intrusion in this area is not readily apparent to the naked eye, presumably from orbit. The basin is north of the equator near the far side's central meridian. Mare material has largely become obscured by an overfill of ejecta from later impacts in the area.) [NASA/GSFC/Arizona State University/DLR].

Freundlich-Sharonov basin is all but invisible in this sampling of roughly the same region within the LROC Featured Image taken from the Clementine (1994) far side albedo mosaic [NASA/DOD].

Juergen Oberst
LROC News System

Large impact structures represent important time markers and clues to the early history of the Moon. Unfortunately, older basins may be highly degraded and are sometimes difficult to identify in images. Digital Terrain Models (DTMs) allow us to make more confident identifications of lunar basins and to study their morphologies. Large numbers of tentatively identified lunar impact basins, thoroughly listed in catalogs [1], are awaiting verification and detailed investigation of their ages.

Previous lunar topographic data sets used for studies of basins include the stereo model derived from Clementine images (5 km resolution). Currently, LRO's Lunar Orbiter Laser Altimeter (LOLA) is collecting a global topographic dataset. Due to LRO's polar orbit, the LOLA topographic products have high resolution (better than 40 meters) at the poles and suffer from orbit gaps of about a kilometer in equatorial areas.

Early LRO/LOLA laser altimetry of the Freundlich-Sharonov basin for comparison with LROC photographic elevation studies and the Clementine visible light albedo image of the region further above [NASA/GSFC].

The DTM of the Nubium basin (below) was made from overlapping LROC Wide-Angle Camera (WAC) images obtained in adjacent orbits. The topography has a uniform global spatial resolution of 500 meters, except at the poles where deep shadow results in areas of no coverage. Using these new WAC topographic data, several degraded impact structures were positively confirmed (opening image and Fig. 2).

Ancient Mare Nubium basin, as represented from data collected from the Lunar Reconnaissance Orbiter. Above the LROC Digital Terrain Model of the near side landmark is set atop a mosaic of multiple LROC Wide-Angle Camera images gathered in adjacent orbital passes.

Figure 2: The geographic location of the ancient Nubium basin (20°S, 344°E) is difficult to determine in images. The color-coded DTM (above-top) and the hill-shaded model (above-bottom) help show Nubium due to a slight topographic depression easily seen in the topographic map. Parts of a rim structure can be identified in the southeast, suggesting a basin diameter of about 675 km (black dashed), which is consistent with previous estimates of 690 km (gray dashed, [1]).

The mean rim height (the height difference between rim and basin floor) is ~1.8 km according to the DTM. The hill-shaded model accentuates Nubium's smooth floor [NASA/GSFC/Arizona State University/DLR].

Though Nubium is a near side landmark it's basin-like features are highly degraded, and it can hardly be recognized as a basin at all in the Clementine albedo mosaic. The LROC WAC elevation study validates a confirmation of Nubium as an authentic basin from laser altimetry gathered by Japan's first lunar orbiter Kaguya (SELENE-1) in 2009.

Finally, for even further context and comparison, here is a bonus look at Mare Nubium in a representation of LRO/LOLA laser data points from the initial release of LOLA data to the Planetary Data System, March 15, 2010 [NASA/GSFC].

Landmark features like Rupes Recta, the Straight Wall, hardly show at all in the early LOLA elevation study, at least not as one has come to expect. Instead, in both LROC and LOLA small-scale representations of data, the marked differences in grade on either side of this famous telescopic target stand out better than the fault itself.

Charles Wood at Lunar Picture of the Day (LPOD) takes up a learned comment on these newly released images of Mare Nubium, HERE.

Other basins, such as Mare Marginis, (Figure 3, below) are not yet positively confirmed.

Mare Marginis is more easily recognized as a telescopic landmark to viewers of an early evening's crescent Moon, straddling the eastern limb and the boundary between the near and far sides of the Moon, further east of Mare Crisium. Above top are the results of elevation analysis from stereoscopic LROC WAC photography of the region, near the equator. Above-bottom is roughly the same area as determined from initial LOLA laser altimetry data [NASA/GSFC/Arizona State University/DLR].

Figure 3: Confirming the location of Marginis basin (20°N, 84°E), with a proposed rim diameter of ~580 km (black dashed, [1]), is difficult. A chain of mountain peaks in the western area may represent remnants of a basin rim. However, this chain could also be part of the neighboring prominent Crisium basin, located to the west. With time the WAC and LOLA topographic maps will have higher resolution and more accuracy to help scientists better decipher the location, size, and relative ages of ancient lunar basins.

Mare Marginis was so-named because it's mare-infill was distinct in the highly-foreshortened and necessarily steep angled views from Earth prior to the Space Age. This mare inundation, whether it is truly distinct to Marginis or coincident with a nearby cataclysm, is still visible from lunar orbit. But it's most striking feature in the Clementine mosaic above, something completely invisible in any elevation study made so far, are countless swirl albedo markings -- perhaps the richest such field on the Moon. These features appear to coincide with a wide-spread, close-cropped crustal magnetic anomaly here, on the face of the Moon directly opposite, or "antipodal," to Mare Orientale. The latter needs little analysis to be confirmed as a basin.

[1] Wood C.A. (2004): Impact Basin Database.