Monday, January 31, 2011

Forty years ago - America's 2nd Return to Space

America's 2nd "Return to Space," January 31, 1971
Apollo 14, with Alan Shepard, Edgar Mitchell & Stu Roosa onboard, departs Kennedy Space Center for the Moon  nine months after the nearly-disastrous Apollo 13 mission. For Admiral Shepard, America's first astronaut, it had been a longer wait. 10 years had passed since that first 15 minute suborbital flight of the Mercury program. After being grounded for an inner ear condition, now in command of only his second (and last) spaceflight, Apollo 14 would become the only flight to the Moon made by any of the "Original Seven." [NASA/ASJ].

IAU names craters to honor Columbia crew

Columbia crater group, Apollo basin (Chang'e-2)
Craters in this grouping on the southeast side of the ancient Apollo basin have been preliminarily named in honor of the crew members of Space Shuttle Columbia, who perished during re-entry February 1, 2003.  Though some in the group seem to be large secondary craters from the same event Husband, formerly Borman L, is older than the others  Field of view from Chang'e-2 global high-Sun mosaic [CAS/CNSA/CLEP].
Keith Cowing, at the Lunar Orbiter Image Recovery Program (LOIRP) website "Moonviews" reports a crater grouping in Apollo basin (35.7°S, 208.0°E) has been provisionally designated by the International Astronomical Union to honor of each of the seven astronauts who died in the catastrophic failure of Space Shuttle Columbia February 1, 2003.

Columbia group, Apollo basin
Columbia crater group, in context with Apollo basin and craters there named after the Space Shuttle Challenger group, among others. The larger crater at center left, named in honor of Apollo 1 crew member Roger Chafee, is roughly 50 km across  [NASA/USGS/ASU].
Columbia crater group, lunar farside (LROC WAC DTM)
Locating the Columbia crater group (arrow) in Apollo basin, itself nested near the edge of the South Pole-Aitken basin, on an orthographic projection of the lunar farside. False color elevation map from LROC Wide Angle Camera digital terrain model (WAC DTM) [NASA/GSFC/ASU].

Saturday, January 29, 2011

New Robotic Lander Prototype skates tests

The Robotic Lander Prototype produced at Marshall Space Flight Center, on modified skateboards and a customized track system (a low-cost solution to control movement during final testing of the prototype’s sensors, on-board computer and thrusters [NASA/TBE].

Kim Newton
Marshall Space Flight Center

NASA engineers successfully integrated and completed system testing on a new robotic lander recently at Teledyne Brown Engineering’s facility in Huntsville in support of the Robotic Lunar Lander Project at NASA's Marshall Space Flight Center in Huntsville, Alabama.

The lander prototype was placed on modified skateboards and a customized track system as a low-cost solution to control movement during final testing of the prototype’s sensors, onboard computer, and thrusters. The functional test focused on ensuring that all system components work seamlessly to sense, communicate, and command the lander's movements.

The prototype will be transported to the United States Army Redstone Arsenal Test Center in Huntsville this week to begin strap-down testing, which will lead to free-flying tests later this year.

The lander prototype will aid NASA’s development of a new generation of small, smart, versatile landers for airless bodies such as the moon and asteroids. The lander's design is based on cutting-edge technology, which allows precision landing in high-risk, but high-priority areas, enabling NASA to achieve scientific and exploration goals in previously unexplored locations.

Development of the lander prototype is a cooperative endeavor led by the Robotic Lunar Lander Development Project at the Marshall Center, Johns Hopkins Applied Physics Laboratory of Laurel, Maryland and the Von Braun Center for Science and Innovation, which includes the Science Applications International Corporation, Dynetics Corporation, Teledyne Brown Engineering, Inc. and Millennium Engineering and Integration Company, all of Huntsville.

For more information on the Robotic Lunar Lander Development Project, please visit

Friday, January 28, 2011

The Challenger Crater Group of Apollo Basin

The Challenger Crater Group in Apollo Basin, on the Moon's farside (36°S, 209°E); LROC Wide Angle Camera monochrome (643nm) mosaic from a series of passes stitched around M118491411ME, gathered over the course of three orbits January 18, 2010. The crater group is named for the crew of the Space Shuttle Challenger killed when America's second orbiter was destroyed by an external tank explosion 73 seconds after launch from Kennedy Space Center, January 28, 1986. Craters elsewhere in the basin were also officially designated to memorialize the crew of Apollo 1 and Columbia [NASA/GSFC/Arizona State University].

Mark Robinson
Principal Investigator
Lunar Reconnaissance Orbiter Camera
Arizona State University

Apollo is a 524 km-diameter impact basin located within the center of the the giant South Pole-Aitken basin. Apollo is also a Constellation Project Region of Interest, identified by NASA as a notional area for future human lunar exploration. The Constellation ROI is located in the southwest corner of the mare deposit that fills this basin-within-a-basin.

After the loss of the Space Shuttle Challenger these seven craters on the eastern rim of Apollo were named after Greg Jarvis, Christa McAuliffe, Ron McNair, Ellison Onizuka, Judy Resnik, Dick Scobee and Mike Smith.

View the WAC mosaic of the entire Apollo basin and surroundings.

Visit NASA's Day of Remembrance webpage, HERE.

NASA Lunar Science Forum IV


Clive R. Neal
University of Notre Dame

The NASA Lunar Science Institute is pleased to announce the 4th annual NASA Lunar Science Forum, to be held July 19-21, 2011.

This year's forum will feature sessions on recent scientific results from the Lunar Reconnaissance Orbiter (LRO) and Lunar Crater Observation and Sensing Satellite (LCROSS), dedicated side-conferences for graduate students and young lunar professionals, as well as the annual recognition of scientific accomplishments and associated keynote lecture.

As in past years, science sessions are structured to report on both recent results and future opportunities for lunar science, exploration, education and outreach.

We also look forward to news on the upcoming lunar missions GRAIL and LADEE and welcome abstracts across the many fields of lunar science.

Abstracts will be accepted starting February 21 through May 2, 2011 at

February's announcement will discuss the Lunar Science Forum logistics, but please save the date now as you make your summer meeting plans.

We look forward to another exciting meeting focusing on science Of, On and From the Moon!

Note: The 4th Annual NLSI Conference will be held once again this year at the NLSI's host facility, NASA's Ames Research Center at Moffett Field, California.

Rille in Aitken Crater

The beginning (or end) of a short rille within Aitken crater. The rille is 5 kilometers long and 600 meters wide. LROC Narrow Angle Camera observation M149391207, LRO orbit 7148, January 11, 2011; resolution 90 cm per pixel [NASA/GSFC/Arizona State University].

Drew Enns
LROC News System

Rilles can be formed by two basic processes: tectonism producing a graben due to faults running beneath the surface or volcanism carving long channels out of the surrounding terrain. Which process formed this rather short rille? The answer is likely volcanism. Two observations support this hypothesis. First the rille is located on a mare surface, itself created from volcanism, and second the rille is not straight, which can be seen in the WAC context image below. However, this does not rule out tectonism. Faulting can, and does, occur in volcanic plains, and faults are never perfectly linear. It's also possible that both forces helped shape the rille. We really don't know right now. The best way to find out would be to place astronauts in the area to conduct field studies. In the mean time scientists can use LROC and LOLA data to compare rilles across the Moon and better our understanding of rille formation.

Location of the linear rille, subject of LROC Featured Image January 27, 2011, within Aitken crater, LROC Wide Angle Camera monochrome mosaic [NASA/GSFC/Arizona State University].

Search for more interesting features in the NAC frame.

Related Posts
Terraced Craters in Aitken Crater
Exposed Boulders in the Aitken Mare

Exposed Boulders in the Aitken Mare

Boulders eroding out of the hillslope and concentrated between two hills. LROC Narrow Angle Camera observation M143480262, LRO orbit 6278, November 4, 2010. Featured Image width = 700 meters, resolution 70 cm per pixel [NASA/GSFC/Arizona State University].

Drew Enns
LROC News System

Boulder fields on the Moon are a fairly common feature. In general, large boulder fields are usually part of an ejecta deposit surrounding their parent crater or a product of gravity-driven mass wasting, where blocks on a slope are dislodged from the regolith or rock outcrops by various geologic processes (including meteorite impacts or moonquakes) and roll downhill. Since this boulder field is located at the base of a slope, it is likely a product of gravity-driven mass wasting. This field has boulders as large as 10 meters in size. Astronauts exploring Aitken crater could use boulder fields like this one, where materials from higher up have fallen to lower, more accessible elevations, to collect samples that otherwise would be very time-consuming to collect.

Location of the boulder field within Aitken crater. LROC Wide Angle Camera monochrome mosaic [NASA/GSFC/Arizona State University].

Can you find more boulders in the NAC image?

Related Posts:
Wrinkle Ridges in Aitken Crater
Terraced Craters in Aitken Crater
Gassendi's Fractures
Bouncing, Bounding Boulders

Tuesday, January 25, 2011

Terraced Craters in Aitken Crater

Small crater within Aitken has a terraced and hummocky floor with boulders strewn about and no bright rays (though when seen in context, below, is situated within a larger debris ray or area of anomalously optically immature regolith. LROC Narrow Angle Camera observation M145855135, LRO orbit 6628, December 1, 2010. Crater is roughly two kilometers wide [NASA/GSFC/Arizona State University].

Drew Enns
LROC News System

This crater has an unusual floor for its size. An impact crater of this size typically has a simple bowl shape, yet this example displays terraces and hummocks. The terraces give us insight into the impact material. A bolide that impacts a solid surface covered by loose material, for example mare covered by regolith, will use less of its energy to break up the loose material than solid material. The "excess" energy goes into excavating more material thus making for a larger diameter. Thus we see terrace at the boundary between the regolith and underlying more coherent material. The fact that the crater has no bright rays indicates that it is old - its rays have weathered into the background.

Location of the terraced crater (LROC Featured Image. January 25, 2011) within the landmark farside crater Aitken (16.8° S 173.4° E) [NASA/GSFC/Arizona State University].

Find more craters in the full NAC frame!

Related Posts:
Wrinkle Ridges in Aitken Crater
Aitken Central Peak, Seen Obliquely
Approaching Aitken Crater - Vertregt J

Saturday, January 22, 2011

Wrinkle Ridges in Aitken Crater

Mare basalts and hummocky ejecta both displaying wrinkle ridges in Aitken crater. LROC Narrow Angle Camera observation M105730242, LRO orbit 731, August 24, 2009; image field of view, ~1.6 kilometers, Sun is from east by northeast (upper left) [NASA/GSFC/Arizona State University].

Drew Enns
LROC News System

Aitken crater, located at 16.8° S 173.4° E, is a 135 km Upper Imbrian-aged crater. It is notable in that its floor is filled by a mare deposit, and that it, along with the Moon’s South Pole, is the namesake for the biggest and most ancient lunar basin, South Pole-Aitken Basin (SPA). Within its flooded floor are many scientifically interesting features, one of which are wrinkle ridges.

Location of wrinkle ridges within Aitken crater. LROC Wide Angle Camera mosaic displays an area 163 kilometers wide [NASA/GSFC/Arizona State University].

The dark mare basalts in the left half of the image were deformed by contractional forces into narrow, very sinuous (winding) landforms called wrinkle ridges. This pattern of deformation is not uncommon in mare basalts, and the small size of the ridges may indicate that the thickness of the volcanic fill in this area of Aitken crater is thin. The light (high albedo) material in the right half of the image is hummocky (hilly) impact ejecta. The same contractional forces that deformed the mare basalts into wrinkle ridges likely thrust up this ejecta forming analogous ridges. Wrinkle ridges are not often found outside of mare, something unusual is at work in Aitken crater! Note that the wrinkle ridge in the ejecta is more uniform in width and less sinuous than the wrinkle ridge in the mare basalt. This contrast in the two tectonic landforms may be an expression of a difference in the strength and other mechanical properties between the mare basalts and ejecta. The ejecta is most likely loose and unconsolidated, while the mare is more coherent. Thus when they are compressed they respond differently.

Search for more wrinkle ridges in the mare and highlands in the whole NAC mosaic.

A wider view of LROC NAC M105730242 and a closer view of the slow shedding of boulders on top of a wrinkle ridge, part of the diverse morphology of Aitken's interior [NASA/GSFC/Arizona State University].

Related Posts:
Aitken's Central Peak, Seen Obliquely.

Thursday, January 20, 2011

Vertregt J: Approaching Aitken

During orbit 7152, January 11, 2011, as LRO slewed to obliquely view Aitken crater (Featured Image, January 17), the northern edge of Vertregt J was serendipitously captured by the Narrow Angle Camera. North is to the left and the image field of view is about 6 kilometers [NASA/GSFC/Arizona State University].

Mark Robinson
Principal Investigator
Lunar Reconnaissance Orbiter Camera
Arizona State University

Extreme oblique views are a luxury with the LRO mission, since most instruments (including LROC) need to be pointed nadir (straight down) most of the time. Also, thermal concerns limit when LRO can look off to the side. The LROC targeting team closely monitors when opportunities arise to target extreme slews and acquire spectacular views (Bhabha crater).

LROC Wide Angle Camera mosaic, centered on the Vertreg J (21.5°S, 174.3°E) oblique NAC featured image, January 19, 2011. Image field of view is 80 kilometers; A = bottom of Aitken crater, V = Vertregt K & VJ = Vertregt J [NASA/GSFC/Arizona State University].

Sometimes LROC obtains images while the spacecraft is slewing to a steady off-nadir position, which takes about ten minutes, in order to acquire oblique views. When possible the LROC targeting team will squeeze in a short NAC image just as the spacecraft is nearing the slew position - when this type of targeting works we sometimes obtain spectacular views such as today's featured image.

The full Narrow Angle Camera oblique view, with the double crater Vertregt J partially seen in the southeast background (right). The full scene is about 30 kilometers wide, LROC NAC M149411489 [NASA/GSFC/Arizona State University].

The region around Vertregt J (21.46°S, 174.32°E) is typical of the highlands - hilly and rugged. About seventy percent of the Moon is mapped as highlands, yet this most common terrain type is only poorly sampled. Only one Apollo mission explored a true highland target: Apollo 16.

As it turns out, results from the Clementine and Lunar Prospector missions showed lunar scientists that the chemistry of Apollo 16 rocks differs significantly from most the highlands. Murphy's law at work!

Lunar scientists need samples from other highland targets, especially inside the South Pole Aitken Basin (SPA) basin, to get a better handle on the origin of the lunar crust and the history of asteroid bombardment early in our solar system's history.

Explore at full resolution the Vertregt J oblique view.

Also visit the oblique view taken a few minutes later across the center of Aitken crater.

Explanation of "lettered craters" on the Moon.

Tuesday, January 18, 2011

Oblique view of Aitken's central peak

Southern end of Aitken crater central peak complex. The upper left is about 1000 meters above the crater floor, which is just seen at lower right. Bright material (high albedo) may be a landslide of local soil, or a secondary impact from a small nearby impact crater. Distance along ridge line is ~4 km [NASA/GSFC/Arizona State University].

Mark Robinson
Principal Investigator
Lunar Reconaissance Orbiter Camera
Arizona State University

Occasionally LRO is commanded to look off to the side at extreme angles to snap spectacular views. On 11 January, 2011 (hot off the press!) LROC shuttered this spectacular of Aitken crater. Here LROC was looking over the southwest ridge of its central peak. In the distance the lower portion of the northeastern walls of Aitken crater itself is just visible. In the center of the image is the Aitken crater Constellation Region of Interest.

LROC NAC oblique view of Aitken crater, including the central peak, northern walls, and the Constellation Region of Interest. Scene is about 30 km wide [NASA/GSFC/Arizona State University].

The Lunar Reconnaissance Orbiter has collected an extremely limited number of these oblique views of the lunar surface, which are useful for engineering purposes and visualizing key geologic features on the lunar surface -- like Aitken. Aitken (~135 km in diameter) is one of the most geologically diverse settings on the farside. The crater is mapped as an Imbrian-aged feature, and its floor is covered in a small puddle of mare basalt; mare deposits are quite rare on the lunar farside, and lunar scientists are still trying to figure out why. Aitken is also on the northern rim of the great South Pole-Aitken basin, the oldest and largest impact basin on the Moon and one of the oldest and largest impact basins in the whole Solar System! Further exploration of the South Pole-Aitken basin is one of the highest priorities for planetary science in the next decade.

LROC WAC mosaic of the central portion of Aitken crater. The arrow indicates a high albedo patch seen in the opening image [NASA/GSFC/Arizona State University].

This latest LROC oblique view gives you a sense of what astronauts will see on their terminal descent into Aitken. Check out the stunning full-resolution image and think about where you would go inside this spectacular geologic feature!

Read some of our previous postings about Aitken crater here, here, and here! And visit the central peak of Bhabha crater.

Friday, January 14, 2011

HEFT, Lies and Videotape

Cost and Schedule of Shuttle sidemount compared with HEFT alternatives. This is the only HLV option that meets all legal requirements and fits within the budget and schedule assumptions of HEFT. Data derived from SSP Study NSTS 60583, dated June 8, 2010.

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

A real comedy of errors and misunderstandings collided this week between the new NASA Authorization Act of 2010 and the agency’s Human Exploration Framework Team (HEFT) Congressionally mandated 90-day report (their initial findings on how to implement agency direction). Thought flush with the usual beautiful graphics and platitudes, the report’s bottom line is that under the existing budget and schedule, the agency cannot make the new heavy lift launch vehicle specified in the new authorization bill. In other words, you can’t get there from here. Can’t be done. Period.

Reading through the new report is an exercise in déjà vu for space policy geeks. It reads very much like the Exploration Systems Architecture Study (ESAS) of 2005. No big surprise, when one realizes that many of the people who wrote that report are involved in the new one. But more than that, the sense of a previous life stems from the rocket design that has resulted from this effort. It looks remarkably similar to the rocket that resulted from the previous effort, the late and not-so-lamented Ares family of heavy lifters. As you may recall, a key conclusion of the oft-cited Augustine Committee report was that the existing program of record (Project Constellation, a.k.a. Ares rocket) was unaffordable without infusions of significant quantities of new money.

Did NASA get a big infusion of cash? No. So no one should be surprised that the same people, working under the same assumptions within the same agency and technology base as the Project Constellation people would reach the same conclusions. In fact, most were not surprised. But apparently, many in the United States Senate did expect a different answer. Or did they?

We now enter the political Hall of Mirrors in which what people say they want isn’t necessarily related to what they really want or don’t want. Let us see if we can chart a path through the maze of motives, desires and statements to fully understand exactly what’s going on. Please stay with me on this until the end; I will try to make things clear.

Seven years ago, we had the Vision for Space Exploration (VSE), a statement of strategic direction in space. The VSE called for returning Shuttle to flight after the Columbia accident, completing construction of the ISS, the building of a new space transportation system, a return to the Moon (“with the goal of living and working there for increasing periods of time”) and finally, human missions to Mars and “other destinations.” After the VSE was announced, NASA “implemented” it by completing steps 1 and 2. Step 3 was started, outlining an architecture and design for a new human spacecraft and new launch vehicles (the ESAS). We never progressed beyond that, although many departments, universities and international partners dug in and began conducting studies of work and instruments needed to live on the Moon.

It is a fool’s errand to design architectures and new space vehicles if you do not know what your mission is. You can design and build a space system without an objective but as it must satisfy many different purposes, it tends to not satisfy any of them particularly well. From the beginning, NASA leadership didn’t acquaint itself with why they were tasked with lunar return, even though the VSE founding documents are quite clear on the purpose and activities associated with lunar return. Because of this strategic confusion, it was largely assumed by many that we would do on the Moon what we did 40 years ago – explore, collect samples, and leave as soon as possible (that last activity being particularly favored within the agency). To accommodate this activity, the Ares launch vehicles were designed to conduct a lunar mission with two launches – the Ares I, which would put the crew vehicle in low Earth orbit and the Ares V, which carried all the other pieces. Additionally, NASA never lost sight of its desire for Mars, so Ares V was sized at a payload capacity of 160 tons, overkill for a lunar mission but thought to be the right number for a human Mars mission, staged completely from the surface of the Earth (whether that’s true is another story).

As Ares rocket development costs rose, other pieces of the lunar return architecture were discarded. Eventually, we had a large rocket-building program but its purpose had become diffuse and nebulous (in 2009, the acting Administrator of NASA told Congress in testimony that he did not know what going to the Moon meant).

Curiously, the new NASA Authorization Act of 2010 was remarkably specific about the requirements of a new heavy lift vehicle the agency had been directed to build. It was to use Shuttle hardware to “the extent practicable” and initially carry 70-100 tons but designed such that it could be stretched to a lift capacity of 130 tons. Where did these numbers come from? It’s not clear, but here’s an interesting coincidence: 130 tons was the lift the capacity of the old Saturn V (118,000 kg = 260,000 pounds = 130 tons). NASA has interpreted the new Congressional language as meaning metric tons (2200 lbs) but the simple language of the law says “tons” (1 ton = 2000 lbs). One might suspect that the calculus was that heavy lift in days of old (Saturn V) meant 130 tons, so that’s what “heavy lift” should be.

In the absence of any specific mission, the payload capacity of your launch vehicle is entirely academic. But this “requirement” has had some serious ramifications. Last summer, a study group at Johnson Space Center released a report (Preliminary Report Regarding NASA’s Space Launch System and Multi-Purpose Crew Vehicle, Pursuant to Section 309 of the NASA Authorization Act of 2010 (P.L. 111-267), SSP Study NSTS 60583, dated June 8, 2010) showing how a heavy lift vehicle could be built and flown under the then-current run out budget (any new budget for NASA is pure guesswork at this stage). It resurrects an old concept of replacing the Shuttle orbiter on the existing stack with a payload fairing and engine pod. This configuration, called Shuttle Side-Mount (updated from the old “Shuttle-C” concept) was not considered by the HEFT study team, but meets the specific language of the new authorization. The advantage of SSM is that, as it is a minimal modification of the existing stack, it uses all of NASA’s existing launch and processing infrastructure – launch pads, mobile crawlers, scaffolding in the VAB and fabrication facilities in Michoud and Utah. SSM initially carries about 80 metric tons (70 (63.3 metric) to 100 (90.7 metric) tons) and can be stretched to meet the 130 ton (118 metric tons) legal requirement with minimal modification (for example, adding 5-segment (instead of 4-segment) Solid Rocket Boosters, 4 Shuttle Main Engines, extended External Tank). So in fact, SSM meets all the technical, budgetary, safety and schedule requirements set out in the NASA Authorization Act of 2010.

So as Oliver Hardy would say, here’s another fine mess we’ve gotten ourselves into. NASA creates an unaffordable architecture (ESAS) to implement the VSE. The response by the new administration is to cancel the VSE and replace it with promises of more distant goals at some nebulous time in the far future. Congress directs the agency to build an HLV anyway, but the vehicle has no mission, so they pull out the specs of the last HLV America flew. NASA responds by saying they can’t do it on the money and schedule specified, even though they themselves have in hand a report that shows how it can be done. Moreover, the agency still claims it doesn’t know why anyone would want to go to the Moon, despite having been shown repeatedly that what we do there will create new space faring capability.

You just gotta love this business.

Tuesday, January 11, 2011

Moon Flower

Moon FlowerDimitre Lima creates a beautiful poster of lunar cycles, shaping them organically and a silver-on-silkscreen finish.

Saturday, January 8, 2011

Rep. Giffords critically injured in shooting

U.S. Rep. Gabrielle Giffords (D-AZ), wife of astronaut Mike Kelly and mother of two, is sworn into the 112th Congress, Wednesday, by newly-elected Speaker of the House John Boehner (R-OH). Rep. Giffords was shot point blank during a public event in Tucson Arizona and critically injured, Saturday January 8. Just out of extensive neurosurgery, her prognosis is "optimistic." Eighteen people were injured in the attack. Among those confirmed dead is a nine-year-old girl and federal Judge John M. Roll.

Jared Loughner (b. 1988) has been arrested in connection with the shooting.

Irresponsible rumors, including deliberate disinformation, about possible political motives for the shooting are flying back and forth, but one friend and fellow "former band member" Caitie Parker of Ohio Valley in Arizona describes the alleged shooter as "reclusive" since alcohol poisoning in 2007.

She described his politics as "definitely left wing," though most sources demonstrate the assailant to be mentally ill.

Thursday, January 6, 2011

Regolith: The "Other" Lunar Resource

The Pantheon of Rome, a 2000-year old concrete structure.

Paul D. Spudis

The Once & Future Moon
Smithsonian Air & Space

In civil engineering, one of the most important material resources on Earth is “construction aggregate” – the sand, gravel and cement building materials that make up the infrastructure of modern industrial life. Aggregate is easily one of the biggest, most valuable economic resources of all mined terrestrial materials – more so than gold, diamonds, or platinum. We depend on aggregates for many different types of objects; they are the fundamental building block of roads and structures. The use of aggregates in building goes back to ancient civilizations; concrete was used in buildings of ancient Egypt. The Romans devised a recipe for a concrete so durable that the molded arches, walls and self-supporting dome of the Pantheon (made over 2000 years ago) stand today. Aggregates in terrestrial use typically depend on a lime-based cement that bonds the particulate material together. Both lime (CaO) and abundant water are needed to make concrete on Earth.

On this blog and elsewhere I have detailed the importance and significance of water at the poles of the Moon. Water is indeed the most important early product to produce from lunar materials but there are other resources on the Moon. A permanent presence on the Moon will require infrastructure that must by necessity use as much local material as possible. Aggregate materials probably will become the primary building blocks of industrial society off planet, just as it has on the Earth. The composition and conditions of local materials will require some adjustments as to how we use lunar aggregate. A little thought reveals some interesting parallels and differences with terrestrial use.

On Earth, gravel pits are carefully located to take advantage of the sorting and layering produced by natural fluvial (river water-eroded) activity. We harvest gravels from alluvial plains and old river beds, where running water has concentrated rocks, sand and silt into deposits that can be easily excavated, loaded, and transported to sites of construction. The highly variable currents, as well as the velocities of flow of our terrestrial streams and rivers, sort the aggregate by size, creating layers of gravel-sized up to cobble-sized stones for the fastest flowing waters. Finer grained material is likewise concentrated where water speeds are low and sand and silt settles out from the suspended sediment (the “bed load”).

No natural process on the Moon creates such deposits, but the lunar surface rock has already been disaggregated by impact into a chaotic upper surface layer called regolith. Regolith is basically ground-up bedrock; impacts of all sizes constantly pummel the surface, breaking, fracturing and grinding up the Moon’s bedrock. Impact both breaks up and creates rock. An impact will destroy a rock both by shock (catastrophic rupture) and through cratering (fragmentation and excavation). The effect of such destruction is to make “soil,” fine-grained rocky material made up of the mineral grains of the bedrock. But impact also creates heat and this heat can weld small fragments into glass-rich aggregate rocks (regolith breccias) as well as quickly cooled fragments of melt that contain mineral inclusions (agglutinates, or glass). In broad terms, impacts destroy and disaggregate more than they create and weld together. Thus, on a given surface, regolith thickness increases with time – older surfaces have thicker regoliths.

The ground up regolith is a readily available building material for construction on the lunar surface. It is an aggregate in the same sense as on Earth, but with some significant differences. We could make lime and water from the surface materials of the Moon but it is very time and energy intensive. Thus, we must adapt and modify terrestrial practice to take advantage of the unique nature of lunar materials. The fractal grain size in the regolith means that we can obtain any specific size fraction we want through mechanical sorting (raking and sieving). Instead of water-set lime-based cement, we can use glass to cement particulate material together. Regolith can be sintered into bricks and blocks, as well as roads and landing pads, using thermal energy (passive solar, concentrated by focusing mirrors) or microwaves that can melt grain edges into a hard, durable ceramic.

The use of aggregate materials on the Moon will likely be gradual and incremental. Our initial presence on the Moon will be supported almost entirely by materials and supplies brought from Earth. As we gain facility using lunar resources, we can incorporate more and more local materials into structures. Simple, unmodified bulk soil is an early useful product. It can be used to build berms to protect an outpost from the rocket blast of arriving or departing spacecraft and to cover surface assets for thermal and radiation protection. The next phase will be to pave roads and pads to keep down randomly thrown dust and provide good traction for the multitude of wheeled vehicles supporting the outpost. Fabrication of bricks from regolith will allow us to construct large buildings, initially consisting of open, unpressurized workspaces and garages but ultimately, habitats and laboratories. Making glass by melting regolith can produce building materials of extreme strength and durability; anhydrous glass made from lunar soil is stronger than alloy steel with a fraction of its mass.

Eventually, we may be able to export these lunar building materials into space. A major drawback is the gravity well of the Moon – its escape velocity is about 2.38 km/s, smaller than that of the Earth but substantial. To use large quantities of lunar materials for space construction, we need to develop an inexpensive means to get material off its surface. Fortunately, the small size and no atmosphere of the Moon make this possible by literally throwing stuff off the Moon into space. A “mass driver” can launch objects off the lunar surface by accelerating them along a rail track using electromagnetic coils that hurl capsulated material into space at specific velocities and directions. We can collect such thrown material at a convenient location, such as one of the libration points. From there, it is a relatively simple matter to send the material to wherever it is needed in cislunar space.

Water remains the most important first lunar product, but the “other” lunar material regolith is almost as important. Lunar rock and soil will be the paving stones of the Solar System. As once all roads led to Rome, all new roads in cislunar space lead to – and from – the Moon.

Monday, January 3, 2011

Quanrantid stream followed by partial eclipse

From 41st Lunar & Planetary Science Conference (2010)

After the meteor shower, observers in Europe, northern Africa, the Middle East and parts of Asia can witness a partial eclipse of the sun.

In western Europe, as much as 86% of the solar disk will be covered by the Moon at dawn, producing a fantastic crescent sunrise on Jan. 4th. Follow the links for a live webcast, an animated map, and details from NASA

Read the story at