Tuesday, December 30, 2014

The mystery of lunar layers

Close-up of Silver Spur (bottom) shows linear “bedding” coincident with topography, suggesting it is real. Its stratigraphic significance is still unknown. From panorama of photographs taken during the initial "Stand-Up" EVA, a 360° survey of the Hadley Rille Delta Apollo 15 landing site from the top hatch of the lunar module Falcon just after midnight (UT), July 31, 1971. Dave Scott's panorama included the layered component atop Mons Hadley Delta, whose slopes 5 km east he and Jim Irwin would later sample and explore [NASA/JSC].
Paul D. Spudis
The Daily Planet
Smithsonian Air & Space

In northern Arizona, a spectacular region of exposed, layered rocks over 6,000 feet thick was carved by the Colorado River. Aptly called the Grand Canyon, it represents over a billion years of Earth’s history. Geologists are able to study the history of past ages in exquisite detail by reading the historical record found in that well-known natural landform. No matter the planet, geologists are always searching for layered rocks. The study of rock layers (stratigraphy, from strata, meaning rock layers) allows scientists to reconstruct the geological history of a region and over time, an entire planet.

The nature of the Moon does not lend itself well to the display of rock layers, yet considerable effort has been expended searching for outcrops. Most layered rocks on the Earth are created from water-laid or wind-blown sediments, and neither of those processes occurs on the Moon. Still, the lunar surface has been built up piecemeal by the sequential deposition of blankets of ejecta—the ground-up rock thrown out radially from the center of impact craters and basins during formation. The overlap relationship of these ejecta deposits allows scientists to reconstruct the history of the Moon, i.e., younger impact craters overlie older ones. This simple methodology has allowed us to decipher the stratigraphy of the Moon.

Exposed layering in an outcrop from the rim of the west wall of Rima Hadley (Hadley Rille). A newly inter-laced Apollo 15 image from a panorama of 500 mm black and white photographs at a range of 1400 meters away, on the opposite rim, at Science Station 9a. Dave Scott, August 2, 1971. Features in this view were successfully compared with LROC NAC observations of the area from low lunar orbit [NASA/JSC].
Parallel bedrock outcrops 50 km southwest of the Apollo 15 landing site, from LRO in orbit 38 years later. (From "Layers near Apollo 15 landing site,") The orbital view shows distinct outcrops occurring at different topographic levels within the rille, strongly suggesting the presence of rock layers. The image of the western rille wall by Dave Scott (above) clearly shows a layered outcrop, about 15 meters thick. Several lines of evidence suggest these lavas are the oldest in the region, about 3.84 billion years old. LROC NAC observation M113941548LE, LRO orbit 1925, November 27, 2009; incidence 59.35° at 50 cm resolution, from 46.04 km over 24.65°N, 2.42°E [NASA/GSFC/Arizona State University].
Given that geologic history, one might expect that some evidence of rock layering was found in the abundant data returned from the Moon, but such evidence is limited and ambiguous. One of the most startling finds during the Apollo missions was a breathtaking view of Mt. Hadley, a lunar mountain north of the Apollo 15 landing site. Astronauts Dave Scott and Jim Irwin were startled to see evenly spaced, sub-horizontal lines in the mountain, similar in appearance to fine-scale layering present in some terrestrial strata. It looked as though the mountain was a single, gigantic crustal block, uplifted and overturned by the impact that created the nearby Imbrium basin. The layering described by the astronauts greatly intrigued the mission scientists, who were unable to clearly see it in real time in the TV pictures sent to Earth.

When the crew returned to Earth, images taken on the surface dramatically showed this layering (above, below). But this presented scientists with a puzzle. Because large impacts are highly energetic, chaotic events, how could they generate evenly spaced, regular layering? Some team members began to suspect that something else was going on. Ed Wolfe and Red Bailey of the U.S. Geological Survey made scale models of the mountain and dusted it with cement powder. They then photographed it under low, oblique illumination, similar to the lighting conditions of the landing site during the mission. Surprisingly, fine-scale linear features were evident in the laboratory “mountain” (above, right), suggesting that the “layering” seen by the astronauts on the Moon may have been an illusion, caused by the low-angle illumination of a particulate, granular surface.

Stratified outcrops steadily shed house-sized boulders from the central peak of Hausen crater (163.24km; 65.111°S, 271.509°E) the formation of which may have excavated among the Moon deeper vertical columns (29 km), in part because of its location on the rim of South Pole-Aitken impact basin. The deepest materials brought to the surface here might include examples of the Moon's mantle, the original material between the Moon's crust and core; time capsules of the Moon's history before the formation of Hadley and the nearside basins. LROC NAC Commissioning observation M105100555LR, orbit 643, August 16, 2009; incidence 72.47° at 48 cm resolution, from 41.38 km over 64.94°S, 271.84°E [NASA/GSFC/Arizona State University].
Full-width mosaic from LROC NAC M105100555LR shows a roughly 1100 meter deep drop from the heights of Hausen's central peak to an intermediate slope of talus in a field of view 2.5 km across [NASA/GSFC/Arizona State University].
Other layered deposits at the Apollo 15 site were less amenable to explanation as an artifact of lighting. A ridge southeast of the landing site named Silver Spur displayed a set of topographic “benches” associated with its apparent layering (below). On Earth, the formation of a bench indicates differential erosion, with hard rocks making up the cliff-forming units and softer rocks being expressed as more gently sloping units. However, such an erosive pattern on the airless, waterless Moon is difficult to envision. To this day, we do not have a good explanation for the origin of Silver Spur. As an example of layering in the highlands, it remains problematical.

Clear and unequivocal layering was observed in the walls of Hadley Rille, a lava channel located near the landing site. In this case, it is easier to accept that we are looking at real layering—the rille cuts into a series of lava flows that cover the landing site (below). Lava flows make up layered deposits on Earth and there is no reason to assume that they wouldn’t do likewise on the Moon. In fact, the layering observed in the walls of Hadley Rille could be significant for another reason, one that may hold great scientific promise for future explorers.

The morphology of the "Aratus CA" collapse pit (24.55°N, 11.78°E) in Mare Serenitatis is unclear, but portions of its southwest rim include layered outcrop, perhaps including a long history of an early intermediate pre-Imbrium period and successive clues to the nature and timing of the catastrophes in our star system's early history called "the Grand Bombardment. 1.74 meter-wide field of view from LROC NAC Commissioning phase observations M104447576LR, LRO orbit 552, August 9, 2009; incidence 57.87° at 1.45 meters resolution, from 145.46 km over 25.15°N, 11.17°E [NASA/GSFC/Arizona State University].
A roughly 11 km-wide field of view from LROC NAC M104447576LR shows the outcrop in context with the larger Aratus CA feature in west central Mare Serenitatis, formed at early period and laid bare by relatively recent events that overburdened the Serenitatis interior [NASA/GSFC/Arizona State University].
After a lava flow is extruded on the Moon, it remains exposed to space. There, over millions of years, the impact bombardment of micrometeorites grinds the once solid lava into a powdery soil called regolith. Because the Moon has no atmosphere, this exposed soil layer contains a record of information about the Sun (gases called the solar wind implant atoms of hydrogen and other light elements in the dust grains) and the galaxy (from high-energy cosmic rays). When a layer is formed and then exposed to space for hundreds of millions of years and subsequently buried (like a time capsule) by another, younger lava flow, that earlier ancient regolith would contain information about the Sun and galaxy not as it is now, but as it was billions of years ago. The idea of an ancient, buried regolith (called a “paleo-regolith”) captured scientists’ imaginations—such a deposit would hold information from an interval of known position and duration in the past (determined by isotopically dating the lavas above and below the ancient regolith).

It appears that such an ancient, buried regolith exists in the walls of Hadley Rille. The lowest layers consist of ancient, relatively aluminous lavas called KREEP basalts. From the dating of Apollo 15 samples, we know that these rocks formed 3.84 billion years ago. Over this layered unit is a covered interval about 10-20 meters thick (a friable, slope-forming unit, like regolith). Above this slope-former are two massive rock layers, a thick massive unit and a thin, finely layered unit. These upper two units probably consist of mare basalt lavas of the two types found at the Apollo 15 site, both of which date to around 3.3 billion years. Thus, the regolith lying between these lava flows may hold the record of more than 500 million years of solar and galactic history, an interval from the distant early portion of Solar System evolution.

The now-notable original oblique view of the Tranquillitatis pit crater (8.34°N, 33.22°E), revealing, layer by layer the invaluable history of an area in the universe occupied by Earth. LROC NAC observation M144395745LE, LRO orbit 6413, November 14, 2010; spacecraft and camera slewed 50.46° from orbital nadir, incidence 47.91° at 81 cm resolution, from 44.23 km over 8.75°N, 35.02°E  [NASA/GSFC/Arizona State University].
In addition to the history of the Sun, this paleo-regolith would also contain fragments of impact-melted rocks and glasses from a distinct, bounded interval of lunar history. Such a sample would allow us to assess whether the impact flux on the Moon in this time period was comparable to or different from the current rate. Such information is relevant to understanding the impact history of the Earth, a factor that we know from lunar science to strongly influence the rate of evolutionary change. Astronauts descending into the rille could sample all of these units in turn, allowing scientists to reconstruct this ancient history in detail. In this sense, Hadley Rille would be analogous to Earth’s Grand Canyon—a slice into the deep time history of the Moon.

New high-resolution images of the Moon from NASA’s Lunar Reconnaissance Orbiter show that layered deposits, such as those seen in Hadley Rille, are common in the walls of rilles and impact craters occurring in the maria, where layered lava flows are expected. Finding layering in the highlands is more problematic, although some large ejecta blocks appear to consist of layered rocks, quarried out of the crust during impact. We seek such rock layering on the Moon for the same reasons that geologists look for them on the Earth—as time capsules to be carefully opened and read, giving us new insights into the complex history of the Moon.

Originally published as his Smithsonian Air & Space Daily Planet column, 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.

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Tuesday, December 16, 2014

Chang'e-3 lander still operational on 1st year anniversary

LROC NAC oblique mosaic M1145007448LR, LRO orbit 20773, January 14, 2014; slew 54° from orbital nadir, incidence 63.54° incidence angle, resolution 2.78 meters from 148.73 km over 45.65°N, 329.82°E [NASA/GSFC/Arizona State University].
ECNS - The Chang'e-3 lander continues to perform following 13 full lunar days, the solar powered spacecraft began its 14th hibernation, beginning its most lunar night since its soft landing one year ago, this past weekend. 

The People's Daily reported on Monday, the Chang'e-3 lander "will continue to carry out additional tasks."

During its year on the moon's surface, which included 13 full dormancies on lunar nights and awakenings on lunar days, the Chang'e-3 lunar probe endured the extreme cold environment and carried out more than 30 radio surveys, says Cui Yan, chief designer of the Chang'e-3 lunar program at the Beijing Aerospace Control Center (BACC).

"The Chang'e-3 lander has accomplished all its scheduled tasks, but given its good condition, we plan to conduct further experiments to accumulate more technical experience for China's deep space exploration," says Cui.

The Chang'e-3 lunar probe was launched at the Xichang Satellite Launch Center in southwest China at 1:30 am on Dec 2, 2013, and soft landed on the moon's surface at 12:14 pm on Dec 14 that year. China is the third country to soft land a spacecraft on the surface of an extraterrestrial body.

Related Posts:
LRO: Finding Chang'e-3 (December 15, 2013)
It's not bragging if you do it (December 9, 2013)
Chang'e-3 launched from Xichang (December 1, 2013)
Helping China to the MoonESA (November 29, 2013)
China's Long March to the Moon (January 14, 2012)

20th Release of LRO data to the PDS

It's time in the Sun finally came, last September. Marius K (3.61 km; 9.4°N, 309.3°E), south of its namesake, southeast of Reiner Gamma in Oceanus Procellarum, was among the few places on the lunar surface not previously imaged at high-resolution by LROC cameras. The closer look came at the end of the observational period in the latest, 20th release to the Planetary Data System, December 15, covering roughly mid-June through mid-September 2014. LROC NAC observation M1165144506R, LRO orbit 23602, September 12, 2014; 17.25° incidence angle, resolution 1.07 meters from 105 km over 9.93°N, 309.4°E [NASA/GSFC/Arizona State University].See a larger reproduction HERE.
Teams operating sensors on-board the Lunar Reconnaissance Orbiter, including the Lunar Reconnaissance Orbiter Camera (LROC), are currently updating the Planetary Data System with another treasure trove of records covering the three months from mid-June through mid-September.

The will be the 20th such Release to the PDS of information gathered from the remarkable LRO which has been orbiting the Moon since June 2009.

Of course, it must be added, this isn't the first time Marius K, transected by Procellarum wrinkle ridges, has been imaged by the LROC Wide Angle Camera. By way of comparison, the small crater is seen here at center in this 34 km-wide field of view in a LROC WAC monochrome (566 nm) mosaic from two sequential passes on July 24, 2011; 63.3 incidence angle, resolution 58.7 meters from 42.16 km [NASA/GSFC/Arizona State University].
Release 20 of Lunar Reconnaissance Orbiter data is now online at the Geosciences Node. This release includes new data acquired between June 15 and September 14, 2014, for CRaTER, Diviner, LAMP, LEND, LOLA, and LROC. Data can be found on the Geosciences Node LRO page. The Lunar Orbital Data Explorer allows one reliable way of searching and downloading LRO data.

Another image really requiring the viewer to select a full-size option to appreciate its detail. A roughly ten kilometer-wide view of the Reiner Gamma contact zone with the Marius Hills, in Oceanus Procellarum. From 20th release of LROC data released to the Planetary Data System (PDS), December 15, 2014. LROC NAC mosaic M1158112330LR, LRO orbit 22614, June 22, 2014; 67.62° incidence angle, resolution 1.07 meters from 105.12 km over 10.32°N, 304.48°E [NASA/GSFC/Arizona State University].
Full resolution view from the mosaic immediately above, showing on of the out-lying Marius domes apparently subject to the same influences that keep the Reiner Gamma swirl optically immature. Those studying processes on the Moon highly anticipate the tri-monthly releases of LRO data to the PDS, and hasten to search out familiar locations for a fresh perspective, or a first high-resolution view, even more than five years after LRO began operations.
Updates and instructions, etc., are regularly posted to the PDS Lunar Node, HERE.

Thursday, December 11, 2014

ESA to explore lunar probe partnership with Russia

Ten years after planning got underway to place an ESA lander on the rim of Shackleton crater, the design of the MoonNEXT probe was improved by development of the ESA's ATV resupply ship. Still the program was scrapped. But, even as tensions continue between European Union  partners and Russia, ESA's managers have agreed to investigate joining forces with Roscosmos in Russia's lunar program, forestalled by loss of partnership with India, the problem-plagued Fregat vehicle and tight budgets [ESA/Astrium].
Elizabeth Gibney

Science ministers in Europe have resurrected plans to explore the Moon’s surface — and the only strategy currently on the table is to join two uncrewed Russian missions. The developments, which follow the shelving of a proposed European Space Agency (ESA) Moon lander two years ago, come amid growing political tensions between Russia and Western nations.

On 2 December, at a meeting in Luxembourg to determine ESA’s policy, the space agency got the go-ahead and funding to investigate “participation in robotic missions for the exploration of the Moon”. Science ministers from the ESA member states did not approve collaboration with Russia specifically, but at the meeting, ESA scientists presented a proposal to join Russia on its missions to put a lander and a rover on the Moon’s south pole.

Money for lunar exploration will come from a pot of €800 million (US$980 million) contributed by ESA’s member states and dedicated to international space exploration; the pot will primarily pay for activities on the International Space Station and the development of a propulsion module for NASA’s Orion spacecraft, which is eventually designed to carry astronauts to deep space, and was tested on 5 December in an uncrewed space flight.

"There be dragons here," no longer applies to the Moon's nearly always, or permanently, shadowed areas at polar latitudes. The Vision for Space Exploration, before it also was scrapped, developed inertia for a brief second golden age of lunar exploration, and it prioritized scientific goals there.

Above, the state of our knowledge about the Moon's south pole in 1994 is compared with where this knowledge base stands today, illustrating one vast improvement in our understanding of the Moon gained at low cost and with great efficiency
[NASA/GSFC/JPL/DOD/USGS/Caltech/Arizona State University].
In the 45 years since astronauts first walked on the Moon, no European country or space agency has launched a mission to the Moon’s surface. And no lander or astronaut has been to the lunar south pole, a region thought to contain ice and thus deemed a probable spot for any future permanent lunar base. A 12-kilometre-deep crater there might provide access to material from the Moon’s interior, also making it attractive for scientific study, says Ian Crawford, a lunar scientist at Birkbeck, University of London. The ancient material could reveal details of the collision between a Mars-sized planet and early Earth that is thought to have produced the Moon. “The idea that we've ‘been there and done that’ did last for a long time, but that’s gone away now,” says Crawford. “The Moon still has a lot to tell us.”

Read the full article at NATURE, HERE.

Sunday, November 30, 2014

Is there an economic case for mining the Moon?

Of necessity, much of the actual work of harvesting resources for true in situ resource utilization (ISRU) will have to be done robotically [Pat Rawlings/SAIC].
Ian Crawford
Birkbeck, University of London

To date, all human economic activity has depended on the material and energy resources of a single planet; understandably, perhaps. It is conceivable though that future advances in space exploration could change this by opening our closed planetary economy to essentially unlimited external resources of energy and raw materials.

Look up at the Moon this evening, and you might be gazing at a solution. The Earth’s closest celestial neighbour seems likely to play a major role and already a number of private companies have been created to explore the possibilities.

It is important to stress that even now, 40 years after the Apollo missions, we still don’t have a complete picture of the Moon’s economic potential, and obtaining one will require a more rigorous programme of lunar exploration than has been undertaken to-date. In part, this is why proposed future lunar exploration missions (such as the recently announced Lunar Mission One) are so important.

"In addition, lunar surface rocks and soils are rich in potentially useful, but heavy (and thus expensive to launch from Earth) raw materials such as magnesium, aluminium, silicon, iron and titanium." - Relative abundances of titanium and iron, as a percentage of weight, plotted against the nearside hemisphere. Note the heaviest incidences appear in the Ocean of Storms and Sea of Tranquility.
Nevertheless, as a result of work over the past four decades, we do now know enough to make a first-order assessment of lunar resource potential. In doing so it is useful to distinguish between three possible future applications of such resources.

Read the full article published at The Conversation, HERE.

NOTE from Mr. Crawford: "This essay is based on a much more detailed review article which will be published next year, and in which references to sources and more extensive discussion will be found here: arXiv.org/abs/1410.6865."

Sunday, November 23, 2014

Dark splotches over high albedo, under a high sun

Unnamed crater (2.2784°N, 116.2125°E) southwest of King, presenting a unique albedo variation in 1.8 km-wide field of view from LROC NAC observation M123812230R, LRO orbit 3380, March 21, 2010; 8.3° incidence angle, resolution 57 cm from 55.36 km over 2.25°N, 116.16°E [NASA/GSFC/Arizona State University].
Hiroyuki Sato
LROC News System

Impact craters routinely excavate subsurface materials, exposing them in crater walls and in ejecta. The Featured Image highlights an unnamed fresh crater (480 meters in diameter) with numerous dark splotches.

Inside the crater cavity, dark splotches (low reflectance materials) occur from the middle to the trim of the crater and spread outward beyond the rim crest.

Several small craters (less than 100 meters in diameter) with similar dark splotches also occur in this region (outside the area shown above, see next image), suggesting that the dark materials were likely excavated from an extensive subsurface layer. The distribution of the dark halo craters informs us about the horizontal extent of these subsurface materials.

Small craters a few thousand meters north of the dark halo crater (DHC) of interest, above, from the same LROC NAC frame M123812230R. Note the crater right of center bottom may be superposed on the rim of a more ancient depression [NASA/GSFC/Arizona State University].
The crater in the opening image is found 116 km from the southwestern rim of King crater (76.2 km; 4.96°N, 120.49°E), located in the farside highlands. Unlike in the mare, pyroclastic deposits are unlikely to be the low-reflectance material (seen in the opening image) here in the middle of the highlands with no indication of volcanic activity near here. So, what is this low reflectance layer?

Context view of the location of today's Featured Image in WAC monochrome mosaic (100 m/pix) overlayed by WAC stereo DTM (GLD100, Scholten et al., 2012). The NAC footprint (blue box) and the exact location of the opening image (yellow arrow) are indicated [NASA/GSFC/Arizona State University]. 
The rays of Necho crater (36.87 km; 5.25°S, 123.24°E) extend out around 680 kilometers (see image below) crossing over King crater and the area in today's Featured Image. Since the area of opening image is crossed by the Necho ray deposits the excavated dark layer might be the original mature surface (now covered by Necho's high reflectance rays).  

Context view of the area of interest in an orthographic LROC WAC mosaic of low-angle observations of the surrounding hemisphere. Arrow points to the location of the crater of interest, within range of ejecta from King, Necho or perhaps, less likely, Giordano Bruno or Goddard A craters, (not unlike the magnetic anomaly east of Firsov) [NASA/GSFC/Arizona State University]. 
Due to the lack of atmosphere on the Moon, the photometric effect is very strong. Thus, it is hard to identify the relationships between the different layers using low-Sun images (images with large incidence angles, near sunrise or sunset); however, high-Sun images (those with low incidence angles, near noon) display clearly the relationships between units, which helps us reconstruct the resurfacing history of this area.

View full-size view of the LROC NAC frame, HERE.

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Tuesday, November 18, 2014

Mottled mound at Firsov

Low-angle incidence view of a curious mound on the floor of Firsov crater (51 km; 4.204°N, 112.697°E). 2.2 km field of view from LROC NAC observation M187506567R [NASA/GSFC/Arizona State University].
Hiroyuki Sato
LROC News System

Firsov is a 51-km diameter crater located in the farside highlands, approximately 240 km east of King crater. The depth of Firsov's floor from the rim crest is an impressive 4.5 km (that’s 2.5 times the depth of the Grand Canyon in Arizona).

The bright (highly reflective) mound on the crater floor is about 200 meters in height, and 2.5 km in diameter, and really catches your eye. The central portion of the crater floor is relatively flat, suggesting that it at least partially consists of a long-solidified pool of impact-melt; the mound is located within this melt pond deposit.

46 km-wide field of view showing  the high-reflectance mound feature, near center of FriFirsovater, from LROC WAC monochrome (643 nm) observation M176892340CE, LRO orbit 11204, November 25, 2011; 62.51 incidence, resolution 58.62 meters from 43.41 km [NASA/GSFC/Arizona State University].
A number of previous Featured Image posts explored the origins of mounds occurring inside impact craters. Hypotheses include volcanic eruptions, impact debris, and the squeeze-ups of impact melt.

Today's Featured Image highlights the degradation of these mounds, instead of their origin. The low-incidence angle of the top image (~9°) highlights differences in albedo on the mound top, what causes these bright patches?

Perhaps, as the mound surface degrades over time, the high-reflectance materials are exposed unevenly, for example, due to a bumpy surface morphology, where local, topographically high portions are exposed faster and newly exposed material is immature (and thus brighter).

Alternatively, the mound may be constructed from non-uniform materials and/or compositions that exhibit a range of reflectivities. However, scientists believe that during impacts any compositional differences within the target are homogenized in melt deposits. This mound would be a great place to examine that hypothesis.

The bright mound southeast of center on the floor of Firsov is not the only albedo "anomaly" in the vicinity of Firsov crater. This cycle of overlapping fields of view, juxtapositioning data ranging from LROC WAC-derived elevation models to Clementine UV-VIS color ratio maps from 1994, brings into stark relief the unnamed Copernican era crater northeast of Firsov, and also the dramatic patch of albedo swirls coincident with a locally intense crustal magnetism, photographed from orbit by the crew of Apollo 10. It seems distant and detached, but still these swirls are likely associated with the widely-scattered swirl fields farther to the west at Mare Marginis, on the opposite side of the Moon from the energetic basin-forming impact that formed Mare Orientale 3.1 billion years ago [NASA/GSFC/Arizona State University].
View full-window, HERE.

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Shiny Mound
Kagami-mochi on the Moon!
Pancakes in a melt pond
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The Domes of Stevinus Crater
That's a Relief

Friday, November 7, 2014

Exploring the lunar subsurface

Two collapsed segments of a lava tube run from the southwest to the northeast, in the Rimae Prinz-Harbinger mountain region of Oceanus Procellarum (27.46°N, 318.33°E). These collapsed segments may provide access to the subsurface, which has never been directly sampled. The average width of the collapsed segments is ~650 meters. The lava tube is ~50 meters deep, seen in this 7 km-wide field of view from a mosaic of unreleased 2014 LROC NAC observation M1165080128 (L&R) [NASA/GSFC/Arizona State University].
H. Meyer
LROC News System

A lava tube is a volcanic conduit through which lava travels beneath the hardened crust of a lava flow. The presence of lava tubes on the Moon and beyond are inferred based on observations of terrestrial lava tubes, such as those found in Hawaii. Oftentimes, a rille suddenly disappears only to reappear a short distance away.

These are called discontinuous rilles and are thought to be areas where a lava tube collapsed. Collapsed lava tube segments may provide access to the subsurface, which is exciting as a possible site to collect rock samples that remain unaltered due to surface weathering (radiation, thermal cycling, micrometeorite bombardment).

Slightly differing, slightly lower resolution, 11.5 x 15.9 km field of view of the area of interest from a mosaic of LROC Narrow Angle Camera (NAC) observation M1152143995RL, LRO orbit 21776, April 14, 2014; resolution averages 1.33 meters per pixel, incidence angle 48.9° from 132.14 km over 26.86°N, 318.11°E. View the original 8706 x 12008 and an assortment of other sizes HERE [NASA/GSFC/Arizona State University].
Sunrise over Mons Harbinger. 65 km-wide field of view from mosaic of three LROC Wide Angle Camera (WAC) monochrome (604 nm) observations, swept up during three sequential orbital passes, December 7, 2011,  from 43 km; resolution 58 meters per pixel, incidence 77° [NASA/GSFC/Arizona State University].
Context for LROC Featured Image released November 6, 2014, field of view in red, full field swept up in LROC NAC observations M1152143995R & L in yellow. LROC WAC mosaic [NASA/GSFC/Arizona State University].
The lava tube from the LROC Featured Image released November 5, 2014 is located to the west of Montes Harbinger, a large kipuka in Oceanus Procellarum, and to the east of the Rimae Prinz region.

The Rimae Prinz region displays exquisite sinuous rilles as well as other elongate depressions, indicating that there could be other lava tubes in the area.

The Prinz, Rimae Prinz and Vera vent region, east of Aristarchus Plateau. The area of interest is marked with a yellow arrow, upper right in this roughly 120 km square field of view from the LROC WAC 100m global mosaic. the Vera vent 'cobra head' of Rima Prinz I rille (on the north-northeast rim of basalt-inundated Prinz crater, at lower left), is the subject of intense study (see HERE). [NASA/GSFC/Arizona State University].
The entire region, pictured above, is of interest for exploration for several reasons. The diversity of volcanic landforms in the area can tell scientists much about the volcanic history of the Moon. By collecting samples from the surface and subsurface in this region and by careful mapping on-site, scientists can better characterize the diverse basaltic lava flows in terms of both age and composition, which also helps us understand the timing and evolution of lunar volcanism and possible heterogeneities in the lunar mantle. Any time a sample is taken from a site on the Moon and age-dated, it can also be used to calibrate crater densities that are currently used to remotely age-date surfaces in the absence of direct sampling (both on the Moon and other planets).

Lava tubes are of particular interest in terms of human exploration because they are not only scientifically valuable, but they might also provide shielding from the radiation that poses a hazard to future explorers. Furthermore, the region surrounding the lava tube from this Featured Image also hosts large pyroclastic deposits, which are a potential in situ resource that will be critical to sustaining a human presence on the Moon.

Scientists and engineers are looking into the possibility of using the natural structure of the lava tube and associated resources (ISRU) to our advantage to construct habitats for explorers.

Explore the full NAC mosaic here! How many features of interest do you see?

Rimae Prinze Region - Constellation ROI
Discontiguous Rilles

Addendum: Under mid to late afternoon sunlight, another LROC WAC mosaic, swept up under conditions remarkably similar in scale with the third image from above, from the same period of low altitude opportunities the LRO mission afforded during orbital maneuvers in the second half of 2011. Differing sun-moon-spacecraft phase angles allows for an excellent comparison. This particular mosaic was also assembled from LROC WAC observations, but five months earlier, and from three sequential orbital passes, at 43 km altitude. The resolution is 59 meters, incidence angle 64° [NASA/GSFC/Arizona State University].

Sunday, November 2, 2014

China celebrates successful “Xiaofei”

Xiaofei, China's 'little flyer,' flight dynamics test platform for the scheduled Chang'e-5 sample return mission in 2017, appears charred but otherwise none the worse for ware following a high-speed direct re-entry from the Moon, encountering Earth's outer atmosphere at an estimated 11.2 km per second, early November 1, 2014 [Xinhua].
Tom Phillips
London Daily Telegraph

China has taken one more step in its ambitious plans to become a global space power by completing the successful re-entry and landing of an unmanned space probe.

The “Xiaofei” or "Little Flyer" lunar orbiter began re-entry into the earth’s atmosphere at 6.13am on Saturday and subsequently landed in Inner Mongolia, state media reported.

The probe was launched eight days ago and travelled more than 520,000 miles during its mission around the Moon.

The mission to the Moon was “another step forward for China's ambition that could eventually land a Chinese citizen there,” Xinhua, China’s official news agency, said. It was “the world's first mission to the Moon and back for some 40 years”.

Saturday’s landing is the latest advance for a space program that China’s leaders see as an important way of commanding international respect. Some Chinese scientists have said they hope space exploration might help them discover precious natural resources that could help satisfy the country’s ravenous hunger for raw materials.

Read the full article from the Telegraph, HERE.

Saturday, November 1, 2014

Lunar exploration will reduce shortage of rare earths

The store of our knowledge of the Moon grew exponentially in the wake of America's brief but still lingering commitment to the Vision for Space Exploration (2004-2009), without which the LCROSS, LRO, LADEE and GRAIL missions would not have been funded.
A planned Russian return to the lunar
surface may benefit from a post-
Fobos-Grunt shakeout.
Aram Ter-Ghazaryan
Special to Russia Beyond the Headlines

As part of the Federal Space Program, Moon exploration operations will be launched in 2016. In 2018 the first spacecraft will be sent to the Moon to deliver comet material back to Earth. 

A manned flight is scheduled for 2030-2031. Future plans include the mining of rare earth metals required for the development of high-tech industries.

Scientists from the Russian Academy of Sciences, the Moscow State University Sternberg Astronomical Institute and the Russian Federal Space Agency are participating in this Moon exploration project.

The first spacecraft to be sent to the Moon will be relatively simple. According to Vladislav Shevchenko, the Sternberg Institute’s Head of the Department of Lunar and Planetary Research, this is because the Russian space program has not carried out a Moon landing for over 40 years.

“The last Luna-24 launch was carried out in 1976. The current spacecraft, Luna-25, is a lot lighter than its predecessor, as its main mission is to bring back ice from the lunar south pole,” Shevchenko said. According to him, the south pole was chosen because according to satellite data, it houses the largest reserves of frozen volatile gases found in comets.

Read the full article at Russia Beyond the Headlines, HERE.

The last direct sample of the Moon returned to Earth was retrieved by the Soviet Union's Luna 24 robotic lander on August 18, 1976 (in total darkness). The vehicle landed on the rim of this 64 meter-wide crater on the southeastern plains of Mare Crisium (12.717°N, 62.222°E) and the Lunar Reconnaissance Orbiter (LRO) LROC Narrow Angle Cameras (NAC) imaged the lander's descent stage (lower left) on November 2, 2011, from only 25.57 km overhead. LROC NAC M174868307L, LRO orbit 10904, resolution 43 cm per pixel [NASA/GSFC/Arizona State University].

Thursday, October 30, 2014

High speed re-entry of test platform expected Nov. 1

The lunar north pole and about 60 percent of the Moon's farside is visible in this view captured from 3300 km over the Moon's farside, Oct. 28, from the solar array camera in flight aboard a Chang'e 5 flight dynamic test platform. From Earth, a low Crescent Moon was visible in the evening sky. The phase angles of this image are comparable with those of the Soviet Union's Luna 3 vehicle and its first photographs of the farside captured October 7, 1959. Now well along on the return trip, a challenging re-entry at above 11 km/second, a first for China and the primary reason for the test mission, will occur Nov. 1, according to the State Administration of Science, Technology and Industry for National Defense (SASTIND). Dynamic control and high-speed re-entry technologies are necessary for the success of the scheduled 2017 robotic sample return mission Chang'e 5 [Xinhua].

Comparisons have been made with the incidence angles of this, mankind's first look at the Moon's farside, from the Soviet Union's unmanned Luna 3, October 7, 1959 and the view above of Moon and Earth together from the Chang'e-5 flight dynamics test platform, October 28, 2014. More of the Moon's nearside and less farside was seen in the 1959 facsimile radioed back to Earth, but both views feature prominently Mare Moscoviense and mare-filled Tsiolkovskiy crater and highlight the now-well known differences between the two hemispheres, tidally locked into their permanent relationships with earthbound viewers [MAS/NASA].

Postdoctoral position in lunar magnetism

Data from the Apollo era and Lunar Prospector (1998-1999) is being augmented with more recent data from Kaguya (2007) and especially LADEE (2014) to create a more comprehensive model of the long-established connection between crustal magnetism at the antipodes of the Moon's youngest basins and the anomalously fresh surface materials found at these points, built up into brighter, sometimes beautiful swirl formations. (Animation from lunar crustal thickness maps from GRAIL (2012) by the Science Visualization Studio at the Goddard Space Flight Center [NASA/GSFC].
The Institut de Physique du Globe de Paris (IPGP) is inviting applications for a postdoctoral position in the broad field of lunar magnetism. This one-year position (renewable for a second year) aims to decipher the origin of crustal magnetism by modeling spacecraft-derived magnetic field data.

Potential research projects include modeling the direction of crustal magnetization, comparisons of derived crustal magnetization with measured properties of lunar samples, and correlations between magnetic anomalies and GRAIL gravity. 

As part of a larger project, the applicant will have the opportunity to collaborate with paleomagneticists at CEREGE (Aix en Provence) and geodynamo modelers at ISTerre (Grenoble).

To apply, please provide a CV, publication list, contact information of two references, and a 2-page letter that motivates the applicant's interest in the topic and that describes prior relevant research experience. Please respond by email to Mark Wieczorek (wieczor@ipgp.fr) before March 23, 2015.

Mark Wieczorek
IPGP Planetary and Space Sciences
University of Sorbonne
Paris Cité
email: wieczor@ipgp.fr
Tel: +33 (0)1 57 27 53 08
web: www.ipgp.fr/~wieczor

Wednesday, October 29, 2014

LADEE impact crater found

LADEE impact site on the eastern rim of Sundman V crater, the spacecraft was heading west when it impacted the surface. The image was created by ratioing two images, one taken before the impact and another after the impact. The bright area shows the impact point and the ejecta (things that have changed between the time of the two images). The ejecta form a V shaped pattern extending to the northwest from the impact point. Ratio constructed with LROC images M1163066820RE and M1101816767RE [NASA/GSFC/Arizona State University].
Mark Robinson
Principal Investigator
Lunar Reconnaissance Orbiter Camera (LROC)
Arizona State University

The Lunar Atmosphere and Dust Environment Explorer (LADEE) was launched from Wallops Island on 6 September 2013 at 11:27 EDT and was visible over much of the eastern coast of the United States. The spacecraft was 2.37 m (7.8 ft) high and 1.85 m (6.1 ft) wide with a mass of 383 kg (844 lb) including the fuel.

After expending most of its fuel during its successful exploration of the Moon the spacecraft had a mass of about only 248 kg (547 lb) when it impacted the surface.

Artist's rendition of the LADEE spacecraft in orbit around the Moon [NASA/JAXA/LP].
Originally LADEE was placed into a retrograde, near-equatorial orbit to study the Moon's surface bound exosphere and dust environment. Since the Apollo era of exploration several conflicting ideas and observations concerning the existence (or not) of near-surface and high altitude dust were debated, and thus one of LADEE’s key science goals was to search for dust particles high above the surface (no dust was found).

LADEE's engines were fired on 11 April 2014 to adjust the orbit in such a way as to guarantee a farside impact if the spacecraft did not survive the 15 April 2014 eclipse. There was a small worry that if the spacecraft failed during the eclipse and was uncontrollable, it might impact near one of the Apollo sites. Over the subsequent 7 days, the low point in LADEE's orbit decreased resulting in an impact on 18 April 2014.

Before and after images of the LADEE impact site [NASA/GSFC/Arizona State University].
As it passed over the western limb as seen from the Earth, the spacecraft impacted the eastern rim of Sundman V crater (11.85°N, 266.75°E). The impact site (11.8494°N, 266.7507°E) is about 780 m from the crater rim with an altitude of about 2590 m, and was only about 295 meters north of its originally predicted location (based on tracking data).

Like the LADEE spacecraft, the impact crater is small, greater than 3 meters in diameter, barely resolvable by the LROC NAC. Based on impact models, a crater of only about 1.8 m (6 ft) diameter is expected. The crater is very small because, as impacts go, LADEE had a low mass and a low density (0.43 g / cm3 vs. larger than 3.0 g / cm3 for an ordinary chondrite meteorite), and was traveling at only a tenth the speed (1699 m/sec - 3800 mph) of an average asteroid.

LADEE impact crater (centered of image) has a distinctive hour-glass albedo pattern indicative of low angle impacts. Bright material extends to the northwest, while only a minor amount was ejected to the southeast; NAC M1163066820RE [NASA/GSFC/Arizona State University].
Because it is so small, the crater is hard to identify among the myriad of small fresh craters that dot the lunar surface. However, as images had been acquired of the impact region before the impact occurred, they could be compared with images acquired after the impact to identify the crater.

Since NAC images are so large (250 megapixels) and the new crater is so small the LROC team coregistered the before and after images (called a temporal pair) and then divided the after image by the before image. In this manner any changes to the surface stick out like a beacon! For the LADEE crater the ejecta forms a triangular pattern primarily downrange (to the west) extending more than 200 meters from the impact site. There is also a small triangular area of ejecta uprange but it extends only about 20-30 meters. The ejecta pattern is oriented WNW consistent with the direction the spacecraft was traveling when it impacted.

Zoomed-in view of the impact site, image is 200 m across, NAC M1163066820RE [NASA/GSFC/Arizona State University].
Explore the catalog of LROC close-ups of lunar spacecraft landing and impact sites, HERE.

Related LADEE Posts:
First Science from LADEE (45th LPSC, March 18 2014)
LADEE's (star tracker) images of the Moon (February 14, 2014)
LADEE economy adds 28 days to mission (February 5, 2014)
LROC captures LADEE from 9,000 meters (January 30, 2014)
Red Moon, Blue Moon Dwayne DayThe Space Review (December 3, 2013)
LADEE begins collecting data (November 22, 2013)
LADEE transitioning out of commissioning phase (November 6, 2013)
Apollo 12 ALSEP first to measure dust accumulation (November 21, 2013)
Chang'e-3 & LADEE: The Role of Serendipity (October 31, 2013)
LADEE LLCD sets new data record (October 25, 2013)
Measuring almost nothing, looking for the almost invisible (October 16, 2013)
LADEE legacies (September 7, 2013)
LADEE Prelaunch Mission Briefing (September 6, 2013)
ESA prepares for LADEE (July 31, 2013)
LADEE arrives at Wallops Island (June 5, 2013)
LADEE ready to baseline dusty lunar exosphere (June 5, 2013)
First laser comm system ready for launch on LADEE (March 16, 2013)
LADEE project manager update (February 6, 2013)
The Mona Lisa test for LADEE communications (January 21, 2013)
Toxicity of lunar dust (July 2, 2012)
Expectations for the LADEE LDEX (March 23, 2012)
The Dust Management Project (August 9, 2010)
LADEE architecture and mission design (July 6, 2010)
DesertRatS testing electrodynamic dust shield (July 5, 2010)
Dust transport and its importance in the origin of lunar swirls (February 21, 2010)
Dust accumulation on Apollo laser reflectors may indicate a surprisingly fast and
more dynamic lunar exosphere
 (February 16, 2010)
NASA applies low cost lessons to LADEE (January 18, 2010)
Nanotech advances in lunar dust mitigation (August 19, 2009)
Moon dust hazard influenced by Sun's elevation (April 17, 2009)
LADEE launch by Orbital from Wallops Island (April 14, 2009)
Understanding the activation and solution properties of lunar dust
for future lunar habitation
 (March 2, 2009)
Respiratory toxicity of lunar highland dust (January 19, 2009)
Toxicological effects of moon dust (June 25, 2008)
Moon dust and duct tape (April 22, 2008)