posted 10-08-2009 08:24 PM               

Credit: NASA/Goddard Space Flight Center/Arizona State University

The crater in the center of this image was formed by Apollo 14's Saturn IVB booster. The booster was intentionally impacted into the lunar surface on Feb. 4, 1971. The impact caused a minor "moonquake" that scientists used to learn about the moon's interior structure. Seismometers placed on the surface by Apollo astronauts returned data on the tremor.

posted 10-29-2009 08:01 AM               

Exploring the Apollo 17 Site

LRO maneuvered into its 50-km mapping orbit on September 15. The next pass over the Apollo 17 landing site resulted in images with more than two times better resolution than previously acquired.

At the time of this recent overflight the Sun was high in the sky (28° incidence angle) helping to bring out subtle differences in surface brightness.

The descent stage of the lunar module Challenger is now clearly visible, at 50-cm per pixel (angular resolution) the descent stage deck is eight pixels across (four meters), and the legs are also now distinguishable. The descent stage served as the launch pad for the ascent stage as it blasted off for a rendezvous with the command module America on 14 December 1972.

Tracks are clearly visible and can be followed to the east, where astronauts Jack Schmitt and Gene Cernan set up the Surface

Electrical Properties (SEP) experiment. Cernan drove the Lunar Roving Vehicle (LRV) in an intersecting north-south and east-west course to mark positions for laying out the SEP thirty-five meter antennas (circle labeled "SEP" marks the area of the SEP transmitter). The dark area just below the SEP experiment is where the astronauts left the rover, in a prime spot for monitoring the liftoff...

Credit: NASA/GSFC/Arizona State University

posted 11-04-2009 04:07 PM               

Apollo 12 Landing Site

The LROC team released their first view of the Apollo 12 landing site earlier this year. Even though that image was collected from the higher LRO commissioning phase orbit, details of the landing site could be discerned, including the trails followed by Astronauts Charles Conrad and Alan Bean, the descent module of the Lunar Module (LM) Intrepid, and the Surveyor 3 robotic lander.

From the lower mapping orbit (50 km) even more details of the landing site are revealed. With the Sun very high in the sky (incidence angle 4°), shadows are minimized and you mostly see variations in albedo (or surface brightness). On the Moon, albedo variations are generally due to either composition (mare vs highlands) or maturity (since fresh, impact-excavated lunar materials tend to have higher albedo, but gradually darken after prolonged exposure to the space environment). Since we're viewing a mare surface far away from highland materials in this image, the albedo variations that you can see are dominantly due to maturity effects. However it is clear from all the LROC landing site images that astronaut activity lowers the albedo, areas of heaviest activity have the lowest albedo, especially around the LM. This effect is most likely due to compaction of a very loose surface powder by simply walking around. The more walking in a given area, the more compaction that takes place, and thus the lower the albedo.

Credit: NASA/GSFC/Arizona State University

posted 11-09-2009 04:04 PM               

LRO Gets Additional View of Apollo 11 Landing Site

"Houston, Tranquility Base here. The Eagle has landed."

With those eight words, astronaut Neil Armstrong let the world know that Apollo 11 had landed safely on the moon, beginning humankind's first exploration of another world. The landing certainly kept the mission operations crew in suspense as Armstrong maneuvered around the bouldery ejecta on the northeast flank of West Crater, finally settling down almost a kilometer to the west with only tens of seconds of fuel remaining.

The Lunar Reconnaissance Orbiter Camera team earlier released two pictures of the Apollo 11 landing site, each taken under different lighting conditions and at lower resolution than this image. This is LROC's first picture of Apollo 11 after LRO dropped into its 50 km mapping orbit. At this altitude, very small details of Tranquility Base can be discerned. The footpads of the LM are clearly discernible. Components of the Early Apollo Science Experiments Package (EASEP) are easily seen, as well. Boulders from West Crater lying on the surface to the east stand out, and the many small craters that cover the moon are visible to the southeast.

Credit: NASA/GSFC/Arizona State University

As the Apollo 11 Lunar Module (LM) neared the surface, Neil Armstrong could see the designated landing area would have been in a rocky area near West Crater. He had to change the flight plan and fly the LM westward to find a safe landing spot. This image is 742 meters wide (about 0.46 miles). North is towards the top of the image.

Credit: NASA/GSFC/Arizona State University

Enlargement of area surrounding Apollo 11 landing site.

posted 03-15-2010 09:32 PM               

New Lunar Images and Data Available to the Public

The public can follow along with NASA on its journey of lunar discovery. On March 15, the publicly accessible Planetary Data System will release data sets from the seven instruments on board NASA’s Lunar Reconnaissance Orbiter.

“The Planetary Data System is a NASA funded program to archive data from past and present planetary missions as well as astronomical observations and laboratory data,” said Dr. John Keller, LRO Deputy Project Scientist from NASA Goddard Space Flight Center in Greenbelt, Md. “The purpose of the Planetary Data System is to make available to the public the fruits of NASA funded research and to allow advanced research on solar system science.”

Each of the seven instruments is unique and will provide data in different formats to the Planetary Data System. Much of the data will be in a relatively low level form, not highly processed, which allows researchers to maximize flexibility in working with the data. The instrument teams will also provide higher level data products in the form of maps and calibrated images for the general public. Many of the images can be accessed using a computer with an internet browser.

Prior to the formal release of LRO data, the Lunar Reconnaissance Orbiter Camera team released several hundred images from the pair of Narrow Angle Cameras on-board the spacecraft. These images were released to give researchers a head start on using the data before the tidal wave of data was unleashed.

“We're able to take advantage of the close proximity of the Moon, compared to other objects in the solar system, to transmit data from LRO back to Earth at a very high rate,” said Keller. “The first data release is 55 terabytes. The one year exploration mission will deliver 130 terabytes of data, enabling a more detailed study our nearest celestial neighbor. We expect LRO to provide more data than all of the previous planetary missions combined.”

LRO was mandated to release data to the Planetary Data System beginning six months after initial operation. Some of the higher level data products require the full year of measurements and won't be released until after the end of the exploration mission. LRO will move into its science phase in September, when the program management responsibility moves from the Exploration Systems to the Science Mission Directorate at NASA Headquarters.

LRO is scheduled for a one year exploration mission in a polar orbit about 31 miles above the lunar surface. During this time, LRO will produce a comprehensive map of the lunar surface in unprecedented detail, search for resources and potential safe landing sites for a potential future return to the moon and measure lunar temperatures and radiation levels.

posted 03-15-2010 09:46 PM               

Credit: NASA/GSFC/Arizona State University

On February 21, 1972, Luna 20 soft landed in the rugged highlands between Mare Fecunditatis and Mare Crisium. The next day a sample return capsule blasted off carrying 55 grams of lunar soil. The Luna 20 descent stage still sits silently on the Moon, clearly visible in LROC NAC image M119482862RE.

Credit: NASA/GSFC/Arizona State University

Luna 20 descent stage, note the shadow of the sampling arm.

Credit: NASA/GSFC/Arizona State University

Luna 24 sitting on the edge of a 60 meter diameter crater, NAC image M119449091RE.

posted 03-23-2010 01:23 PM               

Credit: NASA/GSFC/Arizona State University

Bang! On April 14th 1970, the Apollo 13 Saturn IVB upper stage impacted the Moon North of Mare Cognitum, at -2.55° latitude, -27.88° East longitude. The impact crater, which is roughly 30 meters in diameter, is clearly visible in LROC NAC image M109420042LE.

Rocket impacts recorded by the Apollo seismic network

In April, the Apollo 13 Saturn V blasted off towards the Moon. The Saturn rocket consisted of a 3-stage launching system. While the first and second stage of the launch vehicle dropped back to Earth after launch, the third stage (S-IVB) was used to propel the docked Apollo Command Module and Lunar Module from Earth orbit into a lunar trajectory. The spent rocket booster then separated from the Command Module and later impacted the Moon. From the tracking of the radio signals of the rocket, the impact locations on the Moon and the impact times were fairly well known.

Credit: Popular Science

The impacts by the S-IVB stages represented unique calibration signals for the Apollo seismic station network, which operated on the lunar surface from 1969 - 1977. Since the rocket impacts occurred at known times and places, the seismic wave velocities, in particular those within the upper lunar crust could be measured directly.

At the time of the Apollo 13 mission, only the seismometer at Apollo 12 was available, which had been deployed 5 months earlier. The S-IVB impact occurred at a distance of 135 km from that seismic station.

Analysis by the LROC team now have identified the craters associated with most of the rocket impacts in their predicted areas. Taking advantage of the precise LRO orbit and LROC pointing knowledge, it is now possible to determine the impact coordinates of rockets and their distances from the seismic stations more accurately to within a few hundred meters, over time as the orbit calculations are improved these estimates will in turn become more accurate. The precise impact coordinates may warrant a reanalysis of the seismic calibration data for improved models of seismic wave propagation within the Moon and the Lunar interior structure. The seismograph network recorded more than 13,000 seismic events and delivered some of the most important scientific results of the Apollo missions.

Find the Apollo 13 S-IVB impact crater in the full NAC image. Review an earlier LROC image posting of the Apollo 14 S-IVB impact crater.

posted 06-24-2010 11:08 AM               

Credit: NASA/Goddard

The Lunar Far Side: The Side Never Seen from Earth

Tidal forces between the moon and the Earth have slowed the moon' rotation so that one side of the moon always faces toward our planet. Though sometimes improperly referred to as the "dark side of the moon," it should correctly be referred to as the "far side of the moon" since it receives just as much sunlight as the side that faces us. The dark side of the moon should refer to whatever hemisphere isn't lit at a given time.

Though several spacecraft have imaged the far side of the moon since then, LRO is providing new details about the entire half of the moon that is obscured from Earth. The lunar far side is rougher and has many more craters than the near side, so quite a few of the most fascinating lunar features are located there, including one of the largest known impact craters in the solar system, the South Pole-Aitken Basin.

The image highlighted here shows the moon's topography from LRO's LOLA instruments with the highest elevations up above 20,000 feet in red and the lowest areas down below -20,000 feet in blue.

posted 07-14-2010 01:36 PM               

NASA's Lunar Reconnaissance Orbiter (LRO) is beaming back images of caverns hundreds of feet deep -- beckoning scientists to follow.

"They could be entrances to a geologic wonderland," says Mark Robinson of Arizona State University, principal investigator for the LRO camera. "We believe the giant holes are skylights that formed when the ceilings of underground lava tubes collapsed."

Japan's Kaguya spacecraft first photographed the enormous caverns last year. Now the powerful Lunar Reconnaissance Orbiter Camera (LROC, the same camera that photographed Apollo landers and astronauts' tracks in the moondust) is giving us enticing high-resolution images of the caverns' entrances and their surroundings.

Back in the 1960s, before humans set foot on the Moon, researchers proposed the existence of a network of tunnels, relics of molten lava rivers, beneath the lunar surface. They based their theory on early orbital photographs that revealed hundreds of long, narrow channels called rilles winding across the vast lunar plains, or maria. Scientists believed these rilles to be surface evidence of below-ground tunnels through which lava flowed billions of years ago.

"It's exciting that we've now confirmed this idea," says Robinson. "The Kaguya and LROC photos prove that these caverns are skylights to lava tubes, so we know such tunnels can exist intact at least in small segments after several billion years..."

posted 08-20-2010 08:25 AM               

NASA's LRO Reveals 'Incredible Shrinking Moon'

Newly discovered cliffs in the lunar crust indicate the moon shrank globally in the geologically recent past and might still be shrinking today, according to a team analyzing new images from NASA's Lunar Reconnaissance Orbiter (LRO) spacecraft. The results provide important clues to the moon's recent geologic and tectonic evolution.

The moon formed in a chaotic environment of intense bombardment by asteroids and meteors. These collisions, along with the decay of radioactive elements, made the moon hot. The moon cooled off as it aged, and scientists have long thought the moon shrank over time as it cooled, especially in its early history. The new research reveals relatively recent tectonic activity connected to the long-lived cooling and associated contraction of the lunar interior.

"We estimate these cliffs, called lobate scarps, formed less than a billion years ago, and they could be as young as a hundred million years," said Dr. Thomas Watters of the Center for Earth and Planetary Studies at the Smithsonian's National Air and Space Museum, Washington. While ancient in human terms, it is less than 25 percent of the moon's current age of more than four billion years. "Based on the size of the scarps, we estimate the distance between the moon's center and its surface shrank by about 300 feet," said Watters, lead author of a paper on this research appearing in Science August 20.

"These exciting results highlight the importance of global observations for understanding global processes," said Dr. John Keller, Deputy Project Scientist for LRO at NASA's Goddard Space Flight Center, Greenbelt, Md. "As the LRO mission continues in to a new phase, with emphasis on science measurements, our ability to create inventories of lunar geologic features will be a powerful tool for understanding the history of the moon and the solar system."

The scarps are relatively small; the largest is about 300 feet high and extends for several miles or so, but typical lengths are shorter and heights are more in the tens of yards (meters) range. The team believes they are among the freshest features on the moon, in part because they cut across small craters. Since the moon is constantly bombarded by meteors, features like small craters (those less than about 1,200 feet across) are likely to be young because they are quickly destroyed by other impacts and don’t last long. So, if a small crater has been disrupted by a scarp, the scarp formed after the crater and is even younger. Even more compelling evidence is that large craters, which are likely to be old, don't appear on top any of the scarps, and the scarps look crisp and relatively undegraded.

Lobate scarps on the moon were discovered during the Apollo missions with analysis of pictures from the high-resolution Panoramic Camera installed on Apollo 15, 16, and 17. However, these missions orbited over regions near the lunar equator, and were only able to photograph some 20 percent of the lunar surface, so researchers couldn't be sure the scarps were not just the result of local activity around the equator. The team found 14 previously undetected scarps in the LRO images, seven of which are at high latitudes (more than 60 degrees). This confirms that the scarps are a global phenomenon, making a shrinking moon the most likely explanation for their wide distribution, according to the team.

As the moon contracted, the mantle and surface crust were forced to respond, forming thrust faults where a section of the crust cracks and juts out over another. Many of the resulting cliffs, or scarps, have a semi-circular or lobe-shaped appearance, giving rise to the term "lobate scarps". Scientists aren't sure why they look this way; perhaps it's the way the lunar soil (regolith) expresses thrust faults, according to Watters.

Lobate scarps are found on other worlds in our solar system, including Mercury, where they are much larger. "Lobate scarps on Mercury can be over a mile high and run for hundreds of miles," said Watters. Massive scarps like these lead scientists to believe that Mercury was completely molten as it formed. If so, Mercury would be expected to shrink more as it cooled, and thus form larger scarps, than a world that may have been only partially molten with a relatively small core. Our moon has more than a third of the volume of Mercury, but since the moon's scarps are typically much smaller, the team believes the moon shrank less.

Because the scarps are so young, the moon could have been cooling and shrinking very recently, according to the team. Seismometers emplaced by the Apollo missions have recorded moonquakes. While most can be attributed to things like meteorite strikes, the Earth's gravitational tides, and day/night temperature changes, it's remotely possible that some moonquakes might be associated with ongoing scarp formation, according to Watters. The team plans to compare photographs of scarps by the Apollo Panoramic Cameras to new images from LRO to see if any have changed over the decades, possibly indicating recent activity.

While Earth's tides are most likely not strong enough to create the scarps, they could contribute to their appearance, perhaps influencing their orientation, according to Watters. During the next few years, the team hopes to use LRO's high-resolution Narrow Angle Cameras (NACs) to build up a global, highly detailed map of the moon. This could identify additional scarps and allow the team to see if some have a preferred orientation or other features that might be associated with Earth's gravitational pull.

"The ultrahigh resolution images from the NACs are changing our view of the moon," said Dr. Mark Robinson of the School of Earth and Space Exploration at Arizona State University, Tempe, Ariz., a coauthor and Principal Investigator of the Lunar Reconnaissance Orbiter Camera. "We've not only detected many previously unknown lunar scarps; we're also seeing much greater detail on the scarps identified in the Apollo photographs."

The research was funded by NASA's Exploration Systems Mission Directorate at NASA Headquarters, Washington. The team includes researchers from the Smithsonian, Arizona State, the SETI Institute, Mountain View, Calif., NASA Ames Research Center, Moffett Field, Calif., Cornell University, Ithaca, N.Y., Institut für Planetologie, Westfälische Wilhelms-Universität, Münster, Germany, Brown University, Providence, R.I., and the Johns Hopkins University Applied Physics Laboratory, Laurel, Md.

posted 09-20-2010 05:26 AM               

NASA's Lunar Spacecraft Completes Exploration Mission Phase

NASA's Lunar Reconnaissance Orbiter, or LRO, completed the exploration phase of its mission on Sept. 16, after a number of successes that transformed our understanding of Earth's nearest neighbor.

LRO completed a one-year exploration mission in a polar orbit approximately 31 miles above the moon's surface. It produced a comprehensive map of the lunar surface in unprecedented detail; searched for resources and safe landing sites for potential future missions to the moon; and measured lunar temperatures and radiation levels.

The mission is turning its attention from exploration objectives to scientific research, as program management moves from NASA's Exploration Systems Mission Directorate to the Science Mission Directorate at the agency's Headquarters in Washington.

"LRO has been an outstanding success. The spacecraft has performed brilliantly," said Doug Cooke, associate administrator of the Exploration Systems Mission Directorate. "LRO's science and engineering teams achieved all of the mission's objectives, and the incredible data LRO gathered will provide discoveries about the moon for years to come."

The LRO team will continue to send data gathered during the last year to the Planetary Data System, which archives and distributes scientific information from NASA planetary missions, astronomical observations and laboratory measurements.

By the time LRO achieves full mission success in March, and its data is processed and released to the scientific community, it will have sent more information to the Planetary Data System than all other previous planetary missions combined. During its new phase of discovery, LRO will continue to map the moon for two to four more years.

"The official start of LRO's science phase should write a new and intriguing chapter in lunar research," said Ed Weiler, associate administrator for the Science Mission Directorate. "This mission is one more asset added to NASA's vast science portfolio."

The spacecraft launched from NASA's Kennedy Space Center in Florida carrying a suite of seven instruments on June 18, 2009. LRO formally began its detailed survey of the moon in September 2009.

Results from the mission include: new observations of the Apollo landing sites; indications that permanently shadowed and nearby regions may harbor water and hydrogen; observations that large areas in the permanently shadowed regions are colder than Pluto; detailed information about lunar terrain; and the first evidence of a globally distributed population of thrust faults that indicates the moon has recently contracted and may still be shrinking.

LRO also took high resolution pictures of the Lunokhod 1 rover that had been lost for almost 40 years. The rover, which carries a retroreflector, was located to within approximately 150 feet. The accurate position data enabled researchers on Earth to bounce laser signals off the retroreflector for the first time ever. The retroreflector is providing important new information about the position and motion of the moon.

LRO also supported the Lunar Crater Observation and Sensing Satellite impact, a companion mission sent to determine if the moon's poles harbor water ice, by helping to select a promising impact site. LRO observed both the expanding plume that arose after the impact and the evolving temperature at the site.

NASA's Goddard Space Flight Center in Greenbelt, Md., built and manages LRO for the Exploration Systems Mission Directorate. The Institute for Space Research in Moscow provides the neutron detector aboard the spacecraft.

posted 03-15-2011 04:57 PM               

NASA Lunar Reconnaissance Orbiter Delivers Treasure Trove Of Data

NASA's Lunar Reconnaissance Orbiter (LRO) team released Tuesday the final set of data from the mission's exploration phase along with the first measurements from its new life as a science satellite.

With this fifth release of data, striking new images and maps have been added to the already comprehensive collection of raw lunar data and high-level products, including mosaic images, that LRO has made possible. The spacecraft's seven instruments delivered more than 192 terabytes of data with an unprecedented level of detail. It would take approximately 41,000 typical DVDs to hold the new LRO data set.

"The release of such a comprehensive and rich collection of data, maps and images reinforces the tremendous success we have had with LRO in the Exploration Systems Mission Directorate and with lunar science," said Michael Wargo, chief lunar scientist of the Exploration Systems Mission Directorate at NASA Headquarters in Washington.

Among the latest products is a global map with a resolution of 100 meters per pixel from the Lunar Reconnaissance Orbiter Camera (LROC). To enhance the topography of the moon, this map was made from images collected when the sun angle was low on the horizon. Armchair astronauts can zoom in to full resolution with any of the mosaics -- quite a feat considering that each is 34,748 pixels by 34,748 pixels, or approximately 1.1 gigabytes.

"Because the moon is so close and because we have a dedicated ground station, we are able to bring back as much data from LRO as from all the other planetary missions combined," said LRO Project Scientist Richard Vondrak of NASA's Goddard Space Flight Center in Greenbelt, Md.

LRO's Diviner Lunar Radiometer Experiment is providing new data relating to the moon's surface. These include maps of visual and infrared brightness, temperature, rock abundance, nighttime soil temperature and surface mineralogy. The data are in the form of more than 1700 digital maps at a range of resolutions that can be overlaid easily on other lunar data sets.

The Lyman-Alpha Mapping Project, which collects information to help identify surface water-ice deposits, especially in permanently-shadowed regions of the moon, also has new data. This release includes new maps of far-ultraviolet (FUV) brightness, albedo and water-ice data as well as instrument exposure, illumination and other conditions.

As a complement to the high-resolution digital elevation maps, representing 3.4 billion measurements already released by the Lunar Orbiter Laser Altimeter team, the group is delivering new maps of slope, roughness and illumination conditions. New maps from the Lunar Exploration Neutron Detector, and the latest data from the Cosmic Ray Telescope for the Effects of Radiation and the Miniature Radio Frequency instruments, also are featured.

"All these global maps and other data are available at a very high resolution -- that's what makes this release exciting," said Goddard's John Keller, the LRO deputy project scientist. "With this valuable collection, researchers worldwide are getting the best view of the moon they have ever had."

The complete data set contains the raw information and high-level products such as mosaic images and maps. The data set also includes more than 300,000 calibrated data records released by LROC. All of the final records from the exploration phase, which lasted from Sept. 15, 2009 through Sept. 15, 2010, are available through several of the Planetary Data System nodes and the LROC website.

posted 08-10-2011 05:40 PM               

Today I will begin dipping down from my usual about 50 km orbit to an orbit that will allow me to image the Apollo sites from about 20 km away! This will allow me to obtain images of the Apollo sites that are about four times sharper than my current best images.

Once I reach my new temporary orbit, I'll take images of and around the Apollo sites between August 14 and 19. After that, I'll return to my 50-km-orbit until December.

(A clarification: my project scientists would like to point out that there are several technical challenges associated with getting improved resolution images at the lower altitude orbit.

Example: I will not slow down from my ~1.6 km/s (~3500 mph) speed when I get closer to the Moon's surface, which might cause some image blurring, particularly for the LROC Narrow Angle Camera images.

However, it will certainly be fun to compare the images from the different orbits!)

posted 09-06-2011 10:54 AM               

NASA Spacecraft Images Offer Sharper Views of Apollo Landing Sites

NASA's Lunar Reconnaissance Orbiter (LRO) captured the sharpest images ever taken from space of the Apollo 12, 14 and 17 landing sites. Images show the twists and turns of the paths made when the astronauts explored the lunar surface.

At the Apollo 17 site, the tracks laid down by the lunar rover are clearly visible, along with the last foot trails left on the moon. The images also show where the astronauts placed some of the scientific instruments that provided the first insight into the moon's environment and interior.

"We can retrace the astronauts' steps with greater clarity to see where they took lunar samples," said Noah Petro, a lunar geologist at NASA's Goddard Space Flight Center in Greenbelt, Md., who is a member of the LRO project science team.

All three images show distinct trails left in the moon's thin soil when the astronauts exited the lunar modules and explored on foot. In the Apollo 17 image, the foot trails, including the last path made on the moon by humans, are easily distinguished from the dual tracks left by the lunar rover, which remains parked east of the lander.

"The new low-altitude Narrow Angle Camera images sharpen our view of the moon's surface," said Arizona State University researcher Mark Robinson, principal investigator for the Lunar Reconnaissance Orbiter Camera (LROC). "A great example is the sharpness of the rover tracks at the Apollo 17 site. In previous images the rover tracks were visible, but now they are sharp parallel lines on the surface."

At each site, trails also run to the west of the landers, where the astronauts placed the Apollo Lunar Surface Experiments Package (ALSEP) to monitor the moon's environment and interior.

This equipment was a key part of every Apollo mission. It provided the first insights into the moon's internal structure, measurements of the lunar surface pressure and the composition of its atmosphere. Apollo 11 carried a simpler version of the science package.

One of the details that shows up is a bright L-shape in the Apollo 12 image. It marks the locations of cables running from ALSEP's central station to two of its instruments. Although the cables are much too small for direct viewing, they show up because they reflect light very well.

The higher resolution of these images is possible because of adjustments made to LRO's orbit, which is slightly oval-shaped or elliptical. "Without changing the average altitude, we made the orbit more elliptical, so the lowest part of the orbit is on the sunlit side of the moon," said Goddard's John Keller, deputy LRO project scientist. "This put LRO in a perfect position to take these new pictures of the surface."

The maneuver lowered LRO from its usual altitude of approximately 31 miles (50 kilometers) to an altitude that dipped as low as nearly 13 miles (21 kilometers) as it passed over the moon's surface. The spacecraft has remained in this orbit for 28 days, long enough for the moon to completely rotate. This allows full coverage of the surface by LROC's Wide Angle Camera. The cycle ends today when the spacecraft will be returned to its 31-mile orbit.

"These images remind us of our fantastic Apollo history and beckon us to continue to move forward in exploration of our solar system," said Jim Green, director of the Planetary Science Division at NASA Headquarters in Washington.

posted 09-06-2011 11:16 AM               

LRO's New Views of Apollo 12, 14, and 17 Sites

Apollo 12 landing site Credit: NASA GSFC/ASU

Apollo 12 landing site

The tracks made in 1969 by astronauts Pete Conrad and Alan Bean, the third and fourth humans to walk on the moon, can be seen in this LRO image of the Apollo 12 site. The location of the descent stage for Apollo 12's lunar module, Intrepid, also can be seen.

Conrad and Bean performed two moon walks on this flat lava plain in the Oceanus Procellarum region of the moon. In the first walk, they collected samples and chose the location for the lunar monitoring equipment known as the Apollo Lunar Surface Experiments Package (ALSEP). The ALSEP sent scientific data about the moon's interior and surface environment back to Earth for more than seven years.

One of the details visible in this image is a bright L-shape that marks the locations of cables running from ALSEP's central station to two of its instruments. These instruments are probably (left) the Suprathermal Ion Detector Experiment, or SIDE, which studied positively charged particles near the moon's surface, and (right) the Lunar Surface Magnetometer, or LSM, which looked for variations in the moon's magnetic field over time; these two instruments had the longest cables running from the central station. Though the cables are much too small to be seen directly, they show up because the material they are made from reflects light very well.

In the second moon walk, Conrad and Bean set out from the descent stage and looped around Head crater, visiting Bench crater and Sharp crater, then headed east and north to the landing site of Surveyor 3. There, the astronauts collected some hardware from the unmanned Surveyor spacecraft, which had landed two years earlier.

The two astronauts covered this entire area on foot, carrying all of their tools and equipment and more than 32 kilograms (roughly 60 pounds) of lunar samples.

Apollo 14 landing site Credit: NASA GSFC/ASU

Apollo 14 landing site

The paths left by astronauts Alan Shepard and Edgar Mitchell on both Apollo 14 moon walks are visible in this LRO image. (At the end of the second moon walk, Shepard famously hit two golf balls.) The descent stage of the lunar module Antares is also visible.

Apollo 14 landed near Fra Mauro crater in February 1971. On the first moon walk, the astronauts set up the lunar monitoring equipment known as the Apollo Lunar Surface Experiments Package (ALSEP) to the west of the landing site and collected just over 42 kilograms (about 92 pounds) of lunar samples. Luckily for them, they had a rickshaw-style cart called the modular equipment transporter, or MET, that they could use to carry equipment and samples.

Apollo 17 landing site Credit: NASA GSFC/ASU

Apollo 17 landing site

The twists and turns of the last tracks left by humans on the moon crisscross the surface in this LRO image of the Apollo 17 site. In the thin lunar soil, the trails made by astronauts on foot can be easily distinguished from the dual tracks left by the lunar roving vehicle, or LRV. Also seen in this image are the descent stage of the Challenger lunar module and the LRV, parked to the east.

The LRV gave the Apollo 17 astronauts, Eugene Cernan and Harrison Schmitt, considerable mobility. As in previous Apollo missions, the astronauts set up the lunar monitoring equipment known as the Apollo Lunar Surface Experiments Package (ALSEP), the details of which varied from mission to mission. To the west of the landing site, the cross-shaped path that the astronauts made as they set up the geophones to monitor seismic activity can be seen.

To the east, more rover tracks can be seen. Cernan made these when he laid out the 35-meter antennas for the Surface Electrical Properties, or SEP, experiment. SEP, a separate investigation from ALSEP, characterized the electrical properties of the lunar soil.

Below the SEP experiment is where the astronauts parked the rover, in a prime spot to shoot video of the liftoff of the Challenger module.

posted 05-26-2017 08:18 PM               

ASU's Lunar Reconnaissance Orbiter Camera survives meteoroid hit

On Oct. 13, 2014, something very strange happened to the camera aboard NASA's Lunar Reconnaissance Orbiter (LRO). The Lunar Reconnaissance Orbiter Camera (LROC), which normally produces beautifully clear images of the lunar surface, produced an image that was wild and jittery. From the sudden and jagged pattern apparent in the image, the LROC team determined that the camera must have been hit by a tiny meteoroid.

Above: The first wild back-and-forth line records the moment the left NAC radiator was struck by a meteoroid. (NASA/Goddard Space Flight Center/Arizona State University)

LROC is a system of three cameras mounted on the LRO spacecraft. Two Narrow Angle Cameras (NACs) capture high resolution black and white images. The third Wide Angle Camera captures moderate resolution images using filters to provide information about the properties and color of the lunar surface.

The NAC works by building an image one line at a time. The first line is captured, then the orbit of the spacecraft moves the camera relative to the surface, and then the next line is captured, and so on, as thousands of lines are compiled into a full image.

According to Mark Robinson, professor and principal investigator of LROC at ASU's School of Earth and Space Exploration, the jittery appearance of the image captured is the result of a sudden and extreme cross-track oscillation of the camera. LROC researchers concluded that there must have been a brief violent movement of the left Narrow Angle Camera.

There were no spacecraft events like solar panel movements or antenna tracking that might have caused spacecraft jitter during this period. "Even if there had been, the resulting jitter would have affected both cameras identically," says Robinson. "The only logical explanation is that the NAC was hit by a meteoroid."

How big was the meteoroid?

During LROC's development, a detailed computer model was made to ensure the NAC would not fail during the severe vibrations caused by the launch of the spacecraft. The computer model was tested before launch by attaching the NAC to a vibration table that simulates launch. The camera passed the test with flying colors, proving its stability.

Using this detailed computer model, the LROC team ran simulations to see if they could reproduce the distortions seen on the Oct. 13 image and determine the size of the meteoroid that hit the camera. They estimate the impacting meteoroid would have been about half the size of a pinhead (0.8mm), assuming a velocity of about 4.3 miles (7 kilometers) per second and a density of an ordinary chondrite meteorite (2.7 grams/cm3).

"The meteoroid was traveling much faster than a speeding bullet," says Robinson. "In this case, LROC did not dodge a speeding bullet, but rather survived a speeding bullet!"

How rare is it that the effects of an event like this were captured on camera? Very rare, according to Robinson. LROC typically only captures images during daylight and then only about 10 percent of the day, so for the camera to be hit by a meteor during the time that it was also capturing images is statistically unlikely.

"LROC was struck and survived to keep exploring the moon," says Robinson, "thanks to Malin Space Science Systems' robust camera design."

"Since the impact presented no technical problems for the health and safety of the instrument, the team is only now announcing this event as a fascinating example of how engineering data can be used, in ways not previously anticipated, to understand what is happing to the spacecraft over 236,000 miles (380,000 kilometers) from the Earth," said John Keller, LRO project scientist from NASA's Goddard Space Flight Center in Greenbelt, Maryland.

Launched on June 18, 2008, LRO has collected a treasure trove of data with its seven powerful instruments, making an invaluable contribution to our knowledge about the moon.

"A meteoroid impact on the LROC NAC reminds us that LRO is constantly exposed to the hazards of space," says Noah Petro, deputy project scientist from NASA Goddard. "And as we continue to explore the moon, it reminds us of how precious are the data that is being returned."

posted 07-06-2020 01:22 PM               

Radar Points to Moon Being More Metallic Than Researchers Thought

What started out as a hunt for ice lurking in polar lunar craters turned into an unexpected finding that could help clear some muddy history about the Moon's formation.

Team members of the Miniature Radio Frequency (Mini-RF) instrument on NASA's Lunar Reconnaissance Orbiter (LRO) spacecraft found new evidence that the Moon's subsurface might be richer in metals, like iron and titanium, than researchers thought. That finding, published July 1 in Earth and Planetary Science Letters, could aid in drawing a clearer connection between Earth and the Moon.

"The LRO mission and its radar instrument continue to surprise us with new insights about the origins and complexity of our nearest neighbor," said Wes Patterson, Mini-RF principal investigator from the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Maryland, and a study coauthor.

Substantial evidence points to the Moon as the product of a collision between a Mars-sized protoplanet and young Earth, forming from the gravitational collapse of the remaining cloud of debris. Consequently, the Moon's bulk chemical composition closely resembles that of Earth.

Look in detail at the Moon's chemical composition, however, and that story turns murky. For example, in the bright plains of the Moon's surface, called the lunar highlands, rocks contain smaller amounts of metal-bearing minerals relative to Earth. That finding might be explained if Earth had fully differentiated into a core, mantle and crust before the impact, leaving the Moon largely metal-poor. But turn to the Moon's maria — the large, darker plains — and the metal abundance becomes richer than that of many rocks on Earth.

This discrepancy has puzzled scientists, leading to numerous questions and hypotheses regarding how much the impacting protoplanet may have contributed to the differences. The Mini-RF team found a curious pattern that could lead to an answer.

Using Mini-RF, the researchers sought to measure an electrical property within lunar soil piled on crater floors in the Moon's northern hemisphere. This electrical property is known as the dielectric constant, a number that compares the relative abilities of a material and the vacuum of space to transmit electric fields, and could help locate ice lurking in the crater shadows. The team, however, noticed this property increasing with crater size.

For craters approximately 1 to 3 miles (2 to 5 kilometers) wide, the dielectric constant of the material steadily increased as the craters grew larger, but for craters 3 to 12 miles (5 to 20 kilometers) wide, the property remained constant.

"It was a surprising relationship that we had no reason to believe would exist," said Essam Heggy, coinvestigator of the Mini-RF experiments from the University of Southern California in Los Angeles and lead author of the published paper.

Discovery of this pattern opened a door to a new possibility. Because meteors that form larger craters also dig deeper into the Moon's subsurface, the team reasoned that the increasing dielectric constant of the dust in larger craters could be the result of meteors excavating iron and titanium oxides that lie below the surface. Dielectric properties are directly linked to the concentration of these metal minerals.

If their hypothesis were true, it would mean only the first few hundred meters of the Moon's surface is scant in iron and titanium oxides, but below the surface, there's a steady increase to a rich and unexpected bonanza.

Comparing crater floor radar images from Mini-RF with metal oxide maps from the LRO Wide-Angle Camera, Japan's Kaguya mission and NASA's Lunar Prospector spacecraft, the team found exactly what it had suspected. The larger craters, with their increased dielectric material, were also richer in metals, suggesting that more iron and titanium oxides had been excavated from the depths of 0.3 to 1 mile (0.5 to 2 kilometers) than from the upper 0.1 to 0.3 miles (0.2 to 0.5 kilometers) of the lunar subsurface.

"This exciting result from Mini-RF shows that even after 11 years in operation at the Moon, we are still making new discoveries about the ancient history of our nearest neighbor," said Noah Petro, the LRO project scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland. "The MINI-RF data is incredibly valuable for telling us about the properties of the lunar surface, but we use that data to infer what was happening over 4.5 billion years ago!"

These results follow recent evidence from NASA's Gravity Recovery and Interior Laboratory (GRAIL) mission that suggests a significant mass of dense material exists just a few tens to hundreds of kilometers beneath the Moon's enormous South Pole-Aitken basin, indicating that dense materials aren't uniformly distributed in the Moon's subsurface.

The team emphasizes that the new study can't directly answer the outstanding questions about the Moon's formation, but it does reduce the uncertainty in the distribution of iron and titanium oxides in the lunar subsurface and provide critical evidence needed to better understand the Moon's formation and its connection to Earth.

"It really raises the question of what this means for our previous formation hypotheses," Heggy said.

Anxious to uncover more, the researchers have already started examining crater floors in the Moon's southern hemisphere to see if the same trends exist there.