The Earth From The Moon

All cameras are susceptible to scattered light. You may have seen scattered light in pictures you have taken looking towards the Sun. Sunlight reflects off the optics and sometimes off the structure of the lens, and often appears as a gradient of brightness across the image. Attaching a baffle to your camera, like we did with the LROC Wide and Narrow Angle Cameras, can minimize this effect. More subtle effects are often present but usually you simply just don't notice artifacts because of strong color contrasts in the scene.

Since the Moon has only very small color contrasts, the LROC team must characterize even subtle scattered light effects within the 7-color Wide Angle Camera (WAC) images. Changes in composition (rock types) result in subtle differences of color, typically about 10% or less. For scientists to make accurate interpretations of WAC color maps, the amount of scattered light must be quantified (and preferably corrected). One way of measuring scattered light is imaging a bright object against a dark background. From the Moon, the Earth serves that function well.

While a series of WAC calibration images of the Earth were being acquired, the Narrow Angle Camera (NAC) was shuttered to capture this spectacular Earth view. The bottom of the Earth was clipped because the prediction of the exact time when the cameras' fields of view would cross the Earth was off by a few seconds.

The Earth as seen from the Moon! LROC NAC mosaic of images snapped on 12 June 2010 during a calibration sequence (Images E130954785L and E130954785R). Credit: NASA/Goddard/Arizona State University

Since the NAC acquires only one line of a picture at a time, the spacecraft had to be nodded across the Earth to build up the scene. The NAC Earth view is actually a mosaic of NAC-Left and NAC-Right images put together after calibration. The distance between the Moon and the Earth was 372,335 km when the picture was taken, with a pixel scale of about 3.7 km, and the center of this view of Earth is 25°N latitude, 114°E longitude (a few hundred kilometers north of Hong Kong).

It was a beautiful clear summer day over the North Pole. You can see ice covering most of the Arctic Ocean with a few leads of open water (dark) starting to open up. If you look very close you can follow the Lena River upstream from the Arctic Ocean all the way to Lake Baikal. Much of the Middle East was clear and you can trace spectacular swirl patterns of folded rock layers through Iran, Afghanistan, and Pakistan. These mountains formed as the Eurasian and Arabian tectonic plates collided.

AP: Arabian Peninsula; CS: Caspian Sea; H: Himalayan Mountains; L: Lena River; I: Indian Ocean; A: Australia; J: Japan; P: Pacific Ocean; large yellow arrow indicates approximate position of the North Pole. Credit: NASA/Goddard/Arizona State University

Browse the full-sized image at the LRO Camera website maintained by Arizona State University.

For more information visit http://www.nasa.gov/mission_pages/LRO/multimedia/lroimages/lroc-20100624-earth.html

Soviet Union Lunar Sample Return Missions

The Soviet Union successfully executed three robotic sample return missions as part of the Cold War competition with the United States. The first mission, Luna 16, returned a small sample (101 grams) from Mare Fecunditatis in September of 1970, a time between the US Apollo 12 and 14 manned landings. A year and half later (February 1972) Luna 20 returned 55 grams of soil from the Apollonius highlands region.

On Feb. 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/Goddard/Arizona State University

Luna 16 and 20 were very similar in design and sampling method. A drill at the end of the sampling arm collected soil from a few tens of cm below the surface. The arm then placed the sample into the return capsule on top of the vehicle. The distinctive shadow seen in the LROC image of Luna 20 is most likely that of the sampling arm. The Luna 20 sample contained minerals similar to those sampled by the US Apollo 16 astronauts two months later from the Cayley plains (8°58"S, 15°30"E).

Luna 16 robotic sample return spacecraft. Image courtesy National Space Science Data Center.

Enlargement of Luna 20 descent stage. Note the shadow of the sampling arm. Credit: NASA/Goddard/Arizona State University

In October of 1974 Luna 23 set down on Mare Crisium, however technical difficulties prevented it from successfully acquiring a sample. Undeterred, the Soviets tried again in August of 1976, this time with much better luck. Luna 24 was designed to auger over 2 meters into the lunar soil thus collecting a better section and a larger sample, 170 grams. The positions of Luna 23 and 24 were not well constrained and are reported as within several hundred meters of each other. From the new NAC images we can accurately measure the distance between the two landers to be about 2400 meters. However the absolute position of the landers is only know to about 500 meters accuracy. As the LRO mission ephemeris improves, the Luna absolute positions should be known to better than 100 meters. Scroll around in a mosaic of two NAC high Sun images (M111185087L,R) and find Luna 23 and Luna 24. Look for a few very bright pixels near Luna 24; they may be small pieces of material blown off the descent stage as the ascent staged blasted off towards Earth.

Luna 24 sitting on the edge of a 60 meter diameter crater, NAC image M119449091RE. Credit: NASA/Goddard/Arizona State University

The successful Soviet Luna sample return missions returned small, but important, samples from three locations on the Moon. In this new era of lunar exploration several countries plan to soft land on the Moon in the near future, the first soft-landed spacecraft since Luna 24. India and Russia plan to launch a lander and rover called Chandrayaan 2 in 2013. The Chinese Chang'e lunar exploration program also plans a soft landing in 2013.

For more information visit http://www.nasa.gov/mission_pages/LRO/multimedia/lroimages/lroc-20100316-luna.html

Digital Elevation Models of the Moon

Robotic exploration missions provide NASA vast amounts of data to prepare for future human exploration missions and learn more about the universe.

Objective: The U.S. Geological Survey (USGS) is working with NASA to make lunar maps. Digital elevation models (DEMs) will be used to map terrain, locate lunar resources and assess prospective landing sites.

Description: The USGS constructed this DEM of a 50x80 km area of the Aristarchus Plateau, including the “Cobra Head.” Using Apollo Panoramic Camera images, the elevation of each lunar feature is calculated to an accuracy of 0.75 to 1.2 m.

Timeframe: The new Lunar Mapping and Modeling Project (LMMP) Web site, available in late fall 2010, will build integrated data sets from the Lunar Reconnaissance Orbiter (LRO), and other lunar missions over the next two years. The USGS generated maps will be available on that Web site.

Application: An integrated, easy-to-use Web site allows easy access to current lunar data and can be used by any scientist, student or lunar explorer.

For more information visit http://www.nasa.gov/exploration/multimedia/highlights/2010-09B.html

The Orientale Basin

Using sophisticated so-called "photogrammetric" techniques and computer software, a lunar terrain model can be created combining several images that show similar areas from slightly different angles. LROC's wide angle camera (WAC) has a ground resolution of approximately 100 m/pixel from LRO's nominal orbit altitude of 65 km. The camera is taking image swaths 70 km wide along LRO's ground-track. Therefore, images from adjacent orbits show substantial overlap and strong stereo effects in the overlapping images. Image overlap amounts to approximately 50 percent near the equator.

This image shows a Digital Terrain Model (DTM) of the large Orientale Basin (1,100 km diameter, about 684 miles), located on the western hemisphere of the moon, produced from stereo images obtained by LRO's Wide-Angle Camera, part of the LROC instrument. There are no oceans on the moon, so it doesn't make sense to describe any of these altitudes as above or below sea level, but green areas represent something of an average lunar height. Lower areas are shaded blue, with higher altitudes in red. The lowest areas are about 15,420 feet below the average height, with the highest being about 30,840 feet above average. Mt. Everest, for comparison, is 29,029 feet tall. Credit: NASA/Goddard/Arizona State University

Several hundred WAC images were combined to form this model. It is a subset of an almost global model, which is currently under construction and which will consist of more than 10,000 WAC images. This particular terrain model was produced using a software system that was originally developed by the German Aerospace Center for the High Resolution Stereo Camera (HRSC) on the European Mars Express Mission.

Related Links

› Arizona State University's Web site for the LRO Camera
› More images from Arizona State University's LROC site

For more information visit http://www.nasa.gov/mission_pages/LRO/multimedia/lroimages/lroc-20100120-orientale.html

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LRO Team Begins to Release New Image Series

Today, the LROC Team begins a new series of Featured Images highlighting the regions of interest for potential future human and robotic lunar exploration that LRO is imaging for NASA's Constellation Program. There are 50 of these regions, which were selected prior to LRO’s launch based on expert input from the lunar science community and NASA engineers. For each of these 50 regions, the LROC Team is collecting a comprehensive set of image data.

These images, and the associated information products derived from them (such as boulder distribution maps, slope maps and digital terrain models), will guide engineers and scientists as they develop their plans for how they would continue to explore the moon both robotically and with humans.

A very subtle mare-highlands boundary in Mare Moscoviense on the lunar farside, near the center of the Constellation Program region of interest. The generalized geologic contact between the mare and the highlands has been highlighted (mare to the left, highlands to the right). Image width is 1.8 km. Credit: NASA/Goddard/Arizona State University

Lunar scientists have been studying the vast data returned from the Apollo missions for almost 40 years. As a result, much is known about the moon. Even so, there remains much that we do not know about the moon. Accordingly, each of these 50 regions is associated with either an immensely compelling lunar science question or an exploration-enabling resource, or both, that will be useful to future explorers. However, these 50 regions aren't intended as actual NASA landing sites, but instead are representative locations whose study will provide mission planners and lunar scientists working on future human and robotic lunar exploration with lots of data for a comprehensive suite of interesting and relevant terrains all over the lunar surface.

Figure 2: Mosaics from the Clementine mission showing the lunar near side and lunar far side, with the location of Mare Moscoviense highlighted. Credit: U.S. Geological Survey/Arizona State University

Mare Moscoviense: Window to Far Side Volcanism

It's clear from looking at pictures of the moon that the near side and the far side are very different from a geologic standpoint. The darker, basaltic mare deposits dominate the near side, whereas the far side is dominated by bright deposits of anorthosite thought to be remnants of the moon's original crust. Mare Moscoviense is one of the few (and also the largest) deposits of mare basalts on the lunar far side.

Figure 3: LROC WAC mosaic with the location of the proposed Constellation region of interest indicated with an arrow. Credit:NASA/Goddard/Arizona State University

Why are there so many mare basalts on the near side, but so few on the far side? Lunar scientists simply don't know the answer to that question. One idea is that the far side crust is simply thicker than the near side crust, and rising basaltic magma simply solidified before it was able to push through the thicker far side crust. That's where Moscoviense comes in. We know enough about the Moscoviense region from previous missions that we have a well-defined set of questions that potential future missions might be able to answer. For example, the Lunar Prospector mission showed that there are high concentrations of thorium in the Moscoviense basin. Thorium acts as a tracer for the lunar KREEP (potassium K, rare earth elements, and phosphorus) geochemical component found in abundance on the near side but not on the far side. Understanding the extent and distribution of thorium in the basin may tell us about the global distribution of the lunar KREEP component and thus the evolution of the lunar mantle. We also know from the Clementine mission that the Moscoviense basalts are rich in both iron and titanium. Since basalts form by partial melting of the lunar mantle, sampling Moscoviense basalts provides lunar scientists with vital insights into how the lunar mantle on the far side differs from the near side mantle, which in turn would help us to learn why mare basalts are so much rarer on the far side and provide key insights about the formation of all of the terrestrial planets, including Mars and Earth.

Figure 4: 20x down-sampled mosaic of LROC NAC images M105887165LE and M105887165RE showing location of the proposed Project Constellation design reference exploration area. Credit: NASA/Goddard/Arizona State University

For these reasons, a Constellation Program region of interest is located within Mare Moscoviense. As you can see in Figures 3 and 4, the region is at the edge of Moscoviense, allowing explorers to collect samples from both the mare basalts and the surrounding highlands terrain during their traverses. The materials at the edge of the basin provide important insights into the formation of the Moscoviense basin itself. By exploring and sampling the Moscoviense region, we would date the basalt flows and definitively determine their composition. This sampling would let us determine how Moscoviense basalts differ from the near side basalts sampled during Apollo. Age-dating Moscoviense basalts also provides important insights into the history of lunar volcanism by determining whether the Moscoviense basalts are older or younger than near side basalts.

While the scientific goals of exploring the Moscoviense region are certainly important, no less important is access to key lunar resources. The lunar regolith (the broken-up rocks and impact products that make up the first 10 meters or so of the lunar surface) in this region is derived in part from the local titanium-rich Moscoviense basalts. This regolith material could be used for a variety of vital purposes, including the construction of human habitats, radiation shielding, or as feedstock for local resource utilization. Taking a longer view, titanium is an important industrial material on Earth, and it will be very important for indigenous lunar industrial development.

Related Links

› Arizona State University's Web site for the LRO Camera
› Explore the Mare Moscoviense Constellation site for yourself on Arizona State University's LROC site
› Earlier image showing Mare Moscoviense

For more information visit http://www.nasa.gov/mission_pages/LRO/multimedia/lroimages/lroc-20100107-new-images.html

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LCROSS Impact Data Indicates Water on Moon

The argument that the moon is a dry, desolate place no longer holds water.

Secrets the moon has been holding, for perhaps billions of years, are now being revealed to the delight of scientists and space enthusiasts alike.

NASA today opened a new chapter in our understanding of the moon. Preliminary data from the Lunar CRater Observation and Sensing Satellite, or LCROSS, indicates that the mission successfully uncovered water during the Oct. 9, 2009 impacts into the permanently shadowed region of Cabeus cater near the moon’s south pole.

The impact created by the LCROSS Centaur upper stage rocket created a two-part plume of material from the bottom of the crater. The first part was a high angle plume of vapor and fine dust and the second a lower angle ejecta curtain of heavier material. This material has not seen sunlight in billions of years.

The visible camera image showing the ejecta plume at about 20 seconds after impact. Credit: NASA

"We're unlocking the mysteries of our nearest neighbor and by extension the solar system. It turns out the moon harbors many secrets, and LCROSS has added a new layer to our understanding," said Michael Wargo, chief lunar scientist at NASA Headquarters in Washington.

Scientists have long speculated about the source of vast quantities of hydrogen that have been observed at the lunar poles. The LCROSS findings are shedding new light on the question of water, which could be more widespread and in greater quantity than previously suspected.

Permanently shadowed regions could hold a key to the history and evolution of the solar system, much as an ice core sample taken on Earth reveals ancient data. In addition, water, and other compounds represent potential resources that could sustain future lunar exploration.

Since the impacts, the LCROSS science team has been working almost nonstop analyzing the huge amount of data the spacecraft collected. The team concentrated on data from the satellite's spectrometers, which provide the most definitive information about the presence of water. A spectrometer examines light emitted or absorbed by materials that helps identify their composition.

Data from the down-looking near-infrared spectrometer. The red curve shows how the spectra would look for a "grey" or "colorless" warm (230 C) dust cloud. The yellow areas indicate the water absorption bands. Credit: NASA

"We are ecstatic," said Anthony Colaprete, LCROSS project scientist and principal investigator at NASA's Ames Research Center in Moffett Field, Calif. "Multiple lines of evidence show water was present in both the high angle vapor plume and the ejecta curtain created by the LCROSS Centaur impact. The concentration and distribution of water and other substances requires further analysis, but it is safe to say Cabeus holds water."

The team took the known near infrared spectral signatures of water and other materials and compared them to the spectra collected by the LCROSS near infrared spectrometer of the impact.

"We were only able to match the spectra from LCROSS data when we inserted the spectra for water," said Colaprete. "No other reasonable combination of other compounds that we tried matched the observations. The possibility of contamination from the Centaur also was ruled out."

Additional confirmation came from an emission in the ultraviolet spectrum that was attributed to hydroxyl, one product from the break-up of water by sunlight. When atoms and molecules are excited, they release energy at specific wavelengths that are detected by the spectrometers. A similar process is used in neon signs. When electrified, a specific gas will produce a distinct color. The ultraviolet visible spectrometer detected hydroxyl signatures just after impact that are consistent with a water vapor cloud in sunlight.

The visible camera image showing the ejecta plume at about 20 seconds after impact.Credit: NASA

Data from the other LCROSS instruments are being analyzed for additional clues about the state and distribution of the material at the impact site. The LCROSS science team along with colleagues are poring over the data to understand the entire impact event, from flash to crater, with the final goal being the understanding of the distribution of materials, and in particular volatiles, within the soil at the impact site.

"The full understanding of the LCROSS data may take some time. The data is that rich," said Colaprete. "Along with the water in Cabeus, there are hints of other intriguing substances. The permanently shadowed regions of the moon are truly cold traps, collecting and preserving material over billions of years."

LCROSS was launched June 18, 2009 as a companion mission to the Lunar Reconnaissance Orbiter, or LRO, from NASA's Kennedy Space Center in Florida. After separating from LRO, the LCROSS spacecraft held onto the spent Centaur upper stage rocket of the launch vehicle, executed a lunar swingby and entered into a series of long looping orbits around the Earth.

After traveling approximately 113 days and nearly 5.6 million miles (9 million km), the Centaur and LCROSS separated on final approach to the moon. Traveling as fast as a speeding bullet, the Centaur impacted the lunar surface shortly after 4:31 a.m. PDT Oct. 9 with LCROSS watching with its onboard instruments. Approximately four minutes of data was collected before the LCROSS itself impacted the lunar surface.

Working closely with scientists from LRO and other observatories that viewed the impact, the LCROSS team is working to understand the full scope of the LCROSS data. LRO continues to make passes over the impact site to give the LCROSS team additional insight into the mechanics of the impact and its resulting craters.

What other secrets will the moon reveal? The analysis continues!

Jonas Dino
NASA Ames Research Center

For more information visit http://www.nasa.gov/mission_pages/station/science/hico_raids.html

NASA Moon Mission Wins Second-Best of 'What's New' Award by Popular Science

The Lunar Reconnaissance Orbiter (LRO) is cited as one of the best innovations in aviation in the December issue of Popular Science.

"It is an honor to be selected by Popular Science for Best of What’s New in aviation," said Craig Tooley, LRO project manager from NASA’s Goddard Space Flight Center in Greenbelt, Md. "There was tremendous excitement about the United States returning to the moon after many years. I believe our selection is a result of that excitement."

Each year, the editors of Popular Science review thousands of products in search of the top 100 tech innovations of the year; breakthrough products and technologies that represent a significant leap in their categories. The winners -- the Best of What's New -- are awarded inclusion in the much-anticipated December issue of Popular Science, the most widely read issue of the year since the debut of Best of What's New in 1987. Best of What's New awards are presented to 100 new products and technologies in 11 categories: Automotive, Aviation and Space, Computing, Engineering, Gadgets, Green Technology, Home Entertainment, Security, Home Technology, Personal Health and Recreation.

"For 22 years, Popular Science has honored the innovations that surprise and amaze us -- those that make a positive impact on our world today and challenge our views of what’s possible in the future." said Mark Jannot, editor-in-chief of Popular Science. "The Best of What’s New Award is the magazine’s top honor, and the 100 winners -- chosen from among thousands of entrants -- represent the highest level of achievement in their fields."

Artist concept of the Lunar Reconnaissance Orbiter. Credit: NASA

LRO launched from Kennedy Space Center, Fla. on June 18, 2009. Since that time the spacecraft has completed calibration and commissioning. LRO has already begun its detailed survey of the moon. First results from the mission included -- new looks at 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; and detailed information on terrain roughness.

LRO is scheduled for a one year exploration mission in a polar orbit about 31 miles above the lunar surface. During the next year, LRO will produce a complete map of the lunar surface in unprecedented detail, search for resources and potential safe landing sites for human explorers and measure lunar temperatures and radiation levels.

NASA’s Goddard Space Flight Center built and manages the mission for the Exploration Systems Mission Directorate at NASA Headquarters in Washington. The Institute for Space Research, Moscow, provided the neutron detector aboard the spacecraft.

Nancy N. Jones
NASA's Goddard Space Flight Center

For more information visit http://www.nasa.gov/mission_pages/LRO/news/popular_science.html

LRO Gets Additional View of Apollo 11 Landing Site

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

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.

Enlargement of area surrounding Apollo 11 landing site. Credit: NASA/GSFC/Arizona State University

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

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.

For more information visit http://www.nasa.gov/mission_pages/LRO/multimedia/lroimages/lroc_200911109_apollo11.html

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.

New view of the Apollo 12 landing site in Oceanus Procellarum imaged from the LRO mapping orbit. Small black arrows show locations where astronaut footpaths can be clearly discerned. Image width is 490 meters. Credit: NASA/GSFC/Arizona State University

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.

Astronaut Al Bean unloading the plutonium core that powered the ALSEP. Credit: NASA

At the beginning of the first extravehicular activities (EVA) the astronauts learned to walk in 1/6 gravity, unloaded equipment, and setup the camera and flag resulting in a high traffic area that can now be seen from orbit as a low albedo halo surrounding the LM.

Enlarged view showing details of the Apollo 12 landing site. In the upper left, you can see the Apollo Lunar Surface Experiments Package, or ALSEP. The positions of the ALSEP central station, seismometer, Radioisotope Thermoelectric Generator (RTG), magnetometer, Suprathermal Ion Detector Experiment (SIDE), and Cold Cathode Gauge (CCG) have been highlighted. Credit: NASA/GSFC/Arizona State University

For more information visit http://www.nasa.gov/mission_pages/LRO/multimedia/lroimages/lroc_20091104_apollo12.html

Illumination Comparison of a Mare Crater

These two images, subsets of M104670019L (incidence angle 50.2°) and M107035386L (incidence angle 24.6°) illustrate the effects of illumination angle on recognition of different aspects of the lunar surface. Each scene is about 550 meters wide and 1.1 km tall.

On the left, the morphology of this small mare crater (200 m diameter) is clear, whereas in the image on the right differences in brightness (reflectance or albedo) are highlighted defining ejecta patterns. Explorers might prefer the low-Sun image for landing or planning traverses, while the high-Sun image guides the eye to ejecta. One of the strengths of the LRO mission is that it passes over the same region numerous times, and each time the Sun angle is different allowing LROC to build up an image set over a wide range of angles.

Same crater from two LROC NAC frames under very different lighting. On the left the Sun was low to the horizon and on the right the Sun was high, approaching noon. Under low sun surface roughness is quite evident; under high sun (right) variations in brightness (reflectance) dominate the scene [NASA/GSFC/Arizona State University].

This crater also illustrates the influence of pre-existing regolith (soil) structure on crater morphology. When the regolith is relatively thin, over more-or-less intact bedrock, small craters often do not have a simple bowl shape. This crater is filled with rubble and there are numerous blocks up to 10 m in diameter scattered around the rim and the interior, indicating that bedrock was excavated during the impact. In cases where impacts occur in a thick regolith, the crater does not excavate blocky rocks but rather fine-grained soil, resulting a nicely defined bowl shape.

For more information visit http://www.nasa.gov/mission_pages/LRO/multimedia/lroimages/20091021_mare.html

Diviner Observes LCROSS Impact

The LRO Diviner instrument obtained infrared observations of the LCROSS impact. LRO flew by the LCROSS Centaur impact site 90 seconds after impact at a distance of ~80 km. Diviner was commanded to observe the impact site on eight successive orbits, and obtained a series of thermal maps before and after the impact at approximately two hour intervals at an angle of approximately 48 degrees off nadir. In this viewing geometry, the spatial footprint of each Diviner detector was roughly 300 by 700 meters.

Figure 1 shows the locations of the Diviner LCROSS impact swaths overlain on a grayscale daytime thermal map of the Moon’s south polar region. Diviner data were used to help select the final LCROSS impact site inside Cabeus Crater, which sampled an extremely cold region in permanent shadow that can serve as an effective cold trap for water ice and other frozen volatiles. Credit NASA/GSFC/UCLA

Figure 2 shows preliminary, uncalibrated Diviner thermal maps of the impact site acquired two hours before the impact, and 90 seconds after the impact. The thermal signature of the impact was clearly detected in all four Diviner thermal mapping channels. Since the LCROSS impact feature is predicted to be significantly smaller than a Diviner footprint, its detection is consistent with the notion that the LCROSS impact resulted in significant local heating of the lunar surface. Credit NASA/GSFC/UCLA

LRO Website.

For more information visit http://www.nasa.gov/mission_pages/LCROSS/main/diviner_impacts.html

LCROSS Viewer's Guide

Just imagine. A spaceship plunges out of the night sky, hits the ground and explodes. A plume of debris billows back into the heavens, leading your eye to a second ship in hot pursuit. Four minutes later, that one hits the ground, too. It's raining spaceships!

Put on your hard hat and get ready for action, because on Friday, Oct. 9, what you just imagined is really going to happen--and you can have a front row seat.

The impact site is crater Cabeus near the moon's south pole. NASA is guiding the Lunar Crater Observation and Sensing Satellite (LCROSS for short) and its Centaur booster rocket into the crater's floor for a spectacular double-impact designed to unearth signs of lunar water.

A computer visualization of LCROSS hitting the Moon on Oct. 9th. Credit: NASA

There are two ways to watch the show.

First, turn on NASA TV. The space agency will broadcast the action live from the Moon, with coverage beginning Friday morning at 3:15 am PDT (10:15 UT). The first hour or so, pre-impact, will offer expert commentary, status reports from mission control, camera views from the spacecraft, and telemetry-based animations.

The actual impacts commence at 7:30 am EDT (11:30 UT). The Centaur rocket will strike first, transforming 2200 kg of mass and 10 billion joules of kinetic energy into a blinding flash of heat and light. Researchers expect the impact to throw up a plume of debris as high as 10 km.

Close behind, the LCROSS mothership will photograph the collision for NASA TV and then fly right through the debris plume. Onboard spectrometers will analyze the sunlit plume for signs of water (H2O), water fragments (OH), salts, clays, hydrated minerals and assorted organic molecules.

"If there's water there, or anything else interesting, we'll find it," says Tony Colaprete, the mission's principal investigator.

Next comes the mothership's own plunge. Four minutes after the Centaur "lands," the 700 kg LCROSS satellite will strike nearby, sending another, smaller debris plume over the rim of Cabeus.

The Hubble Space Telescope, the Lunar Reconnaissance Orbiter (LRO) and hundreds of telescopes great and small on Earth will scrutinize the two plumes, looking for signs of water and the unexpected.

And that brings us to the second way to see the show: Grab your telescope.

"We expect the debris plumes to be visible through mid-sized backyard telescopes--10 inches and larger," says Brian Day of NASA/Ames. Day is an amateur astronomer and the Education and Public Outreach Lead for LCROSS. "The initial explosions will probably be hidden behind crater walls, but the plumes will rise high enough above the crater's rim to be seen from Earth."

The Pacific Ocean and western parts of North America are favored with darkness and a good view of the moon at the time of impact. Hawaii is the best place to be, with Pacific coast states of the USA a close second. Any place west of the Mississippi River, however, is a potential observing site.

When the plumes emerge from Cabeus, they will be illuminated by sunshine streaming over the polar terrain. The crater itself will be in the dark, however, permanently shadowed by its own walls. "That's good," says Day. "The crater's shadows will provide a dark backdrop for viewing the sunlit plumes."

In an earlier stage of mission planning, scientists hoped to strike a crater closer to the Moon's limb so that the plumes would billow out against the dark night sky, providing maximum contrast for observers on Earth. However, recent data from NASA's Lunar Reconnaissance Orbiter, Japan's Kaguya spacecraft and India's Chandrayaan-1 probe altered those plans.

"We've just learned that Cabeus may contain relatively-rich deposits of hydrogen and/or frozen water," says Colaprete. "Cabeus is not as close to the lunar limb as we would have liked, but it seems to offer us the best chance of hitting H2O."

The LCROSS team hopes many people—amateurs and professionals alike—will observe and photograph the plumes. "The more eyes the better," says Day. "Remember, we've never done this before. We're not 100% sure what will happen, and big surprises are possible."

Veteran amateur astronomer Kurt Fisher has prepared a 13 MB slideshow to help fellow amateurs locate and witness the plumes: download it . There is also an online LCROSS observer's group where novices can read introductory articles and chat with other observers.

"This is a wonderful opportunity for citizen scientists to join NASA in the process of discovery," says Day, who urges observers to submit their images to the LCROSS Citizen Science Site. "It's a great adventure, and anyone can participate."

Imagine that.

Dr. Tony Phillips
Science@NASA

For more information visit http://www.nasa.gov/mission_pages/LCROSS/main/LCROSS_Viewers_Guide.html

NASA Goddard Shoots the Moon to Track LRO

On certain nights, an arresting green line pierces the sky above NASA's Goddard Space Flight Center in Greenbelt, Md. It's a laser directed at the moon, visible when the air is humid. No, we're not repelling an invasion. Instead, we're tracking our own spacecraft.

28 times per second, engineers at NASA Goddard fire a laser that travels about 250,000 miles to hit the minivan-sized Lunar Reconnaissance Orbiter (LRO) spacecraft moving at nearly 3,600 miles per hour as it orbits the moon.

Goddard's Laser Ranging Facility directing a laser (green beam) toward the LRO spacecraft in orbit around the moon (white disk). The moon has been deliberately over-exposed to show the laser. Credit: Tom Zagwodzki/Goddard Space Flight Center

The first laser ranging effort to track a spacecraft beyond low-Earth orbit on a daily basis produces distance measurements accurate to about four inches (10 centimeters). For comparison, the microwave stations tracking LRO measure its range to a precision of about 65 feet (20 meters).

"Current lunar maps are not as accurate as we’ll need to return people safely to the moon," said Ronald Zellar of NASA Goddard, team lead for the LRO laser ranging system. "In order to make an accurate map, first you need to know where you are. Knowing the precise range to LRO is necessary for its instruments to produce much more accurate maps, with errors reduced to the size of humans or rovers."

"A further benefit of laser ranging to LRO is that it can improve knowledge of the moon's orientation and gravity, which are central to understanding its interior structure and to precision navigation," said Gregory Neumann, a Geophysicist at NASA Goddard.

Engineers use a telescope at the ground station on the Goddard campus to direct laser pulses toward LRO. The range to LRO is calculated by measuring how long it took the laser to reach the spacecraft.

The laser ranging to LRO is one way, meaning that the laser is directed at LRO, which records the time of arrival and sends the data back to ground stations on Earth by its radio telemetry link. This is the first time repeated, one-way tracking has been used for spacecraft ranging. Typical satellite laser ranging, used for spacecraft in low-Earth orbit, is two way, meaning the laser is simply reflected off the spacecraft and the time of flight recorded when it returns to the ground.

The advantage of LRO's one-way system is that a less expensive, lower-power laser system can be used -- especially important since the distance to LRO is hundreds of times greater than that to most Earth-orbiting spacecraft. Also, only a small receiver is needed on the spacecraft instead of a large retro-reflector array.

Goddard's Laser Ranging Facility from another side. Credit: Tom Zagwodzki/Goddard Space Flight Center

LRO's laser tracking presents unique challenges, however. First, there's the issue of avoiding interference. The laser pulses from Earth are received by a small telescope on LRO and transferred to the spacecraft’s laser altimeter instrument. The detector on this instrument performs double-duty, detecting both the laser ranging pulses as well as the pulses from its own laser reflected off the lunar surface. The instrument’s laser is used to build three-dimensional (topographic) maps of the lunar landscape and those pulses could hit the detector at the same time as the laser ranging pulses from Earth, confusing the data. So the pulses from Earth have to be carefully timed to avoid interfering with the instrument’s operation. Since the instrument sends laser pulses 28 times per second to the lunar surface, the laser ranging pulses are sent at the same rate but shifted in time to avoid interference. "It's like shooting at a spinning coin from a mile away and being able to hit it on the edge as it spins," said Neumann.

Another challenge is precise time measurement. Since the range to LRO is calculated by measuring how long it took the laser to reach the spacecraft, any variations in the time measurements will produce variations in the range estimates. LRO has a timing system that uses a crystal oscillator -- the heart of which is a vibrating crystal -- to measure time precisely. The oscillator is accurate to one part in a trillion over an hour. However, the rate at which the crystal vibrates changes with temperature, so the crystal is housed in a small oven which must be carefully controlled to maintain a stable temperature.

Then there's the difficulty of hitting a moving target. Since LRO is constantly moving in its orbit, the ground station must fire the laser pulses at a point in front of the spacecraft to compensate for the spacecraft's motion while the pulse is in-flight toward the moon. This is one of the reasons why LRO still relies on the traditional microwave tracking systems. They need the position of the spacecraft to know where to point the laser. The laser spot is 12 miles wide when it gets to the moon. Although this seems large on a human scale, it’s small in space and it would be easy to miss a tiny spacecraft moving 3,600 miles per hour. Even though the precision isn’t as great, without the microwave tracking system, the laser ranging system won’t work. This requires the LRO Mission Operations Center to track, predict, and communicate the position of the spacecraft to the laser ranging ground station.

Finally, there's the problem of bad weather; specifically, clouds. The laser can't penetrate thick cloud cover, so laser ranging is not available in those situations. Fortunately, there's plenty of opportunity to collect data over the course of LRO's one-year mission. "We're ranging to LRO whenever the moon is visible, 24 hours a day, 7 days a week," said Jan McGarry of NASA Goddard, ground system lead for laser ranging.

"Two-way satellite laser ranging (SLR) was developed at NASA Goddard in the 1960s," adds McGarry. "Since then, SLR has become a global effort, with about 30 countries participating and about 40 satellites carrying laser reflectors. NASA has eight SLR stations around the world, and Goddard is responsible for them. NASA is part of the global International Laser Ranging Service, an organization that provides a coordinated administration for all participating SLR stations and analysis centers." LRO's laser ranging effort is funded by the LRO project.

For more about Goddard's laser ranging facility, refer to:

http://lrolr.gsfc.nasa.gov/

Bill Steigerwald
NASA Goddard Space Flight Center

For more information visit http://www.nasa.gov/mission_pages/LRO/news/LRO_lr.html

NASA's LCROSS Mission Changes Impact Crater

NASA's Lunar Crater Observation and Sensing Satellite mission (LCROSS) based on new analysis of available lunar data, has shifted the target crater from Cabeus A to Cabeus (proper).

The decision was based on continued evaluation of all available data and consultation/input from members of the LCROSS Science Team and the scientific community, including impact experts, ground and space based observers, and observations from Lunar Reconnaissance Orbiter (LRO), Lunar Prospector (LP), Chandrayaan-1 and JAXA's Kaguya spacecraft. This decision was prompted by the current best understanding of hydrogen concentrations in the Cabeus region, including cross-correlation between the latest LRO results and LP data sets.

The general consensus of lunar experts led by the LCROSS science team is that Cabeus shows, with the greatest level of certainty, the highest hydrogen concentrations at the south pole. Further consideration of the most current terrain models provided by JAXA's Kaguya spacecraft and the LRO Lunar Orbiter Laser Altimeter (LOLA) was important in the decision process.The models show a small valley in an otherwise tall Cabeus perimeter ridge, which will allow for sunlight to illuminate the ejecta cloud on Oct. 9, and much sooner than previously estimated for Cabeus. While the ejecta does have to fly to higher elevations to be observed by Earth assets, a shadow cast by a large hill along the Cabeus ridge, provides an excellent, high-contrast, back drop for ejecta and vapor measurements.

The LCROSS team concluded that Cabeus provided the best chance for meeting its mission goals. The team critically assessed and successfully advocated for the change with the Lunar Precursor Robotic Program (LPRP) office. The change in impact crater was factored into LCROSS' most recent Trajectory Correction Maneuver, TCM7.

During the last days of the mission, the LCROSS team will continue to refine the exact point of impact within Cabeus crater to avoid rough spots, and to maximize solar illumination of the debris plume and Earth observations.

Jonas Dino
Ames Research Center, Moffett Field, Calif.

For more information visit http://www.nasa.gov/centers/ames/news/features/2009/LCROSS_new_crater.html

NASA's LCROSS Mission Changes Impact Crater

MOFFETT FIELD, Calif. -- NASA's Lunar Crater Observation and Sensing Satellite mission (LCROSS) based on new analysis of available lunar data, has shifted the target crater from Cabeus A to Cabeus (proper).

The decision was based on continued evaluation of all available data and consultation/input from members of the LCROSS Science Team and the scientific community, including impact experts, ground and space based observers, and observations from Lunar Reconnaissance Orbiter (LRO), Lunar Prospector (LP), Chandrayaan-1 and JAXA's Kaguya spacecraft. This decision was prompted by the current best understanding of hydrogen concentrations in the Cabeus region, including cross-correlation between the latest LRO results and LP data sets.

The general consensus of lunar experts led by the LCROSS science team is that Cabeus shows, with the greatest level of certainty, the highest hydrogen concentrations at the south pole. Further consideration of the most current terrain models provided by JAXA's Kaguya spacecraft and the LRO Lunar Orbiter Laser Altimeter (LOLA) was important in the decision process.The models show a small valley in an otherwise tall Cabeus perimeter ridge, which will allow for sunlight to illuminate the ejecta cloud on Oct. 9, and much sooner than previously estimated for Cabeus. While the ejecta does have to fly to higher elevations to be observed by Earth assets, a shadow cast by a large hill along the Cabeus ridge, provides an excellent, high-contrast, back drop for ejecta and vapor measurements.

The LCROSS team concluded that Cabeus provided the best chance for meeting its mission goals. The team critically assessed and successfully advocated for the change with the Lunar Precursor Robotic Program (LPRP) office. The change in impact crater was factored into LCROSS' most recent Trajectory Correction Maneuver, TCM7.

During the last days of the mission, the LCROSS team will continue to refine the exact point of impact within Cabeus crater to avoid rough spots, and to maximize solar illumination of the debris plume and Earth observations.

The Near Infrared (0.9-1.7 mm) Camera #2 image of Earth as part of a LCROSS payload calibration activity on Sept. 18, 2009. At the time of this image, the LCROSS spacecraft was nominally 348,000 miles (559,400 km) from Earth. The inset shows the Earth face as seen by the LCROSS spacecraft. The Earth’s north pole is indicated by the arrow. The image on right shows water vapor as seen by GOES at a similar time as the LCROSS observation. The red letters indicate potential weather features common in both images. Credit: NASA Ames

Shown here is the slightly greater than quarter-Earth, sized ~1.5 deg along its diameter, in four colors. The false color (where red is warm, blue is cold) mid-infrared images reveal warmer summer mid-Atlantic temperatures about the equator and Northern Hemisphere. The images also reveal the whole Earth’s disk. South America is to the left. Africa is to the right. Antarctica is at the bottom. All instruments performed well during the calibration. Credit: NASA Ames

For more information visit http://www.nasa.gov/mission_pages/LCROSS/main/index.html

Centaur is No Longer the Bridesmaid

Centaur was the unnamed companion to the Atlas V rocket when it launched from Cape Canaveral, Fla., on June 18, 2009. Their mission: lift NASA's Lunar Reconnaissance Orbiter (LRO) into its lunar orbit. Piggybacking a ride on the Centaur was also the Lunar Crater Observation and Sensing Satellite (LCROSS) that will impact the moon in October. But something is different about this mission for Centaur: instead of quietly parking itself in a long-duration orbit of the earth, Centaur accompanied the two spacecraft on their journey toward the moon. What is more, Centaur will be the center of attention for a few glorious minutes this October.

On Cape Canaveral Air Force Station's skid strip in Florida, the crane is being removed from the Centaur stage of the Atlas V rocket after placing the Centaur on the flatbed truck. The Centaur will be transported to the Astrotech facility in Titusville, Fla. Photo credit: NASA/Cory Huston

The main LCROSS mission objective is to confirm the presence or absence of water ice in a permanently shadowed crater near a lunar polar region. Mission scientists have determined that the best way to do this is to send one or more objects into the surface of the moon to generate a large plume that can be studied to determine the presence of water ice. LCROSS is a small spacecraft, and besides not being able to make a major impact, its primary role is to observe a larger impact. That creates the opportunity for Centaur to take center stage.

LCROSS, still attached to its Centaur upper stage rocket, executed a fly-by of the moon on June 23, 2009 and entered into an elongated Earth orbit to position LCROSS for impact on a lunar pole. On final approach, the shepherding spacecraft and Centaur will separate. The Centaur will act as a heavy impactor to create a debris plume that will rise above the lunar surface. Projected impact at the lunar South Pole is currently: Oct 9, 2009 at 7:30 a.m. EDT. The Centaur will excavate a crater approximately 20 meters wide and almost 3 meters deep. More than 250 metric tons of lunar dust will be lofted above the surface of the moon.

Following four minutes behind, the shepherding spacecraft will fly through the debris plume, collecting and relaying data back to Earth before impacting the lunar surface and creating a second debris plume.

On Cape Canaveral Air Force Station's Launch Complex 41, the crane lifts the Centaur upper stage into the Vertical Integration Facility for installation onto the Atlas V first stage, already in the tower. Photo credit: NASA/Jack Pfaller.

For almost 30 years, the NASA Glenn Research Center in Cleveland, Ohio, was responsible for the technical and cost and schedule management of the Centaur rocket. This program had an extraordinary operational success record. It was developed as an upper stage launch vehicle to be used with a first stage booster rocket, the Atlas rocket. Centaur's first mission objective was to send the unmanned Surveyor spacecraft to the Moon. Centaur has been used to boost satellites into orbit and propel probes into space. Mariner, Pioneer, Viking and Voyager spacecraft all got a boost from Centaur and provided invaluable data on these planets. Centaur also helped to revolutionize communication and expand the frontiers of space. In all, Glenn used Centaur for more than 100 unmanned launches. Centaur has quietly continued as the upper stage of the Atlas family of rockets from United Launch Alliance and the retired Titan IV from Lockheed Martin.

For each of its previous missions, Centaur quietly did its job and retreated out of the limelight. This time, Centaur is going out in style!

Go Centaur!

David DeFelice NASA Glenn Research Center

Note: NASA’s Ames Research Center, Moffett Field, Calif., is overseeing the development of the LCROSS mission with its spacecraft and integration partner, Northrop Grumman, Redondo Beach, Calif.

Read more about Centaur's history.

For more information visit http://www.nasa.gov/mission_pages/LCROSS/main/centaur_full_story.html

Lunar South Pole -- Out of the Shadows

During the LRO Commissioning Phase, the high-resolution Lunar Reconnaissance Orbiter Camera (LROC) captured this 1-m pixel scale (angular resolution) two-image mosaic of the lunar south pole, which is located on the rim of the 19-km diameter Shackleton crater. At meter scales features such as boulders and ridges can be mapped, paving the way for future explorers. Right now we know little of the poles and much is to be learned from the data now being returned from LRO. The rim of Shackleton crater is a prime candidate for future human exploration due to its proximity to permanently shadowed regions and nearby peaks that are illuminated for much of the year. The permanent shadow may harbor cold-trapped volatiles deposited as comets and asteroids impacted the Moon over the past billion years or more. Highly illuminated peaks provide opportunities for solar power during most of the year for future human habitation.

Over the past year the Japanese Kaguya and Indian Chandrayaan spacecraft gave us our first high-resolution look at the lunar south pole and Shackleton crater and revealed an exceptionally deep and rugged interior for its size. Usually craters fill in with time as their walls slump and material from afar is thrown in by distant impacts. Since Shackleton crater is so deep and rough inside scientists might infer it is relatively young. However, much of the rim of Shackleton appears rounded and is peppered with smaller craters – indications of a relatively ancient age. Right now it is not clear if Shackleton crater is old or young. Many more LROC Narrow Angle Camera (NAC) images of this area will be obtained over the coming months as the south pole emerges from the shadows of winter and a more complete picture will appear.

The full NAC mosaic reveals a shelf on the southeast flank of the crater that is more than two kilometers across and perfectly suitable for a future landing. The extreme Sun angle gives the surface an exaggerated rough appearance, but if you look closely at this scale any area that is between the small craters might make a good landing site. The NAC can see details with ten times greater resolution than previous datasets allowing lunar geologists to map features at a human scale. Where should explorers land, and where should they visit once on the surface? Where can they find resources, and where can they sample a diversity of geologic materials? Over the coming months the whole area will be characterized in detail by all of the LRO instruments, and scientists will have the data to investigate these questions and more.

The Lunar Reconnaissance Orbiter Camera was built by Malin Space Science Systems in San Diego, California, and is operated from the LROC Science Operations Center, part of the School of Earth and Space Exploration at Arizona State University in Tempe, Arizona.

Related Link:

› For more images and information

For more information visit nasa.gov

LRO Begins Detailed Mapping of Moon's South Pole

NASA's Lunar Reconnaissance Orbiter, or LRO, has successfully completed its testing and calibration phase and entered its mapping orbit of the moon. The spacecraft already has made significant progress toward creating the most detailed atlas of the moon's south pole to date.

Artist's concept of LRO. Credit: NASA/Goddard Space Flight Center

NASA showcased new images from LRO's seven instruments and provided updates about the topography of the moon's south pole during a news conference on September 17.

› NASA press release
› View briefing materials

Five Things to Know about LRO

• LRO is leading NASA’s way back to the moon.
• The primary objective of LRO is to conduct investigations that prepare for future lunar exploration. Specifically LRO will scout for safe and compelling landing sites, locate potential resources (with special attention to the possibility of water ice) and characterize the effects of prolonged exposure to the lunar radiation environment. In addition to its exploration mission, LRO will also return rich scientific data that will help us to better understand the moon’s topography and composition.
• Seven scientific instruments outfit LRO. These instruments will return lunar imagery, topography, temperature measurements and more.
• Launched along with LRO was the Lunar CRater Observation and Sensing Satellite (LCROSS), a partner mission that will search for water ice on the moon.
• In response to LRO's "Send Your Name to the Moon" initiative, the spacecraft carries a microchip with nearly 1.6 million names submitted by the public. Click here to view a photo of the microchip containing the names as engineers prepare to install it on the spacecraft.

For more information visit http://www.nasa.gov/mission_pages/LRO/main/index.html

NASA And ISRO Satellites Perform In Tandem To Search For Ice On The Moon

WASHINGTON – On Aug. 20, 2009 NASA and the Indian Space Research Organization (ISRO) will attempt a novel joint experiment that could yield more information on whether ice exists in a permanently shadowed crater near the north pole of the moon. Currently the ISRO’s Chandrayaan-1 and NASA’s Lunar Reconnaissance Orbiter (LRO) spacecraft are orbiting the moon. While LRO is in its commissioning phase the two spacecraft pass close enough to each other when they are over the lunar north pole to attempt a unique experiment. Both spacecraft are equipped with a NASA Miniature Radio Frequency (RF) instrument that functions as a Synthetic Aperture Radar (SAR), known as Mini-SAR on Chandrayaan-1 and Mini-RF on LRO. The experiment uses both radars to point at Erlanger Crater at the same time.

Normally the Mini-RF Instrument sends radio pulses to the moon and precisely records the radio echoes that bounce straight back from the surface, along with their timing and frequency. From these data scientists can build images of the moon that not only show areas they otherwise couldn’t see, such as the permanently-shadowed areas near the lunar poles, but also contain information on the physical nature of the surface.

NASA/GSFC/Arizona State University - Image of the crater Erlanger (87 N, 28.6 E; 10 km diameter), the target crater for our Bi-Static observations. Mini-SAR images suggest unusual scattering properties of the crater interior compared with its exterior. LROC Narrow Angle Camera image.

For the Bi-Static experiment the Mini-SAR on Chandrayaan-1 performs its normal SAR imaging (transmitting and receiving) while the Mini-RF is set to receive only. The two instruments look at the same location from different angles. Comparing the signal that bounces straight back to Chandrayaan with the signal that bounces at a slight angle to LRO provides unique information about the surface.

Stewart Nozette, Mini-RF principal investigator from the Universities Space Research Association’s Lunar and Planetary Institute, said, “An extraordinary effort was made by the whole NASA team working with ISRO to make this happen”

While this coordination sounds easy, this experiment is extremely challenging because both spacecraft are traveling at about 1.6 km per second and will be looking at an area on the ground about 18 km across. Due to the extreme speeds and the small point of interest, NASA and ISRO need to obtain and share information about the location and pointing of both spacecraft. The Bi-Static experiment requires extensive tracking by ground stations of NASA’s Deep Space Network, the Applied Physics Laboratory, and ISRO.

Arecibo Radiotelescope Puerto Rico - Low resolution Earth-based radar image of the North Pole of the Moon, showing the position of the crater Erlanger (arrow). Radar image (70 cm wavelength).

Even with the considerable planning and coordination between the U.S. and India the two instrument beams may not overlap, or may miss the desired location. Even without hitting the exact location Scientists may still be able to use the Bi-Static information to further knowledge already received from both instruments.

“The international coordination and cooperation between the two agencies for this experiment is an excellent opportunity to demonstrate future cooperation between NASA and ISRO, “says Jason Crusan, program executive for the Mini-RF program, from NASA’s Space Operations Mission Directorate, Washington, D.C.

“In the last few years we have seen a renaissance in international interest and cooperation in the study of the moon” says Gordon Johnson, program executive for the LRO, from NASA’s Exploration Systems Mission Directorate, Washington, D.C. “As LRO completes its commissioning phase, we look forward to LRO’s contribution to this international effort.”

LRO was launched June 18, 2009. Its objectives are to scout for safe landing sites, locate potential resources, characterize the radiation environment, and demonstrate new technology. NASA’s Goddard Space Flight Center in Greenbelt, Md. built and manages the mission for NASA’S Exploration Systems Mission Directorate in Washington. LRO is a NASA mission with international participation from the Institute for Space Research in Moscow. Russia provides the neutron detector aboard the spacecraft.

ISRO/NASA/JHUAPL/LPI - Mosaic of Mini-SAR image strips of the north polar area, showing the crater Erlanger, just south of the crater Peary. North Pole is in the direction of left top, out of frame. Mini-SAR radar image, Chandrayaan-1 mission.

Instrument principal investigators Stewart Nozette (LRO) and Paul Spudis (Chandrayaan-1) are from the Universities Space Research Association’s Lunar and Planetary Institute. NASA’s Space Operations Mission Directorate, NASA Headquarters, manages the Mini-RF program. NASA’s Exploration Systems Mission Directorate, NASA Headquarters, manages the LRO.

In addition to Mini-SAR the Chandryaan-1 spacecraft, which was launched in October 2008 from India’s Satish Dhawan Space Centre, also carries NASA’s Moon Mineralogy Mapper for assessing the moon’s mineral resources.

For more information on the Lunar Reconnaissance Orbiter mission, visit: http://www.nasa.gov/lro and nasa.gov