Lunar Reconnaissance Orbiter

The Lunar Reconnaissance Orbiter, or LRO, is a multipurpose NASA spacecraft launched in 2009 to make a comprehensive atlas of the Moon’s features and resources. Since launch, LRO has measured the coldest temperatures in the solar system inside the Moon’s permanently shadowed craters, detected evidence of water ice at the Moon’s south pole, seen hints of recent geologic activity on the Moon, found newly-formed craters from present-day meteorite impacts, tested spaceborne laser communication technology, and much more.

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  • New Craters on the Moon
    Planetary scientists believe that small impacts regularly bombard the Moon, but until recently, they’ve had no way to distinguish new craters from the already pockmarked lunar surface. In 2009, NASA’s Lunar Reconnaissance Orbiter (LRO) arrived at the Moon and began taking high-resolution photographs. By comparing pictures taken early in the mission with more recent images, the LRO camera team has discovered more than two-dozen new impact craters – including an 18-meter-wide crater caused by a bright flash on March 17, 2013. Learn more about this finding.
  • Supermoon 2014
    On August 10, 2014, the Moon will be full at the same time that it is closest to Earth for the year. This coincidence is sometimes called a supermoon. The Moon's orbit is very slightly elliptical and therefore somewhat off-center relative to the Earth. Each month, the Moon passes through points in its orbit called perigee and apogee, the closest and farthest points from the Earth for that month. Some perigees are a little closer than others. The closest perigee for 2014 occurs on August 10 at around 17:49 Universal Time, when the Moon will be 356,896 kilometers (221,765 miles) away. As it happens, this is only a few minutes before the time of peak full Moon at 18:10 UT, when the Moon's ecliptic longitude differs from the Sun's by exactly 180 degrees. How often does this happen? The period between perigees, called the anomalistic month, is 27.55 days, on average, while the time between Full Moons, called the synodic month, is 29.53 days. These two periods sync up every 413 days, or 1.13 years. 15 anomalistic months are about as long as 14 synodic months, so that's how often the pattern repeats. Recently, a much broader definition of "supermoon" has taken hold. It includes both Full and New Moons, and perigee merely needs to be "close enough," generally within a couple of days. By this definition, there are six or seven supermoons every year, half of which can't be observed. Not so super! The actual shape of the Moon's orbit is another source of confusion. The orbit is often depicted as an almost cigar-shaped ellipse, but this is a misleading exaggeration. If you were to draw the orbit on a sheet of paper, its deviation from a perfect circle would be less than the thickness of your pencil point. The 50,000 kilometer (30,000 mile) difference between perigee and apogee is almost entirely due to the orbit being off-center. The difference between the semimajor and semiminor axes is less than 1000 kilometers (600 miles). The animation begins in mid-July, showing that perigee and Full Moon miss each other by about a day. It then shows apogee on July 28, when the Moon is almost 32 Earth diameters away. It ends on August 10, the day of the supermoon, when the distance to the Moon is 28 Earth diameters. The Moon graphic in the upper left shows the change in the Moon's apparent size as it moves closer and farther in its orbit. (The relative sizes of the Earth and Moon in the main orbit graphic are exaggerated by a factor of 15 to make them more easily visible.)
  • A New Look at the Apollo 11 Landing Site
    Apollo 11 landed on the Moon on July 20th, 1969, a little after 4:00 in the afternoon Eastern Daylight Time. The Lunar Module, nicknamed Eagle and flown by Neil Armstrong and Edwin "Buzz" Aldrin, touched down near the southern rim of the Sea of Tranquility, one of the large, dark basins that contribute to the Man in the Moon visible from Earth. Armstrong and Aldrin spent about two hours outside the LM setting up experiments and collecting samples. At one point, Armstrong ventured east of the LM to examine a small crater, dubbed Little West, that he'd flown over just before landing. The trails of disturbed regolith created by the astronauts' boots are still clearly visible in photographs of the landing site taken by the Lunar Reconnaissance Orbiter (LRO) narrow-angle camera (LROC) more than four decades later. LROC imagery makes it possible to visit the landing site in a whole new way by flying around a three-dimensional model of the site. LROC scientists created the digital elevation model using a stereo pair of images. Each image in the pair shows the site from a slightly different angle, allowing sophisticated software to infer the shape of the terrain, similar to the way that left and right eye views are combined in the brain to produce the perception of depth. The animator draped an LROC photograph over the terrain model. He also added a 3D model of the LM descent stage—the real LM in the photograph looks oddly flat when viewed at an oblique angle. Although the area around the site is relatively flat by lunar standards, West Crater (the big brother of the crater visited by Armstrong) appears in dramatic relief near the eastern edge of the terrain model. Ejecta from West comprises the boulders that Armstrong had to avoid as he searched for a safe landing site. Apollo 11 was the first of six increasingly ambitious crewed lunar landings. The exploration of the lunar surface by the Apollo astronauts, when combined with the wealth of remote sensing data now being returned by LRO, continues to inform our understanding of our nearest neighbor in space.
  • Peeking Into Lunar Pits
    Since 2009, NASA’s Lunar Reconnaissance Orbiter (LRO) has spotted hundreds of conspicuous holes on the Moon. These steep-walled “pits" vary from a few meters to nearly 1 kilometer wide, and can reach depths of over 100 meters. Scientists think that pits may form when part of the Moon’s surface collapses above a lava tube, and high-resolution photographs from LRO suggest that many of the pits widen underground. If so, lunar pits might provide shelter from radiation, meteorite impacts, and extreme temperatures, making them valuable sites for future exploration.
  • Understanding Lunar Eclipses
    What can cause the full Moon to quickly darken, then glow red? A lunar eclipse: a striking display of orbital mechanics that occurs when the Moon passes through the Earth's shadow. To learn more, watch the video below.
  • Need To Know: Lunar Eclipse and LRO
    On April 15th, 2014 there will be a total lunar eclipse visible from North America. Noah Petro, LRO Deputy Project Scientist, discusses this unique event and what effect it will have on the Lunar Reconnaissance Orbiter (LRO).
  • Jim Garvin's Top "Pics" - LROC Images
    In this video series, NASA Scientist Jim Garvin highlights his favorite pictures taken throughout the solar system. This episode focuses on images taken by LROC – the Lunar Reconnaissance Orbiter Camera. Jim explains which pictures made his “top 5” list.
  • Earthrise: The 45th Anniversary
    In December of 1968, the crew of Apollo 8 became the first people to leave our home planet and travel to another body in space. But as crew members Frank Borman, James Lovell, and William Anders all later recalled, the most important thing they discovered was Earth. Using photo mosaics and elevation data from Lunar Reconnaissance Orbiter (LRO), this video commemorates the 45th anniversary of Apollo 8's historic flight by recreating the moment when the crew first saw and photographed the Earth rising from behind the Moon. Narrator Andrew Chaikin, author of A Man on the Moon, sets the scene for a three-minute visualization of the view from both inside and outside the spacecraft accompanied by the onboard audio of the astronauts. The visualization draws on numerous historical sources, including the actual cloud pattern on Earth from the ESSA-7 satellite and dozens of photographs taken by Apollo 8, and it reveals new, historically significant information about the Earthrise photographs. It has not been widely known, for example, that the spacecraft was rolling when the photos were taken, and that it was this roll that brought the Earth into view. The visualization establishes the precise timing of the roll and, for the first time ever, identifies which window each photograph was taken from. The key to the new work is a set of vertical stereo photographs taken by a camera mounted in the Command Module's rendezvous window and pointing straight down onto the lunar surface. It automatically photographed the surface every 20 seconds. By registering each photograph to a model of the terrain based on LRO data, the orientation of the spacecraft can be precisely determined. A Google Hangout discussion of this visualization between Ernie Wright (creator of the visualization), Andrew Chaikin (narrator and script writer for the visualization and author of A Man on the Moon), John Keller (LRO project scientist), and Aries Keck (NASA media specialist) was held on December 20, 2013. A replay of that hangout is available here. This NASA Wavelength blog entry about Earthrise includes links to educator resources related to LRO.
  • LRO 4th Anniversary
    Four years ago, NASA made a long promised return visit to a place so legendary in the history of space exploration that it felt like a reunion with a long lost relative. With the liftoff of the Lunar Reconnaissance Orbiter (LRO), NASA made a bold statement about its commitment to exploring Earth's closest neighbor, as well as other parts of the solar system. In the years since it rose on its rocket, LRO has amassed a stunning array of data on a wide range of subjects. From vital research about the formation of the early solar system, to fundamental research about the structure and natural history of the Moon itself, LRO continues to deliver state-of-the-art information about a place that almost every human being has pondered as it drifts through our skies and our collective imaginations.
  • Water on the Moon
    Since the 1960’s, scientists have suspected that frozen water could survive in cold, dark craters at the Moon’s poles. While previous lunar missions have detected hints of water on the Moon, new data from the Lunar Reconnaissance Orbiter (LRO) pinpoints areas near the south pole where water is likely to exist. The key to this discovery is hydrogen, the main ingredient in water: LRO uses its Lunar Exploration Neutron Detector, or LEND, to measure how much hydrogen is trapped within the lunar soil. By combining years of LEND data, scientists see mounting evidence of hydrogen-rich areas near the Moon’s south pole, strongly suggesting the presence of frozen water.
  • The Moon's Permanently Shadowed Regions
    As you watch the Moon over the course of a month, you'll notice that different features are illuminated by the Sun at different times. However, there are some parts of the Moon that never see sunlight. These areas are called permanently shadowed regions, and they appear dark because unlike on the Earth, the axis of the Moon is nearly perpendicular to the direction of the sun's light. The result is that the bottoms of certain craters are never pointed toward the Sun, with some remaining dark for over two billion years. However, thanks to new data from NASA's Lunar Reconnaissance Orbiter, we can now see into these dark craters in incredible detail.