The Arizona State University team that oversees the imaging system on board NASA's Lunar Reconnaissance Orbiter has released the sharpest images ever taken from space of the Apollo 12, 14 and 17 sites, more clearly showing the paths made when the astronauts explored these areas.
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. Credit: NASA/GSFC/Arizona State University
The higher resolution of these images is possible because of adjustments made to LRO's elliptical orbit. On August 10 a special pair of stationkeeping maneuvers were performed in place of the standard maneuvers, lowering LRO from its usual altitude of 50 kilometers (about 31 miles) to an altitude that dipped as low as 21 kilometers (nearly 13 miles) as it passed over the Moon's surface.
"The new low-altitude Narrow Angle Camera images sharpen our view of the Moon's surface," says Mark Robinson, the Principal Investigator for LROC and professor in the School of Earth and Space Exploration in ASU's College of Liberal Arts and Sciences. The LROC imaging system consists of two Narrow Angle Cameras (NACs) to provide high-resolution images, and a Wide Angle Camera (WAC) to provide 100-meter resolution images in seven color bands over a 57-km swath.
"A great example is the sharpness of the rover tracks at the Apollo 17 site," Robinson says. "In previous images the rover tracks were visible, but now they are sharp parallel lines on the surface!"
The maneuvers were carefully designed so that the lowest altitudes occurred over some of the Apollo landing sites.
At the Apollo 17 site, the tracks laid down by the lunar rover are clearly visible, along with 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 more easily distinguished from the dual tracks left by the lunar rover, which remains parked east of the lander.
At each site, trails also run to the west of the landers, where the astronauts placed the Apollo Lunar Surface Experiments Package (ALSEP), providing the first insights into the Moon's internal structure and first measurements of its surface pressure and the composition of its atmosphere.
One of the details that shows up is a bright L-shape in the Apollo 12 image marking the locations of cables running from ALSEP's central station to two of its instruments. Though the cables are much too small to be resolved, they show up because the material they are made from reflects light very well and thus stand out against the dark lunar soil.
The spacecraft has remained in this orbit for 28 days, long enough for the Moon to completely rotate underneath, thus also allowing full coverage of the surface by LROC's Wide Angle Camera. This low-orbit cycle ends today when the spacecraft will be returned to the 50-kilometer orbit.
These and other LROC images are available at: http://lroc.sese.asu.edu/
Apollo 12 image caption:
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.
A surprising detail of the ALSEP is visible in the image: a bright L-shape 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 image caption:
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, measuring about 5 meters across, 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.
Link to Apollo 17 liftoff video: http://history.nasa.gov/alsj/a17/a17v_1880127.mpg
Nicole Cassis | EurekAlert!
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