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New Lunar Images Show Apollo 15 tracks, Dante Crater and the Hadley Rille
April 23, 2010
 

Dante Crater

Dante Crater on the Moon Highlands terrain inside the Dante Crater site. A portion of LROC NAC image M121044107R, 580 m across. Credit: NASA/GSFC/Arizona State University
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Only a handful of humans have ever seen the farside of the Moon.

There was a time after the Moon's formation when the entire surface was covered by an ocean of magma; the upper layer of this magma ocean crystallized to form a global layer of anorthosite.

Since that time, impacts and other geological processes have broken and churned the surface, but the Dante Crater area may posses significant amounts of these original rocks. Pristine lunar anorthosites are relatively rare in the Apollo sample collections. The ancient regolith contains rocks that formed from impact melt.

Dante Crater on the Moon Portion of LROC WAC image M118668951M, which covers Dante Crater itself. The region of M121044107R (above) is to the west of this scene. Credit:NASA/GSFC/Arizona State University
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The Dante region has abundant aluminum and calcium-rich regolith.





Retracing the Steps of Apollo 15



Overview of the Apollo 15's third EVA to Hadley Rille The third and final EVA of Apollo 15 brought the astronauts to the edge of Hadley Rille (lower left). Disturbed regolith is observed along the crater rim at station 9 and at the edge of the rille at station 9A. Rover tracks are visible between stations 9A and 10. Image width is 520 m, 0.52 m/pixel, LROC NAC M11171816R. Credit: NASA/GSFC/Arizona State University

The Apollo "J" missions were designed to allow the crews to stay and work longer on the Moon's surface and included a Lunar Rover so they could explore several kilometers away from the Lunar Module.

Hadley Rille and the Apennine Mountains provided a dramatic backdrop for the first Apollo "J" mission. This landing site presented Apollo 15 Commander Dave Scott and Lunar Module Pilot Jim Irwin not only a spectacular view, but access to two key geologic features: a "young" volcanic sinuous rille and "older" highland massifs. These geologic features afforded a chance to sample different events from the Moon's geologic history: early crust formation and late stage volcanism.

Over the course of 3 EVAs (Extra-vehicular Activities), Scott and Irwin covered a total distance of approximately 28 km (17.4 miles), collected approximately 77 kg (170 lbs) of rock and soil samples, and spent 18.5 hours exploring the Moon's surface.

The LROC Narrow Angle Cameras (NAC) provided 50 cm/pixel resolution images of the Apollo 15 landing site. Previous images showed the Lunar Module descent stage, Lunar Rover, ALSEP instruments, and darkened paths of regolith disturbed by the crew and the rover.

EVA 2: Station 7 – Collecting the Genesis Rock

LRO image of location of Genesis Rock The Genesis Rock was collected along the rim of Spur crater at Station 7. The arrow points to disturbed regolith along the rim. Rover tracks are visible south of the boulder at Station 6A. Portion of LROC NAC frame M111571816LE. Image width is 520 m, north is up. Credit: NASA/GSFC/Arizona State University
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Station 7 was at Spur crater, a 90 m diameter impact crater on the slope of the massif to the south known as Mount Hadley Delta. The crew parked along the northeast part of the crater rim (on the downslope side) where they could sample the ejecta blanket. This station is famous for the collection of the Genesis Rock, a 4 billion year old sample of anorthosite representative of the original lunar crust. Their excitement of the discovery is evident in the transmission.

145:42:41 Irwin: Oh, man!
145:42:41 Scott: Oh, boy!
145:42:42 Irwin: I got...
145:42:42 Scott: Look at that.
145:42:44 Irwin: Look at the glint!
145:42:45 Scott: Aaah.
145:42:46 Irwin: Almost see twinning in there!
145:42:47 Scott: Guess what we just found. (Jim laughs with pleasure) Guess what we just found! I think we found what we came for.
145:42:53 Irwin: Crystalline rock, huh?
145:42:55 Scott: Yes, sir. You better believe it.


Apollo 15 photograph of the Genesis Rock in situ Image of the Genesis Rock (left of the gnomon) just prior to collection. Apollo 15 image AS15-90-12228 Credit: NASA
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What all the excitement was about:

Apollo 15 Genesis Rock The Genesis Rock in the Lunar Receiving Laboratory at NASA Johnson Space Center. Credit: NASA
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EVA 3: Station 9A - Observations of Hadley Rille

The last EVA allowed the crew to explore the edge of Hadley Rille.

The crew visited a fresh crater with a blocky texture, and a terrace at Station 9A that allowed Scott and Irwin a chance to peer down into the rille, which is approximately 1.3 km wide and 400 m deep along most of its length. The crew was able to observe and photograph bedrock along the upper part of the western rille wall.

Test pilots by profession, the crew went through extensive geology training so that they could communicate their observations effectively and efficiently to the Science Backroom in Houston, Texas.

Most of us are familiar with Neil Armstrong's "One small step..." quote. What is sometimes forgotten is that there was also a great deal of science being accomplished and discussed during the various missions. Field geologists normally have a field notebook to write down and draw their observations in, but on the Moon everything has to be described vocally.

Here is an example from Commander Scott's geologic description of the rille wall at this location and one of the images that corresponds with it. Compare his description with the photograph and this panorama.

165:22:50 Scott: I can see from up at the top of the rille down, there's debris all the way. And, it looks like some outcrops directly at about 11 o'clock to the Sun line. It looks like a layer. About 5 percent of the rille wall (height), with a vertical face on it. And, within the vertical face, I can see other small lineations, horizontal about maybe 10 percent of that unit.
165:23:26 Scott: And that unit outcrops (at various places) along the rille. It's about 10 percent from the top, and it's somewhat irregular; but it looks to be a continuous layer. It may be portions of (mare basalt) flows, but they're generally at about the 10-percent level. I can see another one at about 12 o'clock to the Sun line, which is somewhat thinner, maybe 5 percent of the total depth of the rille. However, it has a more-well-defined internal layering of about 10 percent of its thickness. I can see maybe 10 very well-defined layers within that unit.


Apollo 15 image of basaltic rock on the moon Outcrop of basaltic lava exposed along the western wall of Hadley Rille. Photographed from Station 9A. Letters point to rocks seen in the LROC NAC frame below. Apollo 15 image AS15-89- 12115 Credit: NASA
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The high resolution imagery from LROC (below) allows us to retrace the steps of previous Apollo missions. Compare the Apollo 15 surface photos with the LROC images to see some of the individual rocks and outcrops seen in both perspectives.

LRO view of rocks photographed by Apollo 15 astronauts The same outcrop photographed by Apollo 15 along the western wall of Hadley Rille as shown above, but from an aerial perspective in this section of LROC NAC frame M111571816RE. The letters point to the same rocks in the image above. The outcrop is approximately 75 m long Credit: NASA/GSFC/Arizona State University
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Rimae Prinz Region

The Prinz-Harbinger area contains a concentration of sinuous rilles, massifs, and mare-filled impact craters. The topography is reminiscent of the Apollo 15 landing site, with a rille bound by nearby massifs.

Rilles provide information on lava flow processes that created the lunar maria. The massifs at this site are related to the Imbrium impact basin and have a different lithology from the surrounding mare units, based on multi-spectral data. The regolith contains pyroclastic deposits from volcanic eruptions.

Lava channel on the Moon A sinuous rille created by a lava flow snakes around the base of a massif in the Prinz-Harbinger region on the Moon. Image width is 1.46 km, LROC NAC frame M102429075L Credit: NASA/GSFC/Arizona State University
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Context map showing the Rimae Prinz region of the Moon Apollo 15 image AS15-M-2081 of the Rimae Prinz region. White boxes distances of 10, 20, and 40 km surrounding the rille. Credit: NASA
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The rille adjacent to the massif is approximately 450-500 m wide and a few hundred meters deep. A gap in the rille, (above image) could be a roofed-over portion forming a lava tube. Lunar lava tubes are of high interest for their geologic information about the emplacement of lava flows.

The massif featured below is approximately 600-700 m in relief, while other massifs in the Montes Harbinger chain are up to 2000 m in relief (see above).

The elephantine texture on the southern slopes changes to a smoother, darker texture before the bottom of the hill (arrows). The base of the massif was partially buried by lava flows related to the volcanic activity and rille formation in the area.

Closeup of possible lava flows on the Moon A lunar rille forms at the base of the massif in the Constellation region of interest (CxP ROI). Arrows point to location along massif possibly covered by lava flows, due to the lack of elephant skin texture on this part of the hillslope, LROC NAC M102429075L. Credit: NASA/GSFC/Arizona State University
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More information can be found about LRO at:
http://www.nasa.gov/lro
 

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Page Last Updated: September 19th, 2013
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