Discoveries of the Impact Site Locations of the Apollo Lunar Module Ascent Stages
The impact site was discovered by Michael Marcus, an independent researcher, on 11/21/2013. The impact site was independently discovered by Philip J. Stooke, Ph.D., Department of Geography, University of Western Ontario, London, Ontario, Canada N6A 5C2, on or about 05/20/2016. Please see his announcement of his discovery of the impact site: UnmannedSpaceflight.com > Earth & Moon > Lunar Exploration > LRO & LCROSS, post #381, May 20 2016.
LROC QuickMap View of the Apollo 12 LM Impact Site Location, 0.5 m/pixel - QuickMap view showing a view of a fairly small part of the debris field created by the impact of the Apollo 12 LM Intrepid. This view is centered at approximately the middle of the debris field and in between two bright craters which were somewhat altered by the impact of pieces of the Apollo 12 LM Intrepid. Click the minus (-) zoom button in QuickMap to zoom out so that you can see the entire debris field.
The impact site was discovered by Stooke on or about 03/19/2010. Marcus independently discovered the impact site approximately four years later on 04/18/2015. Please see his announcement of his discovery of the impact site: UnmannedSpaceflight.com > Earth & Moon > Lunar Exploration > LRO & LCROSS, post #62, Mar 19 2010.
LROC QuickMap View of the Apollo 14 LM Impact Site Location, 0.5 m/pixel - QuickMap view showing the impact location of the Apollo 14 LM Antares.
The impact site was discovered by Stooke on or about 02/21/2017. Marcus has confirmed Stooke's discovery of the Apollo 15 LM impact site. Stooke's announcement of his discovery on UnmannedSpaceFlight.com: UnmannedSpaceflight.com > Earth & Moon > Lunar Exploration > LRO & LCROSS, post #398, Feb 21 2017.
LROC QuickMap View of the Apollo 15 LM Impact Site Location, 0.5 m/pixel - QuickMap view showing the impact location of the Apollo 15 LM Falcon.
Marcus discovered the Apollo 17 LM impact site on 04/30/2018. Marcus will have Stooke confirm the discovery. The impact location is near the very top of the east side of the South Massif, and is very close to the impact location calculated by NASA in 1972. The Challenger's impact created a small trench with two very dark lines inside the trench. The impact location is not seen in Apollo 15 and 17 Panorama Camera images which were specially processed and enhanced in order to reveal very fine details. Furthermore, comparisons of the Panorama Camera images and LRO NAC images show that a few small boulders on the east side of the South Massif have moved further downhill, possibly as a result of the impact of the LM Challenger.
LROC QuickMap View of the Apollo 17 LM Impact Site Location, 0.5 m/pixel - QuickMap view showing the impact location of the Apollo 17 LM Challenger.
The Apollo 12 Lunar Module Impact Site
The Apollo 12 LM Intrepid approached from the east on a bearing of approximately 285° clockwise from lunar north. The Intrepid was traveling in a west-northwesterly direction. This bearing is almost exactly the same bearing on which the Intrepid traveled on during its descent and landing to mark the second time in mankind's history in which human beings landed upon and set foot on another world. The Intrepid's angle of descent at impact was 3.7° from horizontal and its velocity at impact was 1680 meters per second (3758 miles per hour).
Apollo 12 LM Impact Site Data
** Each Lunar Module was pressurized at the moment of impact. Each LM essentially was a pressurized aluminum can. At the moment of LM impact with the lunar surface, the bottom of the LM ripped open and the rest of the LM instantly and explosively disintegrated. This resulted in most of the impact energy being directed upwards and away from the lunar surface. The result is that, with the singular exception of the Apollo 17 LM which impacted at a relatively steep angle into the side of the South Massif and which did create an impact crater, no impact crater was created by any of the other LMs.
Google Moon KMZ File for the A12 LM Impact Site
A12_LM_Impact_Site.kmz 63 MB KMZ file of the impact site for use in Google Moon. Since this KMZ file is rather large, you may wish to right-click on the link to download and save the file. After the KMZ file has been downloaded to a location on you computer, you can then open the downloaded file in Google Moon.
Video of the Apollo 12 Lunar Module Intrepid's Impact Site
The best way to see the extent of the impact site is to watch the following video. In the following video, what you are looking for are the dark streaks which were created by the impact of debris from the Intrepid which exploded on impact. Video is credit NASA/GSFC/ASU/Google/GoneToPlaid.
Plotting Error in the Apollo 12 Mission Report Image for the A12 Landing and Impact Sites
I discovered that the Figure 5-2 image NASA-S-70-570 on page 93 (Section 5, page 11) within the Apollo 12 Mission Report contains an erroneously overlaid plot of the Apollo 12 landing site location and the Apollo 12 LM impact site location. See below. I aligned a crop of Lunar Orbiter IV image 4125_h3 to the overlaid NASA-S-70-570 image from the Apollo 12 Mission Report . I then plotted the actual LM landing and impact site locations in yellow. The originally plotted LM landing and impact site locations and their trajectories were highlighted in blue. The original plot was then translated to align with the actual landing site location. With the original plotting error in NASA-S-70-570 now corrected, you can see that the NASA's computed position for the Intrepid's impact site very closely matches the actual impact site location. Correcting these plotting errors allowed me to to know exactly where to search for the impact site. I found the impact site approximately 20 minutes later. See images below.
Where exactly did the LM Intrepid make its initial contact with the lunar surface?
This is a question which has perplexed me since I previously was unable to find any blatantly an obvious point of initial contact further back along my carefully plotted centerline throughout the length of the entire debris field. I would expect to find an obvious and very fresh crater at the Intrepid's initial point of contact with the lunar surface. The debris field itself gives us some clues since the debris field is very long and has a rather narrow fan pattern. Had the Intrepid impacted the lunar surface at a steeper angle relative to the lunar surface, then an obvious crater would have been created with ejecta being strewn throughout a much wider fan of secondary debris. Yet this is not what is seen when looking at the debris field. This lead me to suspect that part of the Intrepid must have just barely grazed the lunar surface at a very shallow angle. Assuming that this is what did indeed occur, the part of the Intrepid which grazed the lunar surface would instantly disintegrate and send shrapnel like a shotgun blast upward and into the LM's pressurized hull. The result would be a virtually instantaneous explosive decompression of the LM's hull.
So for the moment let's assume that the above scenario is what actually occurred. The LM was pressurized with pure oxygen. At 20° Celsius, oxygen molecules have an average speed of 478 meters per second. The LM's speed at impact was 1680 meters per second. Assuming that the oxygen was able to act with 100% efficiency in terms of accelerating the LM's hull fragments, then a 32° wide fan of debris would have been created. But of course this is impossible since this requires the hull fragments to have zero inertia and for the oxygen molecules to have 100% efficiency at imparting their average speed to the hull fragments. Just winging it, I figured that the oxygen would act upon the exploding hull fragments with only 50% efficiency. This results in a 16° wide debris fan. The measured angular width of the actual debris fan is a bit less than this and seems to converge at a point near the west side of an apparent ridge which is located to the east of the debris field.
The above scenario is only a hypothesis for the observed angular width and convergence of the debris fan, and for the lack of any obvious initial impact crater. The above scenario requires the LM to initially barely graze the lunar surface. This in turn also requires the local slope of the lunar surface, within a distance of only a tens of meters downrange of the initial impact point, to become greater than the descent slope of the LM at the point where the LM grazed the lunar surface such that there is a void beneath the LM and its fan of exploding hull fragments as the LM's debris fan traveled and impacted further downrange. In other words, this scenario requires the LM to graze the lunar surface at or very near the westward side of a lunar ridge.
My crash scenario would appear to be extremely unlikely. However unlikely, let's see if there is evidence for the above scenario. For an answer, we will have to look at the Lunar Reconnaissance Orbiter's GLD100 DTM data. After examining the following, you will see that the GLD100 DTM evidence not only supports this scenario, but also appears to impose an upper limit on the trajectory angle of an object which could have created the observed debris field. This upper limit is exactly the same 3.7° angle from horizontal at which the LM Intrepid struck the lunar surface. The eastward convergence of the debris field fan proves that whatever created the debris field impacted from the east and not the west. So in other words, the LRO GLD100 DTM for the debris field appears to be the smoking gun which proves that this is indeed the Apollo 12 Intrepid's lunar impact site. See the images below.
The above GLD100 data appears to support my crash scenario. But my crash scenario falls apart if I can't find signs of the Intrepid's initial point of contact with the lunar surface in the area predicted by the GLD100 data plot, and additionally find signs that the LM's pressurized hull exploded immediately above the surface a few milliseconds later and only a few meters downrange of this initial point of contact. Is anything like this visible in LRO images? The answer is YES, as shown below.
QuickMap View of the Intrepid's Initial Point of Contact with the Lunar Surface
A12 LM Initial Contact Point at 0.5 m/pixel (full link) - QuickMap - QuickMap view (link with full URL) showing a 0.5m/pixel close-up view of the Apollo 12 lunar module Intrepid's initial point (IP) of contact with the lunar surface. This QuickMap view is precisely centered on the IP. A short bit.ly URL which is suitable for use in news articles is: http://bit.ly/1FSI5gt
Alternatively, following is a labeled QuickMap screen capture of the Intrepid's initial point of contact with the lunar surface.
The GLD100 data for the location shown in the above image indicates that the slope of the terrain at this initial contact point location and along the same bearing as the debris field is approximately -2.6°. The LM's descent angle at impact was -3.7°, for a difference of only 1.1°. Roughly 1 degree is an extraordinarily shallow impact angle. I theorize that this extremely shallow impact angle allowed the pressurized LM to explode rather than burrowing into the terrain and creating an impact crater.
So there you have it. The evidence which I presented above would appear to validate my scenario for exactly how and where the Intrepid impacted the lunar surface.
Links to LRO NAC and WAC Images of the Impact Site