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  Apollo 11: Landing site location

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Author Topic:   Apollo 11: Landing site location
MichaelD
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Posts: 77
From: Troy Michigan USA
Registered: May 2009

posted 08-04-2009 08:55 AM     Click Here to See the Profile for MichaelD   Click Here to Email MichaelD     Edit/Delete Message   Reply w/Quote
A silly question, but I am not finding an answer to at all: Did Eagle put down near landing site 1, 2, or 3?

mikej
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Posts: 374
From: Germantown, WI USA
Registered: Jan 2004

posted 08-04-2009 09:53 AM     Click Here to See the Profile for mikej   Click Here to Email mikej     Edit/Delete Message   Reply w/Quote
Apollo 11 put down in its primary landing site, Mare Tranquillitatis. The #2 and #3 landing sites were Sinus Medii and Oceanus Procellarum, respectively. (See page 85 [p. 89 in the PDF] of the Apollo 11 Press Kit [direct link to 8.4 meg PDF] for additional information. Note that the site numbers in the left-hand column refer to the overall list of 30 landing sites considered for the Apollo program, not the sites specifically considered for the Apollo 11 landing.)

One of the operational considerations for landing sites was the local sun angle; favorable sun angles moved farther west as the lunar month progressed. Thus, alternate landing sites progressively farther westward were chosen in case the launch date should slip. See the "Lunar landing site lighting and location" section on this Apollo Flight Journal page.

Since Apollo 11 launched on its first attempt, it makes sense that they were able to land at their primary site.

Fra Mauro
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From: Maspeth, NY
Registered: Jul 2002

posted 08-04-2009 10:37 AM     Click Here to See the Profile for Fra Mauro   Click Here to Email Fra Mauro     Edit/Delete Message   Reply w/Quote
I wonder if the alternate landing sites would have given them as much trouble during the descent as the Sea of Tranquility did. Or in what samples were returned.

ilbasso
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From: Greensboro, NC USA
Registered: Feb 2006

posted 08-04-2009 10:55 AM     Click Here to See the Profile for ilbasso   Click Here to Email ilbasso     Edit/Delete Message   Reply w/Quote
I don't think Site 1 per se caused any greater difficulties in landing than would the other sites. All three of the candidate sites were chosen primarily because they were near the lunar equator and were relatively flat and featureless maria. The goal was to land successfully, period. The crew learned some major features along the route to each site (e.g., the "Highway 1" rille) but didn't focus on targeting to land at any specific feature (like the Apollo 12 "Snowman" crater formation).

As with the unmanned Surveyor landers (and with the Mars landers), Apollo 11 aimed for a "landing ellipse" at each site. The ellipse was considered the general margin of error around a targeted area, anywhere inside of which would probably be ok to land. Part of the problem with Apollo 11 was that Eagle was "long" by several kilometers as it entered powered descent. It was thus farther along the landing ellipse than planned. Since the terrain was relatively featureless, it was difficult for the crew to know exactly where they were. They knew they were long, but not by how much.

There are no completely featureless areas of the Moon, so the crew would have had to deal with craters at any of the three sites. My 3D map of a part of Site 2 in Sinus Medii includes a pretty sizeable crater and a ridge, which certainly would have caused problems for Eagle had the computer been steering it in that direction.

robsouth
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From: West Midlands, UK
Registered: Jun 2005

posted 08-26-2010 07:24 PM     Click Here to See the Profile for robsouth     Edit/Delete Message   Reply w/Quote
NASA chose candidate landing site 2 (shown below) for the touch down spot for Apollo 11. This was a five by three mile oval near the moon's equator. Apollo 11 touched down about three miles west of this area.

I have tried to find out where the actual landing site was in relation to candidate landing site 2. Does anyone know the coordinates for this oval or does anyone know if NASA's Lunar Reconnaissance Orbiter (LRO) has taken a photograph of the site?

What I would really like to see is a LRO image that contains both the Apollo 11 landing site and the area contained in candidate landing site 2.

Editor's note: Threads merged.

ilbasso
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From: Greensboro, NC USA
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posted 08-27-2010 09:06 AM     Click Here to See the Profile for ilbasso   Click Here to Email ilbasso     Edit/Delete Message   Reply w/Quote
There are some nice photos in the Apollo 11 image gallery. This one shows the landing ellipse and landing site marked on a photo taken by Eagle just after separation from Columbia.

This chart is perhaps something more like you're looking for. It was a Lunar Orbiter photo of the landing ellipse, with the actual landing site annotated.

robsouth
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From: West Midlands, UK
Registered: Jun 2005

posted 08-28-2010 09:41 AM     Click Here to See the Profile for robsouth     Edit/Delete Message   Reply w/Quote
Thanks for posting those two links but the oval areas shown in those two images don't seem to show the same crater formations as seen in the image above. Also, the oval shapes don't even seem to be the same size. I would also hazard a guess that the areas shown in the two images in the links cover a much larger area than the one shown above. The image above is a specific area chosen from a lunar orbiter composite image. I would like to find the particular craters shown in it on any LRO images so far returned.

ilbasso
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From: Greensboro, NC USA
Registered: Feb 2006

posted 08-28-2010 04:12 PM     Click Here to See the Profile for ilbasso   Click Here to Email ilbasso     Edit/Delete Message   Reply w/Quote
Rob, these do indeed show the same site. I have put a comparison composite together below. The Apollo 10 image needed to be rotated 90 degrees.

Having extensively studied the Lunar Orbiter and Apollo (and now Lunar Reconnaissance Orbiter) photography of Site 3 in Sinus Medii, I can tell you that changes in lighting angle and resolution between photos can make the same ground features look very different. However, I have annotated these three photos so that you can see the same features in all three of them. Click on the image to see an enlargement.

You are correct that the shape of the ovals is different. The version you posted is a slightly smaller area than the landing ellipse depicted in subsequent documents. The exact boundaries of the initial Apollo landing ellipses were not really precisely drawn between various maps. Rather, they were centered on a common area and had slightly varied major and minor axes.

What's interesting to note is that it appears the actual Apollo 11 landing was outside of the landing ellipse in the image you posted.

robsouth
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Posts: 607
From: West Midlands, UK
Registered: Jun 2005

posted 08-28-2010 07:11 PM     Click Here to See the Profile for robsouth     Edit/Delete Message   Reply w/Quote
That is it! You're right the lighting angle and resolution makes a big difference. After comparing the photos that you posted with the image I have, I can definitely see the same craters.

I took a look at this LRO image and in the photo I posted just left of the area you marked with a red circle there is a crater that looks like it’s been jabbed into the moons surface with a pencil tip. It has a very small, dark centre with a depressed area around it. On the LRO image this crater can be seen east of the Apollo 11 landing site right on the border of the image. To the south west of this crater there is a larger more subdued crater with two small craters on its rim just to the north west and south east, the northern crater is very bright and in the image I posted the southern crater has a white line running vertically through it from where the LO strip photos were joined. This crater marks the western edge of the Site 2 photo that I posted and the landing site is further west than this as seen on the LRO image. This all ties in with the observation that the Apollo 11 LM landed down range of the chosen site.

That's a long time mystery solved for me so to honour that fact and the fact that this is my 500th post, here is a picture of Neil and Buzz seen inside the lunar module following their moonwalk at Tranquility Base.

APG85
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From:
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posted 08-29-2010 08:58 AM     Click Here to See the Profile for APG85     Edit/Delete Message   Reply w/Quote
Neat picture. I've never seen it before...

Blackarrow
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Posts: 2024
From: Belfast, United Kingdom
Registered: Feb 2002

posted 08-29-2010 12:25 PM     Click Here to See the Profile for Blackarrow     Edit/Delete Message   Reply w/Quote
Nobody has until now! Who was the stowaway?

APG85
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posted 08-29-2010 05:31 PM     Click Here to See the Profile for APG85     Edit/Delete Message   Reply w/Quote
Obviously two pics cut together. Still neat...

rasorenson
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Posts: 78
From: Santa Clara, CA, USA
Registered: Nov 2009

posted 08-31-2010 01:33 PM     Click Here to See the Profile for rasorenson   Click Here to Email rasorenson     Edit/Delete Message   Reply w/Quote
Rob- did you compile the two LM interior shots yourself? Any chance you can post a higher resolution image for us to download? Spliced together or not, it's a great image!

robsouth
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Posts: 607
From: West Midlands, UK
Registered: Jun 2005

posted 09-08-2010 03:22 PM     Click Here to See the Profile for robsouth     Edit/Delete Message   Reply w/Quote
Hi, yeah I put the two images together, I like to do that where possible to make new images. I have sent you an email with the Neil and Buzz image attached.

Blackarrow
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Posts: 2024
From: Belfast, United Kingdom
Registered: Feb 2002

posted 09-08-2010 05:34 PM     Click Here to See the Profile for Blackarrow     Edit/Delete Message   Reply w/Quote
quote:
Originally posted by APG85:
Obviously two pics cut together. Still neat...

You don't say! Never thought of that....

ilbasso
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Posts: 1494
From: Greensboro, NC USA
Registered: Feb 2006

posted 09-11-2010 07:02 PM     Click Here to See the Profile for ilbasso   Click Here to Email ilbasso     Edit/Delete Message   Reply w/Quote
I had seen a somewhat similar treatment, but facing toward the aft of the crew compartment, with Apollo 17.

oche16
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posted 09-15-2010 06:57 AM     Click Here to See the Profile for oche16   Click Here to Email oche16     Edit/Delete Message   Reply w/Quote
Rob, awesome photo of the LEM on the surface! Mind if I copy it?

Thought I'd share this press shot, July 11, Canaveral.

ilbasso
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Posts: 1494
From: Greensboro, NC USA
Registered: Feb 2006

posted 09-15-2010 08:10 AM     Click Here to See the Profile for ilbasso   Click Here to Email ilbasso     Edit/Delete Message   Reply w/Quote
New image of a crater pit on the Sea of Tranquility. Aren't we glad Neil didn't have to dodge this one?

robsouth
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Posts: 607
From: West Midlands, UK
Registered: Jun 2005

posted 09-15-2010 08:36 AM     Click Here to See the Profile for robsouth     Edit/Delete Message   Reply w/Quote
quote:
Originally posted by oche16:
Rob, awesome photo of the LEM on the surface! Mind if I copy it?
I don't have a problem with you copying the Neil and Buzz image. Actually if anyone connected with the ALSJ wants to include it on the website with a reference to myself that would be an honour, I do have a higher res copy available.

Lou Chinal
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Posts: 946
From: Staten Island, NY
Registered: Jun 2007

posted 09-15-2010 07:57 PM     Click Here to See the Profile for Lou Chinal   Click Here to Email Lou Chinal     Edit/Delete Message   Reply w/Quote
Jonathan- Thanks for posting the pix!

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