Apollo 11 Lunar Surface


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Contingency Sample

Copyright © 2012 by RenéCantin and  Eric M. Jones.
All rights reserved.
Last revised 30 March 2012.


 1.  Introduction

The contingency sample included  492.12 grams of material finer than 1 cm, as well as 12 rock fragments larger than 1 cm.  Details are given on pages 17 and 18 in the Apollo 11 Lunar Sample Information Catalog, with Contingency Sample material distinguished by "Cont. Bag" in the last column.  Although the Sample Catalog states that "The sample bag was filled with two scoops", the 16-mm film shot out Buzz's window clearly shows that Neil scooped up material at five separate locations.  At one location, he appears to have collected only fines and rock fragment too small to be well resolved on the 16-mm film.  At each of the other four locations, he appears to have collected not only fines and small rocks, but also a rock large enough to be clearly visible in the 16-mm film.  There are  four rock samples bigger than 10 grams: 10021 (250 gm), 10022 ( 95.59 gm), 10023 (66 gm), and 10024 (68.12 gm).  It is tempting to identify these four as the four rocks visible in the 16-mm film that Neil appears to have collected.  Tentative identifications are indicated below in labeled versions of AS11-39-5777, a photo Buzz took out his window before the EVA, and AS11-40-5857, a frame Neil took from near the ladder before he collected the Contingency Sample.

Details for the rock samples are provided in individual PDF documents complied by Charles Meyer in the Lunar Sample Compendium.  Frames from the 16-mm film shot out Buzz's window were captured by Ken Glover from a digital version of the film compiled by Mark Gray.

Contingency Sample
          Sites in 5777 and 5857

Contingency sample locations labeled in pre-EVA shot AS11-39-5777 (top),
taken out Buzz's window, and AS11-40-5857 (bottom), a frame from Neil's ladder pan.
(click on the image for a larger version.)

2. Contingency Sample Collection Timeline

Collection of the contingency sample can be seen in a clip from the 16-mm film shot out Buzz's window. Clip courtesy Colin Mackellar ( 3 min 45 sec; 33 Mb; mpg ).

Ground Elapsed Time
Elapsed Time in Clip

Neil is assembling the sampler.  DAC frame
Aldrin - (Providing commentary as he watches Neil out the window) Okay. The contingency sample is down (that is, Neil has it just off the ground) and it's (garbled). As Neil prepares to take the first scoop, he lowers the sampler head to a spot just to the north of the shadow cast by the plus-Y strut and just down-Sun of the shadow cast by a rock.  The bag opening is facing Neil's left boot.  The rock is labeled in a detail from pre-EVA window shot AS11-39-5777.  See, also, a detail from AS11-40-5857, a frame from Neil's ladder pan.

Neil appears to move the rock a couple of centimeters toward his boot (DAC frame), probably to see if it is sitting on the surface or is mostly buried.  He then turns the sampler so that the bag opening facing away from his boot.  He puts the sampler down on the east side of the rock. 
109:34:04 0:29

He appears to get the rock in the bag (DAC frame), and then pushes the sampler forward a few times, trying to dig deeper into the soil.
109:34:09 0:34
Aldrin: Looks like it's a little difficult to dig through the initial crust...
Neil raises the sampler, revealing the final scoop mark he makes at this location (DAC frame).
109:34:12 0:37
Armstrong: This is very interesting.  It's a very soft surface, but here and there where I plug with the contingency sample collector, I run into a very hard surface.  But it appears to be a very cohesive material of the same sort.


Neil moves forward 30-40 cm and gets a quick scoop.  The approximate location of this sample is indicated in a detail from 5777 and a detail from 5857.  The small rocks visible in both details are not visible in the 16-mm record, so we can't be sure which ones, if any, were collected.
Armstrong: I'll try to get a rock in here.
Neil turns to his left and collects two rocks to the south of the strut shadow.  Figure 3-19 from the Apollo 11 Preliminary Science Report indicates that Neil collected 10022 and 10028 at this third sample location.  See, also, a detail from 5777 and a detail from 5857.
Armstrong:   Just a couple. Neil moves about a meter farther from the LM and collects a rock on the west rim of a foot-size crater.  This rock, at the fourth sample location, is labeled in a detail from 5777 and a detail from 5857.

Neil reaches down to his left with the sampler and scoops up a final sample, including a rock visible in the 16-mm film.  The rock is identified at 10023 in Figure 3-17a (redrawn version) in the Preliminary Science Report.  Note that, in Figure 3-17b, the location is mislabeled.  See, also, Figure 3-19 (redrawn from 5777) in which a smaller rock just north of 10023 is provisionally identified as 10032; and a detail from 5857.
Armstrong: Be advised that a lot of the rock samples out here - the hard rock samples - have what appear to be vesicles in the surface.  Also, I am looking at one now that appears to have some sort of phenocrysts.
Neil heads toward the MESA.  Later, at 111:00:01, he tells Houston, "the thing that I reported as the vesicular before, I don't believe I believe that any more.  I think it's small craters;  they look like little impact craters where BB shot has hit the surface." These tiny craters later came to be known as "zap pits".

3. The Contingency Sample

Neil collected the contingency sample in about 3 minutes 35 seconds, gathering material from five spots.  The total amount of lunar material collected was 1015.29 grams, of which nearly half (492.12 grams) was fines material.  "Fines" are pieces of rock smaller than 1 cm.  Twelve rock samples - by definition, pieces larger than 1 cm in all dimensions - made up the remaining 522 grams of the collected material.  Five of the twelve rocks were pieces of basalt:  10022, 10024, 10029, 10031, and 10032.  The remaining rock samples - 1002110023, 10025, 10026, 10027, 10028, and 10030 (no Compendium entry) - are regolith breccias, made from soil compressed during impacts.  The regolith breccias are described as friable, meaning that they break with relative ease.  In the 10021 entry in the Apollo Sample Compendium, Meyer tells us "10021 is a rather friable soil breccia. It breaks into rounded pieces (for example, figure 1 and figure 6). It was collected as part of the contingency sample from the area immediately in front of the Lunar Module (LM). The sample container (bag?) used for the contingency sample also contained other rather friable samples 10023, 10025, 10026, 10027, 10028 – some or all of which may be pieces of the same (in-situ rock)."

Sample Type
Mass (grams)
Dimensions (cm)
Sample Catalog page
10010 +10033

Fines were collected at all five locations
Rocks > 10 grams
10021 Regolith Breccia
7.5 x 6 x 3.5
Although the other information on page 129 are associated with 66-gram sub-sample 10021.36, the dimensions are more consistent with the whole sample, as shown in S69-45226.
10022 Basalt

Dimensions (2.4 x 2.2 x 2.2) given on page 136 in the Sample Catalog are consistent with the image of 20-gram sub-sample 10022.31 in the Compendium page. The whole rock undoubtedly had a volume roughly five times that of the sub-sample.  The dimensions of the whole rock would have been of the order of 3.5 - 4 cm.
10023 Regolith Breccia 66
6 x 4 x 2

10024 Basalt 68.12
5 x 4 x 2.5

Rocks < 10 grams
10025 Regolith Breccia 8.5
3 x 3 x 1

10026 Regolith Breccia 9.25
2.5 x 2 x 1.5

10027 Regolith Breccia 8.87
3.5 x 2 x 1

10028 Regolith Breccia 3.53
2.5 x 2 x 1

10029 Basalt 5.53
1.5 x 1.5 x 1

10030 Regolith Breccia 1.81
1.5 x 1 x 0.8

10031 Basalt 2.7
2 x 1.5 x 0.5

10032 Basalt 3.13
2 x 1.5 x 0.5


4. Five Sample Locations

4.1 First Sample Location

Rock at First Sample

Details from AS11-39-5777, taken out Buzz's window
and from AS11-40-5857, a frame from Neil's ladder pan.
(Click on the image for a larger version of the 5857 detail.)

There is one rock at the first sample location large enough to show up in the 16-mm film.  Once Neil gets the sampler down, he uses it to move this rock a few centimters toward his left boot, perhaps so he can determine how much of it is buried.  He then turns the sampler head so the opening is facing west and puts it down east of the rock.  He then uses the sample to scrape at the soil, running into densely packed soil (more regolith breccia?) a short ways down.  He then scoops up a sample and, from the way he manipulates the sampler at this first site, it appears that he was targeting the rock.  From the amount of digging he does, he probably gets a considerable amount of soil, too.

Before and After
            of Sample Site 1

"Before" and "after" images of Sample Site 1.  The white lines, which connect distinctive features - rocks, shadows, etc. - visible in both images,  indicate the original location of the Site 1 rock. The scoop mark in the "after" image represents primarily the final motion Neil made with the scoop at Site 1.  The video clip (34 Mb) gives details of the multiple scoop motions he made at this location.  Click on the image for a larger version.

Shadows cast by the
        plus-Y landing gear struts

Shadows cast by the primary and secondary plus-Y struts
in a detail from AS11-37-5777.
As can be seen in a
detail from AS11-40-5915, a frame from Buzz's plus-Y pan,
the secondary struts are covered with more insulation than
is indicated in Scott Sullivan's invaluable Virtual LM (below).

We can estimate the size of the rock by examining the shadows cast by the plus-Y landing gear struts.  As indicated in details from Virtual LM,  the two secondary struts are attached to the primary strut about 1.13 m above the bottom of the plus-Y footpad.  Although the solar elevation was 11.4 degrees at the time 5777 was taken, Eagle landed on ground that sloped up to the west by about 4.4 degrees, which pitched the LM back by that amount.  Consequently, the effective solar elevation is 15.8 degrees and the distance along the ground from the center of the plus-Y footpad to the shadow of the place where the secondary struts are attached to the primary strut is about 4.0 meters.  We get a second point along the shadow of the primary strut by noting that the end of the secondary strut that extends south west from the plus-Y primary strut is about 1.32 meters above the bottom of the footpad and 0.8 meters west of the north-south centerline of the spacecraft.  An effective solar elevation of 15.8 degrees puts the end of the shadow of that secondary strut 7.9 meters from the center of the footpad.  The diameter of the primary strut as can be measured in the detail from AS11-40-5915 is 23 percent of the diameter of the footpad which, in turn is 37 inches (94 cm).  Consequently, the primary strut diameter is 22 cm.  Finally, at distance of 4.0 and 7.8 meters, the diameter of the primary strut's shadow is 18 and 16 cm, respectively.  Because the first sample rock is about 7.3 meters along the primary strut shadow, and the shadow width is about 18 cm, we can estimate the rock's length along the shadow is at least 5.5 cm and probably more because of foreshortening.

Vlad Pustynski has calculated the visible dimensions using a different technique. Data accumulated in his detailed photogrammetric analysis of the landing site gives a distance of 4.5 m from the camera location when Buzz took 5857 to the rock.  The distance uncertainty is about 0.3 meters or about 6.6%.

As we will see in later sections, two of the four large rock pieces in the contingency sample - 10022 and 10023 - were identified by the Apollo 11 geology team as having been collected at the third and fifth sample locations, respectively.  The remaining rocks are 10021, a 250-gram regolith breccia with dimensions of 7.5 x 5 x 3.5 cm, and 10024 , a 68-gram piece of basalt with dimensions of 5 x 4 x 2.5 cm

LRL Photo of Sample

LRL photo S69-45226 of sample 10021.
The end facing the camera has a width of about 5-6 cm.
(Click on the image for a larger version.)

Although the estimated length of the first sample rock is more consistent with the known dimensions of 10021 than 10024, we haven't been able to locate LRL photos of 10021 taken from other view points to compare with the appearance of the rock in 5777 and 5857.  It is also possible that the rock Neil collected at the first site broke during sampling or transit, and that 10021 is the largest fragment.  If so, comparison of lab photos with the shape information available from 5777 and 5857 might not permit a credible identification.

4.2 Second Sample Location

Second Sample
            Site from Buzz's window

Pre-EVA photo 5777 from Buzz's window.
See, also, 5857 from Neil's ladder pan.

Before and AFter
          of Second Sample Site

The details from 5777 and 5857 do not show any rocks on the surface that appear to be bigger than 1 cm.  Nor are any of the small rocks visible in the pre-EVA Hasselblad images visible in the 16-mm film.  Neil takes a quick scoop, not digging at all, and probably only getting fines.  Neil moved the scoop from his right to his left, making the scoop marks nearly horizontal in the DAC image.

4.3. Third Sample Location

Detail from 5777 showing samples 10022
          and, possibly, 10028

Detail from 5777.  See also, detail from 5857.

Neil turns to his left and doing another quick swipe with the scoop, moving it horizontally but a bit deeper and over a longer distance than at site 2, and clearly targeting the large rock nearest him and the smaller one farther away. In the Preliminary Science Report, these are identified as 10022, a 95.6-gram basalt fragment,  and, with less confidence, 10028, a 3.5-gram regolith breccia. He may have gone deeper because the exposed part of 10022 is relatively large. 

Third Sample
            Site Before and After

Click on the image for a larger version.

4.4 Fourth Sample Location

Detail from 5777 showing Fourth site

Detail from 5777.  See also, detail from 5857.

Neil moved about a meter away from the LM and, with his back to the camera, collects a rock from the rim of a one-foot crater.  The sample site is hidden from view by his EMU, but the scoop mark can be seen after Neil moves away.  We get two brief glimpses of the Site 4 rock while Neil is assembling the sampler and, of course, have photos taken out Buzz's window before the EVA.  Comparisons between the various views indicate that the sample rock labeled above was collected at Site 4.

Before and
            After of Sample 4 Rock

Click on the image for a larger version.

If sample 10021 is all or part of the rock Neil collected at the Site 1, the rock collected at the Site 4 is probably 10024.

LRL photo of 10024 befroe any divisions

Sample 10024.  NASA photo S69-46031. Click on the image for a larger version.

4.5 Fifth Sample Site

Contingency Sample Site 5

Detail from AS11-39-5777, taken out Buzz's window before the EVA.  See also, a detail from AS11-40-5857, a frame from Neil's ladder pan.

After collecting material at the fourth site, Neil reached to his right and scooped up a rock and other material just inside the rim of a shallow, two-foot crater.

Fifth Sample
            Before and After

Click on the image for a larger version.

The relatively large rock Neil collected is identified in Apollo 11 Preliminary Science Report figure 3-17a (redrawn version) as sample 10023, a 66-gram regolith breccia.  In figure 3-19 (redrafted from 5777), a small rock just beyond 10023 is tentatively identified as 10032, a 3.1 grams basalt fragment.


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