Three categories of samples were brought back by the Apollo 11 crew: contingency, bulk, and documented (or core) samples. Neil Armstrong collected contingency samples first - about one kilogram of surface material - being careful to get far enough away from the lunar module that the soil would not have been contaminated by the residue from the descent engine exhaust. He sealed this sample in a plastic bag.
For the second category, the bulk sample, one of the two special rock boxes was filled, using a scoop. Not much attention was given to varying selection, since the objective was merely to collect an adequate amount of material for investigation upon return to the earth. But even here, Armstrong did better than expected, gathering 11 rocks of more than a hundred grams each (the largest weighing nearly a kilogram) some distance away from the base of the lander.
When the activity outside the lunar module fell 15 minutes behind schedule, the lunar sample investigators back on earth worried that the crew might not be able to obtain the documented sample, the third category. Fortunately, the smooth functioning of the life support system and the low metabolic usage of the pilots permitted the extension of the extravehicular period. While Edwin Aldrin collected the two core samples (to study the stratification of subsurface material), Armstrong hurriedly gathered 25 more rock specimens, using tongs to pick them up.
The two boxes were sealed and placed in the lunar module, transferred to the command module after the docking, pulled out on the deck of the aircraft carrier, put in the mobile quarantine facility, and flown to Houston, arriving at the Lunar Receiving Laboratory on 25 July 1969.
The bulk and documented samples were placed within a double biological barrier (vacuum chamber and special cabinets), which made handling and working with the materials difficult. (Contingency sample material was put in a nitrogen cabinet, where working conditions were not so restrictive.) Ordinarily simple laboratory tasks, such as photographing and weighing, were very complex. But the boxes were opened in the vacuum chamber and the rocks were examined, described, photographed, weighed, and chipped. More than 21 kilograms of samples were brought back: one-third in rock fragments of one centimeter or more in diameter and two-thirds in smaller particulate material (soil).
Preliminary work on the samples began in the laboratory on 26 July 1969, and specimens of lunar materials were released to more than 140 principal investigators on 12 September. During the 50-day interim, the set period of quarantine, members of NASA's Preliminary Examination Team (among them, E. M. Shoemaker, N. G. Bailey, R. M. Batson, D. H. Dahlem, T. H. Foss, Maurice Grolier, E. N. Goddard, M. H. Hait, H. E. Holt, K. B. Larson, J. J. Rennilson, G. G. Schaber, David Schleicher, H. H. Schmitt, R. L. Sutton, G. A. Swann, A. C. Waters, and Mareta West) tested the materials.
The team's summary report stated that an unexplained erosion process, "unlike any process so far observed on earth," on the lunar surface - shown in photographs from the Ranger, Orbiter, and Surveyor programs - had been confirmed during examination of the samples in the laboratory.
Chemical composition of the fines (powdered material) and igneous rocks (fire-made), according to the report, was different from that of any known terrestrial rock. The team was also of the opinion that there was a "good chance that the time of crystallization of some of the Apollo 11 rocks may date back to times earlier than the oldest rocks on earth."
Apollo 11 had landed in the southwestern part of Mare Tranquillitatis, 0.67 degrees north latitude and 24.39 degrees east longitude. This region is crossed by relatively faint rays, spreading out from large craters in that sector of the moon. There is a possibility that these rays might contain fragments from Craters Theophilus, Alfraganus, and Tycho - although the closest of these, Alfraganus, is 160 kilometers away.
At the landing site, particles ranged from those too small to be seen with a naked eye to two-thirds of a meter in diameter. The surface material formed a layer called the lunar regolith (mantle), porous and weakly coherent on the surface but more densely packed underneath. The bulk of the mantle in the landing area was of fine particles, although there were rock fragments on top of and in the soil.
Around the lunar module, the crew observed that the rocks were varied in shape and that most of them were embedded in the soil to some degree. A majority of the rocks examined had rounded tops, but the bottoms of these same rocks usually had either flat areas or irregular angular shapes. To Armstrong, one rock (not brought back) resembled a distributor cap. He dislodged it with a kick and saw that the buried portion was larger than the exposed end and was angular in shape.
The evaluation team used the term "rock" for any fragment larger than one centimeter in diameter and "fines" for anything smaller. It divided the samples into four types:
The glassy deposits were interesting to the crew and to the investigators. On the moon, Armstrong said, the glass looked like balls of solder that had hit the surface in a fluid state and then hardened. He said the glass appeared to have a metallic luster with multicolored reflections. In the laboratory, the team observed that some glass particles (the samples ranged in size from 10 millimeters to less than 10 microns) were colorless and others were brown, red, green, or black. The brown were the most abundant.
One noticeable feature of the rocks was the rounding of one or more edges and corners. In the softer materials, the breccias, rounding was more pronounced than on the harder crystalline rocks. There were coarser grains poking out of the breccia formations, indicating that the surface had earlier been surrounded by finer grains that had subsequently eroded.
Neither core sample showed any signs of stratification. One of the two did have a lighter zone about six centimeters from the top, but a megascopic (magnified) examination revealed little difference in the lighter and darker materials.
During the preliminary examination, the team conducted microscopic studies, trying to find any living, previously living, or fossilized material. No such material was found in any case. Some of the samples were subjected to germ-free mice, fish, quail, shrimp, oysters, other invertebrates, tissue cultures, insects, plants, and paramecia. There was no evidence that any pathogens were present.