The first stop on our tour is the Normal Change Room. When we first enter the change room, we must wipe our shoes on the mat next to the door and then don overshoes or "booties." Next we must remove all jewelry. We follow these procedures in order to prevent contaminating the lunar samples with particles and other material from our bodies and clothing. Airborne dust is the chief way in which contaminating material could reach the lunar samples. Each cubic foot of ordinary room air commonly contains 100,000 particles of all kinds. The coarser particles eventually settle as dust, but the finer particles stay suspended indefinitely. New particles are generated continuously; for example, dried skin flakes from people, lint and dust from clothing, material carried by shoes and abraded from the floor, metal particles from screw threads, etc.

The Moon is composed of the same chemical elements as the Earth, but in different proportions. Some elements which are very common on Earth occur in lunar samples in very small quantities. A tiny speck of gold from a wedding ring would increase the concentration value measured for gold in a lunar sample many times over the true value and would lead to a false interpretation of the sample's origin.

A number of measures are taken to keep the air clean in the lunar laboratories. The air is circulated through special filters to remove all suspended particles. To keep unfiltered air from entering laboratories, filtered air in the laboratories and vaults is kept at slightly higher pressure than the atmospheric pressure used in the rest of the building. The particulate concentration of the air in the various areas is monitored regularly, and levels routinely test better than performance requirements. Therefore, we have tangible results that the contamination control measures that we take are successful.


If we were entering the Experiment Laboratory or the Return Sample Vault at this point, we would put on smocks, hats, and a second pair of shoe covers before leaving this room. However, we will proceed first into the Pristine Laboratory and Vault areas. The contamination control requirements are stricter there than for the Experiment Laboratory and Return Sample Vault, and, before entering these areas, we must proceed into a second change room known as the Clean Change Room. In this room, we put on specially cleaned clothing which includes nylon coveralls or "bunny" suits, hats, gloves, and a second pair of overshoes. Next we enter an air shower where we remain for 1 minute while filtered air is blown across our bodies from top to bottom.

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