Next we will look at the Core & Saw area of the Pristine Sample Laboratory. This area serves two functions, the dissection of cores and the bandsawing of rock samples. These two operations are never done simultaneously because the vibrations produced by the bandsaw would disturb the very sensitive core samples.


The lunar surface is covered with a layer of crushed and fused rock called regolith. The finest material is called soil, although it does not have organic material like earthly soil. The soil is a result of continual meteorite impacts which break up, melt and vaporize rock. Each impact causes the formation of a crater and throws material, called ejecta, which blankets a circular area around the crater. Occasionally, one ejecta blanket covers another, preserving layers in the soil which can be tied to specific cratering events. However, most often the numerous small meteorites, down to sand size, stir and mix the layers in a process known as "gardening." The top soil surface accumulates radiation and particles spewed out by the Sun. The Apollo astronauts collected tubes of soil, called core samples, from 24 locations on the Moon. These drill cores went as deep as 3 meters (10 ft) into the soil. A soil layer found at the bottom of one drill core was deposited about 500 million years ago and contains evidence about the Sun's behavior at that time.

To capitalize on the wealth of information held within the cores, great care must be taken in opening them and in removing samples for study. X-ray pictures through the metal core tubes give the first data about the core samples. Then, inside a nitrogen cabinet, the core material is pushed out of the tube into a horizontal receptacle. Millimeter by millimeter the material is examined, photographed, and then carefully sliced away and put into separate containers for each interval. A small portion of the material from each interval is distributed for the first analyses, which will guide planning for subsequent studies. A strip along the length of each core is left intact and embedded in plastic as a permanent record of the structure. It takes four to six months to dissect and describe one core section. The 24 cores were collected in 54 separate tubes, 4 of which have yet to be opened and examined for the first time.

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Many studies require precise locations of subsamples within a rock. For example, energetic radiation from the Sun and from space produce nuclear reactions within lunar samples. To deduce the energy of radiation that produced a reaction, it is essential to know the depth within the rock where the reaction occurred - the deeper the penetration of the radiation, the greater their energy. A piece cut across the middle of a rock enables studies of radiation from the Sun and other stars from the least energetic at the surface to the most energetic at the bottom of the rock. Sawing a rock is the only way to produce such pieces and obtain accurately located pieces for other studies. In addition, sawing reveals the complex internal structures of rocks such as breccias.



Special bandsaws have been developed for doing this kind of work. To protect the rocks from contamination and reaction with air, the saws are enclosed in a nitrogen cabinet. The rock is clamped to a sliding table and advanced into a stainless steel blade which has diamonds in the cutting edge. Since the lubricants and cooling liquids normally used in sawing rocks would badly contaminate the lunar samples, the sawing is done dry and very slowly to prevent overheating.

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