(editor: Chris Vancil: These parts were not operating for 2.5 years but siting on the Moon for that length of time. I wonder what the conditions of the bearings in particular would have been if they had been in use and in the subsurface some of the time.)

2. 1 GENERAL CONCLUSIONS AND RECOMMENDATIONS

Extensive studies were conducted on the Surveyor III parts returned from the moon by the Apollo XII astronauts. These studies are believed to have produced a significant amount of useful information directly applicable to future programs. Significant effects of lunar exposure have been noted, including some that had not been previously anticipated (Reference 2). Of equal significance were some effects previously conjectured, for which no apparent evidence was observed.

It is believed that the test program, albeit limited in scope, was reasonably comprehensive. A fairly complete sequence of tests was conducted on the various components and materials, including chemical, physical, mechanical, electrical, and metallurgical examinations. Nevertheless, these tests can by no means be termed exhaustive, and additional work may be warranted. Publication of results of the parallel science investigations still in progress will also help define any additional effort
desired.

It is believed that the results of this investigation to determine the effects of prolonged lunar exposure on a variety of materials and components, coupled with a similar investigation of the Surveyor III television camera presented in a companion report (Reference 1), may be directly applicable to future spacecraft design. It is therefore recommended that a careful review of the test data contained in this report be made in the course of design of future spacecraft. Accordingly, a wide dissemination of this report to space systems designers is suggested. Any additional tests required would thus be determined as appropriate for each particular application.

The principal conclusions of this study are summarized below. A list of major effects observed, as well as comments on some of the effects originally conjectured (Reference 2) but not observed, is presented in Section 2. Z. Section 2.3 cites some examples of possible follow-on studies. The most significant conclusion is that although changes occurred in many properties of the materials no change was found which would have

prevented any material or any part from performing its task even after 2-1/2 years exposure to the rigorous lunar environment. The second most significant was the discovery of a heavy coating of lunar dust on the exposed surfaces. This coating was to a large extent caused by the landing of the Apollo lunar module, in addition to the effect produced by the original abnormal landing of the Surveyor III. It is noteworthy that the Apollo lunar module descent engine was able to produce this effect from the relatively large distance of 500 feet between its landing area and the Surveyor III spacecraft.

Results of the surface discoloration and contamination studies indicated that this effect was primarily caused by radiation damage and lunar dust coverage, with a relatively minor contribution from organic deposits. The relative contributions of radiation and dust varied from all dust in some areas to all-radiation in others, with the majority of exposed surface areas discolored by a combination of these two factors. Radiation induced effects were proportional to the degree of solar exposure. The amount of dust deposited was generally higher than expected.

Future recoveries of valuable hardware from space should carefully consider landing techniques and protection of critical surfaces in light of the information desired. For example, if the interaction with the landing terrain is significant (e. g., lunar dust), the landing should be planned a sufficiently large distance away. If a study of the optical characteristics of the surfaces of the recovered parts is important, the returned parts should be carefully protected from the environmental conditions, such as air, light exposure, etc. In retrospect, it is believed that the results of the analysis of the retrieved Surveyor III parts would have been significantly more informative had it been possible to observe the above recommendations
to a greater degree.

The results of the study-also suggest a possible change in a material process for future applications. The use of inorganic paints on fiberglass structures should be avoided if exposure to severe thermal cycling is anticipated.