On January 11, 1971, the second symposium on Apollo results convened in Houston. Some 400 scientists gathered to hear further findings from the Tranquility samples and the first from Oceanus Procellarum. An added feature of the conference was the presence of Academician Aleksandr Pavlovich Vinogradov, vice-president of the Soviet Academy of Sciences and director of the Vernadsky Institute for Analytical Chemistry in Moscow, who presented the results of examination of lunar samples returned by the Soviet Union's Luna 16 from a site almost 1,000 kilometers (625 miles) east of Tranquility Base.* Like its predecessor of 1970, the lunar science conference of 1971 was rich in detail but poor in large-scale conclusions. This was only to be expected in view of the small number of sites sampled, the complexity of the material returned, and the short time scientists had been studying the samples.
Vinogradov's report indicated nothing especially novel about the site where Luna 16 landed. It was covered with a fine soil essentially similar to the samples Apollo 11 and 12 had brought back.74 Other papers, however, presented fundamentally new information. One of the puzzling aspects of the Apollo 11 investigations had been that lunar rocks seemed to be younger than the soil ("regolith " is the technical term) around them, by as much as a billion years, and differed in chemical composition as well. Material in some of the Apollo 12 samples appeared to offer an explanation of the differences. MSC scientists found some fragments rich in potassium (chemical symbol K), rare-earth elements, and phosphorus (leading to the acronym "KREEP"), best explained as debris from an old bedrock.75 Other investigators found a rock fragment of similar composition, which, they speculated, represented material which originally was located near the surface of an ancient lunar crust.76 These discoveries supported the idea that very early in its history, the moon had had a molten surface layer that slowly cooled to produce a primitive crust, which was then subjected to later episodes of melting. The scientists conjectured that the KREEP material, which showed evidence of having been subjected to considerable shock, was thrown onto the plain of Oceanus Procellarum by the impact of a large meteorite in the highlands.77 This view was consistent with the "chemical anomaly" of the KREEP component compared to the neighboring rocks. It was relatively low in iron and relatively high in aluminum, and the differences decreased the farther the regolith samples were from the highlands, as would be expected if the material responsible had been thrown out by impact.78
The second lunar science conference provided no ultimate key to the origin and history of the moon, any more than the first had done. Besides adding some 200-odd papers to the scientific literature on lunar science, it showed that future missions might be expected to provide more scientific surprises. Future conferences, however, would present new information in a growing context of facts about the moon, established in the first two conferences and rapidly expanding as investigators published their results elsewhere.**
Although the results of the second lunar science conference came too late to influence the choice of a target for Apollo 14 (which was launched two weeks later), they indicated that the Fra Mauro site selected for that mission was likely to be a good choice. Its intrinsic interest as the first nonmare landing site was heightened by the discovery of KREEP, for if that material were found in substantial quantity at Fra Mauro, the tenable hypotheses about the origin and early history of the moon would be considerably restricted.
*The unmanned lunar probe Luna 16 landed in Mare Fecunditatis (lunar latitude 0 degrees 41' south, longitude 56 degrees 18' east, approximately 100 kilometers [63 miles] west of crater Webb) on Sept. 20, 1970. An electrically driven core drill penetrated some 35 centimeters (14 inches) into the lunar soil, collecting about 100 grams (3.5 ounces) of sample, which was dumped into an upper stage of the spacecraft and returned to earth four days later. NASA, Astronautics and Aeronautics, 1970: Chronology in Science, Technology, and Policy (NASA SP-4015) , pp. 299, 316, 325, 349. Vinogradov's presentation at the conference was one aspect of the cooperation in space exploration that was developing at the time, which culminated in a joint American-Soviet manned mission in 1975. See Edward C. Ezell and Linda N. Ezell, The Partnership: A History of the Apollo-Soyuz Test Project, NASA SP-4209 (Washington, 1978).
**The moratorium on publication before the conference, stipulated by NASA and agreed to by the principal investigators of the Apollo 11 samples [see Chapter 9], was lifted after the first lunar science conference. It had been imposed to avoid "a wild scramble for publication immediately after samples became available." Philip H. Abelson, "The Moon Issue," Science 167 (1970): 447. There was evidently a strong feeling that scientists were not immune to the temptation of the publicity that would accrue to the first publication of the results of investigating a lunar sample.
74. A. P. Vinogradov, "Preliminary Data on Lunar Ground Brought to Earth by Automatic Probe Luna-16,'" in Proceedings of the Second Lunar Science Conference, A. A. Levinson, ed. (Cambridge: MIT Press, 1971), pp. 1-16.
75. Norman J. Hubbard and Paul W. Gast, "Chemical composition and origin of nonmare lunar basalts," ibid., pp. 999--1020; John Noble Wilford, "Exotic Fragments Found In Apollo Lunar Samples," New York Times, Jan. 11, 1971.
76. Wilford, Exotic Fragments ;Ursula B. Marvin, J. A.Wood, G. J. Taylor, J. B. Reid, Jr., B. N. Powell, J. S. Dickey, Jr., and J. F. Bower, "Relative Proportions and Probable Sources of Rock Fragments in the Apollo 12 Samples," Proceedings of the Second Lunar Science Conference, pp. 679-99
77. Arthur Hill, "Primitive Lunar Crust Is Hinted by Fragments," Houston Chronicle, Jan. 11, 1971.
78. Cappellari, "Where on the Moon?", pp. 990-94.