aircraft, or one which is practicing an ILS approach but does not actually intend to touch down." In Thayer's opinion, "A ghost echo seems to be ruled out." He concludes that

This must remain one of the most puzzling radar cases on record, and no conclusion is possible at this time. It seems inconceivable that an anomalous propagation echo would behave in the manner described, particularly with respect to the reported altitude changes, even if AP had been likely at the time. In view of the meteorological situation, it would seem that AP was rather unlikely. Besides, what is the probability that an AP return would appear only once, and at that time appear to execute a perfect practice ILS approach?

Condon makes no reference to this case in the section of his summary dealing with radar sightings of UFOs.

Miscellaneous Evidence

Brief mention only will be made of some of the other types of evidence considered in the report. Section CR III, Chapter 6, concerns "Visual Observations Made by U.S. Astronauts" as studied by Professor Franklin E. Roach (Condon & Gillmor, 1968, pp. 176-208). The final paragraph of Roach's "Summary and Evaluation" is as follows:

The three unexplained sightings, which have been gleaned from a great mass of reports are a challenge to the analyst. Especially puzzling is the first one of the list, the daytime sighting of an object showing details such as arms (antennas?) protruding from a body having a noticeable angular extension. If the NORAD listing of objects near the GT4 spacecraft at the time of the sighting is complete as it presumably is, we shall have to find a rational explanation, or alternatively, keep it on our list of unidentifieds.

Condon, in discussing these observations (Condon & Gillmor, 1968, pp. 42-43), quotes Roach's remark that the three sightings are "a challenge to the analyst," and goes on to remark that "nothing definite relating to the ETH aspects of UFOs has been established as a result of these rather sporadic observations."

Concerning "Direct Physical Evidence," Craig (Condon & Gillmor, 1968, pp. 94-97) attaches special significance to "metal fragments that purportedly fell to earth at Ubatuba, São Paulo, Brazil, from an exploding extra-terrestrial vehicle. The metal was alleged to be of such extreme purity that it could not have been produced by earthly technology." Investigation by the Colorado staff showed that a sample of triply sublimed magnesium, supplied by the Dow Chemical Company, had a smaller impurity level than that of the "Brazil UFO." The analysis, however, showed that the fragments contained traces of both barium and strontium, which are not usual impurities in the production of magnesium; these metals were undetectable in the Dow sample. Craig remarks, "The high content of Sr was particularly interesting since Sr is not an expected impurity in magnesium made by usual production methods, and