not space debris from a man-made object, citing four reasons: (1) reentering spacecraft debris does not impact the Earth's surface in a molten state, (2) the 35- to 40-pound mass left no crater or indentation, (3) reported visual sighting was at an altitude of only 500 to 600 feet, where reentering debris would not be glowing and (4) the lack of structural indications is inconsistent with space debris.

Discussion of Element Frequency

     The samples described in the ten cases we have reviewed are summarized in Table 3. They belong, broadly speaking, in two major classes: samples resembling slag or industrial residue, and light silvery alloys, with one incident (case no. 2, Maury Island) involving both types of materials. Unfortunately, as we have seen, the analysis of the original samples in this particular case was never released by authorities, and we can only refer to sources of dubious reliability. In incidents involving slag-like material one primarily finds iron with traces of chromium, manganese and silicon, notably in Jopala and in Council Bluffs.

     In cases involving light silvery material we find references to magnesium (cases 1, 3 and 6) and aluminum (cases 1 and 8), with iron mentioned in trace amounts. Some of the details of the composition remain puzzling: We cannot account for the very high degree of purity of the Ubatuba magnesium sample, or for the absence of water and fluoride in the Bogota specimen.

     We have encountered no case of unknown elements and no case with advanced technology materials exhibiting an unusual structure. However the samples, as analyzed, appear to be consistent with the accounts given by witnesses, lending credibility to the reports in spite of their sometimes extraordinary details.

     In summary, the analysis supports the thesis that an unidentified phenomenon has been repeatedly observed in various parts of the world over a long period, that it manifests through a physical, material support, and that it is amenable to scientific study. On the other hand, the patterns observed in the composition of the samples at our disposal do not point to any clear hypothesis for the nature of the phenomenon.

     The fact that no exotic composition was found in these ten cases cannot be used to negate the theory that an advanced technology of unknown origin may have generated the samples. In the case of our own automobile industry, for example, environmentally compliant engines produce more mundane exhaust (such as pure water) than older models, where one could find complex combination of gases.

Liquid Metal Technology

     The similarities between many of the above cases point to a common scenario for the generation of the recovered samples: metal is observed to be ejected in molten form by an unidentified aerial object, commonly described