DIS Scientific & Technical Memoranda 55/6/99 and 55/2/00

This document consists of two scientific and technical memoranda from the Defence Intelligence Staff (DIS) dated February 2000. The first section, Appendix A5, focuses on the detectability of plasma-based UAP targets by radar. It posits that if a UAP is a stable plasma sphere, its radar cross-section (RCS) would fluctuate based on its density and shape, explaining the intermittent nature of radar detections. The second section, Working Paper No. 6, titled 'Exotic Technologies,' evaluates the feasibility of various advanced propulsion systems, including anti-matter, electric propulsion (arcjets, ion thrusters, field emission), and projected energy (laser and microwave). The report concludes that the majority of UAP sightings are explainable as natural or human phenomena. It explicitly states there is no evidence of extra-terrestrial vehicles visiting Earth, no evidence of communication with occupants, and no evidence that any nation possesses the capability to produce and trap anti-matter for propulsion. Working Paper No. 7 addresses the geometry of sightlines for flying objects, noting that witness reports of speed and altitude are often inaccurate due to the difficulty of estimating range and the tendency for observers to misinterpret natural phenomena like meteorites or satellites as anomalous craft.