Condign volumes 1 to 3

# UNCLASSIFIED

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be obtained, for example for a comparison with conventional hydrogen. The approach is to produce traps to contain, separately, antiprotons and positrons both at liquid helium temperatures. Anti-hydrogen is then obtained by the combination. The work so far has used the highest energies achieveable by the Low Energy Anti-proton Ring (LEAR). No antihydrogen has yet been trapped at low temperature. There are no indications of any current experiments or early developments of future potential applications of anti-matter for propulsion purposes.

12. Former Soviet Union Scientific papers report the conceptual design of antimatter storage devices, for example, positron storage rings. These, including the 'IREN' project are at the design experimental and very early development stages. In particular, important work is proceeding on the use of Gamma-Ray Lasing in the matter and antimatter research fields.

13. France & Italy French aspirations seem to be significantly aimed at whether some stars (and even some entire galaxies) may exist which are made up of anti-matter. The possibility of this scenario will, in theory, be proved if anti-matter (single anti-helium nucleus in cosmic ray flux) are detected in cosmic rays. Results are awaited from the a current Shuttle project. Further work is being funded by NATO and the EU. In 1996, two scientists at the Italian National Nuclear Physics Institute reviewed anti-matter as an area of future research and proposed future experimental projects. They pointed out that the possible existence of anti-matter was first postulated in 1928, and that recent exoatmospheric experiments were delayed following the Shuttle disaster. As a result four balloon-borne experiments had occurred and the planned work (Italy-Russia) will also examine anti-matter components of cosmic rays. The possible existence of cosmological ant-matter, with a symmetric universe and matter and anti-matter separated into domains remains a fundamental question.

14. ROW Nations There is no evidence that any ROW nation has scientific or engineering capability, leading to real developments in the field of anti-matter.

## ELECTRIC PROPULSION TECHNOLOGIES

15. Chemical propulsion requires large propellant mass compared with electrical methods. Hence, assuming that a UAP of undetermined origin could somehow enter and leave earth's atmosphere, (with the capability of some unknown propulsion method) the remaining journey (from wherever it came from and returned to) could presumably use one of the 'electric' propulsion methods for which the technologies are currently understood. However, these produce low thrust levels (mN), as shown at Table 1.

16. Arcjets produce an arc typically in the exhaust nozzle of a chemical thruster. For electric propulsion (EP) although their thrust is higher than other EP methods, there is the mass penalty of the chemical propellant required.

17. Stationary Plasma Thrust (SPT) produces ionised xenon, which draws in electrons from a cathode after the xenon propellant passes through electric and magnetic fields in a discharge chamber.

18. Ion thrusters (IPS) also use ionised xenor propellant.

19. Field Emission Propulsion (FEP) is a future concept assessed to produce a higher specific impulse (Isp) but at low thrust levels.

20. None of the methods at Table 1 were conceived as primary methods of spacecraft propulsion.

21. On board power requirements (for a 18mN UK IPS design with an Isp of 3466) is ~600W, worst case. The thruster exhaust velocity is $ - 4 0, 0 0 0 \mathrm{m}. \mathrm{s}^{-1} $ . For satellite positionkeeping, 40Kg of propellant held in a titanium storage tank (mass $ \sim 1 0 \mathrm{K g} $ ), would provide a planned life of ten years. Even a small thrust,