The Helicon Double Layer Thruster concept is based on the recent discovery of a current-free electric double layer in a helicon plasma expanding in a diverging magnetic field. The potential drop of the double layer is situated in the physical and magnetic nozzle and accelerates the ions generated in the helicon plasma source. The supersonic ion beam measured downstream of the double layer can be used for thrust in a space craft. The Helicon Double Layer Thruster is simple, has no moving parts, no electrodes, and no need for a neutraliser.

Many of the techniques employed for rocket meteorology-"rock-etcasting"-have been adapted from aviation. However, the unique characteristics and requirements of rocketry demand special meteorological procedures and instrumentation, which are only recently becoming satisfactorily defined. The influence of weather parameters on operational rocketry is examined, with special emphasis on the Tanegashima Space Center , Japan. It is concluded that the fundamental requirement for efficient launch operations is a highly sophisticated nowcasting facility, backed by an effective research and development program. On 13 August 1986, the National Space Development Agency of Japan (NASDA) launched from the Osaki rocket range in Tane-gashima three payloads on the inaugural flight of the H-1 launch vehicle. The launch weather was expected to be fine at the range. In the event, a thunderstorm commenced close to the launch area during the last few seconds before launch, which nevertheless proceeded successfully. This incident highlights the uncertainties of rocket operations, particularly in the critical area of the provision of reliable weather information and forecasts. The synoptic conditions at the time of the 13 August launch incident are examined, and a qualitative forecast checklist is suggested to assist in forecasting similar summertime early-morning maritime storms in the future.

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