Wind-field analysis on the basis of METEOSAT images

A method for the determination of cloud motion vectors is proposed by calculating from METEOSAT images the displacement of characteristic formations in the brightness field. The claculations are made for a sector of the Atlantic Ocean (ψ = 48°?38°N, λ = 24°?12°W). The adaptability of the Soebel operator for such calculations is also shown. The calculated wind vectors are in a good agreement with wind data at 850 mb surface.     

Connections between short-period (Pc 1) pulsations and ionospheric parameters

Short-period pulsations recorded at five stations in Finland during the IMS have been compared. The morning occurrences accepted as Pc 1's showed certain peculiarities in their dependence on latitude. A connection was found between the averaged daily duration of Pc 1's and the foF2 parameter. This hints at the influence of propagation conditions. It was found that, after certain geomagnetic storms, the mid-latitude ionospheric absorption of LF radio waves can significantly increase when the Pc 1 activity is also enhanced at each high-latitude station.     

Determining total ozone content in the atmosphere using satellite measurements

In this paper a simple method is presented which is applicable for fast determination of total ozone content in the earth atmosphere by using IR radiation intensity data from satellite measurements. The method is based on the property that transmittance of inhomogeneous atmosphere in the 9.6 μm band can be well approximated by the transmittance of a homogeneous ozone slab characterized by its effective pressure and temperature. The effective pressure and temperature were determined as mean values weighted by the average ozone profile of each season. The transmission functions were computed from an empirical formula. Free parameters in the formula were determined by a multiple regression scheme, on the basis of the transmittance data either measured in the laboratory or evaluated by computations using a line by line integration procedure. The main advantage of the described method is an easy and fast computation procedure. According to comparison with direct ozone sounding the accuracy is good enough: the average relative error lies between 5 and 7%.     

Synthesis of flight results of the Cactus accelerometer for accelerations below 10−9g

The Cactus accelerometer, developed at ONERA and making up the payload of the Castor satellite, has been operating continuously and normally for 40 months. Thanks to the great quantity of data acquired and to a well adapted processing technique, acceleration measurements were in fact obtained with a better sensitivity than that expected before launch.This paper presents a synthesis of the work carried out in the past year and concerning the measurement of very low accelerations. These are due, for the most part, to the Earth IR radiation pressure when the satellite is in the Earth's shadow, and to the thrust it is subjected to under the influence of the anisotropy of its own radiation.     

Biofeedback monitoring-devices for astronauts in space environment

After a reconsideration of the state-of-the-art in biofeedback research the implementation of biofeedback systems is envisioned as a countermeasure of stress for the psychoprophylaxis of the astronaut. A one-session experiment performed on two groups of subjects to assess the interference from EMG-feedback on the performance in a simultaneous psychomotor trial with a view to expanding biofeedback application is described. The results show that the experimental group performed in the same way as the control without feedback, but with less CNS activation. Some general conclusions are drawn from the advances in technology.     

The electromagnetic rocket gun

A novel propulsion concept is proposed which has the potential of accelerating large masses to velocities substantially higher than what is possible with chemical rockets. The novel concept is an electromagnetic gun, where the projectile is a rocket. The proposed concept solves the old problem of magnetic propulsion, which is the resistive dissipation of the induced electric currents into heat which will vaporize the projectile long before it can reach a high velocity. As in a rocket, where the propellant cools and thereby prevents the rocket from burning up, the same happens in the proposed concept where the propellent also cools the projectile and prevents its vaporization. The propellant, however, not only cools the projectile but in addition is resistively heated by the magnetic field and ejected from the projectile with high velocity. The resulting recoil produces an additional thrust which is approximately as large as the thrust exerted by the magnetic field alone. The energy to drive the jet is externally supplied, making the specific impulse much larger than for chemical rockets.     

Hard X-ray emission from the recurrent transient A0535+26 during its 1980 high-intensity outburst

The transient X-ray pulsar A0535+26 was observed on October 4, 1980 during a high level intensity outburst with a balloon borne hard X-ray detector. High statistical quality source spectra were determined up to 100 keV. Both blackbody and Wien laws fit well the data. Pulse phase spectroscopy shows variation of temperature index between 7.5 and 8.5 keV in the off source spectra and between 7.4 and 10.5 keV in the off pulse spectra. The time averaged luminosity above 30 keV is 8×10³⁶ erg/s.     

The Geometry of Escaping Targets

The escape regions for alerted targets are analytically defined.Sets of circles which circumscribe these regions provide simplified meas of the resulting escape involutes and yield important weapon guidance and sensor search parameters. These regions permit the selection of an aimpoint which incorporates the potential of target maneuers. Applications that illustrate the improved performance of these solutions in missile deployment and lost-contact-redetect situations are included.