PowerCore combining structure and batteries for increased energy toweight ratio

Much of the mass of a battery is comprised of nonreactive materials. In an NiH₂ battery, this includes the pressure vessel and 50% of the positive electrode. PowerCore reconfigures the battery materials to serve as a structural sandwich panel. The effective specific energy of the new device can exceed 100 Wh/kg. PowerCore is intended to handle power demands of low Earth orbiting communications satellites such as IRIDIUM. This paper describes the concept and development progress     

BBXRT and Ginga observations of AGN

The X-ray properties of Active Galactic Nuclei (AGN) support recent theories which unify the Seyfert 1 nuclei with the Seyfert 2's and radio-quiet quasars. In these objects the underlying spectrum is strongly distorted by the effects of reflection from the accretion flow and by absorption in partially ionised material. These obscure any intrinsic changes in the spectrum, making it difficult (though not impossible) to constrain the nature of the emission process. Conversely, there is no evidence for either of these spectral distortions in the radio-loud AGN, supporting the hypothesis that the X-rays are dominated by beamed emission from the relativistic jet.     

Massive stars: Setting the stage

The paper gives a summary of the situation mid-1993 of theory and observations regarding massive stars. I describe: stellar mass loss and its implications, pre-main-sequence evolution, the main sequence, problems of atmospheric instability, Luminous Blue Supergiants, Yellow Hypergiants, Wolf-Rayet stars and supernovae.     

The strong stability of most natural motions

Problems of Hamiltonian Mechanics can generally be simplified by some Von Zeipel transformations which reduce the influence of short period parameters and lead to very slowly variable functions: the “quasi-integrals”; however these transformations are implicit and then difficult to use.An explicit construction of the quasi-integrals is presented here and is used to integrate the motion of an artificial satellite perturbed by the zonal harmonics of the Earth gravitational potential; the quasi-integrals are also used to obtain informations on the stability of natural satellites, i.e. lower bounds on the duration of escape or capture.     

The uses of past and present magnetospheric field models for mapping fluxes and calculating conjugate points

Two different utilisations of magnetospheric models are described in this paper. In the first one very crude analytical expressions are used to describe the motion of energetic particles and the evolution of fluxes along a given orbit. In the second one, the exact internal and external fields are used for field line tracing and the determination of conjugate points. Applications to the calculation of synchronous fluxes and the Geos conjugate points are given.     

Space robotics in the '90s

This article describes the use of robots to perform work in space. In particular, telerobotics, which uses human operators to control the movement and operation of the robots, are explored. The relationship between the human operator and the robot is very complex but these systems are being used to explore planetary surfaces and will also be used in the construction of the space station. Research being conducted at NASA facilities is described, providing a picture of the future of space robotics.     

Hydromagnetic motions in the magnetosphere

Following a brief specification and historical review of hydromagnetic motions in the magnetosphere, the principles of the governing and limiting processes are surveyed. A formal proof of the well-known hydromagnetic theorem is included, and its interpretation in terms of frozen fields is discussed. Some consequences of its application to the magnetosphere are then described, and the value of equipotentials as a means of illuminating the discussion is established. Departures from the hydromagnetic approximation are then evaluated, and their resultant currents described.The general principles find application in a number of processes: rotation, high-latitude circulation in quiet and disturbed conditions, more widespread convection under continuous dynamo action, and irregular motion both of an unstable and of a forced type. All these are reviewed, and one emergent point is emphasized: that direct evidence for the hydromagnetic motions is lacking, but that it can and should be sought.     

Comparisons between primrose lake (54°N, 110°W) ROCOB winds (20–60 km) and Saskatoon (52°N, 107°W) M. F. radar winds (60–110 km): 1978–1982

The development of the new CIRA will require the combination of winds from many sources, e.g. rockets (ROCOB) up to ～60 km, and radar winds ～60–110 km. Difficulties are that such rocket data have larger errors at 60–65 km, and tidal effects may become significant. Radar data for 60–80 km may also have tidal contamination, due to ? 16h of data per day: from 80–110 km tidal corrections are usually reliable.Comparisons are made between the unique Saskatoon MF radar set, which is continuous from mid 1978–1983, and the ROCOB data from Primrose Lake, which is only 340 km northwest. While the agreement is satisfactory, special care is required when matching the two regions: particular problems are the low rocket sampling rate, and the unexpectedly large amplitude of the diurnal tide. Important differences from the zonal winds of CIRA-72 emerge, especially in winter months. Meridional cross-sections differ from previous data models in the extent of the summer equatorward flow.     

The variability of stratospheric nitrogen compounds observed by LIMS in the winter of 1978–1979

The LIMS experiment was launched on the Nimbus 7 satellite for the purpose of sounding the vertical structure of temperature and key upper atmosphere trace gases on a global scale. The technique of thermal infrared limb sounding was used to obtain measurements of O₃, H₂O, NO₂, and HNO₃. LIMS collected data almost continuously from late October to late May over the latitude range from 64°S to 84°N. Two of the gases, NO₂ and HNO₃, are important elements in the NO_x chain of chemical reactions leading to ozone destruction. We will describe results for these gases in terms of zonal mean profiles and latitudinal distributions. The period selected for study is January–May 1979, when a major stratospheric warming occurred.