Comparative neutral composition instrumentation and new results

Composition and gas density measurement at all altitudes in the atmospheres of earth and other planets are made by mass spectrometers. Because of the impartiality and large dynamic range they are particularly favored for exploratory missions. Measurements of trace constituents, inert gases and height profiles, especially below clouds, are objectives where mass spectrometry is most useful. Significant advances have been made in recent years in development of light weight automated instruments. Experiments conducted in rarified atmospheres have been more successful or results were less controversial than in attempts to analyze high pressure atmospheres. Gas sampling and conditioning techniques are highly specific because of measurement environments and engineering constraints on the mission, and are usually the most critical elements in the experiment. Chemical sample enrichment and scrubbing for noble gas enhancement are additional sample conditioning techniques now employed. Dynamic range of more than 10⁸ is achievable. Reliable measurements of complex organic or chemically active trace constituents with mixing ratios of less than 10^?9 still require significant instrument development particularly where weight, power and sampling time are severely restricted. Adaptation of familiar and proven laboratory techniques for flight instruments is usually not straightforward and practical.     

A Multimedia Document Server

We describe issues related to the design and performance of a multimedia information server for an office environment. Multimedia documents are composed of text, image, voice, and attribute information. We describe the multimedia document structure, their internal representation and their presentation form. Content addressibility in this environment is achieved by specifying conditions on attributes, text, images, and document presentation form. Query reformulation, multimedia document formation in this environment and communication with the outside world are also discussed. Archived documents are stored in a centralized server. Users submit their queries in their local workstations using a local area network. The server retrieves the qualifying documents and returns them to the users. We analyze the performance of various access methods for multimedia documents that reside in the server.     

The 1980 April 12 flare and transient: Report on progress in interpretation

A multidisciplinary study of this solar-interplanetary event is summarized by two main points: this flare was an incident in a process that began days before the flare, and continued after the flare; and the chain of events can be interpreted most simply in terms of energy input over scales of time and space that are large compared to the flare seen in the light of Hα. In support of these points, 5 aspects of the flare are described here: (1) hours before the flare, slow changes in coronal structure were associated with radio continuum emission, suggesting large-scale magnetic-field changes and the presence of energetic electrons; (2) long-lived X-ray loops require sustained energy input for at least an hour after the flare start; (3) interplanetary disturbance near earth is probably related to this limb flare, although the (expected) absence of a shock makes identification uncertain; (4) the coronal mass ejection overlay decaying magnetic field; (5) speed derived from frequency drift of the type II radio burst in the low corona, and from the travel time of the disturbance to 1 a.u., are about twice as great as the observed speed of the coronal mass ejection and of the disturbed solar-wind speed.     

Wide angle X-ray optics for use in astronomy

Recently there was a suggestion in the literature to apply the principle of the lobster-eye to X-ray astronomy imaging (J.R.P. Angel, Ap. J. 233, 364, 1979). Our own suggestion for a wide angle X-ray telescope made earlier (W.K.H. Schmidt, Nucl. Instr. Meth.127, 285, 1975) is very similar to the above one. It consists of one or two sets of plane mirrors used in a grazing incidence configuration. The advantages of this type of X-ray optics over other systems for particular astronomical observations will be discussed.     

Significance of fluid dynamics aspects for material science experiments

Fluid dynamics aspects for material science experiments may be treated with respect to purely space experiments and preparatory experiments on the ground. Preparatory experiments are necessary because little experience of material science experiments in space is available. Preparatory experiments on earth are needed in the field of surface tension and viscosity, surface layers, forming and positioning of liquids. Concerning space experiments the following subjects may be treated: convection phenomena, capillarity and kinetics of liquids. Convection phenomena (Marangoni convection) can be studied without disturbance by gravitation which has a considerable technological relevance. Under space conditions the kinetics of fluids may be studied in large model structures with changing capillarity and wetting properties.     

Electric Field Detection and Ranging of Aircraft

The electric field transported by charged aircraft during free flight can be observed quantitatively in distances of up to some 100 m. A system of three plane sensors arranged in the corners of a triangle or the Earth surface is described, by which the flight path of aircraft is detected in the range of 40 to 500 m with velocities of approximately 50 m/s. The theory and typical experimental results are discussed.     

Applications of stereoscopic height computations from dual geosynchronous satellite data/joint NASA-Japan stereo project

Stereoscopic heights of the top of an Oklahoma thunderstorm were computed, finding that high cloud tops are not always characterized by very cold IR temperature. The identical method was also applied to the computation of stereo heights based on GOES West and GMS stereo pairs obtained under the NASA-JAPAN cooperative program. It was found that stereo techniques are extremely useful in understanding the structure of thunderstorms in the United States, as well as that of hurricanes over the South Pacific.     

Dynamics of solar cosmic ray events: Processes at large heliocentric distances (⪢1 AU)

Observations of solar cosmic ray events far from the sun (?1 AU) became possible after the launch of Pioneer 10 in 1972. Four spacecraft have now travelled beyond the orbit of Jupiter - Pioneer 10/11 and Voyager 1/2 — and are producing a growing body of distant observations of solar cosmic ray events. Initial studies using Pioneer 10/11 data out to ～6 AU interpreted flare particle observations in terms of a diffusion model, including the effects of convection and adiabatic energy loss. This model enjoyed general success in explaining the time-intensity profiles in cases where the spacecraft connection longitude at the sun did not change significantly with time. The results implied that the radial diffusion coefficient (K_r) increased slowly with distance over that radial range. More recent results at larger distances imply that K_r may begin to decrease beyond ～5 AU. It is not yet clear whether the standard diffusion model will be adequate to explain solar events well beyond 5 AU. The fact that large events at very large distances can last up to two solar rotations implies that solar wind stream structure will also play a role in the event dynamics. In general, however, observations at large distances offer perhaps the best hope of separating interplanetary propagation effects from coronal storage and propagation effects which frequently dominate observed event profiles at 1 AU.     

Performance Analysis of the Modulation Cancellation Altimeter

The performance of the modulation cancellation altimeter is investigated. Several sources of error are considered, specifically: 1) terrain averaging error; 2) output noise fluctuations; 3) errors due to phase shifts; and 4) acquisition ambiguities. The predominant parameters affecting these errors are investigated with a view towards optimizing the performance of the altimeter.