Airborne Performance Analysis by Multiparameter Sampling

Aircraft maintenance has, since its conception, relied primarily on two methods of fault detection and isolation: 1) in-flight observation and reporting by flight personnel 2) ground operation or testing of airborne systems and equipment. Both methods, even when combined to the optimum, are not always sufficient to pinpoint the exact cause of trouble or locate a defective component. A third method, which analyzes airborne system's performance through various techniques of multiparameter sampling, has recently come into the picture and is showing significant promise for advancing the present state-of-the-art in aircraft maintenance. Systems utilizing this technique are discussed and examples of their benefits cited. These benefits not only encompass detection and isolation of defective units or components, but also include predicting impending malfunctions.     

Corotating events in the energy range 4–13 MeV as observed on board Helios 1 and 2 in 1975 and 1976

Intensity increases of 4 – 13 MeV protons correlated with recurrent high speed solar wind streams were observed on board Helios 1 and 2 at heliocentric distances between 0.3 and 1.0 AU. Study of events which occurred in the time period 1975 – 1976 showed that recurrent fast solar wind streams were sometimes not accompanied by corotating events and small events were more frequently observed than large corotating events, which occurred only occasionally. The explanation for these phenomena seems to be the variation of the number of suprathermal particles injected into the acceleration process. Radial gradients of corotating events from February till April 1976 were investigated. The gradient changed its sign in successive solar rotations and exhibited strong time dependence inside 1 AU. Clearly negative gradients were measured in corotating events which occurred in February and April 1976. These observations showed that probably there were no stationary corotating structures in interplanetary space. We suggest that this effect is related to local disturbances of solar origin, e. g. flare initiated shocks.     

The paradoxes of space

‘Space — the commercial opportunities’, an international business strategy conference, London, UK, 31 October–1 November 1984, organized by Online Conferences Ltd, Pinner Green House, Ash Hill Drive, Pinner HA5 2AE, Middlesex, UK.     

On biogenicity criteria for endolithic microborings on early Earth and beyond

Micron-sized cavities created by the actions of rock-etching microorganisms known as euendoliths are explored as a biosignature for life on early Earth and perhaps Mars. Rock-dwelling organisms can tolerate extreme environmental stresses and are excellent candidates for the colonization of early Earth and planetary surfaces. Here, we give a brief overview of the fossil record of euendoliths in both sedimentary and volcanic rocks. We then review the current understanding of the controls upon the distribution of euendolithic microborings and use these to propose three lines of approach for testing their biogenicity: first, a geological setting that demonstrates a syngenetic origin for the euendolithic microborings; second, microboring morphologies and distributions that are suggestive of biogenic behavior and distinct from ambient inclusion trails; and third, elemental and isotopic evidence suggestive of biological processing. We use these criteria and the fossil record of terrestrial euendoliths to outline potential environments and techniques to search for endolithic microborings on Mars.