Demographics of principal investigators involved in NASA-funded research

This report presents the findings of a study of 2875 principal investigators identified through a database maintained by NASA's Office of Space Science and Applications. It was found that there will be a major ‘retirement wave’ involving the loss of approximately 1200 of these experienced scientists within the next 15 years. A manpower crisis can apparently only be averted by reversing the exodus from space science that occurred after the end of the Apollo programme.     

Satellite Navigation Systems for Land Vehicles

Today's motorists often must confirm their route by referring to a roadmap. Looking at a map while driving creates a poor traffic situation, one even more acute for drivers of emergency service vehicles. To address this problem, development engineers at the General Motors Technical Cener and Delco Electronics integrated an experimental GPS receiver into a GM Buick Park Avenue. The receiver is designed to acquire and sequentially track signals from four satellites. The vehicle's precise latitude, longitude, and altitude are determined and presented on a color cathode ray tube (CRT) map display in the car's instrument panel.     

The design features of the GGS wind and polar spacecraft

The Global Geospace Science (GGS) WIND and POLAR spacecraft employ unique configuration and design features driven by the requirements of the science instruments which they host. The WIND and POLAR spacecraft are cylindrically shaped spinners (WIND 20 rpm, POLAR 10 rpm) approximately 2.4 m in diameter and 1.8 m high. Each spacecraft has a pair of lanyard booms, which hold magnetometers, four radial wire antennas and two spin-axis antennas. While satisfying different mission requirements, both share a common basic design. The WIND laboratory contains 8 instruments, designed to optimize measurements of waves, fields and particle distributions. The POLAR laboratory contains 12 instruments, with a similar design emphasis on waves, fields and particle measurements, as well as on auroral imaging. The main difference between the two spacecraft is a despun platform on POLAR which provides a stable environment for the auroral imager instruments. Both laboratories are designed to be launched on Delta II model 7925 launch vehicle and have total masses of approximately 1150 g (WIND) and 1240 kg (POLAR).     

Time-resolved spectroscopy of accretion disks in Algols

Time-resolved spectroscopy during the eclipse of short-period Algol systems, has shown their accretion disks to be small, turbulent structures with non-Keplerian velocity fields and asymmetries between the leading and trailing sides of the disk. These transient disks are produced by the impact of the gas stream on the mass-gaining star, and occur in systems where the star is just large enough to ensure the stream collision is complete. These emission line disks and the excess continuum emission do not always occur together. The permanent accretion disks in at least a few of the long-period Algol systems have features in common with the transient disks including non-Keplerian velocity fields.     

Cosmic ray measurements in High Tatra mountains: 1957–2007

Lomnický Štít (LS, situated at High Tatra mountain, 2634 m above sea level, in the direction of 49.40°N, 20.22°E; geomagnetic vertical cut-off rigidity for cosmic rays ∼4 GV) is a relevant place for cosmic ray studies. After a brief review of the LS research history we present a selection of the results based on the measurements performed by the neutron monitor located at that site. In particular, the characteristics of quasi-periodicities and the diurnal variability amplitude and phase obtained from those data are discussed.     

Locating potential biosignatures on Europa from surface geology observations

We evaluated the astrobiological potential of the major classes of geologic units on Europa with respect to possible biosignatures preservation on the basis of surface geology observations. These observations are independent of any formational model and therefore provide an objective, though preliminary, evaluation. The assessment criteria include high mobility of material, surface concentration of non-ice components, relative youth, textural roughness, and environmental stability. Our review determined that, as feature classes, low-albedo smooth plains, smooth bands, and chaos hold the highest potential, primarily because of their relative young age, the emplacement of low-viscosity material, and indications of material exchange with the subsurface. Some lineaments and impact craters may be promising sites for closer study despite the comparatively lower astrobiological potential of their classes. This assessment will be expanded by multidisciplinary examination of the potential for habitability of specific features.     

Analysis of Warning Times For Collision Avoidance Systems

The time required to execute a successful escape maneuver must be deduced from considerations of the following times: time required to gain adequate altitude separation, delay time due to pilot reaction, aircraft servo-system delay, delay due to missed data, delay due to data arrival time, alarm delay due to ? errors, time to stop turning, and time to level off. Since each of these times is a random variable, the required escape time must be determined in a probabilistic sense. By assigning appropriate probability density functions to each of the times involved, formulas are derived for the escape times required by the CAS hazard logic. The results of a simulation of 10 000 aircraft encounters verify the suitability of the formulas.