Magnetosphere dynamics with artificial plasma clouds

Addition of cold plasma to the magnetosphere outside the plasmasphere can enhance both ion and electron electromagnetic cyclotron (EMC) instabilities. To turn on the ion EMC mode, one needs a cold plasma ion which is not too heavy; in many respects, lithium is ideal. Calculations have been made of total ion-EMC amplification on a single pass through a lithium cloud; these show that as much as 40–80 dB gain can be achieved on a synchronous-orbit field line. The most important effects of adding lithium are to reduce the minimum anisotropy requirement considerably, and to broaden the unstable domain in k-space. The dynamics of the cold lithium cloud have been studied in detail; on a time scale of a few hours, the cloud behaves as an incompressible fluid in the presence of electric convection fields, and should not become so seriously distorted that the total amplification given above is substantially degraded. Some remarks are made about the effects of added cold plasma on the Post-Rosenbluth electrostatic mode; for the most part, growth rates are reduced with addition of cold plasma.     

The commercial development of space: is an international regulatory framework needed?

The commercial space sector to date has failed to develop comprehensive regulations--"rules of the road"--for its international activities. Within the next 5 years, conflicts with respect to international trade in satellite sales and launch services could emerge, highlighting the need for such a regulatory framework. If the commercial space sector is to continue to develop, it is important to begin discussions now, before these conflicts become significant, on the elements of an appropriate international regulatory framework. The existing framework for space activities was developed when government, not commercial, space activities were dominant, or was adapted from regulations in other sectors such as terrestrial telecommunications.     

Autonomous orbit maintenance system

Orbit maintenance is a major cost factor for Earth satellites in specialized orbits, such as a repeating ground track, or in formations. While autonomous attitude control is well established, the spacecraft's orbit is usually uncontrolled or maintained by ground station commands. For small, lower cost satellites, operations costs can be a dominant element of both cost and risk. This implies a need for low-cost autonomous orbit maintenance in order to allow such systems to be economically viable, particularly in today's constrained budget environment.

In addition, if the position of the spacecraft is controlled, it is therefore known in advance. Thus, mission planning can be done as far in advance as desired, without the need for replanning and frequent updating due to unpredictable orbit decay. An interesting characteristic of autonomous orbit maintenance is that it typically requires less software, and less complex software, than does orbit control from the ground. In many cases, an onboard orbit propagator is not needed.     

Space visions from a new generation

Through experiences at the International Space University's 1995 Summer Session, the authors became aware of generational differences of opinion with regard to visions for future space activities. The faculty members had expansionary visions of space exploration and colonization, while the students, having grown up in a very different environment, had concerns which centered around using space to improve life on Earth. This paper addresses possible explanations for these different perspectives. The visions of this younger generation are those which will shape the space policy of the future and are even beginning to shape it today.     

2010: The Symbionic Cockpit

The cockpit of the year 2010 is described in terms of both the capabilities and systems it contains and how the pilot interacts with it. A brief mission narrative is provided describing seveal hours in the life of the Manta air superiority fighter. This is followed by a discussion of the pilot interface components employed in the cockpit including hueristic voice, instrument panel display, canopy display, and holographic display systems. The concept of a ``symbionic' system is then introduced, describing in some detail the capabilities and features of a cockpit system that senses the physiological and mental state of the pilot and responds accrodingly. Finally, conclusions and predictions are made that summarize and emphasize the points made in the paper.     

EM Transient Protection Requirements for Avionics LRUs

Avionics and electronic equipment installed in aircraft and air breathing missiles are required to operate without upset or damage when subjected to EM environments caused by lightning, NEMP, and Intrasystems transients. To simplify the design effort required to protect electronic equipment and minimize overlapping transient requirements and qualification tests, unified test requirements and procedures are needed. The goal of these unified test procedures would be to insure a known susceptibility level for each newly designed electronic Line Replaceable Unit (LRU). Ten avionics equipments in current Air Force inventory were tested for the purpose of developing unified procedure test methods. Operating LRUs were subjected to transients using common mode cable current (CMCC), groung potentials and chatteriing relay cable injection methods. Based on observed test results and review of current test requirements, test methods and test levels for unified test procedures for power-on transient tests of avionics equipment have been formulated.     

IUE observations of supernova remnants

Ultraviolet spectra of supernova remnants obtained with the IUE satellite provide unique information concerning the shock conditions and elemental abundances in the optically bright filaments. High temperature species such as N V provide diagnostics for shock velocities above 100 km s^?1, and strong lines of carbon and silicon in the IUE spectral range make it possible to study the destruction of refractory grains in shocked interstellar gas. Observations of a non-radiative shock at the edge of the Cygnus Loop provide constraints on the physics of the shock front itself. Most of the very young remnants whose optical spectra show anomalous elemental abundances are too highly reddened for IUE observations, but extensive observations of the Crab Nebula and a spectrum of the supernova remnant in NGC 4449 yield carbon to oxygen ratios from which the mass of the progenitor may be estimated.