International Academy of Astronautics 5th cosmic study--preparing for a 21st century program of integrated,Lunar and Martian exploration and development (executive summary)

This report is an initial review of plans for a extensive program to survey and develop the Moon and to explore the planet Mars during the 21st century. It presents current typical plans for separate, associated and fully integrated programs of Lunar and Martian research, exploration and development, and concludes that detailed integrated plans must be prepared and be subject to formal criticism. Before responsible politicians approve a new thrust into space they will demand attractive, defensible, and detailed proposals that explain the WHEN, HOW and WHY of each stage of an expanded program of 21st century space research, development and exploration. In particular, the claims of daring, innovative, but untried systems must be compared with the known performance of existing technologies. The time has come to supersede the present haphazard approach to strategic space studies with a formal international structure to plan for future advanced space missions under the aegis of the world's national space agencies, and supported by governments and the corporate sector.     

MARC-a system for simulation and visualization of space missionscenarios

MARC (modeling, animation, rendering, and compositing), a system using advanced computer graphics and animation techniques for spacecraft mission simulation, is described. The MARC system provides capabilities for generating complex models of both man-made and natural phenomena. The system models orbital dynamics of terrestrial satellites, supports solid models for the Earth, Sun, and Moon, and simulates the dynamics of terrestrial satellites for arbitrary elliptical orbits. A stellar background including magnitudes and spectral types is generated. The elements of the MARC system, including object modeling tools, orbital animation techniques, the rendering system used to compute individual frames, and the compositing techniques used, are discussed. The software architecture of the MARC system and the hardware used to support the system are described     

Lunar palaeomagnetism and its implications

The final great impacts, creating the multi-ring basins on the Moon, must have altered its principal axes of inertia and, assuming solid state creep in its interior, caused successive reorientation relative to its pole of rotation. Lunar palaeomagnetism has been explained by an early lunar magnetic field generated by a core dynamo. The palaeomagnetic directions of the lunar crust determined from the Apollo 15 and 16 subsatellite magnetometer surveys, by L.L. Hood and colleagues, challenges interpretation on this idea. The palaeoequators so determined for Imbrium, Nectarian and pre-Nectarian times place impacts of the same age in low latitude: there must have been small moons in the Earth-Moon system, which impacted the Moon in its retreat from the Earth. Sources of presumed Imbrium age are magnetized in agreement with the dipole formula: proving the existence of an early lunar core-dynamo field.     

Talking space: The European Commission's changing frames in defining Galileo

This paper traces the way in which the European Commission has framed and reframed the issue of EU satellite navigation over 20 years. It investigates how the EU's agenda-setter has ‘talked about’ space policy, with a particular focus on Galileo, and how its own institutional discourse – as revealed in its communications throughout the agenda-setting stage of Galileo's ‘definition’ phase – evolved in the 1990s through the use of ‘frame sets’. In so doing, it illustrates the ways in which, over time, the EU's executive has ‘projected’ the issue of independent satellite navigation capabilities as being politically and economically desirable for Europe, and has sought to persuade decision makers of its cross-policy relevance and potential economic, social and security benefits. The article deconstructs official documents and engages in a close-up analysis of policy formulation, to identify nascent, evolving and mature frames in the definition of Galileo.     

Drag Measurement in a Low-Density Gas Stream

Two methods of measuring the drag of bodies in a low-density gas stream are described. The supersonic stream had a mean free path as great as 4 cm, and the drag forces were small. A drag balance was adapted from an electrical analytical balance to measure forces up to 70 dynes with less than 1-percent error. With this balance, the drag of spheres was measured for the Knudsen number range from 1.0 to 5. The freedrop trajectory method yielded drag coefficients in the range of Knudsen numbers from 2.5 to 30. These tests demonstrated the feasibility of making accurate drag measurements under the free-molecule conditions that can be generated by exhausting a gas into a cryogenically pumped vacuum chamber.