Economizing Electron Beam Welding--Today''''s State of the Art and Trends of Development

The ever-increasing pressure of producing at lower cost with higher quality and the competition, mainly from laser beam welding, are generating a number of new concepts of electron beam machines and electron beam generators. I would like to introduce to you some of these new developments.     

Active sidestick technology – a means for improving situational awareness

The use of an active sidestick in FBW-flight control is discussed and the specific features of both passive and active sidesticks are compared. Additional tactile information which could be provided by active sidesticks is seen as an important factor to improve the situational awareness of the pilot. An unique active sidestick concept based on the electro-magnetic actuation principle (electro-magnetic sidestick, MAGSI) is presented. This system is the key element in DLR's research programme EPIAS (Enhanced Pilot Information by using Active Sidestick) which is scheduled to be flight tested on the ATTAS (Advanced Technologies Testing Aircraft System) in-flight simulator at the beginning of next year.     

The composition of cosmic rays at high energies

Measurements of the composition of the cosmic rays at high energies, and of the energy spectra of the individual components provide the basis for the understanding of the sources, of the acceleration mechanism, and of the galactic containment of these particles. We briefly review the presently available information, and we describe a recent measurement on the Space Shuttle that we performed in order to substantially extend the range of energies in which the elemental composition is known. We present and discuss the results, and we also summarize and discuss recent data on the electron component of cosmic rays. The body of data now available contains several features that are difficult to explain within current models of galactic shock acceleration and “leaky box” containment. We emphasize the need for further measurements, and we briefly discuss possible opportunities for future work.     

The properties of alamethicin incorporated into planar lipid bilayers under the influence of microgravity.

During evolution, life on earth had adapted to the gravity of 1g. Due to space flight, in the last decades the question arose what happens to the brain under microgravity on the molecular level. Ion channels among others are the molecular basis of brain function. Therefore, the investigation of ion channel function under microgravity seems to be a promising approach to gather knowledge on brain function during space flight. In a first step, the ion channel forming peptide Alamethicin was used as a model channel in an artificial membrane. It is well suitable for this kind of investigation, since its properties are well described under standard gravity. For that reason, changes due to microgravity can be detected easily. All experiments were performed in the German drop tower at ZARM-FAB, Bremen. A special set-up was constructed based on the bilayer technique introduced by Mueller and Rudin. All functions of this set-up can be observed and controlled remotely. In the first set of experiments, a dramatic change of electrical properties of Alamethicin under microgravity could be observed. Mainly, the pore frequency is significantly reduced.     

Will space run out of space? The orbital debris problem and its mitigation

An appraisal of current and future risks from space debris is presented with the aid of calculations carried out by the MASTER model. The efficacy of various technical options -- such as fuel venting, de-orbiting and use of a graveyard orbit -- for counteracting the problem is discussed. The article then focuses on governmental and international cooperative measures and looks at the recent work done by subcommittees of the UN COPUOS.     

Cost Engineering – The new paradigm for space launch vehicle design

The paper describes the basic definition and application of 'Cost Engineering' which means to design a vehicle system for minimum development cost and/or for minimum operations cost. This is important now and for the future since space transportation has become primarily a commercial business in contrast to the past where it has been mainly a subject of military power and national prestige. Several examples are presented for minimum-cost space launch vehicle configurations, such as increasing vehicle size and/or the use of less efficient rocket engines in order to reduce development and operations cost. Further a cost comparison is presented on single-stage (SSTO)-vehicles vs. two-stage launchers which shows that SSTOs have lower development and operations cost although they are larger, respectively have a higher lift-off mass than two-stage vehicles with the same performance. The design of a space tourism-dedicated launch vehicle is an extreme challenge for a cost-engineered vehicle design in order to achieve cost per seat not higher than $50,000. Finally an outlook is presented on the different options for manned Earth-to-Moon transportation modes and vehicles – another most important application of 'cost engineering', taking into account the large cost of such a future venture.     

The International Vortex Flow Experiment 2 (VFE-2): Background,objectives and organization

In this paper the background and the objectives for the International Vortex Flow Experiment (VFE-2) as well as its organization within the RTO Task Group AVT-113 are described. The available test facilities and wind tunnel models, the applied experimental techniques and the program of work are outlined. Concerning the realization the close cooperation between the measurements and CFD is emphasized.     

Orbital manoeuvres of free flying platforms for retrieval by space shuttle

In a typical future mission a free flying platform will be released to space by Space Shuttle. After performing its active mission, it will have to wait for a suitable later Shuttle flight for retrieval at its original orbital altitude. To allow for the orbital descent during the total mission time of typically several months, one or several orbit raise manoeuvres have to be performed with the platform's own propulsion system. In the paper, the velocity-requirements Δv for these orbital transfers, depending on Sun activity, rendezvous-altitude, ballistic coefficient and longest expected mission time are treated.The simplest manoeuvre, consisting of one initial ascent transfer and one descent transfer at the actual retrieval date, is shown to be not optimal. Up to 25% of Δv can be saved, if several orbit raising transfers in a certain sequence are applied. A straightforward analytical treatment is presented for the optimization, while a computer program with the CIRA-atmosphere model is used for actual mission planning.     

Lunar ground penetrating radar: Minimizing potential data artifacts caused by signal interaction with a rover body

Ground-penetrating radar (GPR) is the leading geophysical candidate technology for future lunar missions aimed at mapping shallow stratigraphy (<5 m). The instrument’s exploration depth and resolution capabilities in lunar materials, as well as its small size and lightweight components, make it a very attractive option from both a scientific and engineering perspective. However, the interaction between a GPR signal and the rover body is poorly understood and must be investigated prior to a space mission. In doing so, engineering and survey design strategies should be developed to enhance GPR performance in the context of the scientific question being asked. This paper explores the effects of a rover (simulated with a vertical metal plate) on GPR results for a range of heights above the surface and antenna configurations at two sites: (i) a standard GPR testing site with targets of known position, size, and material properties, and; (ii) a frozen lake for surface reflectivity experiments. Our results demonstrate that the GPR antenna configuration is a key variable dictating instrument design, with the XX polarization considered optimal for minimizing data artifact generation. These findings could thus be used to help guide design requirements for an eventual flight instrument.     

Cross-cultural issues in space operations: A survey study among ground personnel of the European Space Agency

Today's space operations involve co-working of people with different ethnical, professional and organisational backgrounds. The aim of this study was to examine the implications of cultural diversity for efficient collaboration within the European Space Agency (ESA), and between ESA employees and representatives from other agencies. ESA employees from European countries (N=576) answered to the CULT Ground Survey. The results showed that differences in relation to leadership and decision making were the most important issues thought to interfere with efficient co-working within ESA, and between ESA employees and colleagues from other agencies. Employees who collaborated with more than three nationalities within ESA indicated most challenges in co-working due to differences in compliance, behavioural norms and competitiveness. Challenges in co-working differed between agencies, and these differences were consistent with value differences in the national populations. The results may have applied value for training of European employees working in international space program teams.