Novel active driven drop tower facility for microgravity experiments investigating production technologies on the example of substrate-free additive manufacturing

Through the striving of humanity into space, new production processes and technologies for the use under microgravity will be essential in the future. Production of objects in space demands for new processes, like additive manufacturing. This paper presents the concept and the realization for a new machine to investigate microgravity production processes on earth. The machine is based on linear long stator drives and a vacuum chamber carrying up to 1000?kg. For the first time high repetition rate and associated low experimental costs can provide basic research. The paper also introduces the substrate-free additive manufacturing as a future research topic and one of our primary application.     

Heavy Elements and Age Determinations

The age of the universe, measured from the Big Bang to the present, is at the focus of cosmology. Its determination relies, however, on the use of stellar objects or their products. Stellar explosions, like type Ia supernovae serve as standard(izable) candles to measure the expansion of the universe. Hertzsprung––Russell diagrams of globular clusters can determine the age of such clusters and thus are lower limits of the age of the galaxy and therefore also the universe. Some nuclear isotopes with half–lives comparable to the age of galaxies (and the universe) can serve as clocks (chronometers) for the duration of nucleosynthesis. The isotopes ²³⁸U and ²³²Th with half–lives of 4.5×10⁹ and 1.4×10¹⁰ yr, decaying via alpha decay chains to Pb isotopes, are well suited to serve this purpose. They are products of the same nucleosynthesis process, the r-process. Therefore, the present paper aims at understanding the necessary environment conditions in the (stellar) production sites, the nuclear physics involved, the observational constraints for r-process nucleosynthesis, the results from nucleocosmochronology, and the remaining challenges and uncertainties which need to be overcome for a full understanding of the nature of the r-process.     

Galaxy Clusters as Probes for Matter in the Universe

Galaxy clusters are ideal tracers of the large-scale structure and evolution of the universe. They are thus good probes for the matter content of the universe, the existence of dark matter, and for the statistics of the large-scale structure of the matter distribution. X-ray observations provide a very effective tool to characterize individual galaxy clusters as well as the cluster population. With the detailed analysis of X-ray observations of galaxy clusters the matter composition of clusters is obtained which can be taken as representative of the matter composition of the universe. Based on galaxy cluster surveys in X-rays a census of the galaxy cluster population and statistical measures of the spatial distribution of clusters is obtained. Comparison of the results with predictions from cosmological models yields interesting cosmological model constraints and in particular favours a low density universe.     

Ionic Charge States of Solar Energetic Particles: A Clue to the Source

The ionic charge of solar energetic particles (SEP) as observed in interplanetary space is an important parameter for the diagnostic of the plasma conditions at the source region and provides fundamental information about the acceleration and propagation processes at the Sun and in interplanetary space. In this paper we review the new measurements of ionic charge states with advanced instrumentation onboard the SAMPEX, SOHO, and ACE spacecraft that provide for the first time ionic charge measurements over the wide energy range of ∼0.01 to 70 MeV/nuc (for Fe), and for many individual SEP events. These new measurements show a strong energy dependence of the mean ionic charge of heavy ions, most pronounced for iron, indicating that the previous interpretation of the mean ionic charge being solely related to the ambient plasma temperature was too simplistic. This energy dependence, in combination with models on acceleration, charge stripping, and solar and interplanetary propagation, provides constraints for the temperature, density, and acceleration time scales in the acceleration region. The comparison of the measurements with model calculations shows that for impulsive events with a large increase of Q _Fe(E) at energies ≤1 MeV/nuc the acceleration occurs low in the corona, typically at altitudes ≤0.2 R _S .     

Raman Spectroscopy—A Powerful Tool for in situ Planetary Science

This paper introduces Raman spectroscopy and discusses various scenarios where it might be applied to in situ planetary missions. We demonstrate the extensive capabilities of Raman spectroscopy for planetary investigations and argue that this technique is essential for future planetary missions.     

Observational Evidence for Transfer of Plasma Across the Magnetopause

There is a long history of particle measurements that have established that plasma is being transferred across Earth's magnetopause in both directions. The paper reviews the nature of the observational evidence as well as the implications regarding the transfer mechanisms and their efficiencies.     

The Swedish Small Satellite Program for Space Plasma Investigations

The success of the Swedish small satellite program, in combination with an active participation by Swedish research groups in major international missions, has placed Sweden in the frontline of experimental space research. The program started with the development of the research satellite Viking which was launched in 1986, for detailed investigations of the aurora. To date, Sweden has developed and launched a total of six research satellites; five for space plasma investigations; and the most recent satellite Odin, for research in astronomy and aeronomy. These fall into three main categories according to their physical dimension, financial cost and level of ambition: nano-satellites, micro-satellites, and mid-size satellites with ambitious scientific goals. In this brief review we focus on five space plasma missions, for which operations have ended and a comprehensive scientific data analysis has been conducted, which allows for a judgement of their role and impact on the progress in auroral research. Viking and Freja, the two most well-known missions of this program, were pioneers in the exploration of the aurora. The more recent satellites, Munin, Astrid, and Astrid-2 (category 1 and 2), proved to be powerful tools, both for testing new technologies and for carrying out advanced science missions. The Swedish small satellite program has been internationally recognized as cost efficient and scientifically very successful.