Universität Stuttgart
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Item Open Access Science planning for the DESTINY+ Dust Analyzer : leveraging the potential of a space exploration instrument(2024) Sommer, Maximilian; Srama, Ralf (Apl. Prof. Dr.-Ing.)The DESTINY+ Dust Analyzer (DDA) is a highly sophisticated planetary science instrument to provide cutting-edge in-situ characterization of individual cosmic dust grains, with respect to their composition, as well as their physical and dynamical properties. As such, it constitutes a critical component of the upcoming JAXA mission DESTINY+, which is scheduled to launch in 2025. After a three-year cruise phase, the spacecraft will perform a flyby of the target asteroid 3200 Phaethon, with the goal of observing the enigmatic Geminids parent body with two camera instruments, and sampling particles released from its surface with the DDA. Until that flyby, DESTINY+ will execute a highly diverse, ion-engine-driven flight plan that allows DDA to extensively study the dust environments of the Earth, Moon, and interplanetary space - a breadth of science opportunities that is unique to this mission and instrument. This dissertation provides a comprehensive study of the dust types and phenomena possibly encountered by DDA during its journey to Phaethon and applies the principles and methods of science planning to prepare for the operational phase of the mission. The work synthesizes technical considerations and scientific analyses of relevant cosmic dust populations, aiming to optimize DDA’s scientific potential. Detailed examinations of spacecraft and instrument factors, such as the dynamic spacecraft attitude during the near-Earth phase or the instrument’s two-axis pointing mechanism, lay the groundwork for the scientific planning. The thorough analysis of known (and lesser known) dust populations in the inner solar system and of previous relevant measurements by other dust instruments form the core of the study. Finally, the findings are consolidated into a draft science activity plan for the entire mission, as well as exemplary pointing timelines to be executed by the instrument for optimal scientific return. The latter is accomplished with the DOPE tool, which aids in intuitive and efficient planning of DDA observations, having been developed in the scope of this project. The presented work builds the foundation for the scientific operations of DDA, setting it up for a successful and scientifically impactful mission. The findings of this study also provide a valuable perspective for other ventures of in-situ dust astronomy to the inner solar system and contribute to the field of cosmic dust as a whole.Item Open Access Simulating asteroid impacts and meteor events by high-power lasers : from the laboratory to spaceborne missions(2023) Ferus, Martin; Knížek, Antonín; Cassone, Giuseppe; Rimmer, Paul B.; Changela, Hitesh; Chatzitheodoridis, Elias; Uwarova, Inna; Žabka, Ján; Kabáth, Petr; Saija, Franz; Saeidfirozeh, Homa; Lenža, Libor; Krůs, Miroslav; Petera, Lukáš; Nejdl, Lukáš; Kubelík, Petr; Křivková, Anna; Černý, David; Divoký, Martin; Pisařík, Michael; Kohout, Tomáš; Palamakumbure, Lakshika; Drtinová, Barbora; Hlouchová, Klára; Schmidt, Nikola; Martins, Zita; Yáñez, Jorge; Civiš, Svatopoluk; Pořízka, Pavel; Mocek, Tomáš; Petri, Jona; Klinkner, SabineMeteor plasmas and impact events are complex, dynamic natural phenomena. Simulating these processes in the laboratory is, however, a challenge. The technique of laser induced dielectric breakdown was first used for this purpose almost 50 years ago. Since then, laser-based experiments have helped to simulate high energy processes in the Tunguska and Chicxulub impact events, heavy bombardment on the early Earth, prebiotic chemical evolution, space weathering of celestial bodies and meteor plasma. This review summarizes the current level of knowledge and outlines possible paths of future development.Item Open Access Spectroscopic characterization of extrasolar planets from ground-, space- and airborne-based observatories(2010) Angerhausen, Daniel; Krabbe, Alfred (Prof. Dr. rer. nat.)This thesis deals with techniques and results of observations of exoplanets from several platforms. In this work I present and then attempt solutions to particular issues and problems connected to ground- and space-based approaches to spectroscopic characterization of extrasolar planets. Furthermore, I present the future prospects of the airborne observatory, SOFIA, in this field of astronomy. The first part of this thesis covers results of an exploratory study to use near-infrared integral-field-spectroscopy to observe transiting extrasolar planets. I demonstrate how adaptive-optics assisted integral field spectroscopy compares with other spectroscopic techniques currently applied, foremost being slit spectroscopy. An advanced reduction method using elements of a spectral-differential decorrelation and optimized observation strategies is discussed. This concept was tested with K-Band time series observations of secondary eclipses of HD 209458b and HD 189733b obtained with the SINFONI at the Very Large Telescope (VLT), at spectral resolution of R~3000. In ground-based near infrared (NIR) observations, there is considerable likelihood of confusion between telluric absorption features and spectral features in the targeted object. I describe a detailed method that can cope with such confusion by a forward modelling approach employing Earth transmission models. In space-based transit spectroscopy with Hubble's NICMOS instrument, the main source of systematic noise is the perturbation in the instrument's configuration due to the near Earth orbital motion of the spacecraft. I present an extension to a pre-existing data analysis sequence that has allowed me to extract a NIR transmission spectrum of the hot-Neptune class planet GJ 436b from a data set that was highly corrupted by the above mentioned effects. Satisfyingly, I was able to obtain statistical consistency in spectra (acquired over a broad wavelength grid) over two distinct observing visits by HST. Earlier reductions were unable to achieve this feat. This work shows that systematic effecting the spectrophotometric light-curves in HST can be removed to levels needed to observe features in the relatively small scale-height atmospheres of hot Neptune class planets orbiting nearby stars. In the third and final part of this thesis, I develop and discuss possible science cases for the airborne Stratospheric Observatory for Infrared Astronomy (SOFIA) in the field of detection and characterization of extrasolar planets. The principle advantages of SOFIA and its suite of instrumentation is illustrated and possible targets are introduced. Possible next generation instrumentation (dedicated to exoplanetary science) is discussed.Item Open Access Machine learning and Monte Carlo based data analysis methods in cosmic dust research(2019) Albin, Thomas; Srama, Ralf (Priv.-Doz. Dr.-Ing.)This work applies miscellaneous algorithms from the fields Machine Learning and Computational Numerics on the research field Cosmic Dust. The task is to determine the scientific and technical potential of using different methods. Here, the methods are applied on two different projects: the meteor camera system Canary Island Long-Baseline Observatory (CILBO) and the Cassini in-situ dust telescope Cosmic-Dust-Analyzer (CDA).Item Open Access Extension of the plasma radiation database PARADE for the analysis of meteor spectra(2021) Loehle, Stefan; Eberhart, Martin; Zander, Fabian; Meindl, Arne; Rudawska, Regina; Koschny, Detlef; Zender, Joe; Dantowitz, Ron; Jenniskens, PeterThe advancement in the acquisition of spectral data from meteors, as well as the capability to analyze meteoritic entries in ground testing facilities, requires the assessment of the performance of software tools for the simulation of spectra for different species. The Plasma Radiation Database, PARADE, is a line‐by‐line emission calculation tool. This article presents the extensions implemented for the simulation of meteor entries with the additional atomic species Na, K, Ti, V, Cr, Mn, Fe, Ca, Ni, Co, Mg, Si, and Li. These atoms are simulated and compared to ground testing spectra and to observed spectra from the CILBO observatory. The diatomic molecules AlO and TiO have now been added to the PARADE database. The molecule implementations have been compared to the results of a simple analytical program designed to approximate the vibrational band emission of diatomic molecules. AlO and TiO have been identified during the airborne observation campaigns of re‐entering man‐made objects WT1190F and CYGNUS OA6. Comparisons are provided showing reasonable agreement between observation and simulation.Item Open Access Können wir dem Schicksal der Dinosaurier entgehen? : ein Beitrag der Raumfahrttechnik zu unserem Überleben(2003) Auweter-Kurtz, MonikaErst seit wenigen Jahren ist bekannt, welches Ereignis zum Aussterben der Dinosaurier geführt hat. Aufnahmen aus dem Weltall haben zur Klärung dieser Frage wesentlich beigetragen. Zunehmend wird man sich der Bedrohung durch andere Himmelskörper bewusst, nicht nur unter Wissenschaftlerinnen und Wissenschaftlern. Auch die politisch Verantwortlichen in den USA und Europa reagieren, und die Wirtschaft horcht auf Die Überwachung unserer Umgebung, die Erforschung erdnaher Objekte und die Entwicklung effizienter Abwehrstrategien sollten in naher Zukunft zu wichtigen Gemeinschaftsaufgaben aller Menschen werden. Die Raumfahrttechnik wird hierfür eine Schlüsseltechnologie sein.Item Open Access Instrument study of the Lunar Dust eXplorer (LDX) for a lunar lander mission(2016) Li, Yanwei; Srama, Ralf (Priv.-Doz. Dr.-Ing.)One of the highest-priority issues for a future human or robotic lunar exploration is the fine lunar dust created by meteoroid bombardment on the lunar surface with an average speed of 17 km/s. This problem should be studied in depth in order to develop an environment model for future lunar explorations. The proposed ESA lunar lander mission requires the measurement of dust transport phenomena above the lunar surface. In response to the mission requirements, an instrument design concept was developed, simulated, manufactured and tested at the Heidelberg dust accelerator facility. In contrast to former detectors, the sensor is capable to measure charged particles in a broader speed window, ranging from as low as meter per second to several kilometers per second. Furthermore, the new instrument approach is optimized for the instrument requirements of the lunar lander concept investigated by ESA. The Lunar Dust eXplorer (LDX) has a low mass of 1.2 kg and consumes a power of 1.1 W (digital electronics). The sensitive area of LDX is approximately 400 cm2. It measures the charge, speed and trajectory of individual dust particles. Meanwhile, LDX has an impact ionization target to monitor the mass of interplanetary dust and high speed ejecta. In the beginning of this study, the charge induction signals of the detector were simulated using the COULOMB software package in order to constrain the sensor accuracies. Simulations reveal trajectory uncertainties of better than 2° with an absolute position accuracy of better than 2 mm. Following simulations, a laboratory model of the LDX sensor was designed, manufactured and tested using the 2 MV Van-de-Graaff accelerator located at the Max-Planck Institute for Nuclear Physics in Heidelberg. This accelerator is a world wide unique facility to simulate hyper-velocity impacts of micron and sub-micron particles. It is currently operated by the Institute of Space System of the University of Stuttgart (IRS, Stuttgart). The experimental results additionally reveal particle primary charge uncertainties of better than ±5% and particle speed uncertainties of better than ±7%. What are the dust populations a sensor like LDX can detect on the lunar surface? How large is the contribution by secondary ejecta falling back to the surface and what is their angular distribution and speed range? To answer these questions, Autodyn 14.0/2D software was used to simulate hyper-velocity impacts of micrometeoroids bombarding the lunar surface. The initial projectiles were selected as 10 mm spheres in diameter with an average speed of 17 km/s. Furthermore, we used impact angles of 15°, 30°, 45°, 60°, 75° and 90°. In the early stage of the impact process, the projectile is coupling its energy and momentum to the target. A part of the ejecta grains created during this early stage can be captured by a sensor located on the lunar surface like e.g. the Lunar Ejecta and Meteorites (LEAM) experiment or mounted on a lander (e.g. LDX). The simulations show, that most of the detectable ejecta have low speeds (< 100 m/s1), and there are also a few grains with high speeds (> 1 km/s). The observation geometry of the sensor was investigated. Here we discuss a trade-off between a lander-mounted sensor and a surface located system. Although the LEAM data are not fully understood until today, our recent re-analysis of the data consider impact ejecta as one of the most likely sources to explain the observed event rates. Meanwhile, our studies show that a sensor mounted on the lander instead of standing on the lunar surface has more chances to measure the high-speed component of the ejecta population. The newly developed LDX sensor system is a powerful tool to study the lunar dust environment. In addition to lunar landers, smaller rover systems are also very interesting in future missions. A dust detector onboard a lunar rover would have several advantages: the measurements by the sensor can be taken at different regions of the lunar surface. Furthermore, the sensor will monitor the interaction of the rover with the lunar dust environment (plasma, electric fields, and dust). On the other hand, there are also disadvantages. The instruments onboard a rover have to maintain severe mass and data volume restrictions. Therefore we developed two further simplified designs with a lower number of electrodes and an even lower instrument mass with respect to the original LDX design. The fundamental difference between the two versions is their housing geometries. One design uses a cylindrical housing (LDX-c), and the second design has a square cross section (LDX-s). The measurement accuracies of these two detector designs are similar to LDX, but the trajectory accuracy decreases slightly by up to 2 degrees. Nevertheless, such an instrument promises, for the first time, reliable data for the properties of the lunar dust environment.Item Open Access Analysis of the technical biases of meteor video cameras used in the CILBO system(2017) Albin, Thomas; Koschny, Detlef; Molau, Sirko; Srama, Ralf; Poppe, BjörnIn this paper, we analyse the technical biases of two intensified video cameras, ICC7 and ICC9, of the double-station meteor camera system CILBO (Canary Island Long-Baseline Observatory). This is done to thoroughly understand the effects of the camera systems on the scientific data analysis. We expect a number of errors or biases that come from the system: instrumental errors, algorithmic errors and statistical errors. We analyse different observational properties, in particular the detected meteor magnitudes, apparent velocities, estimated goodness-of-fit of the astrometric measurements with respect to a great circle and the distortion of the camera. We find that, due to a loss of sensitivity towards the edges, the cameras detect only about 55 % of the meteors it could detect if it had a constant sensitivity. This detection efficiency is a function of the apparent meteor velocity. We analyse the optical distortion of the system and the "goodness-of-fit" of individual meteor position measurements relative to a fitted great circle. The astrometric error is dominated by uncertainties in the measurement of the meteor attributed to blooming, distortion of the meteor image and the development of a wake for some meteors. The distortion of the video images can be neglected. We compare the results of the two identical camera systems and find systematic differences. For example, the peak magnitude distribution for ICC9 is shifted by about 0.2–0.4 mag towards fainter magnitudes. This can be explained by the different pointing directions of the cameras. Since both cameras monitor the same volume in the atmosphere roughly between the two islands of Tenerife and La Palma, one camera (ICC7) points towards the west, the other one (ICC9) to the east. In particular, in the morning hours the apex source is close to the field-of-view of ICC9. Thus, these meteors appear slower, increasing the dwell time on a pixel. This is favourable for the detection of a meteor of a given magnitude.Item Open Access The numerous phases of the interstellar medium in the starburst galaxy NGC 253 : a multi-wavelength study(2024) Beck, André; Krabbe, Alfred (Prof. Dr.)The physical properties of the nuclear region of the starburst galaxy NGC 253 are analysed using observations from various mid- to far-infrared telescopes. The data of these telescopes are homogeneously reduced and combined. Afterwards, the data are used in a complex Monte-Carlo to determine the physical conditions in the observed region.Item Open Access SOFIA - Mission infrarotes Universum(Stuttgart : Universität Stuttgart, Institut für Raumfahrtsysteme, 2025) Krabbe, Alfred; Mehlert, Dörte; Wolf, JürgenWarum haben die NASA und das DLR - die amerikanische und deutsche Raumfahrtagentur - eine fliegende Sternwarte betrieben? Mit welchen Tricks haben Ingenieure und Ingenieurinnen das Teleskop des Stratosphären Observatoriums Für Infrarot Astronomie (SOFIA) stabilisiert? Was ist am infraroten Universum so interessant? Wozu hatte die Universität Stuttgart eine Außenstelle in Kalifornien? Welche Rolle spielte die deutsche Wiedervereinigung während der Entwicklungsphase? Diese und viele weitere Fragen rund um die fliegende Sternwarte SOFIA beantwortet dieses von Insidern geschriebene Buch in Bildern und Texten. Lassen Sie sich auf einen Forschungsflug an Bord des einzigartigen Observatoriums mitnehmen, gewinnen Sie einen Überblick über die wissenschaftlichen Erkenntnisse des Observatoriums und fragen Sie: Wie könnte das nächste Stratosphären-Observatorium für Infrarot-Astronomie aussehen? In diesem Buch finden Sie alles, was Sie schon immer über SOFIA wissen wollten.