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Today, phase A studies of future space systems are often conducted in special design facilities such as the Concurrent Engineering Facility at the German Aerospace Center (DLR). Within these facilities, the studies are performed following a defined process making use of a data model for information exchange. Quite often it remains unclear what exactly such a data model is and how it is implemented and applied. Nowadays, such a data model is usually a software using a formal specification describing its capabilities within a so-called meta-model. This meta-model, often referred as conceptual data model, is finally used and instantiated as system model during these concurrent engineering studies. Such software also provides a user interface for instantiating and sharing the system model within the design team and it provides capabilities to analyze the system model on the fly. This is possible due to the semantics of the underlying conceptual data model creating a common language used to exchange and process design information. This article explains the implementation of the data model at DLR and shows information how it is applied in the concurrent engineering process of the Concurrent Engineering Facility. It highlights important aspects concerning the modeling capabilities during a study and discusses how they can be implemented into a corresponding conceptual data model. Accordingly, the article presents important aspects such as rights management and data consistency and the implications of them to the software’s underlying technology. A special use case of the data model is depicted and shows the flexibility of the implementation proven by a study of a multi-module space station.

Raumfahrt und Raumfahrtanwendungen spielen eine immer grosere Rolle, insbesondere die Satellitennavigation und -kommunikation. Gleichzeitig ist die Erforschung des Sonnensystems und des Weltalls noch immer ein zentraler Inhalt aktueller Raumfahrtprogramme. Fur jede Raumfahrtmission braucht man ausfuhrliche Bahnberechnungen, z.B. um Kontaktzeiten mit Bodenstationen zu bestimmen oder um Treibstoffbedarfe fur Manover zu berechnen. Dieses Buch beleuchtet diese Orbitmechanik auf Basis des Zweikorperproblems und baut darauf dann das Mehrkorperproblem, also die Berucksichtigung mehrerer wirkender Gravitationskrafte, auf. Mit anschaulichen Beispielen wird die Anwendung vertieft, um dem Leser zu ermoglichen, Machbarkeitsanalysen und erste Abschatzungen durchzufuhren. Fur weitergehende Berechnungen werden Hinweise geliefert und Rechenverfahren vorgestellt, die typischerweise mittels Computern durchgefuhrt werden. Das Buch richtet sich an Studierende, Anwender in der Raumfahrt und interessierte Laien.

20 years after the successful ground deployment test of a (20 m)2 solar sail at DLR Cologne, and in the light of the upcoming U.S. NEAscout mission, we provide an overview of the progress made since in our mission and hardware design studies as well as the hardware built in the course of our solar sail technology development. We outline the most likely and most efficient routes to develop solar sails for useful missions in science and applications, based on our developed ‘now-term’ and near-term hardware as well as the many practical and managerial lessons learned from the DLR-ESTEC Gossamer Roadmap. Mission types directly applicable to planetary defense include single and Multiple NEA Rendezvous ((M)NR) for precursor, monitoring and follow-up scenarios as well as sail-propelled head-on retrograde kinetic impactors (RKI) for mitigation. Other mission types such as the Displaced L1 (DL1) space weather advance warning and monitoring or Solar Polar Orbiter (SPO) types demonstrate the capability of near-term solar sails to achieve asteroid rendezvous in any kind of orbit, from Earth-coorbital to extremely inclined and even retrograde orbits. Some of these mission types such as SPO, (M)NR and RKI include separable payloads. For one-way access to the asteroid surface, nanolanders like MASCOT are an ideal match for solar sails in micro-spacecraft format, i.e. in launch configurations compatible with ESPA and ASAP secondary payload platforms. Larger landers similar to the JAXA-DLR study of a Jupiter Trojan asteroid lander for the OKEANOS mission can shuttle from the sail to the asteroids visited and enable multiple NEA sample-return missions. The high impact velocities and re-try capability achieved by the RKI mission type on a final orbit identical to the target asteroid's but retrograde to its motion enables small spacecraft size impactors to carry sufficient kinetic energy for deflection.

Any effort which intends to physically interact with specific asteroids requires understanding at least of the composition and multi-scale structure of the surface layers, sometimes also of the interior. Therefore, it is necessary first to characterize each target object sufficiently by a precursor mission to design the mission which then interacts with the object. In small solar system body (SSSB) science missions, this trend towards landing and sample-return missions is most apparent. It also has led to much interest in MASCOT-like landing modules and instrument carriers. They integrate at the instrument level to their mothership and by their size are compatible even with small interplanetary missions.\ud \ud The DLR-ESTEC Gossamer Roadmap NEA Science Working Groups‘ studies identified Multiple NEA Rendezvous (MNR) as one of the space science missions only feasible with solar sail propulsion. Parallel studies of Solar Polar Orbiter (SPO) and Displaced L1 (DL1) space weather early warning missions studies outlined very lightweight sailcraft and the use of separable payload modules for operations close to Earth as well as the ability to access any inclination and a wide range of heliocentric distances.\ud \ud These and many other studies outline the unique capability of solar sails to provide access to all SSSB, at least within the orbit of Jupiter. Since the original MNR study, significant progress has been made to explore the performance envelope of near-term solar sails for multiple NEA rendezvous.\ud \ud However, although it is comparatively easy for solar sails to reach and rendezvous with objects in any inclination and in the complete range of semi-major axis and eccentricity relevant to NEOs and PHOs, it remains notoriously difficult for sailcraft to interact physically with a SSSB target object as e.g. the Hayabusa missions do.\ud \ud The German Aerospace Center, DLR, recently brought the Gossamer solar sail deployment technology to qualification status in the Gossamer-1 project. Development of closely related technologies is continued for very large deployable membrane-based photovoltaic arrays in the GoSolAr project.\ud \ud We expand the philosophy of the Gossamer solar sail concept of efficient multiple sub-spacecraft integration to also include landers for one-way in-situ investigations and sample-return missions. These are equally useful for planetary defence scenarios, SSSB science and NEO utilization. We outline the technological concept used to complete such missions and the synergetic integration and operation of sail and lander.\ud \ud We similarly extend the philosophy of MASCOT and use its characteristic features as well as the concept of Constraints-Driven Engineering for a wider range of operations.

The International Space Station (ISS) is the greatest endeavour in low Earth orbit since the beginning of the space age and the culmination of human outposts like Skylab and Mir. While a clear schedule has yet to be drafted, it is expected that ISS will cease operation in the 2020s. What could be the layout for a human outpost in LEO with lessons learnt from ISS? What are the use cases and applications of such an outpost in the future? The System Analysis Space Segment (SARA) group of the German Aerospace Center (DLR) investigated these and other questions and developed the Orbital Hub concept. In this paper an overview is presented of how the overall concept has been derived and its properties and layout are described. Starting with a workshop involving the science community, the scientific requirements have been derived and strawman payloads have been defined for use in further design activities. These design activities focused on Concurrent Engineering studies, where besides DLR employees also participants from industry and astronauts were involved. The result is an expandable concept that is composed of two main parts, the Base Platform, home for a permanent crew of up to 3 astronauts, and the Free Flyer, an uncrewed autonomous research platform. This modular approach provides one major advantage: the decoupling of the habitat and payload leading to increased quality of the micro gravity environment. The former provides an environment for human physiology experiments, while the latter allows science without the perturbations caused by a crew, e.g. material experiments or Earth observation. The Free Flyer is designed to operate for up to 3 months on its own, but can dock with the space station for maintenance and experiment servicing. It also has a hybrid propulsions system, chemical and electrical, for different applications. The hub’s design allows launch with just three launches, as the total mass of all hub parts is about 60,000 kg. The main focus of the design is on autonomy and reducing crew maintenance and repair efforts, and reducing the need for extravehicular activities. Following a description of the design approach and technical details, a cost estimation and a detailed discussion of the use cases for such a station concept, along with the possible scenarios of international cooperation, are also presented in this paper.

We present an introductory overview of the capabilities, constraints and challenges to be taken into account in the design of space missions for HVI research and application, focusing on related planetary defence applications, small spacecraft approaches, using our activities and projects as examples. Large lightweight deployable structure applications are discussed, for large-scale photovoltaic arrays in advanced solar-electric propulsion missions, and for solar sailing as a non-fuel-constrained method of achieving high-energy or retrograde orbit and multiple target missions. Small asteroid landers are discussed as vehicles for precursor exploration of impact target asteroids, precision target orbit determination, and for impact process monitoring that also can be deployed from sail-based missions.

An effective and self-sustainable artificial habitat design is essential for human spaceflight and expansion of mankind into orbit or towards other celestial bodies. There are two approaches that need to be implemented in future sustainable habitats: the use of re-cycling technologies in order to gain experience in closed-loop processes and the primary production of resource materials using In Situ Resource Utilisation (ISRU) principles. Various products will be provided and, where applicable, recycled in such a system taking into account basic human factors requirements such as crew work load capacity, safety and well-being, namely: • higher plants (e.g. vegetables, fruits, crops), • animal husbandry (e.g. fishery, insects), • fuel gases (e.g. hydrogen, oxygen), • building materials (e.g. structural and insulation materials), • consumables (e.g. clothes), • base maintenance services (e.g. water or waste recycling) and power supply. Although the theory of closed-loop habitats has been the subject of many research campaigns, the practical implementation and realisation within a real habitat still needs to be established. The paper deals with the interdisciplinary DLR study of a terrestrial Facility of Laboratories for Sustainable Habitation (FLaSH). The first habitat design workshop has been held in DLR's Concurrent Engineering Facility (CEF) of the Institute of Space Systems. The study objectives such as a scenario set-up of selected habitat modules or input–output relationships were fulfilled with the support of experts from the domains of air, water, waste, greenhouse, animal, food processing, human factors, living, sickbay, ISRU, workshop, design and configuration.

With the launch of MESSENGER and Venus Express, a new wave of exploration of the inner solar system has begun. Noting the growing number of probes to the inner solar system, it is proposed to connect the expertise of the respective spacecraft teams and the NEO and IEO survey community to best utilize the extended cruise phases and to provide additional data return in support of pure science as well as planetary defence. Several missions to Venus and Mercury are planned to follow in this decade. Increased interest in the inferior planets is accompanied by several missions designed to study the Sun and the interplanetary medium (IPM) from a position near or in Earth orbit, such as the STEREO probes and SDO. These augment established solar observation capabilities at the Sun-Earth L1 Lagrangian point such as the SOHO spacecraft. Thus, three distinct classes of spacecraft operate or observe interior to Earth's orbit. All these spacecraft carry powerful multispectral cameras optimized for their respective primary targets. MESSENGER is scheduled to end its six-year interplanetary cruise in March 2011 to enter Mercury orbit, but a similarly extended cruise with several gravity-assists awaits the European Mercury mission BepiColombo. Unfortunately, the automatic abort of the orbit insertion manoeuvre has also left Akatsuki (a.k.a. Venus Climate Orbiter (VCO), Planet-C) stranded in heliocentric orbit. After an unintended fly-by, the probe will catch up with Venus in approximately six years. Meanwhile, it stays mostly interior to Venus in a planet-leading orbit. In addition to the study of comets and their interaction with the IPM, observations of small bodies akin to those carried out by outer solar system probes are occasionally attempted with the equipment available. The study of structures in the interplanetary dust (IPD) cloud has been a science objective during the cruise phase of the Japanese Venus probe Akatsuki from Earth to Venus. IPD observations in the astronomical H-band (1.65 µm) are supported by its IR2 camera down to 1.5 µW/m2sr in single 2 minute exposures. In the same setting, point sources of 13 mag can be detected. Obviously, a number of large asteroids exceed this threshold. The Earthguard-1 study, completed in 2003 by the DLR Institute of Planetary Research and Kayser-Threde under ESA contract, proposed a dedicated steerable Ø20...35 cm telescope and CCD camera payload on a probe to the inner solar system, to detect Near-Earth and Inner-Earth Objects (NEOs, IEOs) in favourable opposition geometry. A ride-share on a Mercury orbiter and a dedicated low-thrust propulsion spacecraft to a heliocentric 0.5 AU orbit were studied. A similar-sized telescope is presently being developed for the AsteroidFinder satellite of DLR. Therefore, the technical feasibility of a number of asteroid observation scenarios involving spacecraft and targets interior to Earth’s orbit is assessed based on the latest available spacecraft information and asteroid population models. A rough estimate of the required effort in terms of ground-based spacecraft operations and on-board resources is given for selected representative scenarios.

The concurrent engineering (CE) approach has been successfully applied to the early design phase of space missions. During CE sessions, a software support is needed to allow multidisciplinary design data exchange. At the moment, a spreadsheet-based solution enhanced with macros is used at the German Aerospace Center (DLR) to create a system model of a space mission during the early design phase. Now there is an increasing demand to take advantage of this system model and provide data analysis features which improve the decision making during CE sessions. Since the current approach is limited for such analysis, DLR has started developing a new tool called Virtual Satellite. It offers extended software support required by the Concurrent Engineering Facility of DLR in Bremen. On top of the previous spreadsheet functionalities, it provides means for online data analysis and system modeling. The results of these data analyses are presented to the discipline experts using different views which help in performing an early design optimization. In this paper, the impact of these views on the decision making during the AEGIS space mission study is presented as a proof of concept.

In cooperation with the German non-profit amateur satellite organisation (AMSAT-DL), the German Aerospace Center developed the idea of using AMSAT’s Earth satellite P3-D as a baseline for a Moon mission. For cost-effectiveness, P3-D was launched as an auxiliary payload on Ariane 5 into a geosynchronous transfer orbit (GTO) and used its on-board propulsion system to achieve a Molniya orbit. The present study describes how a similar satellite can reach a 100 × 100 km lunar orbit with the same launch strategy. A delta-v saving transfer scenario using the weak stability boundary transfer was found to be feasible taking a P3-D-like satellite bus into account. It contains phasing orbits as a solution for non-dedicated launch dates and deals with the constraints of Ariane’s GTO. This approach opens up the opportunity to accomplish a low-cost mission to the Moon with public and scientific value.

The magnetic field plays a pivotal role in many fields of Astrophysics. This is especially true for the physics of the solar atmosphere. Measuring the magnetic field in the upper solar atmosphere is crucial to understand the nature of the underlying physical processes that drive the violent dynamics of the solar corona -- that can also affect life on Earth. SolmeX, a fully equipped solar space observatory for remote-sensing observations, will provide the first comprehensive measurements of the strength and direction of the magnetic field in the upper solar atmosphere. The mission consists of two spacecraft, one carrying the instruments, and another one in formation flight at a distance of about 200m carrying the occulter to provide an artificial total solar eclipse. This will ensure high-quality coronagraphic observations above the solar limb. Solmex integrates two spectro-polarimetric coronagraphs for off-limb observations, one in the EUV and one in the IR, and three instruments for observations on the disk. The latter comprises one imaging polarimeter in the EUV for coronal studies, a spectro-polarimeter in the EUV to investigate the low corona, and an imaging spectro-polarimeter in the UV for chromospheric studies. SOHO and other existing missions have investigated the emission of the upper atmosphere in detail (not considering polarization), and as this will be the case also for missions planned for the near future. Therefore it is timely that SolmeX provides the final piece of the observational quest by measuring the magnetic field in the upper atmosphere through polarimetric observations.

The search for a sustainable, CO2-free massive hydrogen production route is a strong need, if one takes into account the world-wide increasing energy demand, the deterioration of fossil fuel reserves and in particular the increasing CO2 concentration leading to global warming. Thermo-chemical cycles for water splitting are considered as a promising alternative of emission-free routes of massive hydrogen production – with potentially higher efficiencies and lower costs compared to alkaline electrolysis of water. The hybrid-sulphur cycle was chosen as one of the most promising cycles from the ‘sulphur family’ of processes. Different process schemes using concentrated sunlight or nuclear generated heat or a combination of both have been elaborated and analysed by a comparative techno-economic study with regard to their potential of a large-scale hydrogen production. Options for a hybridisation of the energy supply between solar and nuclear have been also investigated, particular focused on the coupling of concentrated solar radiation into a round-the-clock operated process. Process design and simulation, industrial scale-up assessments including safety analysis and cost evaluations were performed to analyse reliability and potential of those process concepts.