Entwicklung einer Schnittstelle für verteiltes I/O in einer neuen on-board Computerarchitektur.

This work is a part of the On-Board-Computer Next-Generation (OBC-NG) project by the German Aerospace Centre. The OBC-NG project surveys a concept for distributed computing on space systems. This thesis is about the Interface-Node component which provides access to the sensors and actuators of the space system. At first there will be an overview of existing techniques in the field of distributed systems. Out of this a concept will be developed for use in embedded systems. To evaluate the concept a prototype for a simulation evironment and for embedded systems will be implemented. Based on this implementation the applied techniques will be evaluated for the use in the OBC-NG System. This thesis shows, that techniques which are used in High-Performance-Computing (HPC) Systemd can be adapted to embedded Systems with severe resource restrictions

A Component-Based Middleware for a Reliable Distributed and Reconfigurable Spacecraft Onboard Computer

Emerging applications for space missions require increasing processing performance from the onboard computers. DLR's project “Onboard Computer - Next Generation” (OBC-NG) develops a distributed, reconfigurable computer architecture to provide increased performance while maintaining the high reliability of classical spacecraft computer architectures. Growing system complexity requires an advanced onboard middleware, handling distributed (realtime) applications and error mitigation by reconfiguration. The OBC-NG middleware follows the Component-Based Software Engineering (CBSE) approach. Using composite components, applications and management tasks can easily be distributed and relocated on the processing nodes of the network. Additionally, reuse of components for future missions is facilitated. This paper presents the flexible middleware architecture, the composite component framework, the middleware services and the model-driven Application Programming Interface (API) design of OBC-NG. Tests are conducted to validate the middleware concept and to investigate the reconfiguration efficiency as well as the reliability of the system. A relevant use case shows the advantages of CBSE for the development of distributed reconfigurable onboard software

Space-borne Bose-Einstein condensation for precision interferometry

Space offers virtually unlimited free-fall in gravity. Bose-Einstein condensation (BEC) enables ineffable low kinetic energies corresponding to pico- or even femtokelvins. The combination of both features makes atom interferometers with unprecedented sensitivity for inertial forces possible and opens a new era for quantum gas experiments. On January 23, 2017, we created Bose-Einstein condensates in space on the sounding rocket mission MAIUS-1 and conducted 110 experiments central to matter-wave interferometry. In particular, we have explored laser cooling and trapping in the presence of large accelerations as experienced during launch, and have studied the evolution, manipulation and interferometry employing Bragg scattering of BECs during the six-minute space flight. In this letter, we focus on the phase transition and the collective dynamics of BECs, whose impact is magnified by the extended free-fall time. Our experiments demonstrate a high reproducibility of the manipulation of BECs on the atom chip reflecting the exquisite control features and the robustness of our experiment. These properties are crucial to novel protocols for creating quantum matter with designed collective excitations at the lowest kinetic energy scales close to femtokelvins.Comment: 6 pages, 4 figure

Model Driven Language Framework to Automate Command and Data Handling Code Generation

On-board computer software (OBSW) is an integral part of every space mission. It has been continuously growing in size and complexity. The insufficient level of automation in the development process of such software leads to low software re-usability and drives up the costs. This paper presents a generic approach to describe and model the on-board software in terms of data that is processed by it. Domain Specific Language (DSL) based framework is developed using which provides a DSL editor, a model validator, and a code generator. Using the framework, a system data model is created. The C++ code is generated from it which is then customized to implement low-level behavior. As a proof of concept, the telecommand handling functionality of OBSW is developed to prove the feasibility of applying the solution to the whole system. Based on the analysis conducted on the source code of the TET-1 satellite of the German Aerospace Center (DLR), a DSL is designed and implemented. The resulting DSL-based framework is tested with an example model and target code customization, showing its ease of use and proving that it behaves as expected

A New SpaceWire Protocol for Reconfigurable Distributed On-Board Computers

There are several standardized protocols based on SpaceWire which provide data exchange between several nodes. SpaceWire is also suitable for interprocess communication (IPC), by the help of higher level protocols. However, currently there is no standardized protocol which is targeting IPC on SpaceWire networks. This paper proposes a protocol, which uses the capabilities of SpaceWire to build up networks for distributed computing on a spacecraft. The core of this protocol is the IPC mechanism for communication between the nodes and methods to support a reconfiguration of the network. A key feature of this protocol is an interface for a reconfiguration mechanism, which can be implemented on application level. This enables the utilization of unreliable commercial off the shelf (COTS) nodes, allowing system recovery from erroneous state. Additionally, the reconfiguration can be used to adapt the distributed computer to different mission phases. The protocol has the potential to build the foundation of a distributed on-board computer consisting of COTS components. Such distributed computer could be capable of fulfilling high performance demands as well as high reliability needs. Though, the protocol itself is not restricted to be used solely in fully-featured reconfigurable distributed systems. The IPC methods can be applied stand-alone as well, to establish a lightweight communication between nodes on a SpaceWire network by excluding the reconfiguration parts of the protocol

A Model-driven Software Architecture for Ultra-cold Gas Experiments in Space

Developing software for large and complex experiments is a challenging task. It must incorporate many requirements from different domains, all with their own conceptions about the overall systems. An additional level of complexity is added if the experiment is conducted autonomously during a sounding rocket flight. Without a proper software architecture and development techniques, achieving and maintaining a high code quality is a very cumbersome task. This paper describes the architecture and the model-driven development approach we used to implement the control software of the experiments in the MAIUS-1 mission (matter-wave interferometry in microgravity). In this mission, the software had to handle around 150 experiments in six minutes autonomously and adapt to changes in the control flow according to real-time data from the experiment. The MAIUS-1 mission was the first mission to create Bose-Einstein condensates in space and conduct other experiments with ultra-cold gases on a sounding rocket. Besides the scientific goals in the area of quantum-optics, other important objectives of the mission were the miniaturization and further development of laser systems, vacuum components, optical sensors, and other related technologies. To fulfil these goals, new experimental hardware has been created which had to be integrated and tested with the software of the experiment computer. The custom-made hardware and the considerable number of domains involved brought up many challenges for the software engineering. To face all these challenges of developing software with this high complexity, we chose to follow a model-driven software development approach. Several domain-specific languages (DSLs) accompanied with specialized tools were created to allow the physicists and electronic engineers to describe system components and the experiments in a domain-specific way. These descriptions were then automatically transformed in C++ code for the flight software. This way we could actively incorporate all the domains involved in conducting the experiment directly in building the flight software without compromising the software quality. We created a versatile software platform not only for the MAIUS-1 mission but also for upcoming missions with similar experiments and hardware. With our approach we were able to generate around 84% of the source code for the final flight software from the domain-specific models. Besides the improvement of the development process, the code generation made a significant contribution to the overall software quality as almost all manual coding of error-prone boilerplate code could be mitigated

OBC-NG: Towards a reconfigurable on-board computing architecture for spacecraft

The computational demands on spacecraft are rapidly increasing. Current on-board computing components and architectures cannot keep up with the growing requirements. Only a small selection of space-qualified processors and FPGAs are available and current architectures stick with the inflexible cold-redundant structure. The objective of the ongoing project OBC-NG (On-board Computer - Next Generation) is to find new concepts for on-board-computer to fulfill future requirements. The concept presented in this paper is based on a distributed reconfigurable system, consisting of different nodes for processing, management and interface operations. OBC-NG will exploit the high performance of commercial off-the-shelf (COTS) hardware parts. To compensate the shortcomings of COTS parts the OBC-NG redundancy approach differs from the classic way and error mitigation techniques will work mainly on software level. This paper discusses the hardware and software architecture of the system as well as the redundancy and reconfiguration concept. Our ideas will be proven in an OBC-NG prototype, planned for the next year

OBC-NG Concept and Implementation

OBC-NG is the abbreviation for on-board-computer next generation – a project founded and made by the German Aerospace Center (DLR). The project goal is to provide the basis for future on-board computer (OBC) for space-missions. This document summarizes the conducted work, made in the DLR-project OBC-NG and its predecessor project “Software and Hardware Architecture for Re-configurable Computers”

The MAIUS Sounding Rocket Missions – Recent Results, Lessons Learned and Future Activities

The QUANTUS consortium started activities to perform atom interferometry on a sounding rocket in the year 2011. Three sounding rocket missions (MAIUS-1 to 3) have been planned to demonstrate Bose-Einstein condensation and atom interferometry with rubidium and potassium atoms. Two different payloads MAIUS-A and MAIUS-B are being designed, qualified and integrated in the time frame from 2011 until 2020. The MAIUS-A scientific payload demonstrated the first Bose-Einstein Condensates in Space in the challenging environment aboard a two-staged VSB-30 sounding rocket on the 23rd of January 2017. In order to achieve this ambitious scientific goal the experiment used various sensitive instruments imposing strong requirements on the thermal and mechanical design of the scientific payload. This paper gives a summary of the MAIUS-A and MAIUS-B scientific payload design. Furthermore, the lessons learned from the MAIUS-1 maiden flight as well as the integration and testing activities and their impact on the MAIUS-B scientific payload design are presented. The paper closes with an outlook on future atom interferometry payloads on sounding rockets and beyond

Space-borne Bose–Einstein condensation for precision interferometry

Owing to the low-gravity conditions in space, space-borne laboratories enable experiments with extended free-fall times. Because Bose–Einstein condensates have an extremely low expansion energy, space-borne atom interferometers based on Bose–Einstein condensation have the potential to have much greater sensitivity to inertial forces than do similar ground-based interferometers. On 23 January 2017, as part of the sounding-rocket mission MAIUS-1, we created Bose–Einstein condensates in space and conducted 110 experiments central to matter-wave interferometry, including laser cooling and trapping of atoms in the presence of the large accelerations experienced during launch. Here we report on experiments conducted during the six minutes of in-space flight in which we studied the phase transition from a thermal ensemble to a Bose–Einstein condensate and the collective dynamics of the resulting condensate. Our results provide insights into conducting cold-atom experiments in space, such as precision interferometry, and pave the way to miniaturizing cold-atom and photon-based quantum information concepts for satellite-based implementation. In addition, space-borne Bose–Einstein condensation opens up the possibility of quantum gas experiments in low-gravity conditions1,2