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This paper describes the protocol of the microgravity experiment BEAT (Ballistocardiography for Extraterrestrial Applications and Long-Term Missions). The current study makes use of signal acquisition of cardiac parameters with a high-precision Ballistocardiography (BCG)/Seismocardiography (SCG) measurement system, which is integrated in a smart shirt (SmartTex). The goal is to evaluate the feasibility of this concept for continuous wearable monitoring and wireless data transfer. BEAT is part of the “Wireless Compose-2” (WICO2) project deployed on the International Space Station (ISS) that will provide wireless network infrastructure for scientific, localization and medical experiments.

In this paper, we present the AISat-1 spacecraft, which is a 12 kg nano-satellite developed by the German Aerospace Center (DLR) in Bremen. Its primary purpose is the reception of AIS signals from a Low Earth Orbit (LEO) with the help of a newly developed deployable helix antenna. The bus architecture follows a low-cost approach – making use of commercial-of-the-shelf (COTS) components. The main challenge for the bus design was to reduce complexity as a baseline concept for achieving an adequate in-orbit lifetime with acceptable risk, requiring only a fraction of the overall costs of conventional satellite approaches. The AISat-1 is now 5 years in orbit and still operating. Thus, the challenges, the issues we experienced as well as the conclusions are presented in this paper.

This paper describes the efforts required for the precursor mission Wireless Compose (WICO), a sensing and positioning experiment, which is operated in the Columbus module of the International Space Station (ISS). Moreover, a Ground Reference Model is deployed in the Evolution & Design of Environmentally closed Nutrion-Sources (EDEN) laboratory in Antarctica by German Aerospace Centre (DLR). It evaluates also agriculture/vertical farming concepts in human spaceflight. WICOs main objective is the deployment of a wireless sensor network for sensor data acquisition and the demonstration of positioning capabilities on the ISS. The wireless sensor network (WSN) is based on impulse radio - ultra wideband (IR-UWB) in the physical layer, which also allows time-of-flight measurements between two special locations. The utilization of wireless technologies in space habitats provides a great potential for several kinds of applications, decreasing the harness complexity and providing easier access for installation as well as maintenance tasks. For this reason, WICO also uses energy harvesting from internal light sources to drive the sensor modules thus allowing maintenance-free operation. The paper describes the hardware design, the operational concept and aspects of applied quality and safety requirements for Human Spaceflight. Finally, the status is presented with a focus on the analysis of different applications on Earth and in space for the implementation of wireless sensor networks in order to help and to identify new applications for future space missions.

In recent years, many attempts were made to replace wired connections with wireless communication networks in spacecraft and launchers. The benefits include a simplification of the harness design and routing as well as a reduction of harness cables and thus mass in space systems. However, commonly used wireless communication techniques are less reliable compared to their wired counterparts. Moreover, they are sensitive to RF interferences and multipath fading, which is an important design driver in a spacecraft environment with highly reflective enclosures. This paper presents a novel wireless protocol architecture for intra-spacecraft wireless sensor networks (inspaWSN), which makes use of the impulse-radio ultra wideband (IR-UWB) PHY according to IEEE 802.15.4-2011 and an optimized low latency and deterministic network protocol (LLDN) in order to achieve the strict requirements on existing spacecraft networks, e.g. low and deterministic latency behavior for the attitude and orbit control system (AOCS). The implementation and evaluation of the proposed protocol stack is performed on an STM32 microcontroller network consisting of 3 nodes. The results in this paper show that it is able to fulfill the strict timing requirements in order to accomplish deterministic communication with a latency of 10 ms and less in a typical AOCS configuration.

The off-the-shelf availability of a large variety of Cubesat components from different manufacturers enables building-block-like configuration of Cubesat systems. Is it possible to utilize these components to build a nano satellite for scientific payloads? The German Aerospace Center (DLR) internal engineering group Clavis, with the goal of developing a flexible, modular nano satellite platform, was confronted with implementing their design into the AISat mission. The challenges, solutions and lessons learned is what this paper shall transport. From the early steps in designing a satellite bus for DLR internal small payloads to adapting this concept to a real payload and implementing a lot of experience was gained with respect to cost of modularity, interdependency of commercially available components from different manufacturers, verification, and integration. The initial Clavis concept was intended to be flexible with respect to the payload it may support, to be modular in order to provide for different mission scenarios, and to mainly consist of standardized components which enable a mission life time of up to one year (and possibly beyond). With the adoption of the AISat payload the conceptual design had to be adapted to the specific requirements of the payload since it was already defined.

The mission scenario AsteroidSQUADS/iSSB was developed in response to several of the Recommendations from the 1st IAA Planetary Defense Conference which addressed the need for deflection-related testing and campaign design, studies of momentum transfer in impulsive deflection techniques, and the development of protocols and responsibilities within existing space situational awareness and civil defence infrastructures on a global scale. Several more recommendations put dangerous objects smaller than the current threshold definition for Potentially Hazardous Objects (PHO) in focus. Throughout, the need for increased international participation was emphasized. AsteroidSQUADS/iSSB is intended to enable Serendipitous Quantitative Understanding and Assessment of Deflection Strategies. The advantages and efficiency of modern small-satellite-derived design philosophies evolved and improved for interplanetary spaceflight are highlighted by using the DLR Kompaktsatellit programme's Standard Satellite Bus kit as a study baseline. This spacecraft platform draws strongly on the experiences gained and lessons learned from the DLR small satellites BIRD and TET. It also has been the baseline of choice in many studies at DLR's Bremen Concurrent Engineering Facility, and it is currently used for the AsteroidFinder spacecraft under development. A number of circumstances in today's commercial and scientific spaceflight environment are on their own widely regarded as detrimental or unpleasant situations: For some time now, an uneasy struggle has developed between the test flight requirements of the heavy launch vehicle sector, related costs and risks, commercial and schedule pressures, public relations and insurance contracting concerns, and the choice and motivation of payloads for such development flights. Also, realistic testing in particular of geostationary payload launch vehicles carries a significant risk of polluting the most vital regions of Earth-orbital space with large targets that invite the escalation of space debris collisional cascading (Kessler syndrome). In the planetary science sector, it has always been difficult to obtain funding for missions towards less prestigious target objects in the solar system. For most such missions, target selection was severely constrained by the need to cover as many fields of science as possible within the given launch budget. Resulting spacecraft designs push the launcher performance limit and require gravity-assists from the nearest planets. Accordingly, rather small probes experience extended interplanetary cruise phases, causing high radiation doses on sensitive components and high operational cost. In planetary defence, with few exceptions, lesson-learning has so far been restricted to paper exercises. Though NEO surveys have generally made good progress given the resources assigned, even the basic methods of deflection are hardly explored beyond lab experiments. The AsteroidSQUADS/iSSB mission scenario seeks to benefit from several opportunities which are presented by these situations when their mere co-existence is turned into a synergetic advantage for all potential participants, including all branches of the planetary defence community. It employs a flotilla of simple multi-role spacecraft directed at a suitable sub-PHO size practice target for a brief but intense integrated deflection campaign exercise in real space.

The design of small satellites requires a paradigm shift in the thinking of satellite designers as well as mission scientists, payload users, and programme management - in brief, everyone involved. In a conventional approach, spacecraft design evolves in a mostly linear fashion from mission requirements by well-defined procedures through a series of reviews into a design space that is essentially not limited by constraints other than programmatic. The mission defines a pallet of instruments, their needs then shape the spacecraft bus, and the integrated spacecraft is finally mated to a dedicated launch, to be placed into an orbit carefully custom-tailored by mission analysis and continuously trimmed by on-board propulsion. Components are manufactured to spec, one-off plus spares, and painstaking testing has to iron out the many space firsts and compromises made in an arduous and protracted design process. Small satellite design reverses this comfortable line of thinking. It begins with hard, and not just programmatic constraints on most of the essential parameters that define a satellite. Launch as a secondary payload is the choice, not just for budgetary reasons, but due to the lack of viable dedicated launchers. It requires a small stowed envelope and a tightly limited mass budget. This results in limited surface area for solar panels and radiators. Small project volume enables a high flight cadence which makes re-use of designs and components desirable and feasible, in a self-catalyzing cycle. Re-use and constraints force the system perspective on every participant in a quick succession of sometimes diverging but generally converging iterations that lends itself to the Concurrent Engineering approach. There is simply no space left in a small satellite project for boxes to think in. To exploit the technological convergence that has created powerful and miniaturized science instruments and satellite components, the DLR research and development programme has initiated the Kompaktsatellit line of development. It is intended to enable dedicated missions for science projects that would earlier have resulted in one full-scale scientific instrument among many sharing a ride on a large platform without the perspective of follow-on within an academic career lifetime. In an internal competition, the AsteroidFinder instrument dedicated to the search for small bodies orbiting the Sun interior to Earth’s orbit has been selected as the payload to fly first on a Kompaktsatellit. Alongside, the Standard Satellite Bus kit, /SSB, is being developed, based on extensive re-use of experience, concepts, and components of the DLR satellites BIRD and TET. It is designed to avoid the overhead carried by pre-defined standard bus concepts while allowing for seamless integration of the payload into an organic spacecraft design. Challenges encountered and solutions found across the subsystems of AsteroidFinder/SSB will be presented.

This paper introduces Wireless Compose-2, which is an experiment for the International Space Station (ISS) in order to demonstrate the provision of a flexible and adaptable wireless network infrastructure integrated in a commodity item to conduct and execute low-power, low-weight and wireless experiments in the scientific and medical domain. Recent work revealed a great potential in utilizing wireless sensor networks (WSN) in space habitats; however, the focus was only placed on sensing in the narrowband Industrial Scientific and Medical (ISM) 2.45 GHz band. This work extends these capabilities by utilizing impulse radio ultra wideband (IR-UWB) for ranging and evaluates the use of internal light sources for energy harvesting to drive the sensor nodes. The focus of the Wireless Compose-2 experiment is on the operation of the scientific experiment BEAT (Ballistocardiography for Extraterrestrial Applications and long-Term missions), which is a demonstration of novel ballistocardiography (BCG) sensors to monitor important cardiovascular parameters in a microgravity environment. Integrated in a Smart-Shirt, it will form a Body Area Network and makes use of the IR-UWB communication to transmit the data to the network. This paper describes the operational scenario, and the hardware as well as software concepts are presented in detail. Finally, the expected results are outlined with the focus being on the analysis of the different aspects that will help to identify new applications for future space missions.