Space communication networks face unique challenges that distinguish them from terrestrial systems. As missions extend deeper into the Solar System Internet (SSI), effective Quality of Service (QoS) mechanisms become critical for managing scarce communication resources and ensuring mission success. This paper presents a comprehensive analysis of space communication channel characteristics through both analytical modeling and empirical validation using real mission data, thereby providing the necessary information to design a data-backed QoS framework for space. An analytical model is proposed, consisting of a three-state Markov chain that distinguishes between temporary signal degradation and extended outages due to space and atmospheric phenomena. The analysis of actual communication passes from ESA missions validates the theoretical predictions and identifies the contributors to communication failures. The empirical data also demonstrates the polarized nature of space communication performance, where passes either succeed with minimal losses or fail. These findings set the basis for the accurate channel and error modelling, which will allow for the future development of accurate and tailored QoS mechanisms that tackle the specific challenges of the communication environment.

The growing number of space missions planned in the near future has created a need for a robust communication infrastructure. Such an infrastructure is being developed in the frame of lunar communications by ESA (2023) and NASA (2022) using Delay- and Disruption-Tolerant Networking (DTN) and Bundle Protocol (BP). While their characteristics have made them the standard for future space communications, some areas such as Quality of Service (QoS) or quasi-real-time communications are still to be further developed. This study emphasizes the benefits of using traffic prioritization as a mechanism to enhance QoS and enable quasi-real-time communications between Earth and space. Through a three-state Markov Chain model, the specific channel between Earth and the Moon is modelled realistically, and the impact of traffic prioritization on bundle transmissions is analyzed for several types of transmitting sources. When looking at the amount of high-priority bundles arriving within the 2.5s mark set by ESA for it to be considered quasi-real-time communications, it is shown that there is a significant improvement of up to 23%. This feature is crucial for DTN BP to be able to support the requirements of the upcoming lunar missions, especially those involving extended astronaut stays. Moreover, a priority grid taking into account all the current requirements expressed by both ESA and NASA is presented, as well as implementation proposals to include traffic prioritization in BP as an extension block. Lastly, the need for a common policy for all DTN nodes in order to allow interoperability is highlighted. Therefore, this work contributes to the advancement of DTN BP, bringing it closer to the requirements ahead of us, and paves the way for the needed mechanisms to be implemented.

In this paper we will present the current results of two DTN demonstration activities carried out in the ESA Ground Segment. The first demonstration has been prepared with the OPS-SAT spacecraft, to show the ESA Ground Segment Bundle Protocol implementation capabilities. The second demonstration has been performed in collaboration with Morehead State University, NASA JPL and D3TN, with the aim to show interoperability of DTN implementations across space agencies and external partners.

The Bundle Protocol (BP) was designed to address the challenges inherent in space communications. While already in use in several projects led by various space agencies, including the European Space Agency (ESA) and the National Aeronautics and Space Administration (NASA), there is a need to expand BP's capabilities, including in Quality of Service (QoS) support, an area currently lacking standardization. This document proposes a dual QoS support block for BP which facilitates the definition of QoS requirements at the source in an immutable manner while allowing dynamic adjustments by networks or subnetworks. Furthermore, preliminary results are presented, analyzing the effects of the proposed traffic prioritization system and the weighted queue management. These results show improved end-to-end delay for time-sensitive information, and a higher rate of achieved QoS requirements for all priority classes, as well as a fairer approach to network scheduling.

As more missions aim to explore the Moon, the need for a robust communication infrastructure becomes apparent. Such infrastructure is currently being developed by the European Space Agency (ESA) using Delay and Disruption Tolerant Networks (DTN) with the Bundle Protocol (BP). Nevertheless, these networks are not currently equipped with the necessary means to provide quasi-real time communications over highly stressed communication links as the Earth-Moon one. This paper models this link using a three-state Markov Chain which incorporates realistic data, accounting for long- and short-term losses. Using this model, the benefits of using traffic prioritization are assessed through the delay, and other performance-impacting metrics are analyzed, such as the average length of error bursts. This work proves that traffic prioritization reduces delays for data marked as high-priority, achieving delays below the 2.5s mark for 72% of bundles. Natural phenomena, like solar flares, demonstrate a limited impact on overall delay but shown a larger influence on burst losses, which would be significant for streaming-related applications. These results contribute to the understanding of how to transmit quasi-real time data over DTN BP and help pave the way to an efficient design of future communication systems for lunar missions.

ESOC (the European Space Agency's Operation Centre) is experimenting with Agile and Scrum methodologies in its quest for improving productivity, enhancing project visibility and control, reducing time to market, improve software quality and increasing user satisfaction. In this article we present lessons learned from applying Agile in general and Scrum in particular to a number of projects, from applying a few Agile best practices to full Scrum. ESOC has traditionally developed its software using a waterfall life cycle mostly under Firm Fixed Price contracts, in this context using Agile brings challenges from project management, contracts and quality control perspective. Using a coaching approach, delivered by SixSq a Swiss-based company specialised in agile and Scrum coaching and development, the organisation has managed to accelerate its integration of Scrum, including industrial teams developing the software, and already yields positive results which are promising for the future.

Upcoming file-based operations concepts and more complex communication topologies for space missions require modifications and extensions to the 'traditional' space and ground communication architectures. This paper reports on a study initiated by the European Space Agency (ESA) to analyse the suitability of the CCSDS File Delivery Protocol (CFDP) and Delay Tolerant Networking (DTN) architectures for future ESA missions. Starting from an analysis of potential future missions, generic mission scenarios involving complex communication topologies have been studied and corresponding communication requirements have been defined. Based on these generic mission scenarios and the communication requirements two reference architectures have been designed: one using CFDP on top of already deployed protocols and one combined CFDP/ DTN architecture. A simulation environment to evaluate the reference architectures has been created and various communication scenarios have been evaluated. The paper introduces both reference architectures and presents some results of the simulation activities. These results and further analysis of the reference architectures lead to the conclusion that both architectures are quite similar in terms of performance and can satisfy most requirements. However, in the short to medium-term time frame CFDP without DTN seems to provide the easier way to adoption since it is conceptually simpler and more mature while the additional features of DTN may only be required in the long-term.

A large part of ground segment operations relies on the use of files. Operational data often comes in the form of files (like tracking data) but also configuration data and logging for ground station subsystems is based on files. The reliable and timely transfer of all these files to their final destinations is of utmost importance. Routine file transfers can be fully automated but also file transfers that are only needed under special circumstances (troubleshooting) should be supported. In order to ensure the correct usage of the files and to facilitate the handling of different file versions additional features like version control and support for user-defined file metadata are very desirable. The paper describes the new ESOC approach to ground segment file handling. The FIDES (File Disseminator for ESTRACK Stations) system is used for archiving files in a centralized file archive at the ground stations and for the transfer and retrieval between the station and the control center in ESOC. There, GFTS (Generic File Transfer System) takes care of delivering the files to the users at the control center and EDDS (EGOS Data Dissemination System) provides access to Mission Control System data to external users.

Enterprises face the challenge of managing underspecified, human-centric business processes which are executed in distributed teams in a rather informal, ad-hoc manner. This gave hibernating CSCW and ad-hoc workflow research a new push recently. However, there is still the need to clearly perceive end users as the actual drivers of business processes and to enable them to proactively tailor these processes according to their expertise and problem solving strategies. This paper presents the design and evaluation of a prototype for end-user development of weakly-structured process models through email-integrated task management. The presented CTM (Collaborative Task Manager) prototype uses "programming by example" to leverage user experience with standard email and task management applications and to extend user skills towards the definition of reusable process structures. By closely correlating to the actual user work practices and software environment, the tool provides a "gentle slope of complexity" for process tailoring by end users.

Information sharing between companies within the field of critical infrastructures seems necessary to reduce the risk of failures. However, there are a couple of factors like sensitivity of the information or the difficulties of cross-sector communication hindering an effective information exchange. Therefore, it is suggested to develop a standardised language for the purpose of cross-sector information exchange that takes these factors into account. The paper presents some concepts for such an information exchange and sketches a Risk Management. Language (RML) that could be used for this purpose.

When a disaster strikes the management and coordination of available resources becomes a crucial and challenging task. Hereby, availability of information and effective communication is of utmost importance. Efficient support for first responders and decision makers, coordinating the assignments, is necessary to save time and lives, as many victims might not survive long without appropriate assistance. Context-aware computing and adequate HCI can be key factors, supporting first responders as well as decision makers in their difficult tasks. This position paper discusses preliminary thoughts on basic questions relevant to the design of HCI for emergency management. A short overview of the challenges of HCI in emergency scenarios is given. Some implications of these challenges, the need for context-aware user interfaces as well as the careful design of interaction methods and devices are discussed briefly.

The implementation-service-effect (ISE) metamodel is a general framework for modeling critical infrastructures that can integrate several different perspectives. The metamodel has a technical basis and also provides the abstractions needed for risk assessment and management of critical infrastructures in complex environments. ISE supports an iterative modeling approach that continuously refines models based on new information. By focusing on the services provided by critical infrastructures, the approach bridges the gap between the business and engineering views of critical infrastructures. The technical realization of services is described in the implementation layer of ISE; the effects of the successful (or unsuccessful) delivery of services are described in the effect layer. A sound mathematical foundation provides the basis for analyses ranging from topological evaluations of dependency structures to statistical analyses of simulation results obtained using agent-based models.Keywords: Infrastructure modeling, interdependencies, ISE metamodel

Usability evaluation of new interface concepts often requires a user study to yield valid results. User studies are however a cost intensive method compared to guideline based usability evaluation. In the AUGUR project we conducted a user study to validate a new interface concept, proactive user interfaces. The method for evaluation we used consists of four steps and relies on leveraging existing tools for realizing each step. These tools can highly automate the data gathering step in the usability study and thereby lower the cost for conducting such a study. In particular they allow for remote participation via a web browser. The obtained data can be analyzed to gain insight into the relation of factors to the three subnotions of usability: efficiency, effectiveness and satisfaction as defined in ISO 9241. We applied the developed method to evaluate the proactive user interfaces we develop in the AUGUR project. In the AUGUR project we aim at augmenting existing user interfaces with proactive and multimodal features to enhance the overall usability of the application. In this paper, we also present the results of the study that shows that proactive augmentations are beneficial for the usability of a user interface and serves as a case study for the application of the evaluation method.

The need to involve business users in process modeling is largely perceived in the context of Business Process Management systems. This can facilitate the elaboration of consistent process models which are better turned to users' needs and organizational changes. Despite the variety of tools and notations, process modeling remains hardly accessible for business users, who lack advanced technical skills. This paper presents an integrated approach for end-user driven business process modeling which uses web service based activity tracking to generate weakly-structured process models by capturing data on personal task management. These models can be adapted and reused for ad-hoc process support or exported to formal workflows by delivering the business knowledge to process designers and software developers. Interconnection of ad-hoc and formal workflows results in enhanced process flexibility and allows complementation of formal workflows through deviations at runtime. The approach is validated through the Collaborative Task Management (CTM) prototype.

Letting end users tailor business processes can result in business process management support, which is better turned to userspsila needs and organizational changes. However, such tailoring requires not only the userspsila domain expertise but also advanced skills in computer use, which business users mostly lack. The paper presents the design of the collaborative task manager (CTM) prototype which overcomes this limitation and enables end users to become informed participants in business process composition. CTM uses enterprise-wide ldquoprogramming by examplerdquo by exposing common functionalities for personal task management to the end users and tracking their activities to generate end-to-end process execution examples on a central instance. These can be adapted and reused for ad-hoc process support or exported to formal process models, which enables tailoring as collaboration between business users, end-user tailors and developers. The paper finally reports on trial usage of the tool at a partner company.

The modeling of parallel activities requires a notation which can represent the temporal dependencies as well as variations of the execution order of the activities. This paper introduces ART (Activity Relation Trees), a notation to describe temporal dependencies between activities. ART is based on ConcurTaskTrees (CTT) that are extended with the means to describe temporal relationships. Furthermore, we present an algorithm that allows to automatically generate ART models from observed examples. Because former approaches for automatic model acquisition were restricted to strictly sequential data and cannot be applied in the case of parallel activities, we developed a method to reduce the problem of automatic modeling of parallel activities to the simpler task of modeling sequential data. By grouping activities and distinguishing different phases we are able to form general descriptions of a scenario that include variations in the execution order. The paper defines all necessary concepts and describes the algorithm in detail. The evaluation of the algorithm shows that precise models can be generated by using only few examples.

1 In the AUGUR project we aim at augmenting existing user in2 terfaces with proactive and multimodal features to enhance the 3 overall usability of the application. In this paper, we present a 4 process for interface evaluation. The process consists of four 5 steps and relies on leveraging existing tools for realizing each 6 step. These tools can highly automate the data gathering step 7 in the usability study and allow for remote participation via a 8 web browser. The obtained data is analyzed using ONEWAY 9 ANOVA to gain insight into the relation of factors to the three 10 subnotions of usability: efficiency, effectiveness and satisfac11 tion as defined in ISO 9241. We also present the results of a 12 study where we have applied this process to study the benefits 13 of proactive user interfaces. Finally we show how a PUI could 14 process usage data for online usability improvement. 15

In this paper, we propose a new approach to function approximation based on a growing neural gas (GNG), a self-organizing map (SOM) which is able to adapt to the local dimension of a possible high-dimensional input distribution. Local models are built interpolating between values associated with the map's neurons. These models are combined using a weighted sum to yield the final approximation value. The values, the positions, and the "local ranges" of the neurons are adapted to improve the approximation quality. The method is able to adapt to changing target functions and to follow nonstationary input distributions. The new approach is compared to the radial basis function (RBF) extension of the growing neural gas and to locally weighted projection regression (LWPR), a state-of-the-art algorithm for incremental nonlinear function approximation