Mission Analysis, GNC and ATD for Reusable Launch Vehicles within ASCenSIon: Multi-Orbit Multi-Payload Injection, Re-Entry and Safe Disposal

Reusable Launch Vehicles (RLVs) are not only key for an economically and ecologically sustainable space access but also represent a paramount innovation towards the increasing demand for smaller satellites and mega- constellations. In order to ensure Europe's independent space access capabilities, ASCenSIon (Advancing Space Access Capabilities - Reusability and Multiple Satellite Injection) is born as an innovative training network with fifteen Early Stage Researchers, ten beneficiaries, and fourteen partner organisations across Europe. This paper provides an overview of the mission, ranging from the ascent to the re-entry of the reusable stages and including the multi-orbit injection and the safe disposal. A special focus is put on the activities developed within ASCenSIon regarding Mission Analysis (MA), Guidance Navigation and Control (GNC) and Aerothermodynamics (ATD). The foreseen methods, approaches and goals of the project are presented. These topics require innovation within and a high level of collaboration due to their interconnection. The pre-flight design capability drives the necessity of a MA and GNC missionisation tool coupled with ATD software to test/explore re-entry solutions. Such a reliable and efficient tool will require the development of GNC algorithms for the re-entry of the launcher. Additionally, specific challenges of trajectory optimization for RLVs are addressed, such as integrated multi-disciplinary vehicle design and trajectory analysis, fast and reliable on-board methods. The results of this study are subsequently used to develop the controlled strategy. Moreover, to perform the novel multi-orbit multi-payload injection. This activity is followed by the development of, a GNC architecture capable of optimally steering the vehicle towards a targeted landing site under precision and soft-landing constraints. In addition, ATD affects the mission profile at multiple phases and needs to be considered at each design step. Due to complexity and limited computational resources during the preliminary design phase, surrogate models with low response times are required to predict wall heat fluxes along the considered trajectories based on the pressure topology. The complete profile is wrapped up with the Post Mission Disposal strategies to be used by the launchers in order to ensure the compliance with the space debris mitigation guidelines, as well as preliminary reliability aspects of these strategies. The paper provides a preliminary analysis of the discussed topics and their interconnections within the work-frame of ASCenSIon paving the way towards the development of novel cutting-edge technologies for RLVs

RLV applications: challenges and benefits of novel technologies for sustainable main stages

Within the scope of the European Green Deal, the aerospace industry is currently staking on sustainability. To fulfil the objectives and in order to ensure Europe's independent and cost-effective space access capabilities, the ASCenSIon (Advancing Space Access Capabilities - Reusability and Multiple Satellite Injection) project, funded by H2020, is connecting fifteen Early-Stage Researchers (ESRs) and twenty-four partner organizations all across Europe. The pillar concept within the project is to adopt a Concurrent Research Network (CRN) methodology. Accordingly, different host institutions, each one with its main research program and vision, are connected to develop the design under a new perspective. This approach emphasises the cooperation between the fifteen ESRs, thus covering the design of a Reusable Launch Vehicle (RLV) in its overall complexity, facing the new challenges deriving from the required sustainability in a more efficient manner. Corresponding to work package two (WP2) of ASCenSIon, this paper focuses on main stages for RLVs, and how the goal of sustainability affects their design. Therefore, many different interconnected disciplines, such as propulsion system, structural design, fatigue-life analysis and Health Monitoring (HM) have to be taken into consideration. These different domains are represented by the individual research projects of the ESRs, supported by a collaborative environment which promotes the foreseen interactions. At first, this contribution gives a general State-Of-The-Art overview of the mentioned topics. A preliminary trade-off on RLV architectures is established through multi-disciplinary design analysis and optimization methods based on propulsion modelling, optimal staging and structural sizing. These use performance and cost design metrics as objective functions, accounting for operability and maintainability factors. This investigation is then used to discuss the different Advanced Nozzle Concepts (ANCs) tailored on the system requirements and mission constraints. At this point, a one-dimensional performance analysis addresses the performance gain deriving from altitude-compensation properties of ANCs. Subsequently, the identification of a suitable green propellant will give the needed/accurate/required inputs to conduct a trade-off between engine cycles w.r.t. the fatigue-life of their most critical components. Consequently, fatigue-life analysis contributes to HM and sensing requirements for RLV systems. As a common approach between the ESRs, the data collection is organized in various Databases accessible within the network, which encourages their interconnections and collaborative research. This paper provides a preliminary analysis of the above discussed topics and their interconnections within the framework of ASCenSIon, aiming to develop novel technologies for future sustainable main stages

Human immunodeficiency virus continuum of care in 11 european union countries at the end of 2016 overall and by key population: Have we made progress?

Background. High uptake of antiretroviral treatment (ART) is essential to reduce human immunodeficiency virus (HIV) transmission and related mortality; however, gaps in care exist. We aimed to construct the continuum of HIV care (CoC) in 2016 in 11 European Union (EU) countries, overall and by key population and sex. To estimate progress toward the Joint United Nations Programme on HIV/AIDS (UNAIDS) 90-90-90 target, we compared 2016 to 2013 estimates for the same countries, representing 73% of the population in the region. Methods. A CoC with the following 4 stages was constructed: number of people living with HIV (PLHIV); proportion of PLHIV diagnosed; proportion of those diagnosed who ever initiated ART; and proportion of those ever treated who achieved viral suppression at their last visit. Results. We estimated that 87% of PLHIV were diagnosed; 92% of those diagnosed had ever initiated ART; and 91% of those ever on ART, or 73% of all PLHIV, were virally suppressed. Corresponding figures for men having sex with men were: 86%, 93%, 93%, 74%; for people who inject drugs: 94%, 88%, 85%, 70%; and for heterosexuals: 86%, 92%, 91%, 72%. The proportion suppressed of all PLHIV ranged from 59% to 86% across countries. Conclusions. The EU is close to the 90-90-90 target and achieved the UNAIDS target of 73% of all PLHIV virally suppressed, significant progress since 2013 when 60% of all PLHIV were virally suppressed. Strengthening of testing programs and treatment support, along with prevention interventions, are needed to achieve HIV epidemic control