Search

This work presents an event-triggered controller for spacecraft rendezvous hovering phases. The goal is to maintain the chaser within a bounded region with respect to the target. The main assumption is that the chaser vehicle has impulsive thrusters. These are assumed to be orientable at any direction and are constrained by dead-zone and saturation bounds. The event-based controller relies on trigger rules deciding when a suitable control law is applied. The local control law consists on a single impulse; therefore the trigger rules design is based on the instantaneous reachability to the admissible set. The final outcome is a very efficient algorithm from both computational burden and footprint perspectives. Because the proposed methodology is based on a single impulse control, the controller invariance is local and assessed through impulsive systems theory. Finally, numerical results are shown and discussed Ministerio de Ciencia e Innovación (España) PGC2018-100680-B-C21 Universidad de Sevilla PP2016-6975

GPS observations are critical to both mission operations and scientific experiments on-board the International Space Station (ISS). However, it has long been recognized that this dynamic platform presents a complex, challenging viewing geometry for tracking GPS signals. Many researchers have investigated the ISS multipath environment using simulations and empirical data analysis [1,2,3,4]. The goal of our work is to create high fidelity predictions of GPS satellite visibility and systematic multipath observation errors resulting from interactions between the incident GPS signals and the ISS. GPS visibility and multipath modeling for receivers on-board the ISS presents a unique challenge due to the dynamic structure, extensive sky blockages, and large flat reflectors. This work builds upon the Colorado Center For Astrodynamics Research (CCAR) Advanced GNSS Multipath Model (AGMM) software to enable high fidelity multipath modeling for ISS applications. A high resolution, publicly available CAD model of the ISS structure is incorporated, including realistic orbital and attitude motion of the station, motion of solar panels and radiators. Candidate GPS receivers and antennas can be placed anywhere on the structure for analysis, including comparisons of performance with different tracking parameters and antenna patterns. A significant improvement in computational capability of the AGMM has been achieved with the integration of the open-source Physically Based Rendering Techniques (PBRT) API for modeling of signal ray paths and specular surface reflections. Additional tools for visualizing ray paths and reflections are developed and illustrated, enabling a deeper understanding of the environmental constraints and impacts. Quantitative methods for comparing simulated to observed multipath are introduced to effectively evaluate and ultimately validate the model predictions. This improved simulation has been applied to the Global Ecosystem Dynamics Investigation lidar (GEDI) GPS receiver case study for data gathered on-orbit in January 2019. GEDI is a lidar instrument which provides global measurements of forest vertical structures and is mounted to the Japanese Exposed Facility (JEM-EF). Specifically, GEDI is attached to the anti-velocity side of the JEM-EF. This location creates a non-trivial environment for the receiving antenna. Substantial sky-blockages caused by the JEM, truss, port solar panels, and radiator structures limit the satellites available for tracking and are significant sources of multipath reflections. Figure 1 shows a sky plot of the GEDI antenna bore-sight view. The AGMM software is able to simulate multipath for the GEDI receiver much faster than previously possible, creating a rich dataset from which model comparisons can be drawn. Realistic simulations of the ISS environment are created by incorporating ISS on-orbit position and velocity data, as well as solar panel and radiator rotation angles. Quantitative comparisons between on-orbit and simulated data are performed for satellite visibility statistics code multipath spectral content as well as code multipath magnitude. Simulated satellite visibility matches on-orbit satellite visibility on average 92% of the time for each satellite track present in the GEDI on-orbit data. Code multipath is extracted from the dual frequency receiver using the so-called ionosphere-free code minus carrier observable. The spectral content of oscillations in both simulated and observed multipath data is extracted using auto regressive (AR) techniques. Quantitative comparisons between the AR results show that the simulation performs at a statistically significant level when compared to randomized data. Simulated RMS Code multipath magnitude is within 30 cm of the observed magnitude for a majority of the simulated data. However, large differences between simulated and observed magnitudes are common and likely a result of poor knowledge of the ISS structural properties with regard to reflected L-band signals. This quantitative analysis helps validate the results of the AGMM model, showing utility for mission planning of future GNSS receiver installations on-board the ISS. References: Montenbruck, Oliver, et al. "Orbit determination and prediction of the international space station." Journal of Spacecraft and Rockets 48.6 (2011): 1055-1067. Powe, M., et al. "Analysis of the International Space Station multipath and masking environment for Automated Transfer Vehicle Relative GPS rendezvous manoeuvres." 2012 6th ESA Workshop on Satellite Navigation Technologies (Navitec 2012) & European Workshop on GNSS Signals and Signal Processing. IEEE, 2012. Hwu, Shian U., Susan F. Gomez, and Robert J. Panneton. "Multipath Effects on International Space Station Global Positioning System Performance." Journal of spacecraft and rockets 35.6 (1998): 858-859. Klein, Viliam, and Penina Axelrad. "Advanced multipath modeling and validation for GPS onboard the International Space Station." Navigation 66.3 (2019): 559-575.

ESA’s fifth and final Automated Transfer Vehicle (ATV), Georges Lemaître, performed its fully automated rendezvous and docking with the International Space Station (ISS) on August 12, 2014. The ATV’s navigation sensors have shown their worth docking the 20-ton vehicles with aft port of the Space Station, manoeuvring into position and docking with an excellent accuracy. For the second consecutive time after ATV-4, the accuracy at docking was such that the ATV probe head was directly captured inside the Zvezda docking mechanism without contact with the receiving cone. From 30 km and down to a distance of 250 m, ATV uses GPS (Global Positioning System) information from its own receiver and the Station’s that is transmitted over a radiofrequency link. As it moves closer, ATV switches to laser navigation, using the reflection of laser pulses on reflectors mounted on the Space Station. This paper presents the achievements and performance of ATV GNC (Guidance, Navigation, and Control) across the 5 missions for both types of navigation. It will also discuss the observations made during the various flights regarding unforeseen conditions such as space environment or target pattern contamination having a potential impact on performance and how they were resolved.

ESA’s fifth and last Automated Transfer Vehicle, ATV Georges Lemaître, tested new rendezvous technology before docking with the International Space Station (ISS) in August 2014. The technology demonstration called Laser Infrared Imaging Sensors (LIRIS) provides an unseen view of the ISS. During Georges Lemaître’s rendezvous, LIRIS sensors, composed of two infrared cameras, one visible camera, and a scanning LIDAR (Light Detection and Ranging), were turned on two and a half hours and 3500 m from the Space Station. All sensors worked as expected and a large amount of data was recorded and stored within ATV-5’s cargo hold before being returned to Earth with the Soyuz flight 38S in September 2014. As a part of the LIRIS postflight activities, the information gathered by all sensors is collected inside a flight database together with the reference ATV trajectory and attitude estimated by ATV main navigation sensors. Although decoupled from the ATV main computer, the LIRIS data were carefully synchronized with ATV guidance, navigation, and control (GNC) data. Hence, the LIRIS database can be used to assess the performance of various image processing algorithms to provide range and line-of-sight (LoS) navigation at long/medium range but also 6 degree-of-freedom (DoF) navigation at short range. The database also contains information related to the overall ATV position with respect to Earth and the Sun direction within ATV frame such that the effect of the environment on the sensors can also be investigated. This paper introduces the structure of the LIRIS database and provides some example of applications to increase the technology readiness level of noncooperative rendezvous.

A novel approach to solve the real-time command problem of spacecraft thrusters, called the thruster multi-objective command method, is proposed in this paper. The reaction control system technology uses a set of thrusters in a special setup to simultaneously provide force and torque to the spacecraft. The thruster management function calculates all the candidate solutions that solve the thruster coupling problem. Then, a discrete multi-objective optimization method selects at every control cycle the best combination of thrusters and their firing time duration, which simultaneously optimizes a group of four objectives: the force error, the torque error, the propellant mass consumption, and the total number of pulses. The proposed method is included in a coupled translational and attitude control system applied to the final approach rendezvous scenario. Furthermore, all elements of the guidance, navigation, and control loop are accurately designed and implemented in a simulation framework. Results indicate...

The French space agency (CNES) needed to acquire Ariane 5 launcher telemetry leading up to and including spacecraft separation that would occur south-east of New Zealand for the European Space Agency’s (ESA) Automated Transfer Vehicle (ATV) campaigns to resupply the International Space Station (ISS). No established ground stations were available for this purpose.

Quite a demanding task frequently arises in space engineering, when dealing with the cargo accommodation of modules and vehicles. The objective of this effort usually aims at maximizing the loaded cargo, or, at least, at meeting the logistic requirements posed by the space agencies. Complex accommodation rules are supposed to be taken into account, in compliance with strict balancing conditions and very tight operational restrictions. The context of the International Space Station (ISS) has paved the way for a relevant research and development activity, providing the company with a remarkable expertise in the field. CAST (Cargo Accommodation Support Tool) is a dedicated in-house software package (funded by the European Space Agency, ESA, and achieved by Thales Alenia Space), to carry out the whole loading of the Automated Transfer Vehicle (ATV). An ad hoc version, tailored to the Columbus (ISS attached laboratory) on-board stowage issue, has been further implemented and is to be used from now on. This article surveys the overall approach followed, highlighting the advantages of the methodology put forward, both in terms of solution quality and time saving, through an overview of the outcomes obtained to date. Insights on possible extensions to further space applications, especially in the perspective of the paramount challenges of the near future, are, in addition, presented.

On July 28th 2014, 23:47 UTC, the European Space Agency launched the Haptics-1 Kit to the International Space Station ISS on its last Automated Transfer Vehicle ATV-5. The Kit reached the station two weeks later, marking the first haptic master device to enter the ISS. The first force-feedback and human perceptual motor performance tests started to take place on December 30th 2014, and are the first of their kind in the history of spaceflight. Three astronauts participated in the Haptics-1 experiment until November 2015, allowing the investigation of the effects of microgravity on various psycho-motor performance metrics related with the usage of haptic feedback. Experiments are conducted following full adaptation to the space environment after 3 months in space. This paper introduces the Haptics-1 experiment and associated hardware. Detailed experimental results are reported from a first stiffness just noticeable difference JND experimental study in space, carried out on the ISS and pre-flight on ground with 3 astronauts. The first findings from the experiment show no major alterations in-flight, when compared to on-ground data, if the manipulandum is secured in flight against a sufficiently stiff reference structure.

資料番号: PA1110057000

M ANY space applications involve rendezvous with a vehicle in circular orbit. A subset of these applications requires the visiting vehicle to approach with a constant direction as seen by the target. This is the case for vehicles approaching the International Space Station (ISS), for example. By approaching it in a straight line the crew onboard the station can easily monitor nonnominal situations. The space shuttle employs a straight-line guidance law called glideslope [1]. Vehicles visiting the ISS usually employ a fixed-direction terminal approach, including H-II Transfer Vehicle (HTV) [2], Automated Transfer Vehicle (ATV) [3], and Cygnus [4]. In this work a constant direction guidance law is developed to rendezvous a target in circular orbit. This type of trajectory is referred to as glideslope. Much work exist in the general area of optimal space trajectories, an illustrative early work is that by Lawden [5]. Carter [6] studied minimum delta-v maneuvers to rendezvous with a vehicle in circular orbit. The approach used by Carter and by many authors after him is to optimize the system subject to the linearized dynamics, the socalled Clohessy–Wiltshire equations [7]. The rendezvous strategy by Lembeck and Prussing [8] is to add to an initial impulsive phase a low-thrust phase. Since continuous thrust is necessary to guide on the glideslope, this work also assumes low-thrust propulsion. Various aspects of this problemwere generalized. Carter andHumi [9] study the impulsive rendezvous in proximity of a general Keplerian orbit, while Carter [10] studies the continuous-thrust case. Power limitations and thrust bounds are also studied [11]. Guelman and Aleshin [12] develop a two-stage solution for the fixed-direction terminal approach. The first stage consists of an unconstrained optimization that puts the vehicle on the glideslope. The second stage is along the glideslope. In this work only the terminal phase is considered, when the spacecraft is required to fly on the glideslope. The current work differs considerably from the work of Guelman andAleshin [12]. In their work the constraint is not enforced directly, but the squared distance to the glideslope is added to the performance index with a weighting parameter. The bigger the parameter the closer the constraint is to be satisfied. This work’s approach is to satisfy the constraint exactly. Another difference between the two works is that Guelman and Aleshin solve their optimization numerically, while a closed-form solution is presented in this Note. The optimal guidance solution applies when the vehicle is on the glideslope. In practice, an inner-loop controller is needed tomaintain the vehicle on the desired terminal direction. II. Optimal Guidance

As part of the ESA/NASA Automated Transfer Vehicle (ATV) re-entry mission, we deployed a system of five cameras for visible and near-infrared (NIR) imaging and spectroscopic observation. These instruments were mounted in NASA's DC-8 Airborne Laboratory flying over the South Pacific Ocean. The ATV re-entry occurred on 29 September 2008, at ∼13:30 UT, and was recorded at a viewing distance of approximately 400 km from the site of its fragmentation in the mesosphere. Our instruments included intensified monochrome charge coupled device (CCD) cameras for narrow-field tracking and wide-field visible spectroscopy of the re-entry, and an InGaAs camera fitted with a grism was used for high-resolution NIR spectroscopy. Examples of the acquired data sets are discussed and include detection of visible atomic line emissions, NIR molecular band emissions and tracking of small fragments during the late stages of re-entry. The ATV re-entry campaign data are the first comprehensive airborne measurements of spacecraft break-up and provide important validation and constraint for state-of-the-art re-entry break-up models.

A challenging issue related to the International Space Station utilization concerns the on-board stowage, implying a strong impact on habitability, safety and crew productivity. This holds in particular for the European Columbus laboratory, nowadays also utilized to provide the station with logistic support. The volume exploitation has to be maximized, in compliance with the given accommodation rules. At each upload step, the stowage problem must be solved quickly and efficiently. This leads to the comparison of different scenarios to select the most suitable one. Last minute upgrades, due to possible re-planning, may, moreover arise, imposing the further capability to rapidly readapt the current solution to the updated status. In this context, looking into satisfactory solutions represents a very demanding job, even for experienced designers. Thales Alenia Space Italia has achieved a remarkable expertise in the field of cargo accommodation and stowage. The company has recently developed CAST, a dedicated in-house software tool, to support the cargo accommodation of the European automated transfer vehicle. An ad hoc version, tailored to the Columbus stowage, has been further implemented and is going to be used from now on. This paper surveys the on-board stowage issue, pointing out the advantages of the proposed approach.

This paper proposes amatrix-basedmodeling approach for analyzing spaceflight campaign logistics. A campaign is considered to be a series of coordinatedflights delivering cargo at a location or node. Amatrix representation of the cargo carried by flights for consumption in different time periods (or missions) is formulated. The matrix adopts specific structures based on the nature of the campaign, thereby allowing a quick visualization of the campaign logistics properties. A logistics strategy index is proposed for quantifying manifesting strategies, and a flight criticality index is defined to help in identifying important flights from a cargo-delivery perspective and aid in assessing impact of flight cancellations, failures, and delays. The method is demonstrated on a lunar outpost establishment and is also applied in modeling the logistics of the International Space Station. Amanifest (M) matrix and flight dependency (D) matrix is created for crew provisions cargo delivered to the ISS over a period of 10 years. It is found that the overall logistics strategy index for crew provisions has so far been 0.85 (meaning 85% of the crew provisions cargo is prepositioned on average for each mission) and that the prepositioning is for up to a maximum of four future missions at a time.

The flywheel exercise device (FWED) is planned for use as an in-flight exercise system, to demonstrate its efficacy as a countermeasure device to prevent muscle atrophy, bone loss and impairment of muscle function in human beings in response to long duration spaceflight. It is intended to be used on the International Space Station (ISS) and will be launched by the European cargo carrier, the automated transfer vehicle (ATV) in late 2005. The FWED is a non-gravity-dependent mechanical device based on the Yo–Yo principle, which provides resistance during coupled concentric and eccentric muscle actions, through the inertia of a spinning flywheel. Currently, the development of a FWED Flight and Ground Model is in progress and is due to be completed in May 2004. An earlier developed prototype is available that has been used for various ground studies. Our FWED design provides a maximum of built-in safety and support to the operation by one astronaut. This is achieved in particular by innovative mechanical design features and an easy, safe to use man–machine interface. The modular design is optimized for efficient set-up and maintenance operations to be performed in orbit by the crew. The mechanical subsystem of the FWED includes a μ g disturbance suspension, which minimizes the mechanical disturbances of the exercising subject at the mechanical interface to the ISS. During the FWED operation the astronaut is guided through the exercises by the data management subsystem, which acquires sensor data from the FWED, calculates and displays real-time feedback to the subject, and stores all data on hard disk and personalized storage media for later scientific analysis.

The Automated Transfer Vehicle (ATV) is a European spacecraft intended to service the International Space Station (ISS). It is designed to perform automated phasing, approach, rendezvous and docking to the ISS, then departure and deorbitation manoeuvres. Such an automated rendezvous mission towards a manned facility raises severe performance and safety constraints for the vehicle, which are declined towards the on-board Navigation in terms of availability, accuracy and failure tolerance: the ATV shall be operational after any first failure and safe conditions shall be reached after a second failure. The whole ATV navigation system has been designed to fulfil these very stringent requirements. Based on fully redundant hardware, the navigation algorithms present optimal estimators and multi-layers Failure, Detection, Isolation and Recovery (FDIR) capabilities to ensure the continuity of the state vector in case of failure. Several functions provide state vectors estimations and health reports, according to the flight phase: the attitude and drift estimation function provides the vehicle absolute attitude and angular rate during the whole flight; for the far rendezvous, position and velocity relative to the ISS are estimated by the relative GPS navigation and a dedicated relative navigation with Videometer applies in close rendezvous, in the final approach. All these autonomous navigation functions offer nevertheless a high level of monitoring and control to the ATV Control Centre operators. Thus the ATV innovative navigation chain provides the high level of performance, robustness and autonomy required by modern spacecrafts involved in human programs, today in Earth orbit but also for future space exploration missions.

DOI: 10.2514/1.27610 At the end of its mission to the International Space Station, during its reentry into Earth atmosphere, the automated transfer vehicle is subject to high heat fluxes leading to structural heating and fragmentation of the vehicle. It has been concluded that, depending on the mode of release, onboard residual hypergolic propellants may ignite and explode upon exposure to the hot and reactive flow environment. Because an earlier explosion of the vehicle would change drastically the impact footprint of its fragments onto the Earth surface, this study proposes a reassessment of the explosion potential. From the trajectory analysis, several points of the reentry path have been computed using a Navier–Stokes solver accounting for nonequilibrium effects. Numerical simulations have been performedwithandwithoutperforationofthestructure.Inparallel,acomprehensiveliteraturesurveyonignitionof monomethyl hydrazine and dimethyl hydrazine vapors with pure air or air mixed with nitrogen tetroxide has been performedtoassesstheautoignitionpotentialofthemixture.Finally,theresultsofthecomputational fluiddynamics computationshavebeenusedtoestimatetheexplosionriskinthepresenceofapropellantleakage.Analysisconfirms therisk ofadestruction ofthe automated transfervehicle athigher altitude,which couldinduce adifferent footprint of the fragments on the ground.

Every space system is exposed to the risk of collision with space debris and micro-meteoroids throughout its orbital life. Because of the large collision velocities, debris or meteoroids in the millimetre to centimetre range may cause significant damage to a spacecraft, which can result in potential generation of debris, loss of equipment and mission failure. The current paper deals with the probabilistic risk assessment of spacecraft survivability under micro-meteoroids and orbital debris (MMOD) impact. The typical process to calculate the MMOD induced risk is summarized and the main uncertainties and limitations affecting the assessment are discussed together with a simple example of a MMOD risk assessment performed for the European spaceship automated transfer vehicle. In order to increase the level of accuracy of MMOD risk assessments, improvements are necessary in the following critical areas: failure criteria analysis, project-dedicated hypervelocity impact testing and debris environment models.

The increasing complexity of modern systems makes their design, development and operation extremely challenging and therefore new Systems Engineering and Modeling and Simulation (M&S) techniques, methods and tools are emerging, also to benefit from distributed simulation environments. In this context, one of the most mature tools is the IEEE 1516-2010—Standard for M&S High Level Architecture (HLA). However, building and maintaining distributed simulations components, based on the IEEE 1516-2010 standard, is still a challenging and costly task. To ease the development of full-fledged HLA-based simulations, the paper proposes the MONADS method that, according to the model-driven systems engineering paradigm, allows one to generate the HLA-based simulation code from SysML models by the use of a chain of model-to-model and model-to-text transformations. The effectiveness of the method is shown through a case study that concerns an Automated Transfer Vehicle (ATV) approaching and docking to the International Space Station (ISS).

The fifth Automated Transfer Vehicle was launched on 29 July 2014 with Ariane-5 flight VA 219 into orbit from Kourou, French Guiana. For the first time, the ascent of an Ariane rocket was independently tracked with a Global Navigation Satellite System (GNSS) receiver on this flight. The GNSS receiver experiment OCAM-G was mounted on the upper stage of the rocket. Its receivers tracked the trajectory of the Ariane-5 from lift-off until after the separation of the Automated Transfer Vehicle. This article introduces the design of the experiment and presents an analysis of the data gathered during the flight with respect to the GNSS tracking status, availability of navigation solution, and navigation accuracy.

The positive experience with the knowledge capture project at the European Space Agency (ESA) Automated Transfer Vehicle (ATV) mission has opened a path worth following by the whole Agency. The ATV team has a privileged insight of what to preserve and how to present it so, to enable the user to get the best out of the missionâ??s knowledge, a portal was created and tailored to the specific needs of this mission (ATVCAP project). In order to capitalize from this experience, a spin-off has been developed in the form of a generic system, the KM Toolkit, that can be instantiated in as many business units as necessary. The idea is to offer to other areas a ready-to-go solution that can be tailored to the particularities of the interested party. This toolkit has been designed upon an architecture that integrates its services in several layers (shared services, integration, knowledge, access) and it provides to the end user a comprehensive set of features that use Open Source at their core: a portal as a single entry point (Drupal), wiki functionality (Drupal & MediaWiki), search engine (Apache Solr and ManifoldCF) and Competency Management (an in-house development based on Open Source). In addition to the KM Toolkit, it was developed as well a mechanism that allowed an easy content population, contributing with this to offer a content-rich solution as efficiently as possible. This paper describes how the Knowledge Management team at the European Space Agency has approached this endeavour from the conception and design to its implementation, based on past experiences (e.g. ATVCAP) and describing as well some lessons learned for the future.

Optically sensitive surfaces on the International Space Station (ISS) can be damaged (or eroded/pitted) when impacted by high-velocity particles from unburned liquid propellant present in bipropellant thruster plumes. Surfaces with thin optical coatings, such as solar arrays and radiators, are of primary concern. Thruster plume-induced erosion/pitting of sensitive surfaces has been observed on space shuttle flight experiments. The Boeing ISS Environments Team in Houston has developed an approach to modeling thruster plume-induced erosion/pitting of ISS surface materials. The Boeing team has conducted analyses simulating bipropellant thruster particles impacting sensitive ISS surfaces for various assembly stages. Thruster firings for ISS reboost/attitude control, as well as visiting vehicle thruster firings during approach or separation to ISS docking ports, were simulated. The results of these analyses show that particle impingement angle greatly affects surface damage, with normal impacts being the most severe. Particles with highly oblique impact angles (∼75 deg off normal), however, will essentially skid off surfaces without causing any erosion/pitting. A mitigation technique has been developed to prevent plume erosion/pitting of solar array coatings. Before a thruster-firing event, solar arrays may be rotated to a preestablished position that will eliminate plume particle impact damage to the surface. The preestablished positions are defined based on the geometry of the ISS thrusters relative to the solar array panels to ensure that plume particles will impinge at highly oblique angles (greater than 75 deg off normal). Upcoming ISS milestones will introduce new sensitive surfaces and thrusters, making 2005 a critical year for establishing operational constraints to mitigate thruster plume erosion. Some of these milestones include the space shuttle return to flight, the deployment of new ISS solar arrays, and the maiden voyage of ESA's automated transfer vehicle. Operational constraints for plume erosion mitigation are being coordinated with other solar array operational constraints such as power, thermal, and plume-induced structural loads. An integrated operational solution is being implemented to support the ISS assembly flight sequence. This paper will discuss plume erosion analyses and the implementation of operational mitigation as well as ongoing testing to better characterize plume erosion effects.

The Automated Transfer Vehicle (ATV) uses Relative Global Positioning System (RGPS) to navigate towards the International Space Station (ISS) while performing initial rendezvous manoeuvers. The RGPS solution includes a Global Positioning System (GPS) receiver in the ISS Zvezda module, whose observations are transmitted to, and applied by, the approaching ATV. The characterization of the GPS reception environment of the ISS is, therefore, a key element when planning rendezvous operations. The reception environment of the ISS is time-variant due to the relative motion between the ISS and the GPS satellites and to the sun-tracking orientation of the ISS Solar Array (SA) panels. In order to predict, for a given configuration, the most critical multipath and masking events, a Ray-Tracing (RT) tool has been developed at the European Space Research and Technology Centre (ESTEC) of the European Space Agency (ESA). The tool is based on Geometrical Optics (GO) and evaluates, for each multipath event, the associated effects on the pseudo-range error. The tool was validated using Flight Data Measurements (FDM) collected during two measurements campaigns which took place in 2010 and 2011, respectively. In particular, the validation activities show that the tool is able to timely predict the majority of the most critical multipath events. This paper presents the RT tool, the underlying validation activities and the prediction results which were prepared to support the rendezvous operations for the "Albert Einstein" ATV mission (June 2013). For this mission, three candidate configurations for the ISS were analyzed with the RT tool. Based on the prediction results, the configuration which minimizes the occurrence of the most critical events was also identified.

Analysing Interferometer for Ambient Air (ANITA) is a flight experiment as precursor for a permanent continuous trace gas monitoring system on the International Space Station (ISS). For over 10 years, under various ESA contracts the flight experiment was defined, designed, breadboarded and set up. For the safety of the crew, ANITA can detect and quantify quasi on-line and simultaneously 32 trace gases with ppm or sub-ppm detection limits. The self-standing measurement system is based on Fourier Transform Infrared Spectrometer (FTIR) technology. The system represents a versatile air monitor allowing for the first time the detection and monitoring of trace gas dynamics of a spacecraft atmosphere. It is envisaged to accommodate ANITA in a Destiny (US LAB) Express Rack on the ISS. The transportation to the ISS is planned with the first ATV 'Jules Verne'. The options are either the Space Shuttle or the Automated Transfer Vehicle.

In reaction control thrusters (RCT) propulsed space vehicles the force and/or torque derived from the control law must be translated into thrusters selection and thrusters firing durations. This has often to be done in an optimal way with respect to propellant consumption. Classical catalogue approaches to perform that rely on RCT architectural geometry symmetry properties. When such symmetries are not present at all, use of algorithms such as the linear programming “simplex” one has been advocated. But it presents some risks because the computation duration is not deterministic and no converged solution is granted in a predetermined duration. In-house studies performed at EADS Space Transportation found an optimal catalogue solution for the six DOF (degrees of freedom) problem. This algorithm has been developed for the ATV (Automated Transfer Vehicle) spacecraft. It is based on a precomputed optimal catalogue that is used onboard. However this catalogue depends on the centre of mass and this feature prevents its direct use in the pure attitude control problem. Here it is proposed an adaptation of the 6 DOF optimal catalogue to cope with 3 DOF problems and present some results

The European cargo transfer vehicle ATV will perform an autonomous docking to the International Space Station (ISS). This mission represents from position control point of view a very complex problem, that gather huge constraints on performances but also on safety and validation level. This paper shall focus on the design and validation of the ATV position control loop used for final approach and it is organised as follows. The general problem of ATV to ISS docking is first described, and especially the different Guidance, Navigation and Control (GNC) functions requirements as well as the environmental perturbations likely to disturb it. In a second part, discrete H∞ control approach is applied to the position control loop. Methodology, design and tuning are then fully described and illustrated with ATV application. At last, frequencial validation is presented. Then, GNC algorithms performances are presented to show their compliance with the requirements.

A closed-loop spacecraft rendezvous simulation facility was constructed and cone gured to evaluate a newly developedrelativenavigationalgorithmthatprocessestheobservablesoftheglobalpositioningsystem.Theprimary objective of this effort is to establish the performance of the integrated guidance and navigation architecture for autonomous rendezvous in low Earth orbit. A fundamental component of the relative navigation system is a real-time recursive extended Kalman e lter. To achieve very precise relative navigation, the e lter processes doubledifferenced carrier-phase measurements. Based on the e lter state, all of the maneuvers are computed onboard by solving the Lambert targeting problem. The closed-loop simulation investigations show that 3.5 cm or less relative positioning accuracy and 1.0 mm/srelativevelocity estimation accuracy areachievablein theabsenceof multipath. Withthesehighlyaccuraterelativenavigationresults,coordinatedandautonomousrendezvousmaneuversbecome possible.

This paper addresses the electromagnetic modeling of the communication link between the automated transfer vehicle (ATV) and the Tracking & Data Relay Satellite System (TDRSS). The link is analyzed during the ISS attached phase, i.e. when the ATV is docked on the International Space Station (ISS). The main objective of the study is to verify, by adopting a deterministic approach, if in every ISS orbit there are at least 15 minutes available to safely establish the ATV-TDRSS link.

The avionics architecture of in-orbit infrastructure elements is driven by safety. Safety of the crew inside the Columbus Orbital Facility (COF) laboratory module, safety of the Space Station as a whole for the automated transfer vehicle (ATV) when performing a rendezvous manoeuvre. The design answers on safety requirements, methods and tools used for the development stem from a common concept. The paper first describes the COF Data Management System architecture, basically organised in two layers with a strict hierarchical relationship. The vital layer is in charge of COF initial activation, safety supervision and emergency modes management. The nominal layer is a distributed system, organised around a local area Ethernet network. Under normal conditions, it is in charge of its own fault management supported by management agents distributed in the system. Fault detection criteria are derived from an FMECA (failure mode, effect and criticality analysis) and also from a SEEA (software error effect analysis). Recovery actions are allocated to various decision levels in the hierarchy depending on their time criticality. In ATV, the same principles apply, but the implementation is adapted to the peculiarities of an automated vehicle. The nominal layer, because of the time constraints bearing upon any reconfiguration, implements fault masking (majority voting) instead of fault detection and recovery.The vital layer is allocated the very critical task of monitoring the spacecraft attitude and velocity, and performing if necessary a collision avoidance manoeuvre. An end-to-end comprehensive methodology is put in place to be able to demonstrate the compliance of the systems to technical, product assurance and safety requirements.

Automated Transfer Vehicle (ATV) is the first European Space Cargo Program and is a major contribution of Europe to the International Space Station (ISS). The first model of ATV was launched in 2008 and the fifth and last model of this limited serie will be launched in 2014 ending up 7 years of operations at the ATV-Control Center in Toulouse (CNES France). Command and control of such a spacecraft is of course very different from satellites or interplanetary probes and requires original operations concepts and methods to deal with spacecraft specificities but also with ISS constraints and rules (Human Spaceflight). This paper deals with the organization of the Vehicle Engineer Team which is in charge of commanding, controlling and monitoring the vehicle over all the mission duration from launch to destructive reentry in the atmosphere.

The European Automated Transfer Vehicle is a pressurised unmanned resupply vehicle that is designed to refurbish the International Space Station with propellants and cargo (water, air, dry cargo, payloads and experiments). ATV can also provide propulsive support to reboost the station into a higher orbit, perform debris avoidance manoeuvres and attitude manoeuvres to assist docking/berthing or undocking/unberthing of other visiting vehicles. ATV has successfully completed four of a total of five missions to dock to the International Space Station. The fifth and last flight is scheduled in July this year with an expected re-entry into the Earth’s atmosphere at the beginning of 2015. This paper highlights the main events linked to the past ATV missions, introduces the next and last one and describes shortly the methods in place to perform the so-called “recurrent” missions when facing turn-over and a constantly evolving world like the ISS is.

Dealing with non-standard packing problems, and precisely because they are by definition outside the framework of any conventional classification, poses, from the experimental point of view, non-negligible difficulties. Firstly, a remarkable effort is requested to collect, or even generate ex novo, non-trivial instances. They need, actually, to cover an adequate number of scenarios, representative of a sufficiently wide area of real-world applications. Secondly, the elaboration of instances of practical interest is mostly very time consuming. Therefore, an extensive dedicated test campaign is extremely demanding, both in terms of human and computational resources. This chapter provides insights on relevant experimental aspects.

The Automated Transfer Vehicle (ATV) is a European Space Agency (ESA) funded unmanned spacecraft designed and developed by several European aerospace companies in the frame of the International Space Station (ISS). Its function is threefold: to supply the station with fret and propellant, to reboost ISS to a viable orbit and to retrieve waste from the station and bum them down during ATV re-entry in atmosphere. The ATV will be the first European space vehicle to perform an orbital rendezvous. To fulfill its mission, it relies on a complex avionics architecture (gyro assembly, star tracker, GPS, rendezvous sensors and accelerometers) that is designed to sustain stringent launch environment and to provide measurements in order to perform various missions such as ATV stabilization, collision avoidance maneuver (to ensure ISS safety), autonomous docking to ISS, dedocking and re-entry.