Journal of Space Safety Engineering最新文献

Logistics resupply to the lunar Gateway is one of the candidates for the Japan's contribution to the Artemis program. The Japan Aerospace Exploration Agency (JAXA) is presently developing the HTV-X, a new unmanned spacecraft developed as the successor to the H-II Transfer Vehicle (HTV). The HTV-X will transport supplies to the International Space Station. JAXA is also investigating enhancements to the HTV-X for logistics resupply to the lunar Gateway. A Near-Rectilinear Halo Orbit (NRHO) of the L2 southern family was selected as the Gateway operational orbit. This paper proposes a trajectory design for missions to the Gateway in NRHO. The rendezvous scenario consists of a transfer from the Earth to NRHO, a rendezvous, and proximity operations in NRHO. Monte Carlo simulations are performed in all phases to identify the effects of navigation and control errors. In addition, the simulations evaluate the designed trajectory's fuel consumption, safety, and operational feasibility. This paper also identifies the GN&C requirements for rendezvous in NRHO determined by the study.

The current work deals with a thermal design of a view port for a sub-orbital flight. Geometry of a typical sub-orbital flight was considered for this design. Using a typical suborbital flight trajectory, heat flux was estimated. For atmospheric re-entry, engineering correlations are used to estimate time varying stagnation heat flux from the trajectory data. At a time instant, CFD analysis was carried out to verify the consistency in stagnation heat flux. From CFD analysis, a factor was derived between stagnation heat flux and the heat flux at view port location. This factor was applied over the time varying stagnation heat flux to obtain transient heat flux profile on view port. A grid Independence study was performed and the grid independent results were only used in this study. Different materials were evaluated for the view port and a thermal analysis was carried out to estimate the optimum thickness requirement for each of these material using one dimensional thermal analysis.

When planning lunar bases and during long-term interplanetary (autonomous) flights, the issue of accumulation of pathogenic microbiota in conditions of closed inhabited objects is relevant. This question can be answered on the basis of a long observation period. When conducting microbiological examinations on the International Space Station, it was shown that one of the main features of the human-microorganisms ecological system in the environment of manned spacecraft is the periodic accumulation of the pathogenicity potential of microorganisms. These results were confirmed in isolation ground experiments and in the analysis of the SALYUT-6, 7 and MIR, International Space Station missions. Our work presents databases of microbiota and its antibiotic resistance of cosmonauts and hermetic facility operators at various stages of space flight, or isolation experiments. The databases are designed to assess the evolution of the population of microorganisms and their antibiotic resistance in various parts of the body of cosmonauts and operators of hermetic objects before, during and after a space flight and isolation experiments. Information about the microbiome of astronauts has been streamlined and entered into the database since 1970. The databases contain information about the microbiota in chronological order and its antibiotic resistance in cosmonauts and pressurized facility operators. Samples of various parts of the body were analyzed: forehead, chest, neck, ear, arm, armpit, groin, intestines, plaque, oral cavity, pharynx, tongue, nose, cheeks. Experimental samples of microbiota obtained from the International Space Station are stored at a deep freeze of -76 °С, are examined using a standard bacteriological method, molecular biology research methods and immunochemical methods. The information obtained makes it possible to assess the normal and dysbiotic state of the cosmonauts' microbiota. The databases are constantly updated. Thanks to the adapted database format, it is possible to use neural network and BIG DATA methods for analysis.

The existing rendezvous profiles of Russian crew vehicles in some flight phases are not adapted to contingencies which can be caused by an autonomous rendezvous system failure. If it occurs, the crew can complete the rendezvous in manual mode only at a range of less than a kilometer. However, at a long range the manual rendezvous mode is complicated because the on-board algorithm of the motion control system generates free trajectories that do not provide the crew with a convenient manual control. As a rule, in this case re-rendezvous is required with shifting the docking to the next day. In the case of fast rendezvous profiles (which allow to get to the ISS in 3 h) re-docking should be scheduled only in two days because of the crew adaptation to the weightlessness. In order to allow the crew to complete the rendezvous in manual mode without delaying the docking, it is required to create a more simple procedure for calculating and performing transfer burns. From the Gemini, Apollo and ATV spaceflight heritage, the technique for approaching the target from a coelliptical orbit has been known, that provides a uniform motion and convenient control of the crew vehicle in manual mode. The paper proposes the fast rendezvous profile with the insertion of the crew vehicle into an intermediate orbit coelliptical with the target orbit. In this approach, in case of automatic rendezvous failure, the crew, having a complete understanding of the relative motion, is able to perform the transfer to the target in manual mode without increasing the duration of the flight till the docking. The paper presents the results of testing this approach on a simulator, which in the long term will allow to reduce the rendezvous duration of Russian vehicles to a single orbit.

Long duration deep space exploration missions require an innovative assessment for medical impairment. Task Impairment is a novel, dynamic, and mission-appropriate impairment paradigm which will replace Functional Impairment, the metric used currently by the NASA Integrated Medical Model for probabilistic risk assessment on the International Space Station. To derive Task Impairment, the Human Exploration of Mars: Preliminary List of Crew Tasks was used as the source of likely exploration mission tasks. Tasks were divided into one or more human system task categories (e.g., cardiopulmonary, cognitive, etc.). Subject matter experts across five medical specialties then reviewed medical conditions from the Informing Mission Planning via Analysis of Complex Tradespaces condition list to determine which of the 18 human system task categories were impaired in best and worst-case scenarios for treated and untreated variants of each condition. If a human system task category was determined to be affected by a condition, every task assigned to that category was presumed to be, at least partially, impaired. The resulting total tasks impaired by each medical condition were used to calculate Task Impairment values. As a direct assessment of a crewmember's ability to perform mission specific tasks, Task Impairment has the capacity to yield a higher fidelity measure of reduced crew ability than previous techniques. This technique is easily adapted to future proposed design reference missions and may be useful in defining mission phase-specific disability as well as a future medical loss of mission objectives metric.

Only a few nations had historically made important contributions to space activity, but now a large number of countries are scaling up their space activities, and many have set up national space organizations. Ethiopia is one of the developing countries that has lately launched its own space program in an effort to help its people; yet, the Ethiopian space program's history spans approximately 60 years and lags behind for a number of reasons. Ethiopia's space program is still in its infancy and is still under development. However, the nation has been working hard to improve its space science and technology capability, with a particular emphasis on space research and development capability, human resource capacity building, enhancing space infrastructure, and monitoring and regulating space affairs. The study examines the history and present situation of Ethiopia's space program, highlighting the key milestones and accomplishments. It also explores the opportunities and difficulties the program encounters as well as assesses the potential effects of the program. The paper concludes with recommendations for the future development of the program and discusses Ethiopia's attempts to expand its capabilities, challenges, and prospects.

The increasing menace of space debris, stimulated by the current explosion of the small satellite commercial sector, urges the implementation of effective strategies for debris mitigation. Among these, substituting critical materials with more demisable ones represents an appropriate action to reduce the survivability of the component. Yet, improvements in demisability are often associated to performance penalties. In this contribution, the important topic of design for demise in the framework of material selection for optical elements has been addressed. In accordance with the typical mechanical and thermal stability requirements applied to optical systems, relevant figures of merit for the selection of optical materials have been identified. These have been exploited to optimize the design, aiming for the concurrent minimization of mass and heat required for the ablation of the component. The analysis has been applied to the most common materials currently used to fabricate space mirrors, which constitute one of the fundamental components in optical instrumentation. The proposed approach represents a valuable asset for implementing effective and innovative solutions for the sustainable use of space, aiming to concurrently reduce the casualty risk while avoiding performance penalties.

Habitats for future human spaceflights will require more resilient environmental control and life support systems (ECLSS). To that end, it is important to facilitate decision making in case of unexpected failure by quantifying the uncertain and dynamic nature of the physical phenomena involved. Combining probabilistic and deterministic models is a particularly promising approach to address this issue. In particular, Probabilistic Graphical Model (PGM) based digital twins are relevant as they embed random variables evolving overtime. Previous research used this modeling method for several applications such as monitoring structural health or manufacturing processes. We envision that the space exploration sector can also benefit from this approach by using the insight gained on specific sub-systems. In this study, we propose lessons learned on the implementation process of PGM-based Digital Twin to quantify uncertainties for temperature prognosis in ECLSS. These findings are introduced as a step-by-step guideline which result in developing a probabilistic model applicable to space habitats. We focused on directed acyclic graphs as this type of PGM can integrate expert's knowledge with data which has been proven to enhance accuracy. A literature review was conducted to identify the state-of-the-art practices and the proposed lessons learned were derived from the study of a physical infrastructure meant to predict the behavior of a space habitat. A temperature control failure scenario was considered, and the Digital Twin estimated the time available before the temperature would become critical. Experiments were conducted on three office rooms to simulate the behavior of an ECLSS. The model was trained offline using historical sensor data and performed inference online by computing the conditional probability of a multivariate normal density. We found that a successful implementation process requires to iteratively go through four stages: outline, design, calibrate and evaluate. It involves selecting ECLSS relevant functionalities and an associated decision-making problem that relies on habitability criteria. Observable variables must be chosen according to a sensors architecture that is compatible with a typical habitat infrastructure. As real space systems are not easily available for model validation, we suggest evaluating early designs on high fidelity analogs. In future work, we envisage to further assess the impact of the design stage on the model's performance by considering computational cost and inference capability.

There is much discussion about the further exploration of the moon and its implementation by autonomous robots and rovers. Prognostics and health management approaches are considered for autonomous systems to assure reliable operation. In this context, the reliability-adaptive systems approach deals with the prediction of the remaining useful life (RUL) to avoid maintenance conflicts. The proposed paper introduces a multi-system scenario on the lunar surface consisting of six rovers maintained by a single base. The rovers drill into the lunar surface and bring soil samples back to the base. To estimate the RUL as precisely as possible, the wear of the drill is monitored. Soil density, radiation, and soil versus rover temperature are just a few random aspects which are considered in the calculation of the drill failure rate. The simulation applies different values to the Weibull function shape parameter b > 1. This modeling represents the pessimistic assumption of an increasing soil density per drilling depth on the Moon. The base can maintain only one rover at a time. To avoid maintenance conflicts and to maximize the total scenario soil output, some rovers are derating their performances in order to extend their RUL so that all rovers reach the base preferably one after the other. When predicting the RUL, all previous failures, the current performances, and RUL prognoses of all rovers are considered. The paper discusses the operation algorithm including the rover procedures. The proposed contribution compares the efficiency of systems operated either conventionally in a non-derating mode or in a reliability-adaptive mode. The scenario-wide workload performed by all rovers is the evaluation measure in this approach. The following results have been obtained: Reliability-adaptive systems are operating more efficiently in the given lunar context than the conventional systems operate as the adaptive rovers continuously achieve higher up times in total. The longer the simulation time, the higher is the efficiency of reliability-adaptive operation. It has also been shown that reliability-adaptive systems have a significant influence on reducing delay times when returning to the drilling sites.