Space Station Operations Research Articles

The US Space Program's Path Forward for Low-Earth Orbit (LEO) after Decommissioning of the International Space Station (ISS)

As activities in space rapidly evolve, the International Space Station (ISS) is approaching its retirement date. Since decommissioning of the ISS is scheduled for 2030, the United States (US) must identify paths forward for space station operations in low-earth orbit (LEO). Having a manned LEO space station after the conclusion of the ISS program will allow the US to continue possessing a platform to conduct scientific research, advance technology, and investigate the effects of microgravity on biological physiology. Options to continue LEO operations include having private entities construct and operate commercial space stations, reusing components of the ISS, directing NASA to spearhead efforts in building a new space station, or abandoning US-led space stations in LEO altogether. We recommend that commercial firms build and operate space stations, permitting multiple platforms to be created while maintaining the legacy of the ISS. The US will have facilities in LEO for research and development, thus advancing technological and scientific knowledge for Earth-based applications and future space missions.

High performance assembly of complex structural parts in special environments – research on space manipulator assisted module docking method

PurposeCompared with the robotic manipulation in structured environment, high performance assembly of complex parts in extreme special environment is facing great challenges because of the uncertainty in the environment, and the decline of the control accuracy of the robot and the sensor accuracy. The assembly and construction of the space station is a typical case. An important step in the construction of the space station is the module positioning and docking with the auxiliary of the space manipulator. The operation of the manipulator is faced with many problems, such as low sensing information accuracy, large end position deviation and the requirement of weak impact in the docking process. The purpose of this paper is to design a docking method at the strategy level to effectively solve the problems that may be faced in the docking process.Design/methodology/approachInspired by the research of robotic high-precision compliant assembly, this paper introduces the concept of Attractive Region in Environment (ARIE) into the space manipulator–assisted module docking. The contact configuration space of the docking mechanism and the existence of ARIE are systematically analyzed. The docking strategy based on ARIE framework is proposed, in which the impedance control is used to ensure the weak impact during the docking process.FindingsFor the androgynous peripheral spacecraft docking mechanism, a large range of attractive region exists in the high-dimensional contact configuration space. The docking strategy based on ARIE framework can be designed according to the geometric characteristics of the constraint region and the structural characteristics of the docking mechanism. The virtual models and the simulation environment are established, and the effectiveness of the proposed method is preliminarily verified.Originality/valueBased on the research results of robotic precision compliant manipulation, in this paper, the theory of ARIE is first systematically applied to the analysis of spacecraft docking problem and the design of docking scheme. The effectiveness of the proposed docking method is preliminarily verified for the requirements of large position tolerance and weak impact. The research results will provide theoretical support and technical reference for the assembly and construction of space station and other space manipulator operations.

СОПОСТАВЛЕНИЕ С НОРМАМИ РАДИАЦИОННОЙ БЕЗОПАСНОСТИ УРОВНЕЙ ДОЗ НА КРИТИЧЕСКИЕ ОРГАНЫ ТЕЛА ЧЕЛОВЕКА ПРИ ДЛИТЕЛЬНЫХ ПОЛЕТАХ НА ОРБИТАЛЬНЫХ СТАНЦИЯХ «МИР» И МКС

We analyzed the averaged through the year power of local tissue absorbed doses measured by the standard instruments over 15 years of station Mir operation (28 missions) and analogous data over 22 years of the International space station (ISS) operation (67 missions) within solar cycles (SCs) 22–25. This is a huge set of daily measurements of dosimeters R-16 (ioinization chamber D2) and 4 semiconductor dosimeters DB-8, located in different compartments. We also present the experimental and calculated absorbed and equivalent doses to the skin, lens and hematopoietic system (HPS) received within a day and year in space. It was found that in all Mir and ISS missions the equivalent doses to these tissues were below the limits adopted for orbital missions. In many missions of 6 to 8 months, the effective and equivalent doses to the CNS, lens and skin did not exceed even the lower dose limits prescribed by Russian radiation safety standard NRB-99/2009 for nuclear industry. Maximal equivalent dose values to the lens and skin in a year-long mission did not exceed 404 mSv. These values are less than the existing limits for space missions by 32 % for the lens and 5 times for the skin.

Research and Development of the Tianzhou Cargo Spacecraft

After more than 7 years of development, the Tianzhou cargo spacecraft (TZ), a space station cargo transfer spacecraft, was successfully launched on 2017 April 20. The TZ is robotic spacecraft that is designed to support China space station operation by transporting pressurized cargo, unpressurized cargo, large cargo, propellant, and other supplies. The vehicle is equipped with the crew specifications necessary for astronauts to unload pressurized cargo. TZ can be utilized for a variety of commercial, engineering, scientific, or other proposed activities once its primary mission is complete. TZ is China's first dedicated space cargo transport spacecraft, but the safety designs for crew activities are also particular to TZ. Newly developed technologies were applied to enable high-efficiency cargo shipment. Its development was carried out under the policy of adopting flight-proven technologies to enhance the reliability and safety of a mission. The success of the flight test of the TZ-1 cargo spacecraft marked the perfect end of the mission of the China Space Laboratory and laid the foundation for the smooth implementation of the manned space station project. As a novel manned spacecraft, TZ-1 has broken through key technologies such as cargo transportation, propellant replenishment, and fully autonomous rapid rendezvous and docking. TZ has the characteristics of high transport efficiency, multitasks, and strong self-control ability. The paper describes the phylogeny, main technical schemes, and technological achievements of China TZ.

Integrated planning of on-orbit events and transport visits forlong-term space station operation

Integrated planning of on-orbit events and transport visits forlong-term space station operation

Assessment of Spaceflight Medical Conditions’ and Treatments’ Potential Impacts on Behavioral Health and Performance

Long-duration space exploration missions will pose significant risks to the physical and behavioral health and performance of the crew. We documented the presence and frequency of (1) behavioral health and performance (BHP)-relevant symptoms for each condition in NASA's Exploration Medical Conditions List (EMCL), (2) the BHP-relevant effects of applicable medical treatments in the current International Space Station (ISS) On-Orbit Medication List, (3) the breadth of potential BHP impacts of spaceflight medical treatments, and (4) the likelihood of adverse BHP effects of treating spaceflight medical conditions. BHP symptoms and effects were categorized by the six neurobehavioral domains of the National Institute of Mental Health's Research Domain Criteria (RDoC) framework. Including the cognitive effects of acute and chronic pain (e.g., attention, memory), 94% of spaceflight medical conditions include symptoms relevant to Cognitive Systems (e.g., attention deficits, confusion, psychosis), 36% include symptoms relevant to Negative Valence Systems (e.g., anxiety), 32% include symptoms relevant to Arousal and Regulatory Systems (e.g., sleep disturbances), 22% include symptoms relevant to Sensorimotor Systems (e.g., dizziness), 19% include symptoms relevant to Positive Valence Systems (e.g., mania), and 11% include symptoms relevant to Social Processes (e.g., social withdrawal). Only 2% of spaceflight medical conditions have no documented BHP symptoms. Of the spaceflight medical treatments, 63% affect Arousal and Regulatory Systems, 60% affect Sensorimotor Systems, 59% affect Cognitive Systems, 53% affect Negative Valence Systems, 38% affect Positive Valence Systems, and 31% affect Social Processes. The breadth of potential BHP impacts was bimodal, in that 27% of spaceflight medical treatments had no documented BHP effects; however, 27% of treatments may produce adverse effects across all six neurobehavioral domains. Historical prevalence data on medical conditions, symptoms, and complaints from 14 years of International Space Station operations coupled with documented BHP effects of recommended treatments indicates the potential for up to 481 adverse BHP effects of spaceflight medical treatments per person-year. Assessing the potential BHP impacts of spaceflight medical conditions and their treatments highlights the interactive nature of operational risks, and can provide an enhanced evidence base to support integrated research and countermeasure development strategies for long-duration exploration missions.

Experimental development onboard the ISS Russian segment of the prototype system for quick localization of a puncture in the space station pressure shell

Improving safety of space station operations at the time when the near-Earth space is getting increasingly littered with space junk is one of the principal problems in space station design. Along with the measures to reduce the risk of the station pressure shell penetration resulting from a collision with a meteoroid or a piece of space debris that involve protection of the module pressure shells with shields, there is also a need for developing measures and equipment aimed at mitigating catastrophic consequences of the penetration. One of the key factors allowing successful recovery from an emergency situation caused by station depressurization in case of a puncture is the time needed to locate the puncture, which determines possible scenarios for crew actions during recovery operations and their result. The Immediate Puncture Localization System (IPLS) presented in this paper provides reliable and virtually immediate detection of the time and location of the penetration. The proposed concept for the IPLS architecture is based on the use of piezoelectric sensors of acoustic emissions distributed over the inner surface of the pressurized shell of the module that are connected to an electronic unit for processing signals from the sensors. The paper presents the results of studies of the scientific and engineering feasibility of the IPLS operating principles conducted at RSC Energia and TsNIIMash, as well as results of developmental tests on a prototype of such a system in the Service Module of the International Space Station (ISS) in the space experiment Otklik conducted under the Applied Research Program of the ISS Russian Segment. Key words: International space station, ISS Russian Segment, meteoroid, space debris, pressure shell, immediate puncture localization system, piezoelectric sensor, space experiment, high-velocity impact, penetration.

Nanoracks Low Earth Orbit Commercialization Study: Experiences and Outcomes

This article discusses the conclusions and implications of Nanoracks' NASA-Commissioned Low Earth Orbit Commercialization Study, or LEOCOM. The objective of LEOCOM was to leverage Nanoracks' decade of expertise as a user of the International Space Station as a commercial platform to describe the commercial future of the low Earth orbit (LEO) economic ecosystem. To complete this study, Nanoracks collected a team of 13 commercial suppliers, service providers, users, and consultants. The data these partners provided were utilized by Nanoracks and combined with existing information on current markets to generate a set of key policy and market recommendations. The LEOCOM study specifically focused on the role that platforms play as lynchpins in the LEO economy. In particular, Nanoracks used the Outpost platform as a baseline. Outposts are a Nanoracks concept for creating habitable volume from spent upper stages of multiple launch vehicles, in the case of the LEOCOM study, from United Launch Alliance (ULA) Centaur III and Centaur V stages. Once on orbit, robotic arms autonomously convert the stages after fuel venting, utilizing materials brought up to orbit in mission modules to complete full repurposing of the tanks before astronaut ingress. Although this is one among several platforms being considered by Nanoracks for future crewed platforms, costs associated with repurposing provide the core inputs to the financial model. As a result of this study, Nanoracks generated a higher resolution view of complexities involved in ensuring the sustainability of a LEO commercial marketplace. Coloring these conclusions was an underlining assumption that most actors would require some amount of government investment before attaining true sustainability, since a self-sustaining LEO economy does not yet exist in any appreciable form analogous to vibrant terrestrial markets. In this context, various critical insights were gleaned about the manner in which public and commercial actors could work together to efficiently set appropriate and long-term expectations of stability for government and private investor participation. Along with this analysis, Nanoracks took the unprecedented step of engaging key NASA staff in a Policy Simulation. This simulation focused on 3 hypothetical scenarios that Nanoracks wrote in consultation with NASA, and those were composed with Nanoracks' best assumptions about what forms future real-world policy challenges might take. The purpose of this exercise was not necessarily to receive a response from NASA regarding any particular challenge, but rather to analyze the processes that NASA undertook to answer policy questions likely to arise in the operation of a commercial LEO space station.

Review of space manufacturing technique and developments

Space manufacturing is recognized as one of the key technologies for enhancing human’s extraterrestrial activities and carrying out deep-space exploration missions. Therefore, it has become the frontier of scientific and application research. Compared to conventional manufacturing on the Earth, there are higher requirements and more demands for space manufacturing owing to the proposed missions such as space station operation, lunar base construction, and deep-space exploration. Specifically, the characteristics of environment, including long-term microgravity, strong irradiation, and high vacuum in space, create new challenges for space manufacturing. In addition, there are other technical challenges in the manufacturing accuracy, power consumption, size of manufacturing devices, and intelligence production to adapt to specific application scenarios in space missions. This paper summarizes the research progress on the main technologies in space manufacturing in the world, focuses on the development of space manufacturing on the basis of polymeric, metallic, ceramic, composite, and biomaterials, and discusses several future main directions and trends of space manufacturing to provide a reference for the development of China’s space manufacturing technology.

Sustainable space exploration and its relevance to the privatization of space ventures

Although the majority of humanity's current space programs are currently limited to the operation of the international space station and the deployment of probes to analyze distant planets, visions for future space exploration have long-duration missions in sight (such as manned missions to Mars and asteroid mining). According to contemporary literature these missions have the potential to provide tangible and intangible benefits, but they are also subject to public criticism given that increased awareness for environmental protection and preservation has ignited debates surrounding the socio-environmental and financial sustainability of space exploration. In hindsight of past advancements in outer space exploration, the authors follow the assumption that the commercial development will flourish and will provide auxiliary opportunities to overcome existing challenges. However, it is clear that the germination of private investment in the field of space exploration is contingent on the existence of unequivocal international space laws that permit and stimulate pro-profit decision making. Following this line of thought, this paper will explore the divergent definitions of sustainability that exist in the rhetoric of space exploration and will additionally expound on the privatization of space exploration and its relevance to the controversial legal rationales of international space laws.

Model predykcji pozostałego czasu pracy stacji kosmicznej

Space station is a very complex system, and its remaining useful life will be affected by the key equipment, cosmonauts’ maintenance activities as well as space environments. It is important for the operation management of a space station to predict its remaining useful life (RUL). A valid RUL prediction model is the key foundation for this issue, which motivates the research presented in this paper. Firstly, different types of space station life are defined. Secondly, the function and performance requirements as well as the operation mission program of the space station are analysed, which are further used to confirm the model development precondition. A life prediction model is then proposed by synthetically taking account of the safety, reliability and maintainability restrictions. Finally, the data requirement for supporting the RUL prediction is determined. Based on this work, a comprehensive procedure for RUL prediction model development is constructed for the operation management engineers of the space station. If the data of the development and operation is adequate, RUL prediction of the space station can be well implemented, and can be further leveraged to support the space station operation management.

New Comparative Metric for Evaluating Spacecraft Radiation Shielding

Given the lack of human medical data available to calibrate and tie the sophisticated model calculations of various space radiation exposure metrics, such as “dose equivalent,” to the actual biological harm expected from long-term exposure to galactic cosmic ray (GCR) radiation in the region of cislunar space [nominally at 1 astronomical unit (AU) from the sun], a new spacecraft shielding evaluation metric is proposed that empirically links to the available medical data collected from International Space Station (ISS) operations, and thereby improves shielding material assessment. Adequate protection from radiation is one of the most important unknowns regarding the contemplated long-term spaceflights beyond the Earth’s protective zone afforded by its magnetosphere. This new radiation shielding evaluation metric relies on a comparison of the relative shielding effectiveness of a particular material or shielding design in the cislunar space radiation environment to the verified radiation exposure environment inside the ISS, where hundreds of astronauts have flown and spent considerable time, and for which there is voluminous medical data and continuing medical observation. Thus, the new metric is a measure of how well a proposed shielding protocol operating in the 1 AU cislunar radiation environment replicates the ISS radiation exposure levels. And, because it is calculated on a strict comparable basis, it mitigates the unavoidable errors introduced in the shielding evaluation process inherent in using different GCR models and radiation transport codes, as well as the various versions of radiation quality or weighting factors.

Turn-key use of an onboard 3D printer for international space station operations

Current 3D printing capabilities onboard the International Space Station (ISS) are classified as experimental payloads. As payloads the products of these printers are returned to the ground for testing and analysis. However, it has long been thought that 3D printing must one day become a tool of space operations much like the electrical diagnostic equipment, and the soldering iron. This paper explores a case study in the use of one of the payload 3D printers to manufacture a device to be used by the crew as part of nominal ISS Operations. The nature of this attempt represented a collaboration between the ISS payload community and the systems operations community to capitalize on the strengths of both to accomplish a step in what may one day become a common and cost-savings capability in spaceflight operations. The path from concept development through onboard printing and crew inspection will be described. The lessons learned from this process are reviewed as constructive feedback on how existing processes can be expanded to enable this capability in the future. This experience will be carried forward into the development of a new process which will open the door for future use of 3D printing onboard the ISS.

Transient Floating Potential Variations Attributed to High-Voltage Solar Array Operations

The International Space Station continues to be a productive space research laboratory after over 15 years of operations, and it has proven to be a valuable resource for observing spacecraft floating potential variations related to high-voltage solar array operations in low Earth orbit. Measurements of the ionospheric electron density and temperature along the International Space Station orbit and variations in the International Space Station floating potential are obtained from the floating potential measurement unit. In particular, rapid variations in the International Space Station floating potential during solar array operations on timescales of tens of milliseconds can be recorded due to the 128 Hz sample rate of the floating potential probe, providing insight into high-voltage solar array interaction with the space plasma environment. Comparing the floating potential measurement unit data with the International Space Station operations’ timeline and solar array data provides a means for correlating some of the more complex transient floating potential variations with mission operations. These complex variations are not reproduced by current models and require further study to understand the underlying physical processes. In this paper is presented some of the floating potential transients observed over the past few years along with the relevant space environment parameters and solar array operations data.

Discrete event simulation of long-duration space station operations for rapid evaluation

A long term space station operational scenario involves a large number of on-orbit missions, however, for their successful implementation they require various logistics missions to be performed. Logistics missions are triggered by on-orbit missions and there are complex interactions between different missions. Based on the computational efficiency afforded by event-based simulation, Discrete Event Simulation (DES) is used to model diverse on-orbit and logistics missions holistically within an integrated scenario and schematize it as a discrete system. It helps to quickly evaluate the physical feasibility and performance effectiveness of complex space station operations. Moreover, operational uncertainty is introduced into the DES model, comprising launch delays of visiting vehicles and onboard emergencies hazarding the safeties of space station or astronauts. Monte Carlo simulation is adopted to help in stochastic analyses and five measurable metrics are further defined to quantify the impact of uncertainty on nominal scenarios. The proposed DES model and associated metrics are demonstrated with both nominal and contingency operations. Simulation results indicate that such an approach is effective and efficient in simulating space station operations and able to support the top-level mission design of China's future space station program.

Simulation of collision probability between space station and space debris and structure failure probability

In this paper, the flux distribution of space debris and micrometeoroids in the orbit of space station is analysed, the collision distribution characteristics of space debris and micrometeoroids at different typical positions in different flight attitude during the operation of space station are obtained. The collision probabilities with the space debris during the operation of space station are also obtained. Combined with the space debris distribution and protection requirements, a space station in-orbit protection scheme is proposed. The protection efficiency of the protection scheme is simulated and the simulation analysis data of different protection schemes are obtained. The research results obtained in this paper can provide reference for the design of space station protection scheme.

Design and Realization of Payload Operation and Application System of China’s Space Station

China's Space Station will be launched in the year 2018; this space station is China's largest space science experiment and application platform until now. This paper mainly introduces the function composition of payload operation and application system of China’s space station, system architecture, hardware architecture and the new technology we use to implement the payload operation and application ground system of China's space station.

Novel Method for Predicting Solar Proton Events Based on Grey Relational Analysis and Joint Probability Density

Solar proton event is one of the important sources of interference, which may cause perturbations of the Sun-earth system in a great contingency. Big levels of proton events can also affect the reliability of carrier laboratory equipment in space station. The safe operation of on-orbit space station may be threatened at sometimes. This paper presents a new method to predict the probability of occurrence and estimate the level of proton events based on grey relational analysis and joint probability density forecast. Firstly, the grey relational analysis is applied to extract the most relevant data sequences from numerous related characteristic quantities which characterize events occurrence. Secondly, the characteristic data sequences are made to be dimensionless and the dimensions are compressed. After the sequences of characteristic factors are recombined, the new independent integrated variables can be generated. Finally, the GM(1,N) prediction model for the present and absent event established. At the same time, the joint probability density method is used to analyse the optimized characteristic factor sequence, the joint probability density model of different levels of proton events corresponding characteristic factors can also be obtained. The combination of the model and setting event level threshold value are obtained, and the joint probability density discriminator is constituted. The level of impending proton event is predicted by utilizing the discriminator. The results show that the event predictive precision rate is prior to 90% by selecting the data of solar proton events occuring in 2012 for model prediction, and the prediction accuracy of events level is superior to 85%.

(Invited) Nano-Derived Microsensors for Monitoring Gas Species in Harsh-Environments

The objective of our work is to develop nano-derived, micro-scale sensors to monitor various gases within extreme or harsh-environments. These environments include high temperature and pressure applications, where sensors are required to monitor emissions in applications such as coal gasifiers and turbine generators. The environment may also include applications in extreme cold and low-pressure applications, where sensors are required to monitor chemical leaks, as possible on the International Space Station and satellite servicing operations. Our research focuses on the development of microsensors for both of these extreme temperatures and pressure environments, but the current paper will only focus upon the high-temperature sensor application. In the case of the high-temperature gas sensing, nanomaterials for detecting gases such as H2 and SO2 within high-temperature environments were investigated at 1000°C. The microsensors developed in this work are based upon a resistive-type (chemiresistive) sensor platform.

Space Station Operations Would Extend Until at Least 2024 Under Obama Plan

An 8 January decision by the White House to propose an extension of the International Space Station's (ISS) operation until at least 2024 would allow for increased research on board the floating laboratory, a longer planning horizon for commercial activities, and a continuation of international cooperation in space, administration officials said. The proposal, which has received initial support from some key members of Congress, would be the second extension for ISS under the Obama administration and would accommodate increased research related to long‐duration human space flight, Earth science, and other areas. ISS, which in the United States is authorized under the NASA Authorization Act of 2010, was last extended in 2010 and costs about $3 billion annually to operate.