International Space Station Systems Research Articles

Sleep patterns among shift-working flight controllers of the International Space Station: an observational study on the JAXA Flight Control Team.

BackgroundFlight controllers of the International Space Station (ISS) are engaged in shift work to provide 24-h coverage to support ISS systems. The purpose of this study was to investigate the prevalence and associated factors of shift work sleep disorder (SWSD) among Japanese ISS flight controllers.MethodsA questionnaire study was conducted using the Standard Shiftwork Index to evaluate sleep-related problems and possible associated variables. Among 52 respondents out of 73 flight controllers, 30 subjects were identified as night shift workers who worked 3 or more night shifts per month. Those night shift workers who answered “almost always” to questions about experiencing insomnia or excessive sleepiness in any case of work shifts and days off were classified as having SWSD. Additionally, 7 night shift workers participated in supplemental wrist actigraphy data collection for 7 to 8 days including 3 to 4 days of consecutive night shifts.ResultsFourteen of 30 night shift workers were classified as having SWSD. Significant group differences were observed where the SWSD group felt that night shift work was harder and reported more frequent insomniac symptoms after a night shift. However, no other variables demonstrated remarkable differences between groups. Actigraphy results characterized 5 subjects reporting better perceived adaptation as having regular daytime sleep, for 6 to 9 h in total, between consecutive night shifts. On the other hand, 2 subjects reporting perceived maladaptation revealed different sleep patterns, with longer daytime sleep and large day-to-day variation in daytime sleep between consecutive night shifts, respectively.ConclusionsAs the tasks for flight control require high levels of alertness and cognitive function, several characteristics, namely shift-working schedule (2 to 4 consecutive night shifts), very short break time (5 to 10 min/h) during work shifts, and cooperative work with onboard astronauts during the evening/night shift, accounted for increasing workloads especially in the case of night shifts, resulting in higher or equal prevalence of SWSD to that among other shift-working populations. Further studies are required to collect more actigraphy data and examine the possibility of interventions to improve SWSD.

Intelligent flight support system (IFSS): a real-time intelligent decision support system for future manned spaceflight operations at Mission Control Center

The Mission Control Center Systems (MCCS) is a functionally robust set of distributed systems primarily supporting the Space Shuttle Program (SSP) and the International Space Station (ISS) mission operations. Forged around the uniquely complex and demanding requirements of human spaceflight, the MCCS has evolved within the limits of the technological capabilities of the time. The dynamic environment in which MCCS functions has demanded that the systems architecture continue to evolve as well. The MCCS provides the primary means of controlling crewed spacecraft operated by NASA. Flight controllers (FCs) monitor the spacecraft systems through telemetry sent from the spacecraft to the ground and from the ground to the vehicle. FCs utilize several application software to present telemetry data in a variety of output presentations. While most displays simply provide a densely packed screen of telemetry data, only a few provide graphical representations of the vehicle systems' status. New technological advances in user interface design have not penetrated into MCC especially since the SSP and ISS systems were developed when these technologies were not available. The Intelligent Flight Support System (IFSS) described in this paper promotes situational awareness at MCC with an interactive virtual model of the ISS and Space Shuttle combined with data and decision support displays. IFSS also incorporates an intelligent component to model various characteristics of space vehicle systems when predictable results of unknown scenarios are required. IFSS supports FCs in the planning, communications, command, and control operations of the ISS and Space Shuttle by providing knowledge and skills that are unavailable from internal representation.

Modeling station duty officer operations assistant at Johnson Space Center

The mission operations directorate (MOD) at the Johnson Space Center (JSC) is responsible for the planning and operation of human space flight missions. MOD is being challenged with sustaining and developing new operations capabilities to support increasingly demanding requirements and to improve its processes to accomplish these missions at higher levels of safety, mission success, and effectiveness. Automation is being considered as an enabling technology to meet the aforementioned challenges. The synergistic combination of flight controllers and intelligent software providing the function of ‘operations assistants’ (OA) is being pursued as the key implementation of this technology in the Mission Control Center (MCC). The flight control team (FCT) assesses the condition and operability of the major systems such as electrical power, thermal control, life support, communications, altitude control, and data handling at MCC. OA assist the flight controllers with their tasks of monitoring the status and health of the flight systems. They also help maintain the flight controller's awareness of the operations being performed during the mission and help assure that operational objectives are being met. The station duty officer (SDO) performs the lead operations role for the International Space Station (ISS) during quiescent times when FCT and the flight director are off-duty. SDOs assess the condition and operability of the major ISS systems. This assessment involves monitoring and controlling several periodic processes on systems such as the electrical power, thermal control, life support, communications, altitude control, and data handling systems. The SDO is also responsible for coordinating operations with the Russian FCT. The OA will help the SDO maintain an awareness of all the processes performed on board and will assist with the responses to anomalous conditions. The OA for this position will support the concept of reduced control center staffing during quiescent times. The purpose of this paper is twofold: (1) to present a unique two-stage specification methodology that combines data flow diagrams and petri nets and (2) to apply the proposed methodology in a complex space station system.

Hardware/software integration & verification for the mobile servicing system of the international space station

The system architecture of the Mobile Service System (MSS) forms an integral part of the architecture of the International Space Station (ISS) in which elements interact through data components controlled by their respective element software. Tne element developers produce software components which, subsequent to being validated on their respective elements, are integrated and verified in test environments which are representative of the integrated MSS/ISS system. This is the classical method for integration and verification. If program software requirements are, for various reasons, slow to finalize, the software development process starts later than anticipated, and following the classical development/verification processes, could put the scheduled software deliveries at risk. A new approach to development and verification is needed which must encompass the entire software program from component unit software to fully integrated system software. This paper describes the approach which was taken to perform system hardware/software integration and verification with software components which were essentially incomplete, but were developed in a phased fashion, having mutually compatible functionality. The paper describes the MSS and ISS system architecture, the various software components and an overview of the original integration and verification plan. The paper will then describe the new integration approach which was developed, and discuss the evolution of the various software components in terms of functionality and their phased integration into a system. The paper will conclude by providing a summary of the results of the integration and verification activities, and demonstrate how delivery schedules for the integrated system software were met.