The general functional relationship language system
Symbolic language for expressing functional relationships of space vehicle components
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The Use of Dynamic Visual Acuity as a Functional Test of Gaze Stabilization Following Space Flight
After prolonged exposure to a given gravitational environment the transition to another is accompanied by adaptations in the sensorimotor subsystems, including the vestibular system. Variation in the adaptation time course of these subsystems, and the functional redundancies that exist between them make it difficult to accurately assess the functional capacity and physical limitations of astro/cosmonauts using tests on individual subsystems. While isolated tests of subsystem performance may be the only means to address where interventions are required, direct measures of performance may be more suitable for assessing the operational consequences of incomplete adaptation to changes in the gravitational environment. A test of dynamic visual acuity (DVA) is currently being used in the JSC Neurosciences Laboratory as part of a series of measures to assess the efficacy of a countermeasure to mitigate postflight locomotor dysfunction. In the current protocol, subjects visual acuity is determined using Landolt ring optotypes presented sequentially on a computer display. Visual acuity assessments are made both while standing and while walking at 1.8 m/s on a motorized treadmill. The use of a psychophysical threshold detection algorithm reduces the required number of optotype presentations and the results can be presented immediately after the test. The difference between the walking and standing acuity measures provides a metric of the change in the subject s ability to maintain gaze fixation on the visual target while walking. This functional consequence is observable regardless of the underlying subsystem most responsible for the change. Data from 15 cosmo/astronauts have been collected following long-duration (approx. 6 months) stays in space using a visual target viewing distance of 4.0 meters. An investigation of the group mean shows a change in DVA soon after the flight that asymptotes back to baseline approximately one week following their return to earth. The performance of some subjects nicely parallels the stereotypical recovery curve observed in the group mean data. Others show dramatic changes in DVA from one test day to another. These changes may be indicative of a re-adaptation process that is not characterized by a steady improvement with the passage of time, but is instead a dynamic search for appropriate coordinative strategy to achieve the desired gaze stabilization goal. Ground-based data have been collected in our lab using DVA with one of the goals being to improve the DVA test itself. In one of these studies, the DVA test was repeated using a visual target viewing distance of 0.5 meters. While walking, the relative contributions of the otoliths and semi-circular canals that are required to stabilize gaze are affected by visual target viewing distance. It may be possible to exploit this using the current treadmill DVA test to differentially assess changes in these vestibular subsystems. The postflight DVA evaluations currently used have been augmented to include the near target version of the test. Preliminary results from these assessments, as well as the results from the ground-based tests will also be reported. DVA provides a direct measure of a subject's ability to see clearly in the presence of self-motion. The use of the current tests for providing a functionally relevant metric is evident. However, it is possible to expand the scope of DVA testing to include scenarios other than walking. A facility for measuring DVA in the presence of passive movements is being created. Using a mechanized platform to provide the perturbation, it should be possible to simulate aircraft and automobile vibration profiles. Used in conjunction with the far and near visual displays this facility should be able to assess a subject s ability to clearly see distant objects as well as those that appear on the dashboard or instrument control panel during functionally relevant situations.
Peters, B. T.↗
Kennedy Space Center Payload Processing
This slide presentation reviews the payload processing functions at Kennedy Space Center. It details some of the payloads processed at KSC, the typical processing tasks, the facilities available for processing payloads, and the capabilities and customer services that are available.
Lawson, Ronnie↗
Assessment of Postflight Locomotor Performance Utilizing a Test of Functional Mobility: Strategic and Adaptive Responses
Space flight induces adaptive modification in sensorimotor function, allowing crewmembers to operate in the unique microgravity environment. This adaptive state, however, is inappropriate for a terrestrial environment. During a re-adaptation period upon their return to Earth, crewmembers experience alterations in sensorimotor function, causing various disturbances in perception, spatial orientation, posture, gait, and eye-head coordination. Following long duration space flight, sensorimotor dysfunction would prevent or extend the time required to make an emergency egress from the vehicle; compromising crew safety and mission objectives. We are investigating two types of motor learning that may interact with each other and influence a crewmember's ability to re-adapt to Earth's gravity environment. In strategic learning, crewmembers make rapid modifications in their motor control strategy emphasizing error reduction. This type of learning may be critical during the first minutes and hours after landing. In adaptive learning, long-term plastic transformations occur, involving morphological changes and synaptic modification. In recent literature these two behavioral components have been associated with separate brain structures that control the execution of motor strategies: the strategic component was linked to the posterior parietal cortex and the adaptive component was linked to the cerebellum (Pisella, et al. 2004). The goal of this paper was to demonstrate the relative contributions of the strategic and adaptive components to the re-adaptation process in locomotor control after long duration space flight missions on the International Space Station (ISS). The Functional Mobility Test (FMT) was developed to assess crewmember s ability to ambulate postflight from an operational and functional perspective. Sixteen crewmembers were tested preflight (3 sessions) and postflight (days 1, 2, 4, 7, 25) following a long duration space flight (approx 6 months) on the ISS. We have further analyzed the FMT data to characterize strategic and adaptive components during the postflight readaptation period. Crewmembers walked at a preferred pace through an obstacle course set up on a base of 10 cm thick medium density foam (Sunmate Foam, Dynamic Systems, Inc., Leicester, NC). The 6.0m X 4.0m course consisted of several pylons made of foam; a Styrofoam barrier 46.0cm high that crewmembers stepped over; and a portal constructed of two Styrofoam blocks, each 31cm high, with a horizontal bar covered by foam and suspended from the ceiling which was adjusted to the height of the crewmember s shoulder. The portal required crewmembers to bend at the waist and step over a barrier simultaneously. All obstacles were lightweight, soft and easily knocked over. Crewmembers were instructed to walk through the course as quickly and as safely as possible without touching any of the objects on the course. This task was performed three times in the clockwise direction and three times in the counterclockwise direction that was randomly chosen. The dependent measures for each trial were: time to complete the course (seconds) and the number of obstacles touched or knocked down. For each crewmember, the time to complete each FMT trial from postflight days 1, 2, 4, 7 and 25 were further analyzed. A single logarithmic curve using a least squares calculation was fit through these data to produce a single comprehensive curve (macro). This macro curve composed of data spanning 25 days, illustrates the re-adaptive learning function over the longer time scale term. Additionally, logarithmic curves were fit to the 6 data trials within each individual post flight test day to produce 5 separate daily curves. These micro curves, produced from data obtained over the course of minutes, illustrates the strategic learning function exhibited over a relative shorter time scale. The macro curve for all subjects exhibited adaptive motor learning patterns over the 25 day period. Howev, 9/16 crewmembers exhibited significant strategic motor learning patterns in their micro curves, as defined by m > 1 in the equation of the line y=m*LN(x) +b. These data indicate that postflight recovery in locomotor function involves both strategic and adaptive mechanisms. Future countermeasures will be designed to enhance both recovery processes.
Warren, L. E.↗
Analysis of the shearout failure mode in composite bolted joints
A semi-empirical shearout strength model has been formulated for the analysis of composite bolted joints with allowance for the effects of joint geometry. The model employs a polynomial stress function in conjunction with a point stress failure criterion to predict strength as a function of fastener size, edge distance, and half spacing. The stress function is obtained by two-dimensional plane-stress finite element analysis using quadrilateral elements with orthotropic material properties. Comparison of experimentally determined shearout strength data with model predicted failures has substantiated the accuracy of the model.
Wilson, D. W.↗
Shuttle to Space Station. Heart Assist Implant. Hubble Update. X-30 Mock-Up
Shuttle to Space Station, Heart Assist Implant, Hubble Update, and X-30 Mockup are the four parts that are discussed in this video. The first part, Shuttle to Space Station, is focussed on the construction and function of the Space Station Freedom. While part two, Heart Assist Implant, discusses a newly developed electromechanical device that helps to reduce heart attack by using electric shocks. Interviews with the co-inventor and patients are also included. Brief introduction to Hubble Telescope, problem behind its poor image quality (mirror aberration), and the plan to correct this problem are the three issues that are discussed in part three, Hubble Update. The last part, part four, reviews the X-30 Mockup designed by the staff and students of Mississippi State University.
Source record↗
Communications, tracking, and docking on the Space Station
Many of the communications, tracking, and docking functions on a large manned orbiting Space Station - one that is modular and made of metal - will have to be performed by optical systems out of necessity. This paper discusses four practical approaches to accomplishing Space Station functions using optical communications technology. It also provides the results of preliminary experiments involved in the design of particular systems. Major operational factors considered in each system design include: (a) electromagnetic interference problems, (b) data bandwidth requirements, (c) zero-gravity operations, (d) free-space operations, (e) data security, and (f) modular expansion of the Space Station structure. The technologies discussed are the following: (a) local infrared communications, (b) optical tracking and docking techniques, (c) long distance free space optical communications, and (d) local area optical networks.
Erwin, H. O.↗
Advanced Hall Electric Propulsion for Future In-space Transportation
The Hall thruster is an electric propulsion device used for multiple in-space applications including orbit raising, on-orbit maneuvers, and de-orbit functions. These in-space propulsion functions are currently performed by toxic hydrazine monopropellant or hydrazine derivative/nitrogen tetroxide bi-propellant thrusters. The Hall thruster operates nominally in the 1500 sec specific impulse regime. It provides greater thrust to power than conventional gridded ion engines, thus reducing trip times and operational life when compared to that technology in Earth orbit applications. The technology in the far term, by adding a second acceleration stage, has shown promise of providing over 4000s Isp, the regime of the gridded ion engine and necessary for deep space applications. The Hall thruster system consists of three parts, the thruster, the power processor, and the propellant system. The technology is operational and commercially available at the 1.5 kW power level and 5 kW application is underway. NASA is looking toward 10 kW and eventually 50 kW-class engines for ambitious space transportation applications. The former allows launch vehicle step-down for GEO missions and demanding planetary missions such as Europa Lander, while the latter allows quick all-electric propulsion LEO to GEO transfers and non-nuclear transportation human Mars missions.
Oleson, Steven R.↗
Integrated air revitalization system for Space Station
Fifty-one distinct functions are encompassed by the Space Station's Environmental Control and Life Support System; one exception to this noninteractivity of functions is the regenerative air revitalization system that removes and reduces CO2 and generates O2. The integration of these interdependent functions, and of humidity control, into a single system furnishes opportunities for process simplification as well as for power, weight and volume requirement reductions by comparison with discrete subsystems. Attention is presently given to a system which quantifies these integration-related savings and identifies additional advantages that accrue to this integrating design method.
Boyda, R. B.↗
Design and operation of the U.S. Space Station Freedom Propulsion System
The propulsion functions for the U.S. Space Station Freedom (SSF) are accomplished by two separate systems, the Primary Propulsion System and the Supplemental Reboost System (SRS). The Primary Propulsion System includes self-contained hydrazine modules for station reboost, attitude control and contingency maneuvers. These Propulsion Modules contain reboost and attitude control thrusters, propellant storage, thermal conditioning and electronic controls. The modules are serviced on the ground and launched on the Space Shuttle as replacements for the on-orbit modules which have expended their propellant. The expended modules are returned to the ground for reservicing and subsequent reuse. The Supplemental Reboost System includes a Waste Gas Assembly and Resistojet Modules which are used for reboost maneuvers only. The Waste Gas Assembly contains waste gas storage, compressors and dryers and the Resistojet Modules contain multipropellant resistojet thrusters, electronic pressure regulators and power conditioning equipment.
Morano, Joseph S.↗
Multi-terabyte image storage and distribution for NASA's Hubble Space Telescope
The modular architecture, functionality, and key components of the Hubble Space Telescope Data Archive Distribution Service (DADS) are presented. DADS functions comprise archive management, catalog management, and user interface. The distributed modular architecture utilized is made up of four subsystems, including the archive, host, catalog, and the Science Operations ground System/DADS Interface Processor. All data generated by the HST are archived in DADS on 12-in. optical disks. DADS is a permanent archive with a data capacity of 30 terabytes that can be expanded to 68 terabytes. Supplementary information and stellar observations will be instantly accessible through DADS, which can collect and archive more than 3 gigabytes per day of image and support data over the lifetime of the HST. Electronic and physical media will be accessible through 140 network connections, with a catalogue to assist in data set selection.
Weller, H. W., Jr.↗
Space form of motionsickness
Spacesickness under weightlessness conditions is explained mainly by disruption of the activity of the functional system perceiving space and participating in carrying out the balancing function, consisting, in particular, of the vestibular, proprioceptive, interoceptive, visual and cutaneomechanical analyzers. It can be assumed that, under specific conditions, Coriolis acceleration also is a cause of spacesickness. Adaptation is possible by formation of a new functional system which is adequate to the new mechanical conditions of weightlessness. Selection, training, creation of optimum conditions in the spacecraft cabin, medicinal, and technical improvement of spacecraft play an important role in prophylaxis of the space form of seasickness.
Komendantov, G. L.↗
Linear and circular digital spectral analysis of serial data
Two methods of digital spectral analysis of unevenly sampled data are developed and illustrated here. One method uses a linear function of time (or space), the other uses circular functions. The circular method turns out to be essentially equivalent to a least-squares sine-wave analysis. The linear, anharmonic method uses only the field of real numbers and elementary algebraic operations, and hence it can be made computationally very fast and accurate. Both methods are very general, properly handling all kinds of time series ranging from simple series consisting only of the times of events to complicated series consisting of pulses with long duty cycles. The two methods are here applied to the analysis of annual mean relative sunspot numbers.
Stothers, Richard B.↗
Analysis of delay reducing and fuel saving sequencing and spacing algorithms for arrival traffic
The air traffic control subsystem that performs sequencing and spacing is discussed. The function of the sequencing and spacing algorithms is to automatically plan the most efficient landing order and to assign optimally spaced landing times to all arrivals. Several algorithms are described and their statistical performance is examined. Sequencing brings order to an arrival sequence for aircraft. First-come-first-served sequencing (FCFS) establishes a fair order, based on estimated times of arrival, and determines proper separations. Because of the randomness of the arriving traffic, gaps will remain in the sequence of aircraft. Delays are reduced by time-advancing the leading aircraft of each group while still preserving the FCFS order. Tightly spaced groups of aircraft remain with a mix of heavy and large aircraft. Spacing requirements differ for different types of aircraft trailing each other. Traffic is reordered slightly to take advantage of this spacing criterion, thus shortening the groups and reducing average delays. For heavy traffic, delays for different traffic samples vary widely, even when the same set of statistical parameters is used to produce each sample. This report supersedes NASA TM-102795 on the same subject. It includes a new method of time-advance as well as an efficient method of sequencing and spacing for two dependent runways.
Neuman, Frank↗
Increased Renal Solute Excretion in Rats Following Space Flight
Following space flight a diuresis, due to an increase in free water clearance, has been suggested in humans. To assess the effects of space flight on renal function, rats were flown in space for 14 days. Rats were divided into three groups; vivarium controls (V;n=6; housed 2/shoe box cage), flight controls (FC;n=6; group housed in a flight cage), and flight animals (F;n=6). Upon landing all animals were placed into individual metabolic cages. Urine was collected daily for 7 days and every other day for 14 days. Urine output was increased (p less than 0.05; ANOVA) following flight for 3 days. On postflight day 1, flow rates were, V=6.8 plus or minus 0.9, FC=8.711.8 and F=16.6 plus or minus 2.7 microliter/min. Excretion rates of Na+ and K+ were increased, resulting in an increased osmotic excretion rate (V=7.9 plus or minus 0.9, FC=6.1 plus or minus 0.7 and F=13.5 plus or minus 0.7 uOsm/min). Creatinine excretion rate was increased over the first two postflight days. In the absence of changes in plasma creatinine, Na+, or K+ (samples obtained immediately post flight from similar rats compared to Day 14), GFR was increased following space flight. The increased excretion of solute was thus the result of increased delivery and decreased reabsorption. Osmotic clearance was increased (V=28, FC=27 and F=51 microliter/min), while free water clearance was decreased post flight (V=-21,FC=-18 and F=-34 microliter/min). In rats, the postflight diuresis is the result of an increase in solute (osmotic) excretion with an accompanying reduction in free water clearance.
Wade, Charles E.↗
Pulmonary function evaluation during and following Skylab space flights
Cardiac output measurements were made in the laboratory during preflight and postflight exercise tests. Due to the magnitude of decreases in cardiac output following the first and second manned Skylab missions and because the method used is based upon normal pulmonary function, it was decided to perform more thorough pulmonary function screening in conjunction with the final and longest duration Skylab mission. This paper summarized pulmonary function data obtained during all three Skylab missions.
Sawin, C. F.↗
The evolution of automation and robotics in manned spaceflight
The evolution of automation on all manned spacecraft including the Space Shuttle is reviewed, and a concept for increasing automation and robotics from the current Shuttle Remote Manipulator System (RMS) to an autonomous system is presented. The requirements for robotic elements are identified for various functions on the Space Station, including extravehicular functions and functions within laboratory and habitation modules which expand man's capacity in space and allow selected teleoperation from the ground. The initial Space Station will employ a telerobot and necessary knowledge based systems as an advisory to the crew on monitoring, fault diagnosis, and short term planning and scheduling.
Moser, T. L.↗
NASA Marshall Space Flight Center In-Space Cryogenic Propulsion Capabilities and Applications to Human Exploration
The current focus on lunar exploration and future human missions to Mars is driving in-space propulsion system requirements toward higher performance cryogenic systems with long-duration storage and operational capabilities. Not only do these systems offer higher performance than storable propellant options, but they also enable the potential for in-situ propellant production. Future Mars transit systems are envisioned to utilize either high-thrust nuclear thermal propulsion (with liquid hydrogen propellant), or hybrid systems with both cryogenic chemical systems (likely LOX/CH4) for high acceleration maneuvers and nuclear electric systems for long duration high Isp maneuvers. Exploration architectures based on either of these options require the use of high-performance cryogenic propellants with long-duration storage capabilities for both in-space transportation as well as planetary descent and ascent functions. Current efforts focusing on lunar exploration also rely on cryogenic propellants (either LOX/LCH4 or LOX/LH2) for lunar transit and descent/ascent transportation functions. In-space cryogenic propulsion systems pose numerous technology challenges with respect to long-duration propellant storage and usage, including advanced insulation, tank stratification and pressure management, cryogenic refrigeration to reduce propellant loss through boil off, low leakage cryogenic valves, low temperature liquid acquisition, and cryogenic propellant transfer. NASA has invested in technology development efforts, demonstrating individual technologies and systems-level operations. NASA Marshal Space Flight Center has also invested in multiple test facilities and modular test rigs that allow ground demonstration of numerous integrated technologies and systems concepts of operations. Additional investments have been made to mature analytical capabilities and design tools. These capabilities, both test/demonstration & engineering design/analysis, are available to support internal efforts and industrial partners in the development of exploration and science mission systems. With this increased interest, it is critical to understand the current state of in-space cryogenic propulsion technology, determine risks to its successful application to human exploration, and prepare the engineering, test, and evaluation capabilities to support the ambitious plans for future systems. This paper provides a survey of recent developments in in-space cryogenic propulsion and cryogenic propellant management technologies, as well as facilities and engineering/analytical capabilities ready to support current and future exploration efforts.
Cryogenic propulsion, cryogenic fluid management, ↗