Modifications to interim visual spaceflight simulator Quarterly report, 12 Jan. - 12 Apr. 1967
Modifications to interim visual space flight simulator
FLIGHT SIMULATOR↗
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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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A Study of Codes for Deep Space Telemetry
Computer simulation studies of codes applicable to deep space telemetry links
Lumb, D. R.↗
Shuttle mission simulator. Volume 2: Requirement report, volume 2, revision C
The requirements for space shuttle simulation which are discussed include: general requirements, program management, system engineering, design and development, crew stations, on-board computers, and systems integration. For Vol. 1, revision A see N73-22203, for Vol 2, revision A see N73-22204.
Burke, J. F.↗
A simulation model for the analysis of Space Station gas-phase trace contaminants
A simulation model for the analysis of gas-phase trace contaminants in the cabin air of the NASA Space Station Reference Configuration was developed at the NASA Langley Research Center. The model predicts changes in trace contaminant concentrations from both physical and chemical sources and sinks as a function of time. Simulations were performed in which values for relative humidity, temperature, radiation intensity, pressure, and initial species concentrations were constrained to values for these parameters measured and modeled in the continental tropics at the earth's surface. Species concentrations simulated using the model compared favorably with concentrations in the continental tropics which demonstrated that the chemical mechanism in the trace contaminant model approximates changes in atmospheric species concentrations. The sensitivity of initial species concentrations to producing changes in additional species concentrations was also assessed. Results from the model indicated that chemical reactions will be important in determining the composition of cabin air in the Space Station. It is anticipated that the trace contaminant model will be useful in assessing the impact of experiments and commercial operations on the composition of the cabin air in the Space Station.
Brewer, Dana A.↗
Simulation study of interactions of Space Shuttle-generated electron beams with ambient plasmas
This report summarizes results obtained through the support of NASA Grant NAGW-1936. The objective of this report is to conduct large scale simulations of electron beams injected into space. The topics covered include the following: (1) simulation of radial expansion of an injected electron beam; (2) simulations of the active injections of electron beams; (3) parameter study of electron beam injection into an ionospheric plasma; and (4) magnetosheath-ionospheric plasma interactions in the cusp.
Lin, Chin S.↗
Delay and Disruption Tolerant Networking MACHETE Model
To verify satisfaction of communication requirements imposed by unique missions, as early as 2000, the Communications Networking Group at the Jet Propulsion Laboratory (JPL) saw the need for an environment to support interplanetary communication protocol design, validation, and characterization. JPL's Multi-mission Advanced Communications Hybrid Environment for Test and Evaluation (MACHETE), described in Simulator of Space Communication Networks (NPO-41373) NASA Tech Briefs, Vol. 29, No. 8 (August 2005), p. 44, combines various commercial, non-commercial, and in-house custom tools for simulation and performance analysis of space networks. The MACHETE environment supports orbital analysis, link budget analysis, communications network simulations, and hardware-in-the-loop testing. As NASA is expanding its Space Communications and Navigation (SCaN) capabilities to support planned and future missions, building infrastructure to maintain services and developing enabling technologies, an important and broader role is seen for MACHETE in design-phase evaluation of future SCaN architectures. To support evaluation of the developing Delay Tolerant Networking (DTN) field and its applicability for space networks, JPL developed MACHETE models for DTN Bundle Protocol (BP) and Licklider/Long-haul Transmission Protocol (LTP). DTN is an Internet Research Task Force (IRTF) architecture providing communication in and/or through highly stressed networking environments such as space exploration and battlefield networks. Stressed networking environments include those with intermittent (predictable and unknown) connectivity, large and/or variable delays, and high bit error rates. To provide its services over existing domain specific protocols, the DTN protocols reside at the application layer of the TCP/IP stack, forming a store-and-forward overlay network. The key capabilities of the Bundle Protocol include custody-based reliability, the ability to cope with intermittent connectivity, the ability to take advantage of scheduled and opportunistic connectivity, and late binding of names to addresses.
Segui, John S.↗
A robust method for handling low density regions in hybrid simulations for collisionless plasmas
A robust method to handle vacuum and near vacuum regions in hybrid simulations for space and astrophysical plasmas is presented. The conventional hybrid simulation model dealing with kinetic ions and a massless charge-neutralizing electron fluid is known to be susceptible to numerical instability due to divergence of the whistler-mode wave dispersion, as well as division-by-density operation in regions of low density. Consequently, a pure vacuum region is not allowed to exist in the simulation domain unless some ad hoc technique is used. To resolve this difficulty, an alternative way to introduce finite electron inertia effect is proposed. Contrary to the conventional method, the proposed one introduces a correction to the electric field rather than the magnetic field. It is shown that the generalized Ohm's law correctly reduces to Laplace's equation in a vacuum which therefore does not involve any numerical problems. In addition, a variable ion-to-electron mass ratio is introduced to reduce the phase velocity of high frequency whistler waves at low density regions so that the stability condition is always satisfied. It is demonstrated that the proposed model is able to handle near vacuum regions generated as a result of nonlinear self-consistent development of the system, as well as pure vacuum regions set up at the initial condition, without losing the advantages of the standard hybrid code.
70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
Integrated spacecraft display development Final report
Specification and design of projection display system for fixed base spacecraft simulator with data basis for analog simulator evaluation program
PROJECTION↗
Low cost tracking Navaids error model verification
Features and characteristics of the tracking navaids (Microwave Scanning Beam Landing System, Radar Altimeter, Tacan, rendezvous radar and one way Doppler extracter) were investigated. From the investigation, a set of specifications were developed for building equipment to verify the error model of the tracking navaids. Breadboard verification equipment (BVE) was built for the Microwave Scanning Beam Landing System and the radar altimeter. The breadboard verification equipment generates signals to the tracking navaids which simulate the space shuttles trajectory in the terminal area. The BVE simulates sources of navaids error by generating pseudorandom perturbations on the navaids signals. Differences between the trajectory value and the navaid derived values are taped and form the basis for the navaids error model.
Charych, A.↗
Monitoring and Modeling Astronaut Occupational Radiation Exposures in Space: Recent Advances
In 1982 astronauts were declared to be radiation workers by OSHA, and as such were subject to the rules and regulations applied to that group. NASA was already aware that space radiation was a hazard to crewmembers and had been studying and monitoring astronaut doses since 1962 at the Johnson Space Center. It was quickly realized NASA would not be able to accomplish all of its goals if the astronauts were subject to the ground based radiation worker limits, and thus received a waiver from OSHA to establish independent limits. As part of the stipulation attached to setting new limits, OSHA included a requirement to perform preflight dose projections for each crew and inform them of the associated risks. Additional requirements included measuring doses from various sources during the flight, making every effort to prevent a crewmember from exceeding the new limits, and keeping all exposures As Low As Reasonably Achievable (a.k.a. ALARA - a common health physics principle). The assembly of the International Space Station (ISS) and its initial manned operations will coincide with the 4-5 year period of high space weather activity at the next maximum in the solar cycle. For the first time in NASA's manned program, US astronauts will be in orbit continuously throughout a solar maximum period. During this period, crews are at risk of significantly increased radiation exposures due to solar particle events and trapped electron belt enhancements following geomagnetic storms. The problem of protecting crews is compounded by the difficulty of providing continuous real-time monitoring over a period of a decade in an era of tightly constrained budgets. In order to prepare for ISS radiological support needs, the NASA Space Radiation Analysis Group and the NOAA Space Environment Center have undertaken a multiyear effort to improve and automate ground-based space weather monitoring systems and real-time radiation analysis tools. These improvements include a coupled, automated space weather monitoring and alarm system--SPE exposure analysis system, an advanced space weather data distribution and display system, and a high-fidelity space weather simulation system. In addition, significant new real-time space weather data sets, which will enhance the forecasting and now-casting of near-Earth space environment conditions, are being made available through unique NASA-NOAA-USAF collaborations. These new data sets include coronal mass ejection monitoring by the Solar and Heliospheric Observatory (SOHO) and in-situ plasma and particle monitoring at the L1 libration point by the Solar Wind Monitor (SWIM) and Advanced Composition Explorer (ACE) spacecraft. Advanced real-time radiation monitoring data from charged particle telescopes and tissue equivalent proportional counters will also be available to assist crew and flight controllers in monitoring the external and intravehicular radiation environment.
Weyland, Mark↗
Lubrication and bearing problems in the vacuum of space
Summary information on lubricants and lubrication for use in aerospace environments, and simulation of space environments in vacuum chamber
Bisson, E. E.↗
SpecSims: A Scalable Speculative Tree-based Simulation Cloning Framework for Finite Memory Machines
Simulation cloning is a technique in which cloned simulations whose state spaces differ partially from their parent simulation due to intervening events are spawned at runtime and concurrently advanced. It is a powerful method to carry out what-if analysis by speculatively exploring and evaluating the impact of various permutations of intervening cascade of events. Due to the exponential growth in the number of possible clones even for a small number of distinct intervening events, the practical efficacy of the approach is often severely limited by the maximum available memory of the computing host. In this paper, we introduce a novel speculative simulation cloning framework that executes a simulation cloning campaign capable of efficiently exploring an exponentially large space of clone simulations created by permutation of intervening events under a finite memory constraint. We provide a theoretical analysis of the runtime characteristics of our proposed approach and highlight its novel advantages such as memory-aware and as-long-as-needed execution. Furthermore, in support of our analytical findings and to demonstrate its practical feasibility, we implement a prototype of the cloning framework on a shared memory system and report its performance characteristics in the context of a heat diffusion simulation, and a power grid simulation subject to cascading disruptions from geomagnetic disturbances.
Simulation framework↗
Visual space perception on a computer graphics night visual attachment
A series of experiments was conducted to compare five psychophysical methods of measuring how people perceive visual space in simulators. Psychologists have used such methods traditionally to measure visual space perception in the real world. Of the five tasks - objective-size judgments, angular-size judgments, shape judgments, slant judgments, and distance judgments - only the angular-size judgment task proved to be of potential use as a measure of simulator realism. In this experiment pilots estimated the relative angular size of triangles placed at various distances along a simulated runway. Estimates made when the display was collimated were closer to real-world performance than estimates made with an uncollimated display.
Palmer, E.↗
A Simulation Testbed for Airborne Merging and Spacing
The key innovation in this effort is the development of a simulation testbed for airborne merging and spacing (AM&S). We focus on concepts related to airports with Super Dense Operations where new airport runway configurations (e.g. parallel runways), sequencing, merging, and spacing are some of the concepts considered. We focus on modeling and simulating a complementary airborne and ground system for AM&S to increase efficiency and capacity of these high density terminal areas. From a ground systems perspective, a scheduling decision support tool generates arrival sequences and spacing requirements that are fed to the AM&S system operating on the flight deck. We enhanced NASA's Airspace Concept Evaluation Systems (ACES) software to model and simulate AM&S concepts and algorithms.
Santos, Michel↗
Space Shuttle flight crew/computer interface simulation studies.
An approach to achieving an optimized set of crew/computer interface requirements on the Space Shuttle program is described. It consists of defining the mission phases and crew timelines, developing a functional description of the crew/computer interface displays and controls software, conducting real-time simulations using pilot evaluation of the interface displays and controls, and developing a set of crew/computer functional requirements specifications. The simulator is a two-man crew station which includes three CRTs with keyboards for simulating the crew/computer interface. The programs simulate the mission phases and the flight hardware, including the flight computer and CRT displays.
Callihan, J. C.↗
Simulation of the Attitude Determination System for Space Station berthing dynamics research
Langley has developed a simulator of the Space Station coupled to the Space Shuttle via the Remote Manipulator System for use in evaluating handling during Station assembly. To date, evaluations of this scenario had included the Station Attitude Control System (ACS), assuming that the Station Attitude Determination System (ADS) provides perfect information on the coupled configuration. Herein, the complete Station digital autopilot (DAP) is considered including both the ADS and ACS systems. The ADS, its modelling and simulation are briefly overviewed and studies concerning the closed-loop operation of the DAP during local-coordinate, orbital attitude hold are presented. Results show that the presence of a type 0 filter in the ADS angular velocity signal processing has an adverse effect on attitude estimation because of the error in steady-state tracking of the angular velocity following reaction control jet firings. This error propagates into the attitude estimate almost linearly with time and star tracker updates are required at frequent, 3-second intervals if a .001 degree accuracy is to be maintained.
Montgomery, Raymond C.↗
Simulation Results for Airborne Precision Spacing along Continuous Descent Arrivals
This paper describes the results of a fast-time simulation experiment and a high-fidelity simulator validation with merging streams of aircraft flying Continuous Descent Arrivals through generic airspace to a runway at Dallas-Ft Worth. Aircraft made small speed adjustments based on an airborne-based spacing algorithm, so as to arrive at the threshold exactly at the assigned time interval behind their Traffic-To-Follow. The 40 aircraft were initialized at different altitudes and speeds on one of four different routes, and then merged at different points and altitudes while flying Continuous Descent Arrivals. This merging and spacing using flight deck equipment and procedures to augment or implement Air Traffic Management directives is called Flight Deck-based Merging and Spacing, an important subset of a larger Airborne Precision Spacing functionality. This research indicates that Flight Deck-based Merging and Spacing initiated while at cruise altitude and well prior to the Terminal Radar Approach Control entry can significantly contribute to the delivery of aircraft at a specified interval to the runway threshold with a high degree of accuracy and at a reduced pilot workload. Furthermore, previously documented work has shown that using a Continuous Descent Arrival instead of a traditional step-down descent can save fuel, reduce noise, and reduce emissions. Research into Flight Deck-based Merging and Spacing is a cooperative effort between government and industry partners.
Barmore, Bryan E.↗
Physics-Based Simulator for NEO Exploration Analysis & Simulation
As part of the Space Exploration Analysis and Simulation (SEAS) task, the National Aeronautics and Space Administration (NASA) is using physics-based simulations at NASA's Jet Propulsion Laboratory (JPL) to explore potential surface and near-surface mission operations at Near Earth Objects (NEOs). The simulator is under development at JPL and can be used to provide detailed analysis of various surface and near-surface NEO robotic and human exploration concepts. In this paper we describe the SEAS simulator and provide examples of recent mission systems and operations concepts investigated using the simulation. We also present related analysis work and tools developed for both the SEAS task as well as general modeling, analysis and simulation capabilites for asteroid/small-body objects.
Dshell↗