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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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At least 1,369 records · Page 76
All sourcesNASA NTRSDOE OSTI
NASA NTRS1990

Mars outpost - System and operations challenges

The paper addresses the challenges inherent in establishing an outpost on the planet Mars. For background purposes, the unique, remote Martian environment and the developmental phases of a settlement in such an environment are discussed. Challenges are identified in terms of surface systems and operations. Due to its importance to habitability, the life support system (LSS) is highlighted with various options identified. Operations for the Mars outpost, earth-based and local, are characterized by a decentralized concept. The challenge of integrating logistics analysis early in system design and operations strategy is also addressed. In order to understand and reduce the system and operations challenges, the application of terrestrial and lunar testbeds is explained.

Roberts, Barney↗
NASA NTRS1990

An automated environment for multiple spacecraft engineering subsystem mission operations

Flight operations at the Jet Propulsion Laboratory (JPL) are now performed by teams of specialists, each team dedicated to a particular spacecraft. Certain members of each team are responsible for monitoring the performances of their respective spacecraft subsystems. Ground operations, which are very complex, are manual, labor-intensive, slow, and tedious, and therefore costly and inefficient. The challenge of the new decade is to operate a large number of spacecraft simultaneously while sharing limited human and computer resources, without compromising overall reliability. The Engineering Analysis Subsystem Environment (EASE) is an architecture that enables fewer controllers to monitor and control spacecraft engineering subsystems. A prototype of EASE has been installed in the JPL Space Flight Operations Facility for on-line testing. This article describes the underlying concept, development, testing, and benefits of the EASE prototype.

Bahrami, K. A.↗
NASA NTRS1991

Control center operations at the Goddard Space Flight Center

Information is given in viewgraph form on control center operations at the Goddard Space Flight Center. Information is given on multi-mission, dedicated and attached payload support; the mission operations environment; technical challenges; Hubble Space Telescope (HST) science planning interface; operations engineering life cycle; Special Analysis of Maneuverable Satellites (SAMS) operations; and user interface applications.

Connerton, Robert M.↗
NASA NTRS1991

The Rocketdyne Multifunction Tester. Part 2: Operation of a Radial Magnetic Bearing as an Excitation Source

The operation of the magnetic bearing used as an excitation source in the Rocketdyne Multifunction Tester is described. The tester is scheduled for operation during the summer of 1990. The magnetic bearing can be used in two control modes: (1) open loop mode, in which the magnetic bearing operates as a force actuator; and (2) closed loop mode, in which the magnetic bearing provides shaft support. Either control mode can be used to excite the shaft; however, response of the shaft in the two control modes is different due to the alteration of the eigenvalues by closed loop mode operation. A rotordynamic model is developed to predict the frequency response of the tester due to excitation in either control mode. Closed loop mode excitation is shown to be similar to the excitation produced by a rotating eccentricity in a conventional bearing. Predicted frequency response of the tester in the two control modes is compared, and the maximum response is shown to be the same for the two control modes when synchronous unbalance loading is not considered. The analysis shows that the response of this tester is adequate for the extraction of rotordynamic stiffness, damping, and inertia coefficients over a wide range of test article stiffnesses.

Hawkins, L. A.↗
NASA NTRS1991

Operations mission planner beyond the baseline

The scheduling of Space Station Freedom must satisfy four major requirements. It must ensure efficient housekeeping operations, maximize the collection of science, respond to changes in tasking and available resources, and accommodate the above changes in a manner that minimizes disruption of the ongoing operations of the station. While meeting these requirements the scheduler must cope with the complexity, scope, and flexibility of SSF operations. This requires the scheduler to deal with an astronomical number of possible schedules. The Operations Mission Planner (OMP) is centered around minimally disruptive replanning and the use of heuristics limit search in scheduling. OMP has already shown several artificial intelligence based scheduling techniques such as Interleaved Iterative Refinement and Bottleneck Identification using Process Chronologies.

Biefeld, Eric↗
NASA NTRS1992

Low-Isp derated ion thruster operation

The performance and lifetime expectations of 30 cm xenon ion thruster technology at low values of specific impulse were evaluated, with emphasis on 1000-2500 s operation. Power levels of up to 2.0 kW, appropriate for auxiliary and orbit maneuvering propulsion, were processed at thrust-to-power ratios up to 57 mN/kW. These tests were conducted using a derated 30 cm ion thruster with high-perveance design two-grid ion optics with xenon propellent. Lifetime projections were made based on a simple analysis of critical component erosion rates, and it was found that a strong correlation exists with the ratio of the specific impulse-to-input power. Under all operating conditions for which the projected thruster lifetime is less than 10,000 hrs, the life-limiting component of this technology is erosion of the accelerator grid due to charge-exchange ions. The use of alternative grid materials such as carbon is estimated to increase useful thruster lifetimes by as much as an order of magnitude and may enable long-life high thrust-density, sub-2500 s Isp operation. The performance and life of the derated thruster appears similar to that of the Russian SPT-100 thruster in the 1.0-2.0 kW, 1600-2000 s operational envelope.

Patterson, Michael J.↗
NASA NTRS1990

Using new aggregation operators in rule-based intelligent control

A new aggregation operator is applied in the design of an approximate reasoning-based controller. The ordered weighted averaging (OWA) operator has the property of lying between the And function and the Or function used in previous fuzzy set reasoning systems. It is shown here that, by applying OWA operators, more generalized types of control rules, which may include linguistic quantifiers such as Many and Most, can be developed. The new aggregation operators, as tested in a cart-pole balancing control problem, illustrate improved performance when compared with existing fuzzy control aggregation schemes.

Berenji, Hamid R.↗
NASA NTRS1990

Development of a compact dilution refrigerator for zero gravity operation

A compact dilution refrigerator design based on internal charcoal adsorption is being tested for operation in zero gravity. This refrigerator is self-contained with no external pumps or gas handling system and provides reliable operation since it has no moving parts. All operations are performed with heaters and are completely computer controlled. The refrigerator is capable of providing many hours of operation at very low temperature before the charcoal pumps must be recycled.

Roach, Pat R.↗
NASA NTRS1992

Cost, capability, and risk for planetary operations

The three key factors for flight projects - cost, capability, and risk - are examined with respect to their interplay, the uplink process, cost drivers, and risk factors. Scientific objectives are translated into a computer program during the uplink process, and examples are given relating to the Voyager Interstellar Mission, Galileo, and the Comet Rendezvous Asteroid Flyby. The development of a multimission sequence system based on these uplinks is described with reference to specific subsystems such as the pointer and the sequence generator. Operational cost drivers include mission, flight-system, and ground-system complexity, uplink traffic, and work force. Operational risks are listed in terms of the mission operations, the environment, and the mission facilities. The uplink process can be analyzed in terms of software development, and spacecraft operability is shown to be an important factor from the initial stages of spacecraft development.

Mclaughlin, William I.↗
NASA NTRS1992

NLS Advanced Development - Launch operations

Attention is given to Autonomous Launch Operations (ALO), one of a number of the USAF's National Launch System (NLS) Launch Operations projects whose aim is to research, develop and apply new technologies and more efficient approaches toward launch operations. The goal of the ALO project is to develop generic control and monitor software for launch operation subsystems. The result is enhanced reliability of system design, and reduced software development and retention of expert knowledge throughout the life-cycle of the system.

Parrish, Carrie L.↗
NASA NTRS1992

In-space operations for lunar and Mars space transfer vehicles

The in-space operations required to process the lunar and Mars mission vehicles foreseen in early studies for the SEI are discussed. Those studies that have examined the degree to which on-orbit operations alter as a function of the earth-to-orbit launch vehicle size, identified a common set of on-orbit vehicle processing tasks, and generated functional requirements for in-space processing nodes, are summarized. Attention is focused on the amount of time these processing operations might necessitate and how this time duration changes as a result of how the operation is executed and how the hardware is designed.

Raper, James L., Sr.↗
NASA NTRS1991

Operator-coached machine vision for space telerobotics

A prototype system for interactive object modeling has been developed and tested. The goal of this effort has been to create a system which would demonstrate the feasibility of high interactive operator-coached machine vision in a realistic task environment, and to provide a testbed for experimentation with various modes of operator interaction. The purpose for such a system is to use human perception where machine vision is difficult, i.e., to segment the scene into objects and to designate their features, and to use machine vision to overcome limitations of human perception, i.e., for accurate measurement of object geometry. The system captures and displays video images from a number of cameras, allows the operator to designate a polyhedral object one edge at a time by moving a 3-D cursor within these images, performs a least-squares fit of the designated edges to edge data detected with a modified Sobel operator, and combines the edges thus detected to form a wire-frame object model that matches the Sobel data.

Bon, Bruce↗
NASA NTRS1992

Recursive formulation of operational space control

A recently developed spatial operator algebra approach to modeling and analysis of multibody robotic systems is used to develop O(n) recursive algorithms that compute the operational space mass matrix and the operational space coriolis/centrifugal and gravity terms of an n-link serial manipulator. These algorithms enable an O(n) recursive implementation of operational space control.

Kreutz-Delgado, K.↗
NASA NTRS1992

The U.S. Antarctic Program's operational goals, strategies, and concepts - Correlations and lessons learned for the Space Exploration Initiative

Results of an assessment of two programs, NASA SEI and the National Science Foundation's U.S. Antarctic Program (USAP) are presented. The assessment was aimed at determining the elements of USAP's operations which are relevant to living and working on the moon and Mars and at identifying operational concepts, procedures, and techniques which might be considered by NASA as it formulates the SEI concept. The assessment shows strong similarities in goals, related operational functions and accommodations, and fundamental strategies and policies for mission execution. Besides, both programs share logistical and operational constraints. There are differences in concepts for execution because of the unique aspects of accessing, living, and working in these environments.

Buoni, Corinne↗
NASA NTRS1992

Requirements for on-orbit operations

Consideration is given to the impact of on-orbit operations during the assembly and checkout of potential piloted Mars spacecraft, and the development of the requirements for those operations. An operational scenario is developed based on assumed earth-to-orbit capability, a ground based support capability, and a baseline Mars Space Transfer Vehicle. The scenarios developed define each of the operations that must transpire at the system level, thus expanding the planning horizon for the SEI.

Cockrell, Charles E.↗
NASA NTRS1992

Automated support for system's engineering and operations - The development of new paradigms

Technological developments in spacecraft ground operations are reviewed. The technological, operations-oriented, managerial, and economic factors driving the evolution of the Mission Operations Control Center (MOCC), and its predecessor the Operational Control Center are examined. The functional components of the various MOCC subsystems are outlined. A brief overview is given of the concepts behind the The Knowledge-Based Software Engineering Environment, the Generic Spacecraft Analysis Assistant, and the Knowledge From Pictures tool.

Truszkowski, Walt↗
NASA NTRS1992

Measurement and analysis of operating system fault tolerance

This paper demonstrates a methodology to model and evaluate the fault tolerance characteristics of operational software. The methodology is illustrated through case studies on three different operating systems: the Tandem GUARDIAN fault-tolerant system, the VAX/VMS distributed system, and the IBM/MVS system. Measurements are made on these systems for substantial periods to collect software error and recovery data. In addition to investigating basic dependability characteristics such as major software problems and error distributions, we develop two levels of models to describe error and recovery processes inside an operating system and on multiple instances of an operating system running in a distributed environment. Based on the models, reward analysis is conducted to evaluate the loss of service due to software errors and the effect of the fault-tolerance techniques implemented in the systems. Software error correlation in multicomputer systems is also investigated.

Lee, I.↗
NASA NTRS1992

Enabler operator station

The objective of this project was to design an onboard operator station for the conceptual Lunar Work Vehicle (LWV). This LWV would be used in the colonization of a lunar outpost. The details that follow, however, are for an earth-bound model. Several recommendations are made in the appendix as to the changes needed in material selection for the lunar environment. The operator station is designed dimensionally correct for an astronaut wearing the current space shuttle EVA suit (which includes life support). The proposed operator station will support and restrain an astronaut as well as provide protection from the hazards of vehicle rollover. The threat of suit puncture is eliminated by rounding all corners and edges. A step-plate, located at the front of the vehicle, provides excellent ease of entry and exit. The operator station weight requirements are met by making efficient use of grid members, semi-rigid members and woven fabrics.

Bailey, Andrea↗