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Results for “system requirements”

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 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
NASA NTRS1987

Space station resistojet system requirements and interface definition study

A conceptual design study of the resistojet orbital replacement unit (ORU) was conducted. The ORU consists of four 500-W multipropellant resistojets, fluid components downstream of the waste fluid storage subsystem, a power controller, structure, and micrometeorite shielding. The fluid components include latch valves, a water vaporizer, two pressure regulators or flow control valves, filters, check valves, fluid tubing, and interface couplings. Separate fluid components are provided for oxidizing fluids, reducing fluids and water. Different flow and power control methods were studied. The most promising methods consist of a constant pressure/on-off power control and a constant power/variable pressure control. The closed-loop power control incorporates a feedback signal which is proportional to resistojet heater temperature.

Finden, L. E.↗
NASA NTRS1990

Navigation systems requirement analysis for the Aeroassist Flight Experiment (AFE)

Navigation requirements for Aeroassist Flight Experiment (AFE) spacecraft passing through the earth's atmosphere have been studied using a 6-DOF dynamics model, an Inertial Measurement Unit model, a baseline AFE aeropass flight guidance logic, and a baseline AFE aeropass control model. The goal of this study is to determine, in a statistical sense, how much flight path angle error can be tolerated at Entry Interface (EI) and still have acceptable delta-V requirements at exit to position the AFE spacecraft for recovery. Assuming there is fuel available to produce 370 ft/sec of delta-V at atmospheric exit, a 3-sigma standard deviation in flight path angle error of 0.04 degree at EI would result in a 98 percent probability of mission success. In addition to the required delta-V at exit, other aeropass parameters such as maximum aeroheating rate, fuel consumption, and the science requirements affecting mission success are also investigated.

Huang, K. H.↗
NASA NTRS1991

System requirements and design for the Space Infrared Telescope Facility (SIRTF)

The Space Infrared Telescope Facility (SIRTF) is the fourth in NASA's series of Great Observatories and will feature a one-meter class telescope in high earth orbit. Planned for launch around the turn of the century, the lifetime of this cryogenically cooled observatory will be approximately five years. This paper presents an overview of the current status of the requirements and design for SIRTF. This iterative process is described, and some examples are drawn from the upper end of the hierarchy.

Mclaughlin, William I.↗
NASA NTRS1992

System requirements specification for SMART structures mode

Specified here are the functional and informational requirements for software modules which address the geometric and data modeling needs of the aerospace structural engineer. The modules are to be included as part of the Solid Modeling Aerospace Research Tool (SMART) package developed for the Vehicle Analysis Branch (VAB) at the NASA Langley Research Center (LaRC). The purpose is to precisely state what the SMART Structures modules will do, without consideration of how it will be done. Each requirement is numbered for reference in development and testing.

Source record↗
NASA NTRS1992

Power system requirements

An overview of electrical power requirements for each mission of a baseline and alternate plan for space activities in the 1990-2035 timeframe is presented. The specific missions included low earth orbit (LEO), geosynchronous earth orbit (GEO), lunar, Mars, and asteroid related projects.

Conway, Edmund J.↗
NASA NTRS1992

Tool for simulating space exploration initiative (SEI) operations as a means of obtaining intelligent systems requirements

The Lyndon B. Johnson Space Center Automation and Robotics Division has developed a simulation tool for use in evaluating the feasibility and effectiveness of proposed candidate mission concepts, such as the First Lunar Outpost design reference missions. The tool helps in defining requirements for such missions at the beginning of the definition activities and can be applied iteratively thereafter on a short cycle basis as changes are made to the mission definition. The simulation is applicable to the amount and capabilities of automation and robotics; number and skills of crew; amount of engineering work, science, and in-space materials utilization to be accomplished; impact of provision for maintenance and repair; and flight schedules and manifests. The simulation accounts for supply and demand of resources to accomplish tasks and accounts for elapsed time in carrying out mission processes and tasks.

Erickson, Jon D.↗
NASA NTRS1985

Advanced EVA system design requirements study: EVAS/space station system interface requirements

The definition of the Extravehicular Activity (EVA) systems interface requirements and accomodations for effective integration of a production EVA capability into the space station are contained. A description of the EVA systems for which the space station must provide the various interfaces and accomodations are provided. The discussion and analyses of the various space station areas in which the EVA interfaces are required and/or from which implications for EVA system design requirements are derived, are included. The rationale is provided for all EVAS mechanical, fluid, electrical, communications, and data system interfaces as well as exterior and interior requirements necessary to facilitate EVA operations. Results of the studies supporting these discussions are presented in the appendix.

Woods, T. G.↗
NASA NTRS1976

Atmospheric cloud physics laboratory project study

Engineering studies were performed for the Zero-G Cloud Physics Experiment liquid cooling and air pressure control systems. A total of four concepts for the liquid cooling system was evaluated, two of which were found to closely approach the systems requirements. Thermal insulation requirements, system hardware, and control sensor locations were established. The reservoir sizes and initial temperatures were defined as well as system power requirements. In the study of the pressure control system, fluid analyses by the Atmospheric Cloud Physics Laboratory were performed to determine flow characteristics of various orifice sizes, vacuum pump adequacy, and control systems performance. System parameters predicted in these analyses as a function of time include the following for various orifice sizes: (1) chamber and vacuum pump mass flow rates, (2) the number of valve openings or closures, (3) the maximum cloud chamber pressure deviation from the allowable, and (4) cloud chamber and accumulator pressure.

Schultz, W. E.↗
NASA NTRS1984

Requirements for a transformerless power conditioning system

Requirements for development of a Transformerless Power Conditioning Subsystem (TPCS) that will meet utility, manufacturer, and customer needs are detailed. Issues analyzed include current utility guidelines, safety and grounding issues that appear as local codes, various kinds of TPCS connections that can be developed, dc injection, and a brief survey of TPCS circuit topologies that will meet requirements. The major result is that a finite time exists for control operation before dc injection into the distribution transformer causes customer outage (on the order of seconds). This time permits the control system to sense a dc injection condition and remove the TPCS from the utility system. Requirements for such a control system are specified. A three wire connection will ensure balanced operation for customer loads and two wire connections caused average value dc to be injected into single phase loads. This type of connection also allows for the lowest array voltage. The conclusion is that requirements for a TPCS can be determined and that there are not showstopping issues preventing implementation. The actual design and topology of the TPCS was left for further study.

Klein, J.↗
NASA NTRS1986

Advanced solar dynamic space power systems perspectives, requirements and technology needs

Projected NASA, Civil, Commercial, and Military missions will require space power systems of increased versatility and power levels. The Advanced Solar Dynamic (ASD) Power systems offer the potential for efficient, lightweight, survivable, relatively compact, long-lived space power systems applicable to a wide range of power levels (3 to 300 kWe), and a wide variety of orbits. The successful development of these systems could satisfy the power needs for a wide variety of these projected missions. Thus, the NASA Lewis Research Center has embarked upon an aggressive ASD reserach project under the direction of NASA's Office of Aeronautics and Space Technology (DAST). The project is being implemented through a combination of in-house and contracted efforts. Key elements of this project are missions analysis to determine the power systems requirements, systems analysis to identify the most attractive ASD power systems to meet these requirements, and to guide the technology development efforts, and technology development of key components.

Dustin, M. O.↗
NASA NTRS2007

Mars Reconnaissance Orbiter Mission: Systems Engineering Challenges on the Mars Reconnaissance Orbiter Mission

MRO project is a system of systems requiring system engineering team to architect, design, integrate, test, and operate these systems at each level of the project. The challenge of system engineering mission objectives into a single mission architecture that can be integrated tested, launched, and operated. Systems engineering must translate high-level requirements into integrated mission design. Systems engineering challenges were overcome utilizing a combination by creative designs built into MRO's flight and ground systems: a) Design of sophisticated spacecraft targeting and data management capabilities b) Establishment of a strong operations team organization; c) Implementation of robust operational processes; and d) Development of strategic ground tools. The MRO system has met the challenge of its driving requirements: a) MRO began its two-year primary science phase on November 7, 2006, and by July 2007, met it minimum requirement to collect 15 Tbits of data after only eight months of operations. Currently we have collected 22 Tbits. b) Based on current performance, mission data return could return 70 Tbits of data by the end of the primary science phase in 2008.

systems engineering↗
NASA NTRS1981

Definition study of land/sea civil user navigational location monitoring systems for NAVSTAR GPS: User requirements and systems concepts

A low-cost GPS civil-user mobile terminal whose purchase cost is substantially an order of magnitude less than estimates for the military counterpart is considered with focus on ground station requirements for position monitoring of civil users requiring this capability and the civil user navigation and location-monitoring requirements. Existing survey literature was examined to ascertain the potential users of a low-cost NAVSTAR receiver and to estimate their number, function, and accuracy requirements. System concepts are defined for low cost user equipments for in-situ navigation and the retransmission of low data rate positioning data via a geostationary satellite to a central computing facility.

Devito, D. M.↗
NASA NTRS1998

Mars Ascent Vehicle Flight Analysis

The scientific objective of the Mars Surveyor Program 2005 mission is to return Mars rock, soil, and atmospheric samples to Earth for detailed analysis. The present investigation focuses on design of Mars Ascent Vehicle for this mission. Aerodynamic, aerothermodynamic, and trajectory design considerations are addressed to assess the ascent configuration, determine aerodynamic stability, characterize thermal protection system requirements, and ascertain the required system mass. Aerodynamic analysis reveals a subsonic static instability with the baseline configuration; however, stability augmentation options are proposed to mitigate this problem. The ascent aerothermodynamic environment is shown to be benign (on the order of the sea-level boiling point of water on Earth). As a result of these low thermal and pressure loads, a lightweight, low rigidity material can be employed as the aftbody aerodynamic shroud. The required nominal MAV lift-off mass is 426 kg for a December 2006 equatorial launch into a 300-km circular orbit with 30-degree inclination. Off-nominal aerodynamic and atmospheric conditions are shown to increase this liftoff mass by approximately 10%. Through performance of these analyses, the Mars Ascent Vehicle is deemed feasible with respect to the current mission mass and size constraints.

Desai, P. N.↗