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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 235 records · Page 13
All sourcesNASA NTRSDOE OSTI
NASA NTRS1975

Large space telescope control moment gyro test program

The underlying theory and design of test instrumentation and computer techniques used to determine the power spectral density (PSD) of the third generation gyro are described in detail. Acceptance test results on the completed instrument are presented as well as composite PSD plots. The measured RMS noise over the frequency band 0.0025 - 10 Hz was 0.012 arc seconds. Results obtained at Martin Company indicate an RMS noise of 0.009 arc seconds (0.05 - 10 Hz). The results obtained showed the TGG performance was close to the proposed LST requirements but that additional development work would be needed to reduce the TGG noise to within more desirable limits.

Salamin, E.↗
NASA NTRS1975

Design of a graphite/epoxy metering truss for the Large Space Telescope

This paper presents the design development of a truss-type structure which utilizes graphite/epoxy as the primary material system. A review is given of an on-going NASA sponsored program to develop a structural assembly which is required to have a very high degree of dimensional stability. Methods of material characterization and selection are given along with property data such as strength, stiffness, outgassing and thermal expansion. Finite element (NASTRAN) analysis will be discussed and deflection plots of the lowest mode frequencies will be presented. Proposed full scale tests: static, dynamic, and thermal/vacuum will be described.

Oken, S.↗
NASA NTRS1975

Preliminary design report, Large Space Telescope OTA/SI Phase B study: High speed area photometer

A photometer is examined which combines several features from separate instruments into a single package. The design presented has both point and area photometry capability with provision for inserting filters to provide spectral discrimination. The electronics provide for photon counting mode for the point detectors and both photon counting and analog modes for the area detector. The area detector also serves as a target locating device for the point detectors. Topics discussed include: (1) electronic equipment requirements, (2) optical properties, (3) structural housing for the instrument, (4) motors and other mechanical components, (5) ground support equipment, and (6) environment control for the instrument. Engineering drawings and block diagrams are shown.

Source record↗
NASA NTRS1976

An Evaluation of Reaction Wheel Emitted Vibrations for Large Space Telescope

Emitted force and torque vibration were measured in three axes for three Sperry reaction wheels. Data were taken for both hard and soft mounts; tests were conducted at constant speeds and during runup-rundown over a 0 to 5000 rpm range. A FSC, 7 ft-lb-sec and HEAO, 30 ft-lb-sec ball bearing reaction wheel and a model magnetic bearing were tested. Data analysis was conducted to identify the principal resonances in the 10 to 120 Hz region. Although some particular phenomena remain unexplained, in general good agreement is attained between the analytical predictions and test data. Predictions were also made of the expected emitted vibrations for an LST sized ball bearing and magnetic bearing reaction wheel using engineering judgment and the test data obtained. Additional tests were also run on the 101H duplex bearing pairs used in the reaction wheel suspension to determine bearing stiffness characteristics in the pre-breakaway zero speed region.

Source record↗
NASA NTRS1975

Large Space Telescope external interfaces

Key interfaces are described for all LST mission phases: ground test and integration, prelaunch and launch operations, ascent, deployment, operations, on-orbit maintenance, retrieval, deorbit and landing, and refurbishment. These interfaces can be categorized as test and integration, launch operations, Shuttle, data, and mission operations. The interface with the Shuttle and the Shuttle crew is emphasized here because the Shuttle allows a new capability: on-orbit maintenance and ground return. The LST will communicate with the ground elements of the LST system through a space link by means of the Tracking Data Relay Satellite System or directly to the stations of the Space Tracking and Data Network.

Collart, R. E.↗
NASA NTRS1975

Large Space Telescope Program status

This paper provides an overview of the current status of the LST Program. The history of the program is treated briefly, with emphasis placed on the recent Phase B definition activity. The background and rationale leading to the decision of the aperture size of the LST primary mirror are discussed. The current technical definition status of the LST Optical Telescope Assembly and Support Systems Module is treated in a summary fashion. Key milestone events during the balance of the Phase B definition effort and schedule and over-all planning for the development phase of the program are described.

Downey, J. A., III↗
NASA NTRS1975

Analysis and experimental measurement of straylight suppression systems for the large space telescope

A computer program for straylight suppression system design and analysis was developed to analyze various proposed LST straylight suppression systems. Simultaneously, experimental measurements are being made on a simplified LST straylight suppression system in a unique facility. The experimental measurements are being used to verify and improve the computer program. The facility represents the state-of-the-art in straylight suppression measurements, and transmission factors of 10 to the minus 12th power have been measured.

Wyman, C. L.↗
NASA NTRS1977

A scientific operations plan for the large space telescope

The paper describes an LST ground system which is compatible with the operational requirements of the LST. The goal of the approach is to minimize the cost of post launch operations without seriously compromising the quality and total throughput of LST science. Attention is given to cost constraints and guidelines, the telemetry operations processing systems (TELOPS), the image processing facility, ground system planning and data flow, and scientific interfaces.

West, D. K.↗
NASA NTRS1980

Study of stray light suppression for the large space telescope

Analysis of light scattering, using the APART computer program, begins at the image plane and progresses through the optical system to the front end of the telescope tube. The approach identifies all critical surfaces, computes the geometrical configuration factors (GCF) from each area of the system under study to all other areas of the system, and determines incident and reflected angles which are important for baffle surfaces which do not have Lambertian scattering characteristics. The power input into the optical surface from either point source objects or extended objects such as the bright Earth are computed. The surface scattering characteristics and the GCF values are combined so that the power transfer to the image plane is computed. Capabilities for handling light scattering from baffle surfaces, specular reflectance from black surfaces, scattering from mirror surfaces, diffraction, internal scattering from transmissive optics, and internal thermal emission are assessed.

Fannin, B. B.↗
NASA NTRS1980

A very large space telescope for optical/UV astronomy

A concept is presented for a Ritchey-Chretien optical-UV telescope to be deployed in orbit using a preassembled segmented primary mirror of 8 meter aperture, carried into orbit inside the modified interstage of the Space Shuttle External Tank. Shuttle revisits allow major assembly tasks to proceed such as the installation of the light shield, fine alignment of the system and attachment of scientific instrument modules to the instrument adapter. Prime technology requirements for the VLST are assessed in this paper.

Nein, M. E.↗
NASA NTRS1984

Support structures for large infrared telescopes

An infrared telescope requires an accuracy of its reflecting surfaces of less than a micrometer. Future missions may require such accuracy from telescopes that are 20 meters or larger in diameter. The structure for supporting such a telescope will most probably take the form of a deep truss. Various approaches for constructing the primary mirror in space are illustrated. One that employs automated deployment of interconnected reflector-structure modules was described in detail. Estimates were made of the precision obtainable with properly configured truss structures and the required ability of active control systems for achieving the desired accuracy.

Hedgepeth, J. M.↗
NASA NTRS1985

An optical technology study on large aperture telescopes

The difficult and crucial problem of selecting a suitable telescope concept for an advanced space observatory was examined. To this end two and four mirror telescopes were analyzed and compared. Both configurations are very practical and structurally similar. Parabolic primary and spherical primary four mirror telescope were compared with respect to their performance and the alignment sensitivities of the three correction mirrors. A 1 meter class afocal telescope system with lag angle compensation, to be used in a LIDAR experiment, was examined.

Korsch, D.↗
NASA NTRS1990

Construction of the 16 meter Large Lunar Telescope (LLT)

The different materials that could be used to design the pedestal for a Moon based 16 meter telescope are discussed. The material that should be used has a low coefficient of thermal expansion, high modulus of elasticity, and high compressive and tensile strengths. For the model developed in this study, an aluminum-manganese alloy was used because of its low coefficient of thermal expansion. Due to variations in lunar soil conditions, both vertically and horizontally, three foundation systems are presented. The spudcan footing can be used in the case where dense soil is more than three meters. The spread footing is recommended where the dense soil is between one and three meters. Finally, in the third system, the Lunar Excursion Vehicle (LEV) is used as a base support for the telescope's pedestal. The LEV support requires a prepared site. The soil should be compacted and stabilized, if necessary, to reduce settlement.

Omar, Husam Anwar↗
NASA NTRS2002

Status of NASA Mirror Technology Development for Large Space Telescopes

This paper presents the current status of several NASA technology development activities, including: Sub-scale Beryllium Mirror Demonstrator (SBMD), NGST (Next Generation Space Telescope) Mirror System Demonstrator (NMSD), Advanced Mirror System Demonstrator (AMSD), etc.. It also describes how these activities map into future NASA mission requirements, including: Next Generation Space Telescope (NGST), Single Aperture Far Infrared Observatory (SAFIR), Space Ultraviolet/Optical Observatory (SUVO), etc..

Stahl, H. Philip↗
NASA NTRS2002

Status of NASA Mirror Technology Development for Large Space Telescopes

This talk will present the current status of several NASA technology development activities, including: SBMD, NMSD, AMSD (Advanced Mirror System Demonstrator), etc.. And will discuss how these activities map into future NASA mission requirements, including: NGST (Next Generation Space Telescope), SAFIR, SUVO, etc.

Stahl, H. Philip↗
NASA NTRS2009

Formation Flying of Components of a Large Space Telescope

A conceptual space telescope having an aperture tens of meters wide and a focal length of hundreds of meters would be implemented as a group of six separate optical modules flying in formation: a primary-membrane-mirror module, a relay-mirror module, a focal-plane-assembly module containing a fast steering mirror and secondary and tertiary optics, a primary-mirror-figure-sensing module, a scanning-electron-beam module for controlling the shape of the primary mirror, and a sunshade module. Formation flying would make it unnecessary to maintain the required precise alignments among the modules by means of an impractically massive rigid structure. Instead, a control system operating in conjunction with a metrology system comprising optical and radio subsystems would control the firing of small thrusters on the separate modules to maintain the formation, thereby acting as a virtual rigid structure. The control system would utilize a combination of centralized- and decentralized-control methods according to a leader-follower approach. The feasibility of the concept was demonstrated in computational simulations that showed that relative positions could be maintained to within a fraction of a millimeter and orientations to within several microradians.

Mettler, Edward↗