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At least 703 records · Page 39
All sourcesNASA NTRSDOE OSTI
NASA NTRS1984

The electron Echo 6 mechanical deployment systems

The Echo 6 sounding rocket payload was flown on a Terrier boosted Black Brant vehicle on March 30, 1983. The experiment requirements resulted in the new design of a rocket propelled Throw Away Detector System (TADS) with onboard Doppler radar, a free-flyer forward experiment designated the Plasma Diagnostic Package (PDP), and numerous other basic systems. The design, developmental testing, and flight preparations of the payload and the mechanical deployment systems are described.

Meyers, S. C.↗
NASA NTRS1984

Proceedings of the Large Deployable Reflector Science and Technology Workshop. Volume 1: Executive Summary

A large ambient temperature, for infrared submillimeter telescope in space was discussed. The results of the scientific and technical activities were summarized. The scientific effort consisted of reviewing the science rationale for the Large Deployable Reflector (LDR) and arriving at a concensus set of scientific requirements. The telescope requirements were then compared to the current and anticipated state of the various technologies involved, and the technological shortfalls identified.

Leidich, C. A.↗
NASA NTRS1984

Simulation requirements for the Large Deployable Reflector (LDR)

Simulation tools for the large deployable reflector (LDR) are discussed. These tools are often the transfer function variety equations. However, transfer functions are inadequate to represent time-varying systems for multiple control systems with overlapping bandwidths characterized by multi-input, multi-output features. Frequency domain approaches are the useful design tools, but a full-up simulation is needed. Because of the need for a dedicated computer for high frequency multi degree of freedom components encountered, non-real time smulation is preferred. Large numerical analysis software programs are useful only to receive inputs and provide output to the next block, and should be kept out of the direct loop of simulation. The following blocks make up the simulation. The thermal model block is a classical heat transfer program. It is a non-steady state program. The quasistatic block deals with problems associated with rigid body control of reflector segments. The steady state block assembles data into equations of motion and dynamics. A differential raytrace is obtained to establish a change in wave aberrations. The observation scene is described. The focal plane module converts the photon intensity impinging on it into electron streams or into permanent film records.

Soosaar, K.↗
NASA NTRS1984

Large Deployable Reflector Science and Technology Workshop. Volume 3: Systems and Technology Assessment

The results of five technology panels which convened to discuss the Large Deployable Reflector (LDR) are presented. The proposed LDR is a large, ambient-temperature, far infrared/submillimeter telescope designed for space. Panel topics included optics, materials and structures, sensing and control, science instruments, and systems and missions. The telescope requirements, the estimated technology levels, and the areas in which the generic technology work has to be augmented are enumerated.

Leidich, C. A.↗
NASA NTRS1984

Large Deployable Reflector Science and Technology Workshop. Volume 3: Systems and Technology Assessment. Conclusions

The physical parameters of the Large Deployable Reflector (LDR) required to achieve the anticipated astronomical objectives are reviewed briefly. System parameters and performance requirements for the LDR are enumerated. The LDR was compared with the Cosmic Background Experiment (COBE), the Infrared Astronomical Satellite (IRAS), and the Space Infrared Telescope Facility (SIRTF). Angular resolution and high resolution spectroscopy requirements for LDR were considered.

Source record↗
NASA NTRS1984

Studies of low-mass star formation with the large deployable reflector

Estimates are made of the far-infrared and submillimeter continuum and line emission from regions of low mass star formation. The intensity of this emission is compared with the sensitivity of the large deployable reflector (LDR), a large space telescope designed for this wavelength range. The proposed LDR is designed to probe the temperature, density, chemical structure, and the velocity field of the collapsing envelopes of these protostars. The LDR is also designed to study the accretion shocks on the cores and circumstellar disks of low-mass protostars, and to detect shock waves driven by protostellar winds.

Hollenbach, D. J.↗
NASA NTRS1983

Large Deployable Reflector (LDR) - A concept for an orbiting submillimeter-infrared telescope for the 1990s

The history and background of the Large Deployable Reflector (LDR) are reviewed. The results of the June 1982 Asilomar (CA) workshop are incorporated into the LDR science objectives and telescope concept. The areas where the LDR may have the greatest scientific impact are in the study of star formation and planetary systems in the own and nearby galaxies and in cosmological studies of the structure and evolution of the early universe. The observational requirements for these and other scientific studies give rise to a set of telescope functional requirements. These, in turn, are satisfied by an LDR configuration which is a Cassegrain design with a 20 m diameter, actively controlled, segmented, primary reflector, diffraction limited at a wavelength of 30 to 50 microns. Technical challenges in the LDR development include construction of high tolerance mirror segments, surface figure measurement, figure control, vibration control, pointing, cryogenics, and coherent detectors. Project status and future plans for the LDR are discussed.

Swanson, P. N.↗
NASA NTRS1982

Development of the structural technology of a large deployable antenna

The current NASA-sponsored Antenna Technology Development Program of the offset wrap-rib antenna concept is based on a ground test program of 'proof of concept' hardware whose potential on-orbit performance is based on analytical estimates. The ground demonstration hardware represents a partial 55-meter diameter reflector and feed support structure. Testing will include automated deployment, reflector surface quality evaluation and validation of analytical performance models. Test results and hardware fabrication costs will be used to refine the models that will be the basis for the preliminary design of a 100-meter diameter wrap-rib antenna system. Additionally, the design, processes, tooling, fabrication techniques, fixturing and assembly approaches used for the 'proof of concept' hardware are directly applicable to building flight systems up to 100 meters in diameter.

Wada, B. K.↗
NASA NTRS1982

Approximating a finite element model of a hybrid deployable truss by a discrete mass model

The NASTRAN finite element model of the MSFC/hybrid deployable truss is approximated by a model consisting of four bodies serially connected by a spring hinge suspension. The truss is decomposed into four serially connected modules determining the total mass and rotational inertias for a rigid body with its mass center on the axis of the truss for each module. A five-body cantilever truss model is developed along with an undamped form of this model. Spring coefficient values are generated to match eigenvalues of the latter model with those of the NASTRAN model. Damping coefficients are then determined that provide n percent of critical damping for the model.

Chichester, F. D.↗
NASA NTRS1985

Deployable M-Braced Truss

Tension/compression and shear separated structurally in deployable beam. M-Braced Sections Packaged using combination of hinges and telescoping sections. When upper sections telescope into base, diagonals hinge, telescope, and rotate along batten. Components of M-braced truss fabricated from conventional metallic materials or nonmetallic materials such as graphite/epoxy. Applications include masts for antenna feed horns and ribs for solar array blankets.

Mikulas, M. M., Jr.↗
NASA NTRS1985

Diffraction Analysis of Mesh Deployable Reflector Antennas

A formulation and many representative numerical results for mesh reflector antennas are presented. The reflection coefficient matrix for the prescribed mesh configuration was determined and the local coordinate system of the mesh cells at each point on the curved reflector surface was accentuated. A novel strip aperture model was used to formulate the transmission coefficient matrix for a variety of mesh cell configurations. Numerical data are tailored to the dimensions of a conceptually designed land mobile satellite system (LMSS) which employs a large mesh deployable offset parabolic antenna. Results are shown for an offset parabolic reflector with mesh surfaces similar to the mesh surface of tracking and data relay satellite system (TDRSS).

Rahmat-Samii, Y.↗
NASA NTRS1985

Large Deployable Reflector (LDR) Requirements for Space Station Accommodations

Top level requirements for assembly and integration of the Large Deployable Reflector (LDR) Observatory at the Space Station are examined. Concepts are currently under study for LDR which will provide a sequel to the Infrared Astronomy Satellite and the Space Infrared Telescope Facility. LDR will provide a spectacular capability over a very broad spectral range. The Space Station will provide an essential facility for the initial assembly and check out of LDR, as well as a necessary base for refurbishment, repair and modification. By providing a manned platform, the Space Station will remove the time constraint on assembly associated with use of the Shuttle alone. Personnel safety during necessary EVA is enhanced by the presence of the manned facility.

Crowe, D. A.↗
NASA NTRS1985

Design of a dual fault tolerant space shuttle payload deployment actuator

As the Shuttle Transportation System (STS) becomes operational, the number and variety of payloads will increase. The need to deploy these cargo elements will require a variety of unique actuator designs, all of which will have to conform with STS safety policy. For those missions where payload operations extend beyond the payload bay door envelope, this policy deems the prevention of door closure as a catastrophic hazard. As such, it must be controlled by independent, primary and backup methods. The combination of these methods must be two fault tolerant. The design of such an actuator is described. The device consists of a single linear ballscrew with two ballnuts, each bellnut forming an independent actuator using the common ballscrew. The design requirements, concept development, hardware configuration, and fault tolerance rationale are highlighted.

Teske, D. R.↗
NASA NTRS1985

Appendange deployment mechanism for the Hubble Space Telescope program

The key requirements, a design overview, development testing (qualification levels), and two problems and their solutions resolved during the mechanism development testing phase are presented. The mechanism described herein has demonstrated its capability to deploy/restow two large Hubble Space Telescope deployable appendages in a varying but controlled manner.

Greenfield, H. T.↗
NASA NTRS1983

Alignment and phasing of deployable telescopes

The experiences in coaligning and phasing the Multi-Mirror Telescope (MMT), together with studies in setting up radio telescopes, are presented. These experiences are discussed, and on the basis they furnish, schemes are suggested for coaligning and phasing four large future telescopes with complex primary mirror systems. These telescopes are MT2, a 15-m-equivalent MMT, the University of California Ten Meter Telescope, the 10 m sub-mm wave telescope of the University of Arizona and the Max Planck Institute for Radioastronomy, and the Large Deployable Reflector, a future space telescope for far-IR and sub-mm waves.

Woolf, N. J.↗
NASA NTRS1983

Survey of deployable antenna concepts

Deployable space antenna concepts are surveyed. Precision reflector antennas, stiffened membrane antennas, truss antennas, infrared antennas, and electrostatically figured membrane reflectors are described.

Freeland, R. E.↗