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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 1,153 records · Page 64
All sourcesNASA NTRSDOE OSTI
NASA NTRS2001

Cryogenic (70K) measurement of an all-composite 2-meter diameter mirror

The Herschel Space observatory (formerly known as FIRST) consists of a 3.5 m space telescope. In order to develop lightweight telescope technology suitable for this mission, COI designed and fabricated aspherical, f/1 2 m aperture prototype primary mirror using solely carbon fiber reinforced polypmer (CFR) materials. To assess the performance of this technology, optical metrology of the mirror surface was performed from ambient to an intended operational temperature for IR-telescopes of 70K. Testing was performed horizontally in a cryogenic vacuum chamber at Arnold Engineering Development Center (AEDC), Tennessee.

lightweight mirrors cryogenic testing composite ma↗
NASA NTRS2001

Optical metrology for testing an all-composite 2-meter diameter mirror

The Herschel Space Observatory (formerly known as FIRST) consists of a 3.5 m space telescope designed for use in the long IR and sub-milimeter wavebands. To demonstrate the viability of a carbon fiber composite telescope for this application, Composite Optics Incorporated (COI) manufactured a fast (f/1), large (2 m), lightweight (10.1 kg/m squared) demonstration mirror. A key challenge in demonstrating the performance of this novel mirror was to characterize the surface accuracy at cryogenic (70 K) temperatures. A wide variety of optical metrology techniques were investigated and a brief survey of empirical test results and limitations of the various techniques will be presented in this paper. Two complementary infrared (IR)techniques operating at a wavelength of 10.6 microns were chosen for further development: (1) IR Twyman-Green Phase Shifting Interferometry (IR PSI) and (2) IR Shack-Hartmann (IR SH) Wavefront Sensing. Innovative design modifications made to an existing IR PSI to achieve high-resolution, scannable, infrared measurements of the composite mirror are described. The modified interferometer was capable of measuring surface gradients larger than 350 microradians. The design and results of measurements made with a custom-built IR SH Wavefrong Sensor operating at 10.6 microns are also presented. A compact experimental setup permitting simultaneous operation of both the IR PSI and IR SH tools is shown. The advantages and the limitations of the two key IR metrology tools are discussed.

IR metrology phase shifting interferometry Shack-H↗
NASA NTRS2000

Marine benefits from NASA's global differential system: sub-meter positioning, anywhere, anytime

Precise real-time, onboard knowledge of a platform s state (position and velocity) is a critical compponent in many marine applications. This article describes a recent technology development that provides a breakthrough in this capability for platforms carrying a dual-frequency GPS receiver - seamless global coverage and roughly an order of magnitude improvement in accuracy compared to state-of-the-art.

GPS positioning marine↗
NASA NTRS1998

A One-Meter X-Band Inflatable Reflectarray Antenna

Inflatable antenna technology is being developed by JPL/NASA to enable the capabilities of low-mass, high packaging efficiency, and low-cost deployment for future spacecraft high-gain antennas. One of the technologies being studied is the inflatable microstrip reflectarray.

inflatable antenna microstrip reflectarray X-band↗
NASA NTRS1996

Natural Radio Source and Spacecraft Signal Measurements at Ka-Band (32.0 GHz) and X-Band (8.4 GHz) Using a 34-Meter Beam-Waveguide Antenna

From Intro.: NASA'a Deep Space Network (DSN) Technology Program at the Jet Propulsion Laboratory (JPL) is evaluating the use of the Ka-Band frequency allocation band (31.8 GHz to 32.3 GHz) for deep space to Earth telecommunications...This paper addresses the three current Ka-Band and X-Band activities, 1)KaAp, 2)SURSAT-1, and 3)KaBLE-II's upcoming Ka-Band experiments aboard Mars Global Surveyor.

Deep Space Network DSN Ka-Band Ka frequency↗
NASA NTRS1995

Positions and Intensities in the 3v2/v2+v4 Vibrational System of 14NH3 Near 4 micron meters

Ammonia is the fourth most abundant constituent in the atmospheres of Jupiter and Saturn, after hydrogen, helium and methane. This relative abundance is attested by the presence in the infrared planetary spectra of many absorption features observed in the range of fundamental bands and also in the higher bands. Reported are experimental line positions and intensities of selected ammonia bands.

ammonia Jupiter Saturn spectroscopy planetary gass↗
NASA NTRS2003

Thermal distortion analyses of a three-meter inflatable reflectarray antenna

Gossamer space structures are relatively large, flimsy, and lightweight. As a result, they are more easily affected or degraded by space thermal environments compared to other space structures. This study examines the structural integrity of a three-meeter Ka-band inltable/self-rigidizable reflectarray antenna under space thermal environments.

thermal inflatable temperature buckling boom anten↗