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  • 1
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    Large deployable reflector: An infrared and submillimeter orbiting observatory (1983)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The Large Deployable Reflector (LDR) is to be a dedicated astronomical observatory in space. It will operate in the 1 mm to 30 micron wavelength region where the Earth's atmospheric opacity makes ground-based observations nearly impossible. The primary mirror will be 20 m in diameter, made up of 37 individual segments. The reflector will be actively controlled to provide an overall surface accuracy of less than or approximately 2 microns. The LDR will be placed in orbit by the Space Shuttle and revisited at approximately 2 year intervals during its 10 year lifetime.
    Keywords: LAUNCH VEHICLES AND SPACE VEHICLES
    Type: NASA. Langley Research Center Large Space Antenna Systems Technol., Pt. 1; p 53-60
    Format: text
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  • 2
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    System concept for a moderate cost Large Deployable Reflector (LDR) (1986)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: A study was carried out at JPL during the first quarter of 1985 to develop a system concept for NASA's LDR. Major features of the concept are a four-mirror, two-stage optical system; a lightweight structural composite segmented primary reflector; and a deployable truss backup structure with integral thermal shield. The two-stage optics uses active figure control at the quaternary reflector located at the primary reflector exit pupil, allowing the large primary to be passive. The lightweight composite reflector panels limit the short-wavelength operation to approximately 30 microns but reduce the total primary reflector weight by a factor of 3 to 4 over competing technologies. On-orbit thermal analysis indicates a primary reflector equilibrium temperature of less than 200 K with a maximum gradient of about 5 C across the 20-m aperture. Weight and volume estimates are consistent with a single Shuttle launch, and are based on Space Station assembly and checkout.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Optical Engineering (ISSN 0091-3286); 25; 1045-105
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  • 3
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    The solar brightness temperature at millimeter wavelengths (1976)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Measurements of the brightness temperature of the sun near 36 GHz and 93 GHz were made using the new moon as a calibration source. Provided the brightness temperature of the moon is known and all measurements are reduced to the same zenith angle, a simple expression can be used for the sun-to-new moon ratio which is independent of antenna gain, atmospheric absorption and reemission, and radiometer calibration constants. This ratio was measured near 36 GHz and at two frequencies near 93 GHz with a Dicke switched superheterodyne radiometer system and a 2.4 m Cassegrain antenna. The slopes of the solar brightness temperature spectrum based on these ratios were measured. The absolute solar brightness spectrum derived from all current available measurements supplemented by the present ones is also plotted and discussed.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics; 48; May 1976
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  • 4
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    183 GHz water line variation - An energetic outburst in Orion KL (1984)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Observations of the 3(13)-2(20) transition of water vapor in the direction of Ori MC1 in 1980 February show a 50 percent flux increase and an apparent additional red shift of approximately 2 km/s relative to the line observed in 1977 December. From a detailed examination of the amplitude and frequency calibration, it appears unlikely that the effect is due to systematic error. The increase is attributed to the appearance of a new component at a velocity of 12 km/s with respect to the local standard of rest. The new component also has broad wings. Increased emission from a region in the high-velocity core of Ori MC1 can be due either to additional far-IR radiation to pump the 1983 GHz transition or to a change in the physical conditions in the gas. Statistical equilibrium calculations using the large-velocity-gradient formalism were carried out to develop a model for the emission. The calculations support a model in which the gas in the region of enhanced emission is hotter than the dust. The temporal coincidence between the 183 GHz increase and the 22 GH1 water maser outburst suggests a common, impulsive cause, which has heated the gas in a part of the HV source, enhancing the emission in both transitions.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 283; 106-116
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  • 5
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    Millimeter radiometer system technology (1989)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: JPL has had a large amount of experience with spaceborne microwave/millimeter wave radiometers for remote sensing. All of the instruments use filled aperture antenna systems from 5 cm diameter for the microwave Sounder Units (MSU), 16 m for the microwave limb sounder (MLS) to 20 m for the large deployable reflector (LDR). The advantages of filled aperture antenna systems are presented. The requirements of the 10 m Geoplat antenna system, 10 m multified antenna, and the MLS are briefly discussed.
    Keywords: SPACECRAFT INSTRUMENTATION
    Type: NASA, Langley Research Center, Earth Science Geostationary Platform Technology; p 167-177
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  • 6
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    36 GHz travelling wave maser. (1968)
    In:  Other Sources
    Details
    Publication Date: 2011-08-12
    Description: Traveling wave maser with 6 db amplification at 36 GHz, using Cr ion doped rutile as active material and superconducting magnet for DC magnetic field
    Keywords: MASERS
    Type: ; STITUTION OF ENGINEE
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  • 7
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    Large Deployable Reflector (LDR) - A concept for an orbiting submillimeter-infrared telescope for the 1990s (1983)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: 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.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Optical Engineering (ISSN 0091-3286); 22; 725-731
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  • 8
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    A search for 183 GHz emission from water in late-type stars (1984)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: A search was made for 183 GHz line emission from water vapor in the direction of twelve Mira and two semiregular variables. Upper limits to the emission are in the range of 2000 to 5000 Jy. It is estimated that thermal emission from the inner regions of late type stellar envelopes will be on the order of ten Jy. Maser emission, according to one model, would be an order of magnitude stronger. From the limited set sampled, the possibility of very strong maser emission at 183 GHz cannot yet be ruled out.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 286; 310-313
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  • 9
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    Mini-STEP: A Minimal Satellite Test of the Equivalence Principle Experiment (1995)
    In:  Other Sources
    Details
    Publication Date: 2018-06-08
    Description: The Mini-STEP concept was conceived from a desire by NASA to reduce the cost of the Satellite Test of the Equivalence Principle (STEP) experiment below that of the already downsized Quick STEP concept. The goal was for the total cost, including payload, spacecraft, launch vehicle, reserves and operations to be in the $50 million range.
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  • 10
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    A search for 183-GHz emission from water in late-type stars (1984)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A search was made for 183 GHz line emission from water vapor in the direction of twelve Mira and two semiregular variables. Upper limits to the emission are in the range of 2000 to 5000 Jy. It is estimated that thermal emission from the inner regions of late type stellar envelopes will be on the order of ten Jy. Maser emission, according to one model, would be an order of magnitude stronger. From the limited set sampled, the possibility of very strong maser emission at 183 GHz cannot yet be ruled out.
    Keywords: ASTRONOMY
    Type: NASA-TM-85987 , A-9825 , NAS 1.15:85987
    Format: application/pdf
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