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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 307 records · Page 17
All sourcesNASA NTRSDOE OSTI
NASA NTRS2009

Non-invasive Optical End-to-End Test of a Large TMA Telescope (JWST) from the Intermediate Focus

The James Webb Space Telescope (JWST) requires testing of the full optical system in a cryogenic vacuum environment before launch. Challenges with the telescope architecture and the test environment lead to placing removable optical test sources at the Cassegrain intermediate focus of the Telescope. The Science Instrument suite will be used to align the telescope and to verify the wavefront error. The Science Instruments capture test images that are analyzed using focus diverse phase retrieval. The wavefront sensing algorithms have the large dynamic range required to measure the relatively small wavefronts of interest in the presence of the large aberrations resulting from the off-axis source locations at the intermediate focus. These inherent aberrations of the off-axis design are removed analytically from the measured data. The test design and in-situ wavefront sensing process enables a number of tests to verify the alignment and optical quality of the system.

Whitman, Tony↗
NASA NTRS1988

Submillimeter heterodyne receiver for the CSO telescope

This task is to build a cryogenically cooled 620 to 700 GHz astronomical receiver that will be used as a facility instrument at the CalTech Submillimeter Observatory (CSO) on Mauna Kea, Hawaii. The receiver will have applications as a very high resolution spectrometer to investigate spectral lines in planetary and satellite atmospheres, and comets. The receiver will also be used to make continuum measurements of planets, satellites, and asteroids. During FY88, a scale model (200 GHz) SIS mixer radiometer was built and intrgrated into a cryostat designed for use on the CSO telescope. This system will serve as a model to guide the work on the higher frequency mixer. A solid state local oscillator source that covers two bands in the 600 to 700 GHz has been developed under contract JPL and will be delivered before the end of the year. Work has continued on the SIS materials needed for the 620 to 700 GHz mixer. Test hardware has been developed which allow the 1 to 5 curves for SIS material to be easily measured.

Gulkis, S.↗
NASA NTRS2002

The Planck Mission

Planck, scheduled for launch in 2007, will be the third space mission to observe the cosmic microwave background (CMB). Two cryogenic instruments and an off-axis telescope will provide an unprecedented combination of sensitivity, angular resolution, and frequency coverage. Planck is designed to measure the temperature anisotropies of the CMB to limits set not by the instruments, but rather by the Universe itself. In addition, it will measure the E-type polarization of the CMB, and provide all-sky surveys at nine frequencies between 30 and 857GHz.

cosmic↗
DOE OSTI2022

Simons Observatory: characterizing the Large Aperture Telescope Receiver with radio holography

Here, we present near-field radio holography measurements of the Simons Observatory Large Aperture Telescope Receiver optics. These measurements demonstrate that radio holography of complex millimeter-wave optical systems comprising cryogenic lenses, filters, and feed horns can provide detailed characterization of wave propagation before deployment. We used the measured amplitude and phase, at 4 K, of the receiver near-field beam pattern to predict two key performance parameters: 1) the amount of scattered light that will spill past the telescope to 300 K and 2) the beam pattern expected from the receiver when fielded on the telescope. These cryogenic measurements informed the removal of a filter, which led to improved optical efficiency and reduced sidelobes at the exit of the receiver. Holography measurements of this system suggest that the spilled power past the telescope mirrors will be less than 1%, and the main beam with its near sidelobes are consistent with the nominal telescope design. This is the first time such parameters have been confirmed in the lab prior to deployment of a new receiver. This approach is broadly applicable to millimeter and submillimeter instruments.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
NASA NTRS2022

Simons Observatory: Characterizing the Large Aperture Telescope Receiver with Radio Holography

We present near-field radio holography measurements of the Simons Observatory Large Aperture Telescope Receiver optics. These measurements demonstrate that radio holography of complex millimeter-wave optical systems comprising cryogenic lenses, filters, and feed horns can provide detailed characterization of wave propagation before deployment. We used the measured amplitude and phase, at 4 K, of the receiver near-field beam pattern to predict two key performance parameters: 1) the amount of scattered light that will spill past the telescope to 300 K and 2) the beam pattern expected from the receiver when fielded on the telescope. These cryogenic measurements informed the removal of a filter, which led to improved optical efficiency and reduced sidelobes at the exit of the receiver. Holography measurements of this system suggest that the spilled power past the telescope mirrors will be less than 1%, and the main beam with its near sidelobes are consistent with the nominal telescope design. This is the first time such parameters have been confirmed in the lab prior to deployment of a new receiver. This approach is broadly applicable to millimeter and submillimeter instruments.

Grace. E. Chesmore↗
NASA NTRS1979

Design of a one-year lifetime, spaceborne superfluid helium dewar

The Infrared Astronomical Satellite is an Explorer Mission and a joint venture of the Netherlands, the United Kingdom, and the United States scheduled for launch into earth orbit in 1981. The cryogenic system is a major part of the satellite; it incorporated many unique and state-of-the-art design features to satisfy the requirements of a one-year orbital lifetime, a focal plane temperature less than 4K, minimal launch weight, and zero-gravity operation. The 60-centimeter diameter telescope is contained within a superfluid helium dewar having a capacity of 540 liters. The telescope aperture cover employs an independent cryogenic system containing a 54-liter supercritical helium tank. The aperture cover, which is ejected two weeks after launch, protects the telescope from contamination and provides the low-temperature background needed to perform focal plane health checks. Design and predicted performance of the cryogenic systems are discussed in detail.

Hopkins, R. A.↗
NASA NTRS2013

Cryogenic Optical Performance of a Lightweighted Mirror Assembly for Future Space Astronomical Telescopes: Correlating Optical Test Results and Thermal Optical Model

A 43cm diameter stacked core mirror demonstrator was interferometrically tested at room temperature down to 250 degrees Kelvin for thermal deformation. The 2.5m radius of curvature spherical mirror assembly was constructed by low temperature fusing three abrasive waterjet core sections between two CNC pocket milled face sheets. The 93% lightweighted Corning ULE® mirror assembly represents the current state of the art for future UV, optical, near IR space telescopes. During the multiple thermal test cycles, test results of interferometric test, thermal IR images of the front face were recorded in order to validate thermal optical model.

Eng, Ron↗
NASA NTRS2018

The Origins Space Telescope Cryo-Thermal Architecture

The Origins Space Telescope (OST) is studied as a future Mid- and Far-Infrared flagship-class observatory. OST will cover the wavelength range from 6 to 600 microns. To reach the sky background for 200-micron wavelengths temperatures of 4 degrees Kelvin or lower are required. To achieve this low temperature active cooling is required, along with passive shielding and passive radiation to deep space. Currently two concepts are being studied: Concept 1 with a 9-meter-diameter primary and a suite of 5 extremely capable instruments providing both imaging and spectroscopy over the entire wavelength range. Concept 2 is a more modest sized telescope with a collecting area equivalent to a 5-meter primary, fewer deployments and 3 or 4 instruments also covering the entire wavelength range for imaging and spectroscopy, although with somewhat reduced spectroscopic resolution, and somewhat slower mapping speed. This paper will describe OST Concept 2's cryogenic thermal architecture and thermal model results.

Space Telescope↗
NASA NTRS1987

Cryogenics program overview

An overview of the cryogenics program of the Goddard Space Flight Center is given in viewgraph form. Goddard's role and the flight programs requiring cryogenics are outlined. Diagrams are given of the Cosmic Background Explorer, the Broad Band X-Ray Telescope, the Hubble Space Telescope, an adiabatic demagnetization refrigerator, a liquid cryogenic cooler for the Shuttle Glow Experiment, a liquid helium dewar, and the X-ray spectrometer on the Advanced X-Ray Astrophysics Facility.

Castles, Stephen H.↗
DOE OSTI2025

Simons Observatory: Characterization of the Large Aperture Telescope Receiver

The Simons Observatory (SO) is a ground-based cosmic microwave background (CMB) survey experiment that currently consists of three 0.42 m small-aperture telescopes and one 6 m large-aperture telescope (LAT), located at an elevation of 5200 m in the Atacama Desert in Chile. At the LAT’s focal plane, SO will install >62,000 transition-edge sensor detectors across 13 optics tubes (OTs) within the Large Aperture Telescope Receiver (LATR), the largest cryogenic camera ever built to observe the CMB. Furthermore we report on the validation of the LATR in the laboratory and the subsequent dark testing and validation within the LAT. We show that the LATR meets cryogenic, optical, and detector specifications required for high-sensitivity measurements of the CMB. At the time of writing, the LATR is installed in the LAT with six OTs (corresponding to >31,000 detectors), and the LAT mirrors and remaining seven OTs are undergoing development.

Astronomical instrumentation↗
NASA NTRS1983

Positional repeatability measurements of stepper motors at cryogenic temperatures

For cryogenically-cooled infrared instruments and telescopes employed in space, reliable and predictable motor operations at 4 K in vacuum are in most cases necessary. For the Shuttle Infrared Telescope Facility (SIRTF), stepper motors may be employed in a number of applications. A test facility was designed and built for measuring stepper motor positional repeatability, in vacuum, over a temperature range from ambient to liquid helium temperature. Tests regarding positional repeatability were conducted at different motor speeds, directions of motor rotation, step sizes, and power conditions. In addition, tests were performed with respect to the ability of the motor to remain in a position with no power applied to the motor.

Pompea, S. M.↗
NASA NTRS1985

Far-infrared and submillimeter survey of the galactic center and nearby galactic plane

Maps are presented with 12-arcmin resolution of the Galactic Center and adjacent galactic plane, from l(Pc) = 359 deg to l(Pc) = 5 deg. The data were obtained with the Steward Observatory's cryogenically-cooled, balloon-borne telescope. The data are from channels filtered for a bandpass of 70 to 110 microns and for a longpass of wavelength greater than 80 microns. For the typical effective temperature of 25 K of a galactic H II region at this spatial resolution, the effective wavelengths of the channels are 93 microns and 145 microns. Continuous emission is mapped along the galactic plane in both wavelengths. There are two contrasts between the immediate vicinity of SgrA l(Pc) smaller than 1 deg, and the galactic plane in general. Firstly, for l(Pi) greater than 1 deg the galactic plane narrows dramatically at 93 microns, while retaining its width at 145 microns. Secondly, the individual sources at l(Pc) (which are associated with H II regions) have greater peak brightness in the 145-micron channel than the 93-micron channel, while SgrA has approximately equal peak brightness in each. The maps demonstrate the importance of submillimeter wavelengths to galactic surveys.

Campbell, M. F.↗
NASA NTRS2001

XRCF Testing Capabilities

The Space Optics Manufacturing Technology Center's X-ray Calibration Facility has been recently modified to test Next Generation Space Telescope (NGST) developmental mirrors at cryogenic temperatures (35 degrees Kelvin) while maintaining capability for performance testing of x-ray optics and detectors. The facility's current cryo-optical testing capability and potential modifications for future support of NGST will be presented.

Reily, Cary↗
NASA NTRS1989

Assembly, alignment, and cold focus test methods utilized on CLAES optics

This paper describes the techniques and the equipment used in the assembly and alignment of the Cryogenic Limb Array Etalon Spectrophotometer (CLAES) Telescope and Spectrometer, together with those used to test the system at operating temperatures in order to establish the correct focus for the detector array and other system components. In addition, cryogenic tests were used to determine the stability of the optics over the specified environment, and blur size measurements were performed at operational temperatures.

Dawson, Juan C.↗
NASA NTRS1993

Arrays: The Heart and Soul of SIRTIF

This paper describes the status of NASA's Space Infrared Telescope Facility (SIRTF) program. SIRTF will be a cryogenically cooled observatory for infrared astronomy from space and is planned for launch early in the next decade. It will be the first cryogenic observatory to make extensive use of the powerful infrared detector array technology discussed at this conference. We summarize a newly developed SIRTF mission concept and show how the availability of detector arrays has shaped the scientific rationale for SIRTF, and how the arrays themselves have become part of the definition of the SIRTF mission.

SIRTF infrared detector arrays Space Infrared Tele↗
NASA NTRS1985

Impact of chopping on image quality in the SIRTF telescope

The initial Phase-A concept for the Space Infrared Telescope Facility (SIRTF), which was established in 1981, is concerned with a cryogenically cooled, 85 cm diameter, f/24 Ritchey-Chretien telescope, followed by a Multiple Instrument Chamber (MIC), containing six scientific instruments. In 1982, the Phase-A concept was reviewed with the aim to assess the technical readiness for the next phase of development. Various areas of concern were subsequently investigated in three parallel studies by industry. Two of the arising questions are considered in the present paper, taking into account the system and technology implications of achieving diffraction-limited resolution at 2 microns, and the limitations on the size of the imaging field under this condition. The conducted study takes into account an evaluation of the different methods of chopping. Attention is given to the telescope parameters, symmetric chopping, asymmetrical chopping, focus and alignment errors, the wavefront-error budget, and image quality.

Bottema, M.↗
NASA NTRS1988

Cryogenic mirror analysis

Due to extraordinary distances scanned by modern telescopes, optical surfaces in such telescopes must be manufactured to unimaginable standards of perfection of a few thousandths of a centimeter. The detection of imperfections of less than 1/20 of a wavelength of light, for application in the building of the mirror for the Space Infrared Telescope Facility, was undertaken. Because the mirror must be kept very cold while in space, another factor comes into effect: cryogenics. The process to test a specific morror under cryogenic conditions is described; including the follow-up analysis accomplished through computer work. To better illustrate the process and analysis, a Pyrex Hex-Core mirror is followed through the process from the laser interferometry in the lab, to computer analysis via a computer program called FRINGE. This analysis via FRINGE is detailed.

Nagy, S.↗