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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 19 records
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NASA NTRS1980

Contamination control of the Infrared Astronomical Satellite

The Infrared Astronomical Satellite, to be launched in August 1981, will perform an all-sky survey in the 8-120 micron wavelength region. High sensitivity to thermal radiation and the low operating temperature of optics and thermal control surfaces make the IRAS telescope extremely vulnerable to contamination. Four special topics of importance are discussed in this paper: (1) deposition of atmospheric gases; (2) sighting of particles released from the satellite; (3) functions of a deployable aperture cover; and (4) degradation of a radiatively cooled sunshade from spacecraft outgassing. These topics demonstrate how mission strategy, ground cleaning and handling, and hardware design are used to avoid contamination which would degrade telescope performance.

Andreozzi, L. C.↗
NASA NTRS1981

Sunshade/radiative cooler for IRAS infrared astronomical satellite

The Infrared Astronomical Satellite (IRAS) is a joint project shared by the United States and the Netherlands with the United Kingdom providing tracking and ground support services. IRAS features a cryogenically cooled telescope designed to perform an unbiased all-sky survey of the far infrared spectrum from 8 to 120 microns and to observe objects of special interest. The sunshade is designed to protect the telescope aperture and sunshade radiators from: direct solar radiation; direct earth radiation; radiation exchange with satellite structures; excessive aperture heating caused by sunshade inner cone emission. The sunshade three-stage radiative cooler design meets the listed requirements and, in addition, provides some contamination protection for the telescope aperture and optical surfaces during pointing maneuvers when the telescope is tilted in the direction of the velocity vector. Unless protected by the sunshade, the ram effect can cause molecules to enter the aperture and deposit on the cooled optical surfaces. This paper describes the sunshade design, the thermal analyses, and the results of thermal balance testing of the flight hardware.

Anderson, R. R.↗
NASA NTRS1985

Design and performance of the cryogenic focal plane optics assembly for the Infrared Astronomical Satellite (IRAS)

The Infrared Astronomical Satellite (IRAS) has successfully completed its mission of providing an unbiased all-sky survey of astronomical objects in the 8 to 120 micrometer wavelength region. The design and performance of the Focal Plane Optics Assembly (FPOA) for the IRAS instrument is described in this paper. The FPOA consists of 62 survey field stops, 62 individual small field lenses, 124 small spectral filters, and a precision multi-part aluminum housing. The FPOA is capable of repeated thermal cycling from ambient temperature to 2 Kelvin. The spectral filters, along with the detector spectral responses, provide infrared bandpasses of 8-15, 18-30, 46-78, and 85-117 micrometers. The combination of very long wavelengths, liquid helium temperatures, and small size provided a significant design challenge. Spectral filter and field lens designs for the four spectral bands are described. Also, discussed are techniques which were developed for mechanical mounting of the small lenses and spectral filters, and to assure their optical alignment.

Bamberg, J. A.↗
NASA NTRS1984

Preliminary scientific results from the first six months of the Infrared Astronomical Satellite (IRAS)

The Infrared Astronomical Satellite (IRAS) was successfully launched on January 25, 1983. This paper presents results based on analysis of early scientific data returned from IRAS. Among the early results of IRAS are the discovery of comet IRAS-Araki-Alcock, evidence for a shell of large particles around the nearby bright star Vega, detection of stars in the process of formation, and detection of many infrared bright galaxies. These early results demonstrate that the IRAS data will be a treasure chest for astronomers for years to come.

Soifer, B. T.↗
NASA NTRS1976

A telescope for the Infrared Astronomical Satellite /IRAS/

The Infrared Astronomical Satellite (IRAS) will be used to survey the 8 to 120 micron spectrum of the entire sky to the faintest flux levels possible by using state-of-the-art detectors and preamplifiers. As a result of a recently completed study of the telescope and focal plane, a concept has been devised that demonstrates the feasibility of using stored cryogen to cool the telescope for one year of operation in a polar twilight orbit at an altitude of 900 km. Predictions regarding noise equivalent flux density, cryogenic lifetime, and the number of noise spikes caused by Van Allen belt radiation are presented. The telescope is cooled both by supercritical and by superfluid helium. The on-board signal processing includes provisions for suppressing noise spikes.

Hedden, R. L.↗
NASA NTRS1980

The Infrared Astronomical Satellite - IRAS

The Infrared Astronomical Satellite (IRAS), to be launched in the autumn of 1981, is expected to reveal much that is new and exciting. The paper discusses the design features and performance of IRAS, illustrates the meaning of this performance in terms of known phenomena, and stipulates how it may extrapolate to the early universe. The ability of IRAS to observe the universe at large redshift is examined.

Clegg, P. E.↗
NASA NTRS1984

Cryogenic telescope on the Infrared Astronomical Satellite (IRAS)

The Infrared Astronomical Satellite (IRAS) has completed an unbiased all-sky survey at wavelengths from 10 to 100 microns. The design and performance of the focal plane array is described with emphasis on in-orbit measurements of the sensitivity and stability. In the four broad spectral bands centered at 12, 25, 60, and 100 microns, the system noise equivalent flux density (NEFD) values are in Jy/(Square root of Hz), 0.03, 0.025, 0.046, and 0.21, respectively (Jansky = 10 to the -26th W/sq m/Hz). For point sources, a single scan at the survey rate of 3.8 arcmin/s yields limiting flux densities at the 3-sigma confidence level of 0.36, 0.30, 0.39, and 1.2 Jy. The dc stability of the junction field effect transistor (JFET) amplifiers and the excellent off-axis rejection of the telescope permit total flux measurements of extended infrared emission at levels below 6,000,000 Jy/sr. Response of the extrinsic silicon and germanium photo-detectors to ionizing radiation is described.

Low, F. J.↗
NASA NTRS1980

Use of the transect method in satellite survey missions with application to the infrared astronomical satellite /IRAS/

The coverage of the celestial sphere or the surface of the earth with a narrow-field instrument onboard a satellite can be described by a set of swaths on the sphere. A transect is a curve on this sphere constructed to sample the coverage. At each point on the transect the number of times that the field-of-view of the instrument has passed over the point is recorded. This information is conveniently displayed as an integer-valued histogram over the length of the transect. The effectiveness of the transect method for a particular observing plan and the best placement of the transects depends upon the structure of the set of observations. Survey missions are usually characterized by a somewhat parallel alignment of the instrument swaths. Using autocorrelation and cross-correlation functions among the histograms the structure of a survey has been analyzed into two components, and each is illustrated by a simple mathematical model. The complex, all-sky survey to be performed by the Infrared Astronomical Satellite (IRAS) is synthesized in some detail utilizing the objectives and constraints of that mission. It is seen that this survey possesses the components predicted by the simple models and this information is useful in characterizing the properties of the IRAS survey and the placement of the transects as a function of celestial latitude and certain structural properties of the coverage.

Mclaughlin, W. I.↗
NASA NTRS2023

Protoplanetary Disk Science with the Orbiting Astronomical Satellite Investigating Stellar Systems (OASIS) Observatory

The Orbiting Astronomical Satellite for Investigating Stellar Systems (OASIS) is a NASA Astrophysics MIDEX-class mission concept, with the stated goal of Following water from galaxies, through protostellar systems, to Earth’s oceans. This paper details the protoplanetary disk science achievable with OASIS. OASIS’s suite of heterodyne receivers allow for simultaneous, high spectral resolution observations of water emission lines The Orbiting Astronomical Satellite for Investigating Stellar Systems (OASIS) is a NASA Astrophysics MIDEX-class mission concept, with the stated goal of Following water from galaxies, through protostellar systems, to Earth’s oceans. This paper details the protoplanetary disk science achievable with OASIS. OASIS’s suite of heterodyne receivers allow for simultaneous, high spectral resolution observations of water emission lines HD in 100+ disks, allowing for the most accurate determination of total protoplanetary disk gas mass to date. When combined with the contemporaneous water observations, the HD detection will also allow us to trace the evolution of water vapor across evolutionary stages. These observations will enable OASIS to characterize the time development of the water distribution and the role water plays in the process of planetary system formation.

Kamber R Schwarz↗
NASA NTRS1984

The Infrared Astronomical Satellite (IRAS) mission

The Infrared Astronomical Satellite (IRAS) consists of a spacecraft and a liquid helium cryostat that contains a cooled IR telescope. The telescope's focal plane assembly is cooled to less than 3 K, and contains 62 IR detectors in the survey array which are arranged so that every source crossing the field of view can be seen by at least two detectors in each of four wavelength bands. The satellite was launched into a 900 km-altitude near-polar orbit, and its cryogenic helium supply was exhausted on November 22, 1983. By mission's end, 72 percent of the sky had been observed with three or more hours-confirming scans, and 95 percent with two or more hours-confirming scans. About 2000 stars detected at 12 and 25 microns early in the mission, and identified in the SAO (1966) catalog, have a positional uncertainty ellipse whose axes are 45 x 9 arcsec for an hours-confirmed source.

Neugebauer, G.↗
NASA NTRS1977

Infrared Astronomical Satellite

The objective of the Infrared Astronomical Satellite is to produce an unbiased all-sky survey in the wavelength region between 8 and 120 microns. Using a 60 cm diameter helium cooled telescope and detector arrays which are essentially zodiacal light background photon noise limited, heretofore unprecedented sensitivity can be achieved. The optical design, the focal plane layout and expected performance of the current design concept are discussed.

Aumann, H. H.↗
NASA NTRS1978

Simulation of the Infrared Astronomical Satellite /IRAS/ telescope system

The Infrared Astronomical Satellite (IRAS), a joint Dutch-British-U.S. project scheduled for launch in February 1981, will conduct the first all-sky infrared survey between 8 and 120 microns using a 60-cm aperture, cryogenically-cooled telescope. A computer simulation program has been developed at Ames Research Center to aid in the design of this complex telescope. The development and implementation of the IRAS Telescope Simulator (IRTS), its input data sources, and its output data products are described.

Henderson, E.↗
NASA NTRS1985

System test and flight results from infrared astronomical satellite external thermal subsystem

The Infrared Astronomical Satellite (IRAS) received its system level thermal testing in a solar simulator in September and October 1982 and was launched in January 1983. In order to reduce costs and meet a tight launch schedule, a system thermal test approach was employed which combined the goals of thermal design development tests, thermal balance tests, and thermal vacuum qualification tests. This approach relied heavily on the use of a computer-controlled automatic data handling and heater control system which reduced reliance on human monitoring of test data in comparison to past projects. The validity of this approach has been borne out by flight results. During the whole mission most temperatures were within the desired range and close to predictions. Included under the external thermal subsystem are room temperature electronics and radiatively cooled surfaces with temperatures below 100 and 200K.

Salazar, R. P.↗
NASA NTRS1982

Bidirectional reflectance distribution function of the Infrared Astronomical Satellite solar-shield material

The Infrared Astronomical Satellite (IRAS) telescope has an outer shield on it which is used to reduce the amount of thermal radiation that enters the telescope. The shield forms the first part of the baffle structure which reduces the photon incidence on the focal plane. It was, therefore, necessary to model this structure for scattering, and a required input for such modeling is the scattering characteristic of this surface. Attention is given to the measurement of the bidirectional reflectance distribution function (BRDF), the reflected radiance divided by the incident irradiance at 10.6 micrometers, 118 micrometers, and at several angles of incidence. Visual observation of the gold sample shows that there are striations which line up in a single direction. The data were, therefore, taken with the sample oriented in each of two directions.

Hubbs, J. E.↗
NASA NTRS1984

Early results from the Infrared Astronomical Satellite

The discoveries made with the Infrared Astronomical Satellite (IRAS) are reviewed. Findings on large-scale extended infrared emission associated with the solar system and the Galaxy and medium-scale extended infrared emission associated with zodiacal dust bands and infrared cirrus clouds are described. Comets have been found to be much dustier than previously thought. Solid material orbits Vega and other stars, and emission from cool interstellar material has been traced throughout the Galaxy up to the poles. Stars in the process of formation have been detected. The far-infrared sky away from the galactic plane has been found to be dominated by spiral galaxies, some of which emit more than 50 percent and as much as 98 percent of their energy in the infrared.

Neugebauer, G.↗
NASA NTRS1978

Infrared astronomical satellite

Design and mission characteristics of the Infrared Astronomical Satellite (IRAS) are reviewed with attention to the satellite/telescope configuration. The IRAS will be launched into a 900 km near-polar orbit (inclination 99 deg), with a cryogenically cooled 60 cm telescope capable of collecting 700 million bits of data per day. The telescope is expected to add from 6000 to one million new IR sources to the astronomical catalogs. Objects for study include stars, extended sources, asteroids, zodiacal light, artificial satellites, high energy protons, and dust.

Mclaughlin, W. I.↗
NASA NTRS1980

Infrared Astronomical Satellite /IRAS/ Scientific Data Analysis System

The Infrared Astronomical Satellite (IRAS), to be launched in 1982, is discussed. It will systematically survey the entire sky over a large percentage of the infrared spectrum, in the wavelength region of 8 to 120 microns, at sensitivities a hundred times greater than previously achieved from high-altitude observatories, aircraft, balloons or sounding rockets. The Scientific Data Analysis System (SDAS), an off-line data processing facility, is examined. Its primary function is to produce a catalog of inertially fixed infrared-emitting point sources (mainly stars and galaxies) observed during the IRAS survey. Details for source detection and confirmation are given. It is estimated that the catalog will contain approximately a million objects having a brightness of 10 amtowatts per square centimeter or greater; 125,000 SDAS detections, if spurious events of signal-to-noise ratios greater than 2.5 are included, will be made every day.

Duxbury, J. H.↗