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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 523 records · Page 29
All sourcesNASA NTRSDOE OSTI
NASA NTRS1990

Exploring the Universe with the Hubble Space Telescope

A general overview is given of the operations, engineering challenges, and components of the Hubble Space Telescope. Deployment, checkout and servicing in space are discussed. The optical telescope assembly, focal plane scientific instruments, wide field/planetary camera, faint object spectrograph, faint object camera, Goddard high resolution spectrograph, high speed photometer, fine guidance sensors, second generation technology, and support systems and services are reviewed.

Source record↗
NASA NTRS1991

Hubble Space Telescope: A cosmic time machine

The mission of the Hubble Space Telescope (HST) is to explore the expanding and evolving universe. During the 3,000 operating hours every year for the next 15 years or more, the HST will be used to study: galaxies; pulsars; globular clusters; neighboring stars where planets may be forming; binary star systems; condensing gas clouds and their chemical composition; and the rings of Saturn and the swirling ultraviolet clouds of Venus. The major technical achievements - its nearly perfect mirrors, its precise guidance system of rate gyroscopes, reaction wheels, star trackers, and fine guidance sensors are briefly discussed. The scientific instruments on board HST are briefly described. The integration of the equipment and instruments is outlined. The Space Telescope Science Institute (STScI) has approved time for 162 observations from among 556 proposals. The mission operation and data flow are explained.

Westphal, J. A.↗
NASA NTRS1991

Hubble Space Telescope secondary mirror vertex radius/conic constant test

The Hubble Space Telescope backup secondary mirror was tested to determine the vertex radius and conic constant. Three completely independent tests (to the same procedure) were performed. Similar measurements in the three tests were highly consistent. The values obtained for the vertex radius and conic constant were the nominal design values within the error bars associated with the tests. Visual examination of the interferometric data did not show any measurable zonal figure error in the secondary mirror.

Parks, Robert↗
NASA NTRS1991

Hubble Space Telescope observations of Mars

Hubble Space Telescope (HST) afforded the possibility of resolving features as small as 100 km on the Martian surface even when it is at the far point of its orbit. Therefore it is ideally suited for monitoring seasonal changes on the red planet. The objectives research include: the study of Martian dust storms; use of images obtained through different filters to study the spectral reflectance of regions on the Martian surface; use of ultraviolet images and spectra to measure the amount of ozone in the planet's atmosphere as a function of location of the planet; use of images to study changes in the albedo of the Mars surface; and use of Planetary Camera images to study Martian clouds and to measure the opacity of the atmosphere.

James, Philip B.↗
NASA NTRS1991

Long range science scheduling for the Hubble Space Telescope

Observations with NASA's Hubble Space Telescope (HST) are scheduled with the assistance of a long-range scheduling system (SPIKE) that was developed using artificial intelligence techniques. In earlier papers, the system architecture and the constraint representation and propagation mechanisms were described. The development of high-level automated scheduling tools, including tools based on constraint satisfaction techniques and neural networks is described. The performance of these tools in scheduling HST observations is discussed.

Miller, Glenn↗
NASA NTRS1991

Inner coma imaging of Comet Levy (1990c) with the Hubble Space Telescope

Observations of comet Levy were carried out with the Hubble Space Telescope (HST) on UT 27 Sep. 1990. The comet was imaged with the Wide Field Camera (WFC) through both red and blue filters, which were selected to isolate continuum emission peaking sharply at the nucleus. The longest exposures (4 sec) through the red filter had sufficient signal to noise that image deconvolution could be used to recover virtually the full spatial resolution of HST. These images reveal a fan-shaped inner coma in which the sunward-facing hemisphere is significantly brighter than the tailward hemisphere, consistent with volatile sublimation occurring primarily on the dayside of the nucleus.

Weaver, Harold A.↗
NASA NTRS1991

The in-flight calibration of the Hubble space telescope attitude sensors

A detailed review of the in-flight calibration of the Hubble Space Telescope attitude sensors is given. The review, which covers the period from the April 24, 1990 launch of the spacecraft until April 1991, describes the calibrations required and accuracies achieved for the four principal attitude sensing systems on the spacecraft: the magnetometers, the fixed-head star trackers, the gyroscopes, and the fine guidance sensors.

Welter, Gary L.↗
NASA NTRS1990

Enhancing orbital servicing operations: Providing positive and effective management of spare and installed hardware - A case study of the Hubble Space Telescope

The Satellite Resources Management and Tracking System was developed specifically for the Hubble Space Telescope (HST) program, and now, NASA has the ability to immediately access the necessary data for planning successful orbital satellite servicing operations. This system is an online, real-time data base system that contains a plethora of data on each item identified to support the HST throughout its planned 15 year life. Some of the information provided includes the current status, location, quantity, and history of each asset, a separate record for each discrete serial numbered item, procurement lead times on items sensitive to technology obsolescence, and the maintenance and repair history of each asset. Finally, details are provided on organizational, operational and logistics requirements.

Randolph, Joseph L.↗
NASA NTRS1990

Lessons learned from the Hubble Space Telescope planning and scheduling system implementation and operation

The major challenge of the NASA Hubble Space Telescope (HST) Ground System has been the implementation of the planning and scheduling system. This paper describes the operational flow of HST from science proposals to the actual execution of science observations on board the HST. The paper provides a collection of lessons learned over the 10 years that have covered the definition, development, test, and initial operation of HST's planning and scheduling system.

Ruitberg, Edward O.↗
NASA NTRS1990

Scattered light in the echelle modes of the Goddard high-resolution spectrograph aboard the Hubble Space Telescope. I - Analysis of prelaunch calibration data

A study of scattered light in the echelle mode of the Goddard high-resolution spectrograph (GHRS), one of the first-generation science instruments aboard the Hubble Space Telescope, is reported. The data analyzed are from the GHRS ground-based test program and include observations with the 500 channel Digicon detectors through the small science aperture of UV emission-line sources, continuum sources, and continuum sources viewed through molecular absorption cells. The two largest contributors to scattered light are the echelle and cross-disperser, the effects of which have been quantified. A computer simulation using the derived scattering functions demonstrates that the combined effects of these sources of scattered light adequately explain the observed level of interorder light when viewing UV continuum sources. Observing strategies and data reduction algorithms for measuring and removing the effects of the scattered light are discussed.

Cardelli, Jason A.↗
NASA NTRS1991

The rate and efficiency of high-mass star formation along the Hubble sequence

Data obtained with IRAS are used to compare and contrast the global star formation rates for a galactic sample which represents essentially all known noninteracting spiral and lenticular galaxies within 40 Mpc. The distribution of 60 micron luminosity is similar for spirals of types Sa-Scd inclusively, although the luminosities of the very early and very late types are, on average, one order of magnitude lower. High-mass star formation rates are similar for early, intermediate, and late type spirals, and the average high-mass star formation rate per unit molecular gas mass is independent of type for spiral galaxies. A remarkable homogeneity exists in the high-mass star-forming capabilities of spiral galaxies, particularly among the Sa-Scd types. The Hubble sequence is therefore not a sequence in the present-day rate or production efficiency of high-mass stars.

Devereux, Nicholas A.↗
NASA NTRS1991

Astrometry using the Hubble Space Telescope fine guidance sensors

Plans for the use of the three fine guidance sensors (FGSs) of the NASA Hubble Space Telescope for direct astrometric observations are reviewed. Topics addressed include the optical elements and detectors of the FGSs, the basic and astrometric operating modes of the FGSs, spacecraft pointing control during astrometric observations, and the astrometric data-reduction software provided to HST users. Particular attention is given to the calibration procedures for optical-field angle distortion, the plate scale, filter-wedge errors, lateral color effects, secular changes, velocity aberration, and transfer function. Also discussed are the steps being taken to verify the HST orbit. It is pointed out that the performance of the interferometric FGSs should not be affected by the focusing problems of the main HST instrument.

Duncombe, Raynor L.↗
NASA NTRS1990

Hubble Space Telescope electrical power system

The Hubble Space Telescope (HST) electrical power system (EPS) is supplying between 2000 and 2400 W of continuous power to the electrical loads. The major components of the EPS are the 5000-W back surface field reflector solar array, the six nickel-hydrogen (NiH2) 22-cell 88-Ah batteries, and the charge current controllers, which, in conjunction with the flight computer, control battery charging. The operation of the HST EPS and the results of the HST NiH2 six-battery test are discussed, and preliminary flight data are reviewed. The HST NiH2 six-battery test is a breadboard of the HST EPS on test at Marshall Space Flight Center.

Whitt, Thomas H.↗
NASA NTRS1990

The Hubble Space Telescope nickel-hydrogen battery design

Details are presented of the HST (Hubble Space Telescope) battery cell, battery package, and module mechanical and electrical designs. Also included are a summary of acceptance, qualification, and vibration tests and thermal vacuum testing. Unique details of battery cell charge retention performance characteristics associated with prelaunch hold conditions are discussed. Special charge control methods to minimize thermal dissipation during pad charging operations are summarized. This module design meets all NASA fracture control requirements for manned missions.

Nawrocki, D. E.↗
NASA NTRS1990

Multi-terabyte image storage and distribution for NASA's Hubble Space Telescope

The modular architecture, functionality, and key components of the Hubble Space Telescope Data Archive Distribution Service (DADS) are presented. DADS functions comprise archive management, catalog management, and user interface. The distributed modular architecture utilized is made up of four subsystems, including the archive, host, catalog, and the Science Operations ground System/DADS Interface Processor. All data generated by the HST are archived in DADS on 12-in. optical disks. DADS is a permanent archive with a data capacity of 30 terabytes that can be expanded to 68 terabytes. Supplementary information and stellar observations will be instantly accessible through DADS, which can collect and archive more than 3 gigabytes per day of image and support data over the lifetime of the HST. Electronic and physical media will be accessible through 140 network connections, with a catalogue to assist in data set selection.

Weller, H. W., Jr.↗
NASA NTRS1989

Atomic oxygen resistant protective coatings for the Hubble Space Telescope solar array in low earth orbit

The Hubble Space Telescope back-up solar array (BSFR-ATOX) was designed with atomic oxygen resistant materials to replace the original high efficiency cell (HEC) array. Pending qualification of the BSFR-ATOX array, protective coatings for application to the existing HEC array were evaluated. Three polysiloxane-type coating materials, SWS V-10, DC-100, and CV-1144 were evaluated with respect to atomic oxygen resistance, outgassing, contamination potential, stability under UV irradiation, electron-proton irradiation, thermal cycling, and long-term storage after application. Atomic oxygen testing included characterization of the atomic oxygen plasma using comparison of Kapton reaction to existing flight data, residual gas analysis, and temperature measurements. Results from these tests show DC-100 as a greater contamination concern if used in the vicinity of sensitive optical surfaces, i.e., solar cell cover glasses. The SWS V-10 and CV-1144 coatings met all acceptance criteria.

Burns, H. D.↗
NASA NTRS1991

Hubble Space Telescope imaging of Eta Carinae

New high spatial resolution observations of the material around Eta Carinae, obtained with the Hubble Space Telescope Wide Field/Planetary Camera, are presented. The star Eta Carinae is one of the most massive and luminous stars in the Galaxy, and has been episodically expelling significant quantities of gas over the last few centuries. The morphology of the bright central nebulosity (the homunculus) indicates that it is a thin shell with very well defined edges, and is clumpy on 0.2 arcsec (about 10 to the 16th cm) scales. An extension to the northeast of the star (NN/NS using Walborn's 1976 nomenclature) appears to be a stellar jet and its associated bow shock. The bow shock is notable for an intriguing series of parallel linear features across its face. The S ridge and the W arc appear to be part of a 'cap' of emission located to the SW and behind the star. Together, the NE jet and the SW cap suggest that the symmetry axis for the system runs NE-SW rather than SE-NW, as previously supposed. Overall, the data indicate that the material around the star may represent an oblate shell with polar blowouts, rather than a bipolar flow.

Hester, J. J.↗
NASA NTRS1991

Initial refinement of minor planet orbits for pointing and observation with the Hubble Space Telescope

Refinements of the orbital elements for 24 minor planets that will be observed with the Fine Guidance Sensors (FGSs) on the Hubble Space Telescope (HST) are presented. The accuracy of these orbits is discussed in the context of the ephemeris requirements for target acquisition with the FGSs. Comparisons with standard catalog orbits are made to evaluate the suitability of the use of the catalog orbits for HST pointing. It is found that the orbits published in the most recent Minor Planet Circulars are capable of positional predictions that are accurate at the 1-arcsec level. However, there are still many orbits that have not been revised in the last 10 yr and these should not be used for critical pointing ephemerides. In many cases, the orbital elements will have to be refined using recent ground-based observations before a minor planet can be reliably observed by HST.

Whipple, Arthur L.↗