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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 415 records · Page 23
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DOE OSTI2026

Hubble Space Telescope Imaging of Three Isolated Faint Dwarf Galaxies beyond the Local Group: Pavo, Corvus A, and Kamino

We present new Hubble Space Telescope (HST) imaging of three recently discovered star-forming dwarf galaxies beyond the Local Group: Pavo, Corvus A, and Kamino. The discovery of Kamino is reported here for the first time. They rank among the most isolated faint dwarf galaxies known; hence they provide unique opportunities to study galaxy evolution at the smallest scales, free from the environmental effects of more massive galaxies. Our HST data reach ∼2–4 magnitudes below the tip of the red giant branch (TRGB) for each dwarf, allowing us to measure their distances, structural properties, and recent star formation histories (SFHs). All three galaxies contain a complex stellar population of young and old stars, and are typical of field galaxies in this mass regime (M V = −10.62 ± 0.08 and $D = 2.16_{-0.07}^{+0.08}$ Mpc for Pavo, M V = −10.91 ± 0.10 and D = 3.34 ± 0.11 Mpc for Corvus A, and M V = −12.02 ± 0.12 and $D = 6.50_{-0.11}^{+0.15}$ Mpc for Kamino). Our HST-derived SFHs reveal differences among the three dwarfs: Pavo and Kamino show relatively steady, continuous star formation, while Corvus A formed ∼60% of its stellar mass by 10 Gyr ago. These results align with theoretical predictions of diverse evolutionary pathways for isolated low-mass galaxies.

Mutlu-Pakdil, Burçin [Dartmouth College, Hanover, ↗
NASA NTRS1977

Hypersonic transport technology

The possibility of developing a hypersonic commercial transport (HST) for the early 21st century is explored in terms of potential performance characteristics and recent advances in propulsion and structures technology. Range-gross weight characteristics indicate that a 200 passenger, Mach 6 aircraft with a range of 9200 km (5000 n.mi.) would have a gross take-off weight not too different from that of current wide-body subsonic transports. The low cruise sonic boom overpressures generated by the HST opens the possibility of supersonic overland flight which, if permitted, would greatly increase the attractiveness of this type of aircraft. Recent advances in hypersonic propulsion systems and long-lived hypersonic aircraft structure are also discussed. The airframe-integrated scramjet and the actively-cooled airframe structure are identified as the most promising candidates for the HST and current approaches are described in some detail.

Kirkham, F. S.↗
NASA NTRS1986

The Hubble Space Telescope Scientific Instruments

The paper describes the status of the five Scientific Instruments (SI's) to be flown on the Hubble Space Telescope (HST) which is planned to be launched by the Space Transportation System in the last half of 1986. Concentration is on the testing experience for each of the instruments both at the instrument level and in conjunction with the other instruments and subsystems of the HST. Since the Acceptance/Flight Qualification Program of the HST is currently underway a description of the test and verification plans to be accomplished prior to shipment to the Kennedy Space Center (KSC) and pre-launch tests plans prior to launch are provided. The paper concludes with a brief description of anticipated orbital performance.

Moore, J. V.↗
NASA NTRS1987

Development of the helium signature test for orbiter main propulsion system revalidation between flights

This paper presents the development of a test technique for revalidation of the Space Shuttle Orbiter Main Propulsion System during ground turnaround operations between flights of the Space Transportation System (STS). The Main Propulsion System consists of the three Space Shuttle Main Engines (SSME's) and the Main Propulsion System (MPS) connecting the SSME's to the orbiter/ground and orbiter/External Tank (ET) interfaces. The Helium Signature Test (HST) performs an end-to-end leak check of the MPS/SSME subsystems that serves as a final validation of those systems for reuse. The test was initially developed during the ground processing flow prior to the STS-6 launch of orbiter Challenger. The test was developed to fulfill a requirement for an overall subsystem leak check as a result of experience gained during the STS-6 Challenger Flight Readiness Firing (FRF) series, during which leaks were encountered in the SSME's that were not detected by routine fluid joint leak checks. The HST technique is described in detail, including orbiter and test equipment configuration, and compared to other leak detection methods used to revalidate MPS/SSME systems for reuse. The HST data base accumulated since STS-6 is summarized and future test applications are described.

Bilardo, Vincent J., Jr.↗
NASA NTRS1987

Feasibility of observations of stratospheric trace gases using the Hubble Space Telescope

The stellar occultation method has been successfully used in the past from orbiting observatories to measure concentrations of certain trace gases in the earth's mesosphere. The greatly improved spectroscopic capabilities of the Hubble Space Telescope (HST) have prompted recent suggestions for its use to measure stratospheric C10. This possibility is examined along with that for other species relevant to the chemistry of the ozone layer. It is concluded that stratospheric (as opposed to mesospheric) observations with HST are not practical, in part because of its orbital and pointing characteristics, but primarily because the high opacity of stratospheric ozone over most of the bandpass of the HST's most suitable spectrometer will obscure observation of other trace species, such as C10, having mixing ratios of less than 0.001.

Jaramillo, M.↗
NASA NTRS1986

Technology and the Hubble Space Telescope Satellite

The hardware components of the HST and their capabilities are examined. The free-flying satellite observatory is 13.1-m long, 4.2-m in diameter, weighs 11,000 kg, is in a 600-km orbit, and is remotely controlled. The HST is divided into four sections: (1) optical telescope assembly, (2) support system module, (3) scientific instruments, and (4) solar arrays. The optical telescope assembly contains the f24 Cassegrain primary optics. The support system module is the host spacecraft for the optical and scientific system. The scientific instruments consist of the Wide Field Planetary Camera, Faint Object Camera, High Speed Photometer, Faint Object Spectrograph, and High Resolution Spectrograph; and the 48,760 solar cells are deployed on-orbit in a window shade fashion. Consideration is given to the operation and maintenance of the HST.

Odom, James B.↗
NASA NTRS1987

Hubble Space Telescope servicing - Experience base for a new era

An account is given of the conceptual evolution of the Hubble Space Telescope's (HST) maintenance methodology, and the belated recognition of its long-term support requirements, as well as measures conceived for the extension of this orbiting observatory's service life, and the prospective benefits derivable by comparable programs from HST experience. Attention is given to HST cost and capability tradeoffs, the maintenance concept's definition, the integrated logistic support planning instituted by the program and its failure-prediction methods, as well as the institutional support base employed.

Welch, James C.↗
NASA NTRS1987

Ultraviolet observations of starburst systems with Astro and the Hubble Space Telescope

The capabilities of the Astro observatory and the Hubble Space Telescope (HST) for UV astronomical observations are discussed. The advantages of using UV for studying extragalactic problems are reviewed, including sensitivity to hot sources, the rich UV line spectra, sensitivity to interstellar dust, and dark UV sky background. The HST and Astro instrumentation and plans for launching the systems are described. Possibile uses of HST and Astro include the study of massive stars in the Galaxy and nearby galaxies, interstellar medium, the UV excess component in old stellar populations, deep UV surveys (filter imaging and slitless spectroscopy), active galactic nuclei, quasars, and starburst systems.

O'Connell, Robert W.↗
NASA NTRS1987

Long-lived space observatories for astronomy and astrophysics

NASA's plan to build and launch a fleet of long-lived space observatories that include the Hubble Space Telescope (HST), the Gamma Ray Observatory (GRO), the Advanced X Ray Astrophysics Observatory (AXAF), and the Space Infrared Telescope Facility (SIRTF) are discussed. These facilities are expected to have a profound impact on the sciences of astronomy and astrophysics. The long-lived observatories will provide new insights about astronomical and astrophysical problems that range from the presence of planets orbiting nearby stars to the large-scale distribution and evolution of matter in the universe. An important concern to NASA and the scientific community is the operation and maintenance cost of the four observatories described above. The HST cost about $1.3 billion (1984 dollars) to build and is estimated to require $160 million (1986 dollars) a year to operate and maintain. If HST is operated for 20 years, the accumulated costs will be considerably more than those required for its construction. Therefore, it is essential to plan carefully for observatory operations and maintenance before a long-lived facility is constructed. The primary goal of this report is to help NASA develop guidelines for the operations and management of these future observatories so as to achieve the best possible scientific results for the resources available. Eight recommendations are given.

Savage, Blair D.↗
NASA NTRS1988

Automated observation scheduling for the VLT

It is becoming increasingly evident that, in order to optimize the observing efficiency of large telescopes, some changes will be required in the way observations are planned and executed. Not all observing programs require the presence of the astronomer at the telescope: for those programs which permit service observing it is possible to better match planned observations to conditions at the telescope. This concept of flexible scheduling has been proposed for the VLT: based on current and predicted environmental and instrumental observations which make the most efficient possible use of valuable time. A similar kind of observation scheduling is already necessary for some space observatories, such as Hubble Space Telescope (HST). Space Telescope Science Institute is presently developing scheduling tools for HST, based on the use of artificial intelligence software development techniques. These tools could be readily adapted for ground-based telescope scheduling since they address many of the same issues. The concept are described on which the HST tools are based, their implementation, and what would be required to adapt them for use with the VLT and other ground-based observatories.

Johnston, Mark D.↗
NASA NTRS1990

Spike: Artificial intelligence scheduling for Hubble space telescope

Efficient utilization of spacecraft resources is essential, but the accompanying scheduling problems are often computationally intractable and are difficult to approximate because of the presence of numerous interacting constraints. Artificial intelligence techniques were applied to the scheduling of the NASA/ESA Hubble Space Telescope (HST). This presents a particularly challenging problem since a yearlong observing program can contain some tens of thousands of exposures which are subject to a large number of scientific, operational, spacecraft, and environmental constraints. New techniques were developed for machine reasoning about scheduling constraints and goals, especially in cases where uncertainty is an important scheduling consideration and where resolving conflicts among conflicting preferences is essential. These technique were utilized in a set of workstation based scheduling tools (Spike) for HST. Graphical displays of activities, constraints, and schedules are an important feature of the system. High level scheduling strategies using both rule based and neural network approaches were developed. While the specific constraints implemented are those most relevant to HST, the framework developed is far more general and could easily handle other kinds of scheduling problems. The concept and implementation of the Spike system are described along with some experiments in adapting Spike to other spacecraft scheduling domains.

Johnston, Mark↗
NASA NTRS1990

What the longest exposures from the Hubble Space Telescope will reveal

NASA's Hubble Space Telescope (HST) is expected to reveal the sizes, shapes, and contents of faint, distant galaxies. Results are presented from detailed simulations of the longest HST exposures of representative galaxy fields, together with predictions of the numbers and types of objects that will emerge on exposures of different duration. Observations made during the first year of HST operations should confirm or disprove the quantitative understanding of telescopic capabilities reflected in the present simulations and predictions; significant departures would indicate that novel populations of astronomical objects may be present.

Bahcall, John N.↗
NASA NTRS1990

The design and development of the Hubble space telescope neutral buoyancy trainer

The design and fabrication of Hubble Space Telescope (HST) Extra Vehicular Activity (EVA) training hardware for zero-gravity simulations in the Marshall Space Flight Center Neutral Buoyancy Simulator (NBS) are discussed. The HST NBS hardware was also used to support flight hardware development and development of EVA crew servicing procedures. The design and fabrication of simulator training and development hardware, the associated test support from utility divers, test conductors, and test subjects have all been with the common goal of enabling HST program management to use NBS EVA data to make design and program decisions.

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

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 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.↗
NASA NTRS1990

Hubble Space Telescope. Update: 18 months in orbit

In April 1990, Space Shuttle Discovery launched the Hubble Space Telescope (HST). An 18 month in-orbit update of the operations and performance of the HST is presented. Numerous color photographs are shown of objects already observed, and mission plans are presented for future observations by the HST.

Source record↗
NASA NTRS1992

A gravitational lens candidate discovered with the Hubble Space Telescope

Evidence is reported for gravitational lensing of the high-redshift (z = 3.8) quasar 1208 + 101, observed as part of the Snapshot survey with the HST Planetary Camera. An HST V image taken on gyroscopes resolves the quasar into three point-source components, with the two fainter images having separations of 0.1 and 0.5 arcsec from the central bright component. A radio observation of the quasar with the VLA at 2 cm shows that, like most quasars of this redhsift, 1208 + 101 is radio quiet. Based on positional information alone, the probability that the observed optical components are chance superpositions of Galactic stars is small, but not negligible. Analysis of a combined ground-based spectrum of all three components, using the relative brightnesses of the HST image, supports the lensing hypothesis. If all the components are lensed images of the quasar, the observed configuration cannot be reproduced by simple lens models.

Maoz, Dan↗