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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 199 records · Page 11
All sourcesNASA NTRSDOE OSTI
NASA NTRS2007

Gamma-Ray Bursts: A Mystery Story

With the success of the Swift Gamma-Ray Burst Explorer currently in orbit, this is quite an exciting time in the history of Gamma Ray Bursts (GRBs). The study of GRBs is a modern astronomical mystery story that began over 30 years ago with the serendipitous discovery of these astronomical events by military satellites in the late 1960's. Until the launch of BATSE on the Compton Gamma-ray Observatory, astronomers had no clue whether GRBs originated at the edge of our solar system, in our own Milky Way Galaxy or incredibly far away near the edge of the observable Universe. Data from BATSE proved that GRBs are distributed isotropically on the sky and thus could not be the related to objects in the disk of our Galaxy. Given the intensity of the gamma-ray emission, an extragalactic origin would require an astounding amount of energy. Without sufficient data to decide the issue, a great debate continued about whether GRBs were located in the halo of our own galaxy or were at extragalactic - even cosmological distances. This debate continued until 1997 when the BeppoSAX mission discovered a fading X-ray afterglow signal in the same location as a GRB. This discovery enabled other telescopes, to observe afterglow emission at optical and radio wavelengths and prove that GRBs were at cosmological distances by measuring large redshifts in the optical spectra. Like BeppoSAX Swift, slews to new GRB locations to measure afterglow emission. In addition to improved GRB sensitivity, a significant advantage of Swift over BeppoSAX and other missions is its ability to slew very quickly, allowing x-ray and optical follow-up measurements to be made as early as a minute after the gamma-ray burst trigger rather than the previous 6-8 hour delay. Swift afterglow measurements along with follow-up ground-based observations, and theoretical work have allowed astronomers to identify two plausible scenarios for the creation of a GRB: either through core collapse of super massive stars or colliding compact objects in distant galaxies. The pieces of the puzzle are beginning to fall into place and yet the story isn't quite finished. I will frame the history of gamma-ray bursts as a mystery story and will end with a description of what we still don't know and what we'll have to do to get the next clues.

Parsons, Ann↗
NASA NTRS1992

Remote observatory access via the Advanced Communications Technology Satellite

An investigation of the potential for using the ACTS to provide the data distribution network for a distributed set of users of an astronomical observatory has been conducted. The investigation consisted of gathering the data and interface standards for the ACTS network and the observatory instrumentation and telecommunications devices. A simulation based on COMNET was then developed to test data transport configurations for real-time suitability. The investigation showed that the ACTS network should support the real-time requirements and allow for growth in the observatory needs for data transport.

Horan, Stephen↗
DOE OSTI2023

The Astroparticle Detectors Array—An Educational Project in Cosmic Ray Physics

ADA, short for Astroparticle Detectors Array, is an educational project aiming to detect cosmic radiation and possibly high-energy particles known as ultra-high-energy cosmic rays (UHECRs) or even to spot a supernova event. Its working process is the same as that used in professional cosmic ray observatories: it consists of simple detectors spread over the entire Italian territory and beyond. The detectors are hosted among high schools, associations, and private astronomical observatories. ADA has been operating since 2013 and was brought about with the intention of promoting astroparticle physics to any given level of outreach. Furthermore, ADA is becoming an interesting tool not only for teachers but also for independent and keen scientists. Over the years, we have discovered the importance of having a long series of data for studying the relation between and among cosmic rays, weather, and space weather and to investigate the main cause of oscillations in cosmic ray data. In this paper, we show what we find to be the most compelling results, such as the beautiful symmetry of the behavior between muons and the atmospheric temperature and, likewise, the evident anti-correlation between the intensity of the muons at ground level compared with solar activity.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
NASA NTRS1977

The Space Telescope

The Space Telescope is a NASA program intended to launch a long-lived 2.4 meter astronomical observatory in 1983. It will contain optical and pointing systems producing a resolution of at least 0.1 arc seconds over periods of 10 hours. This capability will allow a new regime of imaging astronomical observations to be undertaken from below Lyman-alpha to the millimeter wavelength range. The optical, optical metering structure, pointing and guidance system, and control system will be described.

Odell, C. R.↗
DOE OSTI2026

Spatially resolved polarization swings in the supermassive binary black hole candidate OJ 287 with first Event Horizon Telescope observations

We present the first Event Horizon Telescope 1.3 mm observations of the supermassive binary black hole candidate OJ 287. The observations achieved an unprecedented angular resolution of 18 μas and reveal significant structural and polarization variability over just five days, marking the shortest timescale on which such changes have been directly imaged in this source. The inner jet exhibits a twisted ridgeline structure, with features displaying apparent superluminal motions up to about 22 c. The linear polarization maps reveal three main polarized features whose electric-vector position angles (EVPAs) change substantially over the time span of our observations, including a component with a radial polarization consistent with being produced by a recollimation shock. Most notably, we directly resolved two innermost jet components whose EVPAs rotate in opposite directions. The faster component, moving at 2.4 ± 0.9 μas/day (17.4 ± 6.5 c), exhibits counterclockwise EVPA swings of roughly 3.7° per day, while the slower component, with a proper motion of 1.4 ± 0.3 μas/day (10.2 ± 2.2 c), rotates clockwise at approximately 2.5° per day. Previous studies inferred helical magnetic fields in AGN jets from time-resolved or integrated polarization variability but lacked the angular resolution to directly image this effect. Our results provide spatially resolved evidence that a helical magnetic field threads the jet’s collimation and acceleration zone, ruling out models based on the superposition of unresolved components. Our analysis suggests that propagating shocks interact with a Kelvin–Helmholtz plasma instability, illuminating different phases of the helical magnetic field and producing the observed polarization spatial and temporal variability. Moreover, our model naturally accounts for the more rapid polarization rotation observed in the faster moving component. Our model predicts even more rapid swings in polarization, which could be tested with future observations featuring a more densely sampled time coverage.

OJ 287↗
NASA NTRS1983

Space Telescope maintenance and refurbishment

The Space Telescope (ST) represents a new concept regarding spaceborne astronomical observatories. Maintenance crews will be brought to the orbital worksite to make repairs and replace scientific instruments. For major overhauls the telescope can be temporarily returned to earth with the aid of the Shuttle. It will, thus, be possible to conduct astronomical studies with the ST for two decades or more. The five first-generation scientific instruments used with the ST include a wide field/planetary camera, a faint object camera, a faint object spectrograph, a high resolution spectrograph, and a high speed photometer. Attention is given to the optical telescope assembly, the support systems module, aspects of mission and science operations, unscheduled maintenance, contingency orbital maintenance, planned on-orbit maintenance, ground maintenance, ground refurbishment, and ground logistics.

Trucks, H. F.↗
NASA NTRS1993

Hubble Space Telescope First Servicing Mission Prelaunch Mission Operation Report

The Hubble Space Telescope (HST) is a high-performance astronomical telescope system designed to operate in low-Earth orbit. It is approximately 43 feet long, with a diameter of 10 feet at the forward end and 14 feet at the aft end. Weight at launch was approximately 25,000 pounds. In principle, it is no different than the reflecting telescopes in ground-based astronomical observatories. Like ground-based telescopes, the HST was designed as a general-purpose instrument, capable of using a wide variety of scientific instruments at its focal plane. This multi-purpose characteristic allows the HST to be used as a national facility, capable of supporting the astronomical needs of an international user community. The telescope s planned useful operational lifetime is 15 years, during which it will make observations in the ultraviolet, visible, and infrared portions of the spectrum. The extended operational life of the HST is possible by using the capabilities of the Space Transportation System to periodically visit the HST on-orbit to replace failed or degraded components, install instruments with improved capabilities, re-boost the HST to higher altitudes compensating for gravitational effects, and to bring the HST back to Earth when the mission is terminated. The largest ground-based observatories, such as the 200-inch aperture Hale telescope at Palomar Mountain, California, can recognize detail in individual galaxies several billion light years away. However, like all earthbound devices, the Hale telescope is limited because of the blurring effect of the Earth s atmosphere. Further, the wavelength region observable from the Earth s surface is limited by the atmosphere to the visible part of the spectrum. The very important ultraviolet portion of the spectrum is lost. The HST uses a 2.4-meter reflective optics system designed to capture data over a wavelength region that reaches far into the ultraviolet and infrared portions of the spectrum.

Source record↗
NASA NTRS2009

The International X-ray Observatory

The International X-Ray Observatory, a joint NASA-ESA-JAXA effort, is a next generation X-ray telescope that will answer many fundamental questions in contemporary astrophysics such as how do supermassive black holes influence galaxy evolution and how do galaxy clusters evolve (and how does this constrain dark energy and dark matter)? As a powerful astronomical observatory, IXO will also address questions ranging from the neutron star equation of state to the distribution and dynamical state of intergalactic material. X-ray spectroscopy, polarimetry, and timing studies provided by IXO's instruments will give detailed measures of abundances, temperatures, densities, magnetic fields and gravitational potentials. These measurements will be complementary to the next generation of observatories such as ALMA, JWST, and future ground-based optical-NIR telescopes. This mission will be ready for launch in the 2020-2021 timeframe and will launch on an Atlas V or Ariane V launch vehicle to L2. It employs a deployable optical bench to achieve the 20 meter focal length and a suite of five instruments. This talk will describe the motivating science for this mission as well as the spacecraft, instruments and optics

Hornschemeier, A.↗
NASA NTRS1989

Science exploration opportunities for manned missions to the Moon, Mars, Phobos, and an asteroid

Scientific exploration opportunities for human missions to the Moon, Phobos, Mars, and an asteroid are addressed. These planetary objects are of prime interest to scientists because they are the accessible, terresterial-like bodies most likely to be the next destinations for human missions beyond Earth orbit. Three categories of science opportunities are defined and discussed: target science, platform science, and cruise science. Target science is the study of the planetary object and its surroundings (including geological, biological, atmospheric, and fields and particle sciences) to determine the object's natural physical characteristics, planetological history, mode of origin, relation to possible extant or extinct like forms, surface environmental properties, resource potential, and suitability for human bases or outposts. Platform science takes advantage of the target body using it as a site for establishing laboratory facilities and observatories; and cruise science consists of studies conducted by the crew during the voyage to and from a target body. Generic and specific science opportunities for each target are summarized along with listings of strawman payloads, desired or required precursor information, priorities for initial scientific objectives, and candidate landing sites. An appendix details the potential use of the Moon for astronomical observatories and specialized observatories, and a bibliography compiles recent work on topics relating to human scientific exploration of the Moon, Phobos, Mars, and asteroids. It is concluded that there are a wide variety of scientific exploration opportunities that can be pursued during human missions to planetary targets but that more detailed studies and precursor unmanned missions should be carried out first.

Nash, Douglas B.↗
NASA NTRS1976

Space Telescope science program

The advantages of an orbiting astronomical observatory are discussed. The principal consequence of having the telescope in space is that more light will be concentrated in the images, which has two effects: (1) the ability to view more accurately complex sources, and (2) the ability to detect and measure extremely faint point sources. The fact that higher resolution will reveal complex and unexpected detail is demonstrated by comparing a well-known astronomical scene with an image artifically degraded. Five scientific functions are envisaged for the Space Telescope. The first flight will feature performance of four of these functions with these four pieces of equipment: the f24 field camera, the faint object spectrograph, the infrared photometer, and the faint object camera. Astrometry will be done not by any specialized scientific instrument but with the fine guidance and pointing system.

Odell, C. R.↗
NASA NTRS1984

The National Symposium and Workshop on Optical Platforms, Huntsville, AL, June 12-14, 1984, Proceedings

The present conference is concerned with space-based observatories (including future systems), interplanetary observation platforms, Space Station optical utilization, orbital earth viewing systems, and Spacelab's use as an observations platform. Attention is given to the pointing system for the Space Telescope, the Advanced X-ray Astrophysics Facility, the conceptual definition of the Space IR Telescope Facility's spacecraft, satellite servicing in light of the Solar Maximum Repair Mission, a large deployable reflector telescope concept, moon-based astronomical observatories, Space Station-based remote sensing of the earth, optical systems is geosynchronous orbit, multispectral linear array detector technology, Spacelab-based space plasma and materials processing investigations, and space construction technology for large space observatories. Also discussed are military optical platforms for sea, land and air stationing.

Wyman, C. L.↗
NASA NTRS1972

The large space telescope instrumentation.

Aspects of the Large Space Telescope project (LST) as it is developing at the Goddard Space Flight Center are presented and a brief discussion is given of the types of observing program that might be handled. The special characteristics of an LST are large light-gathering power, good spectral efficiency from 900 A to 5 microns, near diffraction limited performance, launch by the space shuttle into a low orbit like that of the Orbiting Astronomical Observatories, and a lifetime of at least 10 years. A basic set of instruments to be used with the telescope might include on-axis cameras with broad-band filter response, an imaging spectrograph, a low-resolution spectrograph, a high-resolution spectrograph, spectrum scanners, narrow-band photometers, interferometers for use in the near infrared, polarimeters for use in the ultraviolet, and provision for measuring the time variations of the light from astronomical objects on a scale of milli-seconds as well as on a scale of minutes, hours, days, and weeks.

Underhill, A. B.↗
DOE OSTI2021

Detecting optical transients using artificial neural networks and reference images from different surveys

ABSTRACT We present a technique to detect optical transients based on an artificial neural networks method. We describe the architecture of two networks capable of comparing images of the same part of the sky taken by different telescopes. One image corresponds to the epoch in which a potential transient could exist; the other is a reference image of an earlier epoch. We use data obtained by the Dr. Cristina V. Torres Memorial Astronomical Observatory and archival reference images from the Sloan Digital Sky Survey. We trained a convolutional neural network and a dense layer network on simulated source samples and then tested the trained networks on samples created from real image data. Autonomous detection methods replace the standard process of detecting transients, which is normally achieved by source extraction of a difference image followed by human inspection of the detected candidates. Replacing the human inspection component with an entirely autonomous method would allow for a rapid and automatic follow-up of interesting targets of opportunity. The toy-model pipeline that we present here is not yet able to replace human inspection, but it might provide useful hints to identify potential candidates. The method will be further expanded and tested on telescopes participating in the Transient Optical Robotic Observatory of the South Collaboration.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2024

Dr. Sahar Said Allam (1964-2022): A Memoriam

In this short talk, we memorialize the scientific life of AAS member Dr. Sahar Said Allam (1964-2022), an alumna of Cairo University and the National Research Institute of Astronomy \& Geophysics (NRIAG). Her scientific career took her to the Universitaet Potsdam (Germany), New Mexico State University (USA), the Space Telescope Science Institute (USA), and the Fermi National Accelerator Laboratory (Fermilab; USA), as well as to astronomical observatories in New Mexico, Arizona, Hawaii, Chile, and Australia. Among other projects, she worked on the Sloan Digital Sky Survey (SDSS) and the Dark Energy Survey (DES), achieving the coveted “Builders” status on both these projects. She was the discoverer of the (at the time) brightest known Lyman Break Galaxy, the strongly lensed “8 O’Clock Arc”, and played an important role in the discovery of the optical counterpart to the gravitational wave event GW170817. During her final illness, she began work as a Data Preview 0 (“DP0”) De legate for the Vera C. Rubin Legacy Survey of Space & Time (LSST) and was even the Principal Investigator on a successful observing proposal submitted posthumously. The asteroid “135979 Allam” is named after her.

Tucker, Douglas L.↗
DOE OSTI2024

helioLuna: Prospect for cislunar spacecraft and near-earth asteroid detection using heliostat fields at night

We experimentally and computationally investigate a proposed frequency-domain method for detecting and tracking cislunar spacecraft and near-earth asteroids using heliostat fields at night. Unlike imaging, which detects spacecraft and asteroids by their streak in sidereally-fixed long-exposure photographs, our proposed detection method oscillates the orientation of heliostats concentrating light from the stellar field and measures the light’s photocurrent power spectrum at sub-milliHertz resolution. If heliostat oscillation traces out an ellipse fixed in the galactic coordinate system, spacecraft or asteroids produce a peak in photocurrent power spectrum at a frequency slightly shifted from the starlight peak. The frequency shift is on the scale of milliHertz and proportional to apparent angular rate relative to sidereal. Relative phase corresponds to relative angular position, enabling tracking. A potential advantage of this frequency-domain method over imaging is that detectivity improves with apparent angular rate and number of heliostats. Since heliostats are inexpensive compared to an astronomical observatory and otherwise unused at night, the proposed method may cost-effectively augment observatory systems such as NASA’s Asteroid Terrestrial-impact Last Alert System (ATLAS).

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2020

High-resolution Spectroscopic Study of Dwarf Stars in the Northern Sky: Lithium, Carbon, and Oxygen Abundances

Abundances of lithium, carbon, and oxygen have been derived using spectral synthesis for a sample of 249 bright F, G, and K Northern Hemisphere dwarf stars from the high-resolution spectra acquired with the VUES spectrograph at the $Mol\dot{e}tai$ Astronomical Observatory of Vilnius University. The sample stars have metallicities, effective temperatures, and ages between (–0.7 ÷ 0.4) dex, (5000 ÷ 6900) K, (1 ÷ 12) Gyr, accordingly. We confirm a so far unexplained lithium abundance decrease at supersolar metallicities—A(Li) in our sample stars, which drop by 0.7 dex in the [Fe/H] range from +0.10 to +0.55 dex. Furthermore, we identified stars with similar ages, atmospheric parameters, and rotational velocities, but with significantly different lithium abundances, which suggests that additional specific evolutionary factors should be taken into account while interpreting the stellar lithium content. Nine stars with predominantly supersolar metallicities, i.e., about 12% among 78 stars with C and O abundances determined, have the C/O number ratios larger than 0.65, thus may form carbon-rich rocky planets. Ten planet-hosting stars, available in our sample, do not show a discernible difference from the stars with no planets detected regarding their lithium content.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2022

The Astropy Project: Sustaining and Growing a Community-oriented Open-source Project and the Latest Major Release (v5.0) of the Core Package

The Astropy Project supports and fosters the development of open-source and openly developed Python packages that provide commonly needed functionality to the astronomical community. A key element of the Astropy Project is the core package astropy, which serves as the foundation for more specialized projects and packages. In this article, we summarize key features in the core package as of the recent major release, version 5.0, and provide major updates on the Project. We then discuss supporting a broader ecosystem of interoperable packages, including connections with several astronomical observatories and missions. We also revisit the future outlook of the Astropy Project and the current status of Learn Astropy. We conclude by raising and discussing the current and future challenges facing the Project.

79 ASTRONOMY AND ASTROPHYSICS↗