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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 91 records · Page 5
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NASA NTRS1983

The Arecibo Observatory as an MST radar

The radars and other systems at the Arecibo Observatory were designed and built, originally, for incoherent-scatter and radio-astronomy research. More recently, important additions have been made for planetary radar and artificial RF heating of the ionosphere. Although designed and built for a different application, these systems have shown to be very powerful tools for tropospheric, stratospheric and mesospheric research. The Observatory at present has two main radars: one at 430 and the other at 2380 MHz. In addition, 50-MHz MST radar work has been done using portable transmitters brought to the Observatory for this purpose. This capability will become permanent with the recent acquisition of a transmitter at this frequency. Furthermore, control and data processing systems have been developed to use the powerful HF transmitter and antennas of the HF-heating facility as an HF bistatic radar. A brief description of the four radars available at the Observatory is presented.

Woodman, R. F.↗
NASA NTRS1985

Astronomical research at the Hopkins Phoenix Observatory

After trying astrophotography and radio astronomy it was decided that the best way to do meaningful astronomical research at a small private observatory was by doing photoelectric photometry. Having the observatory located in the back yard of a private residence affors the luxury of observing any time the sky conditions permit. Also modest equipment is all that is needed to do accurate UBV photometry of stars 8th magnitude and brighter. Since beginning in 1980 the Hopkins Phoenix Observatory has published papers on several RS CVn star systems, 31 Cygni, 22 Vul, 18 Tau Per, and has followed the 1982-1984 eclipse of Epsilon Aurigae from its start to the present with over 1000 UBV measurements. In addition the Hopkins Phoenix Observatory has developed several pieces of photometry equipment including the HPO PEPH-101 photometer head and photon counting electronics.

Hopkins, J. L.↗
NASA NTRS1986

Arecibo Observatory support of the US international cometary Explorer mission encounter at comet Giacobini-Zinner

The Arecibo Observatory in Puerto Rico participated in the support of the U.S. International Cometary Explorer (ICE) mission when the ICE spacecraft passed through the tail of comet Giacobini-Zinner on September 11, 1985. The Arecibo Observatory is a research facility of the National Astronomy and Ionosphere Center (NAIC) operated by Cornell University under contract to the National Science Foundation (NSF). Coverage of the encounter involved the use of the observatory's 305-m (1000-ft) radio reflector antenna and RF and data system equipment fabricated or modified specifically for support of the ICE mission. The successful implementation, testing, and operation of this temporary receive, record, and data relay capability resulted from a cooperative effort by personnel at the Arecibo Observatory, the Goddard Space Flight Center, and the Jet Propulsion Laboratory.

Gordon, D. D.↗
NASA NTRS1987

Servicing operations for the SIRTF Observatory at the Space Station

This paper describes the servicing requirements, plans, and proposed Space Station-based servicing operations for the Space Infrared Telescope Facility (SIRTF) Observatory. SIRTF is a cryogenically-cooled, long-life, one meter class space telescope which will be operated by NASA as a free-flying observatory for infrared astronomy, in the mid-1990's. To achieve its 5-year lifetime requirement (10 year goal), SIRTF must be replenished periodically with cryogenic helium and have its life-limited modular subsystems replaced; capability for contingency repair of warm components will also be provided in the Observatory design. A general description of the SIRTF Observatory is given, including options for the support systems (spacecraft). The overall servicing philosophy and plans are addressed with scheduling and needed support elements described. A proposed Space Station-based servicing scenario is described, including orbital transfer, servicing and checkout operations. A detailed description and timeline for liquid helium replenishment operations is provided, including a conceptual design and technology development program for the cryogenic helium transfer dewar (tanker). Finally, a preliminary SIRTF spares/logistics philosophy is outlined, including tradeoffs to be considered.

Wiltsee, Christopher B.↗
NASA NTRS1988

Planetary research at Lowell Observatory

Scientific goals include a better determination of the basic physical characteristics of cometary nuclei, a more complete understanding of the complex processes in the comae, a survey of abundances and gas/dust ratios in a large number of comets, and measurement of primordial (12)C/(13)C and (14)N/(15)N ratios. The program also includes the observation of Pluto-Charon mutual eclipses to derive dimensions. Reduction and analysis of extensive narrowband photometry of Comet Halley from Cerro Tololo Inter-American Observatory, Perth Observatory, Lowell Observatory, and Mauna Kea Observatory were completed. It was shown that the 7.4-day periodicity in the activity of Comet Halley was present from late February through at least early June 1986, but there is no conclusive evidence of periodic variability in the preperihelion data. Greatly improved NH scalelengths and lifetimes were derived from the Halley data which lead to the conclusion that the abundance of NH in comets is much higher than previously believed. Simultaneous optical and thermal infrared observations were obtained of Comet P/Temple 2 using the MKO 2.2 m telescope and the NASA IRTF. Preliminary analysis of these observations shows that the comet's nucleus is highly elongated, very dark, and quite red.

Baum, William A.↗
NASA NTRS1989

Lunar observatories

Issues related to the establishment of lunar observatories are briefly addressed. The advantages of placing an observatory in a crater at one of the poles, where permanent darkness exists, are pointed out, and the methods required to emplace and operate such an observatory are considered. Planning for the installation of the first set of observatory instruments is discussed.

Burke, J. D.↗
NASA NTRS1990

Lunar astronomical observatories - Design studies

The best location in the inner solar system for the grand observatories of the 21st century may be the moon. A multidisciplinary team including university students and faculty in engineering, astronomy, physics, and geology, and engineers from industry is investigating the moon as a site for astronomical observatories and is doing conceptual and preliminary designs for these future observatories. Studies encompass lunar facilities for radio astronomy and astronomy at optical, ultraviolet, and infrared wavelengths of the electromagnetic spectrum. Although there are significant engineering challenges in design and construction on the moon, the rewards for astronomy can be great, such as detection and study of earth-like planets orbiting nearby stars, and the task for engineers promises to stimulate advances in analysis and design, materials and structures, automation and robotics, foundations, and controls. Fabricating structures in the reduced-gravity environment of the moon will be easier than in the zero-gravity environment of earth orbit, as Apollo and space-shuttle missions have revealed. Construction of observatories on the moon can be adapted from techniques developed on the earth, with the advantage that the moon's weaker gravitational pull makes it possible to build larger devices than are practical on earth.

Johnson, Stewart W.↗
NASA NTRS1991

The great observatories for space astrophysics

The nation's strategy for astrophysics research during the rest of this century and into the next is a coordinated, multispectral examination of the universe. NASA plans to launch a family of large orbital observatories, each tuned to a different part of the electromagnetic spectrum. They are as follows: the Gamma Ray Observatory (GRO); the Advanced X Ray Astrophysics Facility (AXAF); the Hubble Space Telescope (HST); and the Space Infrared Telescope Facility (SIRTF). To complement these sensitive space telescopes, a powerful new radio observatory system is envisioned: the Very Long Baseline Array (VLBA), an intercontinental network of radio telescopes, working with radio observatories in space to perform orbiting very long baseline interferometry (OVLBI). Observing the universe across the spectrum requires different kinds of telescopes based on quite different techniques of detection. An optical telescope has little in common with a gamma ray detector; they do not look alike, nor do they operate on the same principles. No single telescope can answer all the questions or make all the discoveries that await.

Source record↗
NASA NTRS1991

FLARE: The Far Side Lunar Research Expedition. A design of a far side lunar observatory

This document outlines the design completed by members of Lone Star Aerospace, Inc. (L.S.A.) of a lunar observatory on the far side of the Moon. Such a base would not only establish a long term human presence on the Moon, but would also allow more accurate astronomical data to be obtained. A lunar observatory is more desirable than an Earth based observatory for the following reasons: instrument weight is reduced due to the Moon's weaker gravity; near vacuum conditions exist on the Moon; the Moon has slow rotation to reveal the entire sky; and the lunar surface is stable for long baseline instruments. All the conditions listed above are favorable for astronomical data recording. The technical aspects investigated in the completion of this project included site selection, mission scenario, scientific instruments, communication and power systems, habitation and transportation, cargo spacecraft design, thermal systems, robotic systems, and trajectory analysis. The site selection group focused its efforts on finding a suitable location for the observatory. Hertzsprung, a large equatorial crater on the eastern limb, was chosen as the base site.

Bishop, David W.↗
NASA NTRS1999

The Chandra X-Ray Observatory: Overview

The Chandra X-ray Observatory, formerly, the Advanced X-ray Astrophysics Facility (AXAF), has now joined the Hubble Space Telescope and the Compton Gamma-Ray Observatory, as the third of NASA's "Great Observatories". Chandra provides unprecedented arcsecond imaging and spectrometric imaging and high-resolution dispersive spectroscopy, to address a large range of topics in x-ray astronomy and astrophysics. Here we provide an overview of the Observatory, its operation, and initial results.

Weisskopf, M. C.↗
NASA NTRS2000

The Chandra X-Ray Observatory: First Year of Operation

The Chandra X-ray Observatory - formerly, the Advanced X-ray Astrophysics Facility (AXAF) - has now joined the Hubble Space Telescope and the Compton Gamma-Ray Observatory, as the third of NASA's "Great Observatories". Chandra provides unprecedented arcsecond imaging and spectrometric imaging and high-resolution dispersive spectroscopy, to address a large range of topics in x-ray astronomy and astrophysics. Here we provide an overview of the Observatory, its operation, and results obtained during its first year of operation.

Weisskopf, M. C.↗
NASA NTRS2001

An Overview of the Performance and Scientific Results From the Chandra X-Ray Observatory (CXO)

The Chandra X-Ray Observatory (CXO), the x-ray component of NASA's Great Observatories, was launched on 1999, July 23 by the Space Shuttle Columbia. After satellite systems activation, the first x-rays focused by the telescope were observed on 1999, August 12. Beginning with the initial observation it was clear that the telescope had survived the launch environment and was operating as expected. Despite an initial surprise due to the discovery that the telescope was far more efficient for concentrating CCD-damaging low-energy protons than had been anticipated, the observatory is performing well and is returning superb scientific data. Together with other space observatories, most notably XMM-Newton, it is clear that we have entered a new era of discovery in high-energy astrophysics.

Weisskopf, M. C.↗
NASA NTRS2001

Site Selection and Deployment Scenarios for Servicing of Deep-Space Observatories

The deep-space environment and relative transportation accessibility of the Weak Stability Boundary (WSB) region connecting the Earth-Moon and Sun-Earth libration points makes the Sun-Earth L2 an attractive operating location for future observatories. A summary is presented of key characteristics of future observatories designed to operate in this region. The ability to service observatories that operate within the region around the Lagrange points may greatly enhance their reliability, lifetime, and scientific return. The range of servicing missions might begin with initial deployment, assembly, test, and checkout. Post-assembly servicing missions might also include maintenance and repair, critical fluids resupply, and instrument upgrades. We define the range of servicing missions that can be performed with extravehicular activity, with teleoperated robots, and with autonomous robots. We then describe deployment scenarios that affect payload design. A trade study is summarized of the benefits and risks of alternative servicing sites, including at the International Space Station, at other low-Earth-orbit locations, at the Earth-Moon L1 location, and on-site at the Sun-Earth L2 location. Required technology trades and development issues for observatory servicing at each site, and with each level of autonomy, are summarized.

Willenberg, Harvey J.↗
NASA NTRS2002

Grand Observatory

Various concepts have been recently presented for a 100 m class astronomical observatory. The science virtues of such an observatory are many: resolving planets orbiting around other stars, resolving the surface features of other stars, extending our temporal reach back toward the beginning (at and before stellar and galactic development), improving on the Next Generation Space Telescope, and other (perhaps as yet) undiscovered purposes. This observatory would be a general facility instrument with wide spectral range from at least the near ultraviolet to the mid infrared. The concept espoused here is based on a practical, modular design located in a place where temperatures remain (and instruments could operate) within several degrees of absolute zero with no shielding or cooling. This location is the bottom of a crater located near the north or south pole of the moon, most probably the South Polar Depression. In such a location the telescope would never see the sun or the earth, hence the profound cold and absence of stray light. The ideal nature of this location is elaborated herein. It is envisioned that this observatory would be assembled and maintained remotely through the use of expert robotic systems. A base station would be located above the crater rim with (at least occasional) direct line-of-sight access to the earth. Certainly it would be advantageous, but not absolutely essential, to have humans travel to the site to deal with unexpected contingencies. Further, observers and their teams could eventually travel there for extended observational campaigns. Educational activities, in general, could be furthered thru extended human presence. Even recreational visitors and long term habitation might follow.

Young, Eric W.↗
NASA NTRS2002

Three Years of Operation of the Chandra X-Ray Observatory

The Chandra X-Ray Observatory is a NASA facility that provides scientific data to the international astronomical community in response to proposals for its use. Data becomes public at most one year after the observation. The Observatory is the product of the efforts of many commercial, academic, and government organizations in the United States and Europe. NASA's Marshall Space Flight Center (MSFC) manages the Project and provides Project Science TRW Space and Electronics Group served as prime contractor responsible for providing the spacecraft, the telescope, and assembling and testing the observatory the Smithsonian Astrophysical Observatory (SAO) provides technical support and is responsible for around operations including the Chandra X Ray Center (CXC).

Weisskopf, Martin C.↗
NASA NTRS2002

Highlights from Three Years of the Chandra X-Ray Observatory

August 12, 2002 marked the third anniversary of the first light observed with the Chandra X-Ray Observatory (CXO) which had been launched on July 23 of that same year. The CXO is the X-ray component of NASA's Great Observatory Program that also includes the Hubble Space Telescope for observations in the visible portion of the electromagnetic spectrum, the now defunct Compton Gamma-Ray Observatory and the soon-to-be-launched Space Infra-Red Telescope Facility. The scientific return from the Observatory has been spectacular. Images of objects as local as the moon's of Jupiter and comets, to those which show the details of the emission of the hot gas pervading clusters of galaxies have been obtained. The technical status of the instrumentation and the performance of the X-ray optics will be reviewed and an overview of some of the exciting results will be presented.

Weisskopf, Martin C.↗
NASA NTRS2003

Improving the Science Observing Efficiency of the Chandra X-ray Observatory via Chandra Radiation

The Chandra X-ray Observatory (CXO), NASA' latest "Great Observatory", swas launched on July 23, 1999 and reached its final orbit on August 7, 1999. The CXO is in a highly elliptical orbit, approximately 140,000 km x 10,000 km, and has a period of approximately 63.5 hours (approx. 2.65 days). It transits the Earth's Van Allen belts once per orbit during which no science observations can be performed due to the high radiation environment. The Chandra X-ray Observatory Center currently uses the National Space Science Data Center's "near Earth" AP-8/AE-8 radiation belt model to predict the start and end times of passage through the radiation belts. Our earlier analysis demonstrated that our implementation of the AP-8/AE-8 model (a simple dipole model of the Earth's magnetic field) does not always give sufficiently accurate predictions of the start and end times of transit of the Van Allen belts. This led to a change in our operating procedure whereby we "padded" the start and end times of transit by 10 kiloseconds (ks) so that ACIS, the primary science instrument on-board Chandra, would not be exposed to the "fringes" of the Van Allen belts on ingress and egress for any given transit. This additional 20 ks per orbit during which Chandra is unable to perform science observations sums to approximately 3 Ms of "lost" science time per year and therefore reduces the science observing efficiency of the Observatory. To address the need for a higher fidelity radiation model appropriate for the Chandra orbit, the Chandra Radiation Model (CRM) was developed. The CRM is an ion model for the outer magnetosphere and is based on data from the EPIC/ICS instrument on-board the Geotail satellite as well as data from the CEPPAD/IPS instrument on-board the Polar satellite. With the production and implementation of the CRM, we present the results of a study designed to investigate the science observing time that may be recovered by using the CRM as a function of the additional low-energy proton exposure to ACIS.

Virani, Shanil↗
NASA NTRS2003

Improving the Science Observing Efficiency of the Chandra X-Ray Observatory via the Chandra Radiation Model

The Chandra X-ray Observatory (CXO), NASA's latest "Great Observatory", was launched on July 23, 1999 and reached its final orbit on August 7, 1999. The CXO is in a highly elliptical orbit, approximately 140,000 km x 10,000 km, and has a period of approximately 63.5 hours (N 2.65 days). It transits the Earth's Van Allen belts once per orbit during which no science observations can be performed due to the high radiation environment. The Chandra X-ray Observatory Center currently uses the National Space Science Data Center's "near Earth" AP-8/AE-8 radiation belt model to predict the start and end times of passage through the radiation belts. Our earlier analysis demonstrated that our implementation of the AP-8/AE-8 model (a simple dipole model of the Earth's magnetic field) does not always give sufficiently accurate predictions of the start and end times of transit of the Van Allen belts. This led to a change in our operating procedure whereby we "padded" the start and end times of transit by 10 kiloseconds (ks) so that ACIS, the primary science instrument on-board Chandra, would not be exposed to the "fringes" of the Van Allen belts on ingress and egress for any given transit. This additional 20 ks per orbit during which Chandra is unable to perform science observations sums to approximately 3 Ms of "lost" science time per year and therefore reduces the science observing efficiency of the Observatory. To address the need for a higher fidelity radiation model appropriate for the Chandra orbit, the Chandra Radiation Model (CRM) was developed. The CRM is an ion model for the outer magnetosphere and is based on data from the EPIC/ICS instrument on-board the Geotail satellite as well as data from the CEPPAD/IPS instrument on-board the Polar satellite. With the production and Implementation of the CRM, we present the results of a study designed to investigate the science observing time that may be recovered by using the CRM as a function of the additional low-energy proton exposure to ACIS.

Virani, Shanil↗