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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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NASA NTRS1976

Hot interstellar tunnels. 1: Simulation of interacting supernova remnants

The theory required to build a numerical simulation of interacting supernova remnants is developed. The hot cavities within a population of remnants will become connected, with varying ease and speed, for a variety of assumed conditions in the outer shells of old remnants. Apparently neither radiative cooling nor thermal conduction in a large-scale galactic magnetic field can destroy hot cavity regions, if they grow, faster than they are reheated by supernova shock waves, but interstellar mass motions disrupt the contiguity of extensive cavities necessary for the dispersal of these shocks over a wide volume. Monte Carlo simulations show that a quasi-equilibrium is reached in the test space within 10 million yrs of the first supernova and is characterized by an average cavity filling fraction of the interstellar volume. Aspects of this equilibrium are discussed for a range of supernova rates. Two predictions are not confirmed within this range: critical growth of hot regions to encompass the entire medium, and the efficient quenching of a remnant's expansion by interaction with other cavities.

Smith, B. W.↗

NASA NTRS1964

A Study of the Navigator's Sighting Accuracy Using a Simulated Vehicle-Mounted Space Sextant and a Description of the Sextant Simulator

Sextant simulator for midcourse guidance of manned spacecraft during interstellar travel

MIDCOURSE GUIDANCE↗

NASA NTRS1991

Space physics strategy-implementation study. Volume 1: Goals, objectives, strategy. A report to the Space Physics Subcommittee of the Space Science and Applications Advisory Committee

Space physics is defined as the study of the heliosphere as one system; that is, of the Sun and solar wind, and their interactions with the upper atmospheres, ionospheres, and magnetospheres of the planets and comets, with energetic particles, and with the interstellar medium. This report contains a number of reports by different panels on the major topics in the space physics program including: (1) the cosmic and heliospheric physics program for the years 1995 to 2010; (2) ionosphere, thermosphere, and mesosphere studies; (3) magnetospheric physics; (4) solar physics; and (5) space physics theory.

Source record↗

NASA NTRS1980

Abundance determinations for interstellar gas

The results of general abundance studies, using the Copernicus satellite are reviewed. The general pattern of depletion of some elements such as Si, Al, Mn, Fe, and Mg, near the sun is described. Techniques for obtaining abundances for various species are discussed, as are the aspects of the analysis which are uncertain. Variations in gas phase abundance from region to region are found for Fe and Si, similar to variations now known to exist for Ca and Ti based on visible spectra. A new generation of space instruments, with higher efficiency and resolution, in particular for 920-1400 A, can provide detailed interstellar line profiles.

York, D. G.↗

NASA NTRS2005

Assessing Potential Propulsion Breakthroughs

The term, propulsion breakthrough, refers to concepts like propellantless space drives and faster-than-light travel, the kind of breakthroughs that would make interstellar exploration practical. Although no such breakthroughs appear imminent, a variety of investigations into these goals have begun. From 1996 to 2002, NASA supported the Breakthrough Propulsion Physics Project to examine physics in the context of breakthrough spaceflight. Three facets of these assessments are now reported: (1) predicting benefits, (2) selecting research, and (3) recent technical progress. Predicting benefits is challenging since the breakthroughs are still only notional concepts, but kinetic energy can serve as a basis for comparison. In terms of kinetic energy, a hypothetical space drive could require many orders of magnitude less energy than a rocket for journeys to our nearest neighboring star. Assessing research options is challenging when the goals are beyond known physics and when the implications of success are profound. To mitigate the challenges, a selection process is described where: (a) research tasks are constrained to only address the immediate unknowns, curious effects or critical issues, (b) reliability of assertions is more important than their implications, and (c) reviewers judge credibility rather than feasibility. The recent findings of a number of tasks, some selected using this process, are discussed. Of the 14 tasks included, six reached null conclusions, four remain unresolved, and four have opportunities for sequels. A dominant theme with the sequels is research about the properties of space, inertial frames, and the quantum vacuum.

Millis, Marc G.↗

NASA NTRSDate not supplied

Applications of Nuclear Thermal Propulsion Systems for Deep Space Science Missions

Nuclear thermal propulsion (NTP) systems occupy a unique area in the space propulsion technology landscape due to their ability to combine moderate-to-high thrust systems normally seen in chemical propulsion systems with specific impulses that are closer to those observed in some electric propulsion systems. Consequently, NTP systems have the potential to greatly expand access to deep space and can enable a variety of missions that achieve the science goals outlined in NASA’s decadal surveys. This paper leverages previous analysis performed to show the applicability of NTP systems for notional science missions, expanding the analyzed portfolio to encompass additional science mission profiles and demonstrating how the use of NTP affects various mission parameters, such as trip time and delivered mass. This paper also outlines efforts to improve the fidelity of the existing NTP design concepts and vehicles that are utilized by leveraging previous work on nuclear propulsion systems for human-Mars missions. The fidelity of the analysis in this work is improved over previous studies, permitting commensurate improvements in the analyses of previous mission concept studies –the Triton lander, the solar polar orbiter, and the interstellar medium probe missions.

Nuclear thermal propulsion↗

NASA NTRS1981

Three new 'nonterrestrial' molecules

Eight new interstellar lines have been detected from three molecules not previously observed spectroscopically in space or in the laboratory. One is a linear or nearly linear molecule with microwave constants B0 equals 21,337.15 plus or minus 0.06 MHz, D0 equals 21.4 plus or minus 1.5 kHz. This is the thioformyl ion HCS(plus), first identified because B0 and D0 are close to those calculated, and now confirmed by laboratory detection of one of the present lines (Gudeman et al.). The second molecule, also linear or nearly so, has microwave constants B0 equals 10,691,406 plus or minus 0.043 MHz, D0 equals 1.84 plus or minus 0.91 kHz close to those expected for the isoelectronic systems HOCO(plus) and HOCN; a choice between the two cannot be made on the basis of the available astronomical data. The existence of a third molecule is deduced from an unidentified line at 85,338 MHz that has been found in many sources, is fairly intense in several, and may be self-absorbed in Sgr B2.

Thaddeus, P.↗

NASA NTRS1987

Exobiology and life science

The following types of experiments for a proposed Space Station Microgravity Particle Research Facility are described: (1) biogenic elements in the interstellar medium; (2) organic material in the solar nebula; (3) volatiles in comets and icy planetesimals; (4) pre-biotic atmospheric chemistry; (5) analysis of cosmic dust particles; and (6) microbial exposure. The required capabilities and desired hardware for the facility are detailed.

Mckay, C. P.↗

NASA NTRS1987

Prospective EUV observations of hot DA white dwarfs with the EUV Explorer

The Extreme Ultraviolet Explorer (EUVE) will perform a high sensitivity EUV all-sky survey. A major category of sources which will be detected with the EUVE instruments consists of hot white dwarfs. Detailed preliminary studies of synthetic EUV observations of white dwarfs have been carried out using the predicted EUVE instrumental response functions. Using available information regarding space densities of white dwarfs and the distribution of neutral hydrogen in the interstellar medium, the numbers of DA white dwarfs which will be detectable in the different EUV bandpasses have been estimated.

Finley, David S.↗

NASA NTRS1989

The Voyager Neptune travel guide

The Voyager mission to the giant outer planets of our solar system is described. Scientific highlights include interplanetary cruise, Jupiter, Saturn, Uranus, and their vast satellite and ring systems. Detailed plans are provided for the August 1989 Neptune encounter and subsequent interstellar journey to reach the heliopause. As background, the elements of an unmanned space mission are explained, with emphasis on the capabilities of the spacecraft and the scientific sensors. Other topics include the Voyager Grand Tour trajectory design, deep-space navigation, and gravity-assist concepts. The Neptune flyby is animated through the use of computer-generated, flip-page movie frames that appear in the corners of the publication. Useful historical information is also presented, including facts associated with the Voyager mission. Finally, short summaries are provided to describe the major objectives and schedules for several space missions planned for the remainder of the 20th century.

Kohlhase, Charles↗

NASA NTRS1995

The evolution of C/O in dwarf galaxies from Hubble Space Telescope FOS observations

We present UV observations of seven H II regions in low-luminosity dwarf irregular galaxies and the Magellanic Clouds obtained with the Faint Object Spectrograph (FOS) on the Hubble Space Telescope (HST) in order to measure the C/O abundance ratio in the interstellar medium (ISM) of those galaxies. We measure both O III 1666 A and C III 1909 A in our spectra, enabling us to determine C(+2)/O(+2) with relatively small uncertainties. The results from our HST observations show a continuous increase in C/O with increasing O/H, consistent with a power law having an index of 0.43 +/- 0.09 over the range -4.7 to -3.6 in log (O/H). One possible interpretation of this trend is that the most metal-poor galaxies are the youngest and dominated by the products of early enrichment by massive stars, while more metal-rich galaxies show increasing, delayed contributions of carbon from intermediate-mass stars. Our results also suggest that it may not be appropiate to combine abundances in irregular galaxies with those in spiral galaxies to study the evolution of chemical abundances. Our measured C/O ratios in the most metal-poor galaxies are consistent with predictions of nucleosynthesis from massive stars for Weaver & Woosley's best estimate for the 12C(alpha, gamma) 16O nuclear reaction rate, assuming negligible contanmination from carbon produced in intermediate-mass stars in these galaxies. We detect a weak N III 1750 A multiplet in SMC N88A and obtain interesting upper limits for two other objects. Our 2 sigma uppr limits on the 1750 A feature indicate that the N(+2)/O(+2) ratios in these objects are not significantly larger than the N(+)/O(+) ratios measured from optical spectra. This behavior is consistent with predictions of photionization models, although better detections of N III are needed to confirm the results.

Garnett, D. R.↗

NASA NTRS2003

Excited Ejecta in Light of Sight from Eta Car

In the NUV spectrum of Eta Car, we have resolved many narrow absorption lines of neutral and singly-ionized elements with the Space Telescope Imaging Spectrograph. We report for the first time the detection of interstellar vanadium in absorption, and many highly-excited absorption lines of Fe, Cr, Ti, Ni, Co, Mn, and Mg. These elements, normally tied up in dust grains in the ISM, are located within wall of the Homunculus within 20,000 A.U. of Eta Car. Stellar radiation and stellar wind are interacting with the wall. Dust is likely being modified and/or destroyed. Previous Homunculus studies have demonstrated that nitrogen is overabundant and that carbon and oxygen emission lines are weak, or non-existent. Are the large column densities of these heavy elements due to abundance effects, excitation mechanisms, or modified grains? We may gain insight as Eta Car goes through its spectroscopic minimum in the summer of 2003.

Vieira, G.↗

NASA NTRS1992

LDEF: 69 Months in Space. First Post-Retrieval Symposium, part 1

This document is a compilation of papers presented at the First Long Duration Exposure Facility (LDEF) Post-Retrieval Symposium. The papers represent the preliminary data analysis of the 57 experiments flown on the LDEF. The experiments include materials, coatings, thermal systems, power and propulsion, science (cosmic ray, interstellar gas, heavy ions, and micrometeoroid), electronics, optics, and life

Space experiment↗

NASA NTRS1997

SWAS Spacecraft T/V Test, Unique In Chamber Tests Systems Actuation

The Sub-Millimeter Wave Astronomy Satellite (SWAS) is the third mission of the Small Explorer (SMEX) Project at Goddard Space Flight Center (GSFC). It is a path finding mission to study the chemical composition of interstellar galactic clouds to help determine the process of star formation. The spacecraft recently completed a month-long then-nal vacuum/thermal balance test in the Solar Environmental Simulator, the largest thermal vacuum facility at Goddard. Rather extensive fixturing was required for the test, considering the small size of the spacecraft, and two unusual deployments were completed in order to accomplish the goals of the test. This paper discusses the space simulation testing of the fully integrated SWAS spacecraft and the unique fixturing required.

Dunn, Jamie L.↗

NASA NTRS1991

LDEF: 69 Months in Space. First Post-Retrieval Symposium, part 3

Space experiment↗

NASA NTRS1983

Antenna technology for orbital Very Long Baseline Interferometry (VLBI)

Since it is not economically feasible to construct steerable antennas much larger than 100 meters on Earth (400 meters for fixed telescopes), radio interferometry became a very useful technique for high resolution astronomy observations of quasars, galactic nuclei, and interstellar hydroxyl (OH) and water vapor (H2O) masers. The subsystems necessary to do the space VLBI experiment appear are available but require space qualifications. There are several 50-meter antenna concepts that could be used. Certainly there are problems to be solved. Feed positioning with respect to reflector, pointing such a large structure to accuracy indicated, and integration into the Shuttle control system are all significant engineering challenges. However, there are no problems that are insurmountable in the latter part of this decade.

Hamilton, E. C.↗

NASA NTRS1986

Protostellar formation in rotating interstellar clouds. V - Nonisothermal collapse and fragmentation

Numerical calculations are presented for rigorous models spanning a four-dimensional parameter space of initial conditions of the three-dimensional collapse of rotating protostellar clouds, encompassing radiative transfer in the Eddington approximation and detailed thermodynamical relations. It is found that protostellar formation may involve a few stages of hierarchical fragmentation terminated by increased thermal pressure in the nonisothermal regime, that high thermal energy clouds remain nearly axisymmetric during the first dynamic collapse phase, and that very slowly rotating clouds can fragment. The presolar nebula was probably formed from a cloud with very little initial rotation.

Boss, Alan R.↗

NASA NTRS2019

High-Resolution Mid-Infrared Molecular Line Survey of the Orion Hot Core

The basic building blocks of life are synthesized in space as part of the natural stellar evolutionary cycle, whereby elements ejected into the interstellar medium by dying stars are incorporated back into the dense clouds, which form the next generation of stars and planets. The formation of stars and planets are fundamental to the evolution of matter in the Universe as complex molecules are created and destroyed during this step. Understanding these processes will allow us to answer “What is the relation between the molecules we see in the ISM and the molecular inventory of Earth and the terrestrial planets in the Solar System?” Measuring and cataloging the inventory of organic molecules and understanding their evolution requires observations over a broad wavelength range (IR, MIR, FIR, (sub)mm, and radio) to cover all stages of this evolutionary cycle needed to link interstellar material to that delivered to planets. High-resolution molecular line surveys provide chemical inventories for star forming regions and are essential for studying their chemistry, kinematics and physical conditions. Previous high spectral resolution surveys have been limited to radio, sub-mm and FIR wavelengths; however, Mid-infrared observations are the only way to study symmetric molecules that have no dipole moment and thus cannot be detected in the (sub)mm line surveys from ALMA. Past midinfrared missions such as ISO and Spitzer had low to moderate resolving power that were only able to link broad features with particular molecular bands and could not resolve the individual rovibrational transitions. JWST will provide exceptional sensitivity in the MIR, but will also not have sufficient spectral resolution, which can lead to confusion in identifying the contribution from strong to moderate strength molecular species. We present new results from an on-going high resolution (R ~ 60,000) line survey of the Orion hot core between 12.5 - 28.3 μm and 7 - 8 μm, using the EXES instrument on the SOFIA airborne observatory. SOFIA's higher-resolution and smaller beam compared to ISO allows us to spatially and spectrally isolate the emission towards the hot core. This survey will provide the best infrared measurements (to date) of molecular column densities and physical conditions, providing strong constraints on the current chemical network models for star forming regions. This survey will greatly enhance the inventory of resolved line features in the MIR, making it an invaluable reference to be used by the JWST and ALMA scientific communities.

Rangwala, Naseem↗