Star Passages Through the Oort Cloud
Random passing stars regularly penetrate the Oort cloud, resulting in major perturbations to the orbits of comets there.
major perturbations to orbits of comets hyperbolic↗
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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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The Spatial Distribution of Organic Matter and Mineralogical Relationships in Carbonaceous Chondrites
Organic matter present within primitive carbonaceous meteorites represents the complex conglomeration of species formed in a variety of physically and temporally distinct environments including circumstellar space, the interstellar medium, the Solar Nebula & Jovian sub-nebulae and asteroids. In each case, multiple chemical pathways would have been available for the synthesis of organic molecules. Consequently these meteorites constitute a unique record of organic chemical evolution in the Universe and one of the biggest challenges in organic cosmochemistry has been in deciphering this record. While bulk chemical analysis has provided a detailed description of the range and diversity of organic species present in carbonaceous chondrites, there is virtually no hard experimental data as to how these species are spatially distributed and their relationship to the host mineral matrix, (with one exception). The distribution of organic phases is nevertheless critical to understanding parent body processes. The CM and CI chondrites all display evidence of low temperature (< 350K) interaction with aqueous fluids, which based on O isotope data, flowed along thermal gradients within the respective parent bodies. This pervasive aqueous alteration may have led to aqueous geochromatographic separation of organics and synthesis of new organics coupled to aqueous mineral alteration. To address such issues we have applied the technique of microprobe two-step laser desorption / photoionization mass spectrometry (L2MS) to map in situ the spatial distribution of a broad range of organic species at the micron scale in the freshly exposed matrices of the Bells, Tagish Lake and Murchison (CM2) carbonaceous chondrites.
Clemett, S. J.↗
Coordinated Chemical and Isotopic Imaging of Bells (CM2) Meteorite Matrix
Meteoritic organic matter is a complex conglomeration of species formed in distinct environments and processes in circumstellar space, the interstellar medium, the Solar Nebula and asteroids. Consequently meteorites constitute a unique record of primordial organic chemical evolution. While bulk chemical analysis has provided a detailed description of the range and diversity of organic species present in carbonaceous chondrites, there is little information as to how these species are spatially distributed and their relationship to the host mineral matrix. The distribution of organic phases is nevertheless critical to understanding parent body processes. The CM and CI chondrites all display evidence of low temperature (< 350K) aqueous alteration that may have led to aqueous geochromatographic separation of organics and synthesis of new organics coupled to aqueous mineral alteration. Here we present the results of the first coordinated in situ isotopic and chemical mapping study of the Bells meteorite using a newly developed two-step laser mass spectrometer (mu-L(sup 2)MS) capable of measuring a broad range of organic compounds.
Clemett, S. J.↗
Laboratory Experiments on Astrophysical Dust Analogs at NASA/MSFC
No abstract available
dust interstellar space↗
Interstellar beamer engineering
The fundamental differences between solar sails and interstellar beam riders are presented. Design requirements and design considerations are developed for an interstellar beamer phased array of gigantic proportions of photon pushing beam riding spacecraft to significant fractions of the speed of light.
interstellar↗
Precursor Mission to Interstellar Exploration
This paper summarizes material developed over a three-month period by a JPL team of mission architects/analysis and advanced technology developers for presentation to NASA Headquarters on the summer of 1998.
Interstellar↗
Vector space methods of photometric analysis - Applications to O stars and interstellar reddening
A multivariate vector-space formulation of photometry is developed which accounts for error propagation. An analysis of uvby and H-beta photometry of O stars is presented, with attention given to observational errors, reddening, general uvby photometry, early stars, and models of O stars. The number of observable parameters in O-star continua is investigated, the way these quantities compare with model-atmosphere predictions is considered, and an interstellar reddening law is derived. It is suggested that photospheric expansion affects the formation of the continuum in at least some O stars.
Massa, D.↗
Magnetic Flux Compression Concept for Aerospace Propulsion and Power
The objective of this research is to investigate system level performance and design issues associated with magnetic flux compression devices for aerospace power generation and propulsion. The proposed concept incorporates the principles of magnetic flux compression for direct conversion of nuclear/chemical detonation energy into electrical power. Specifically a magnetic field is compressed between an expanding detonation driven diamagnetic plasma and a stator structure formed from a high temperature superconductor (HTSC). The expanding plasma cloud is entirely confined by the compressed magnetic field at the expense of internal kinetic energy. Electrical power is inductively extracted, and the detonation products are collimated and expelled through a magnetic nozzle. The long-term development of this highly integrated generator/propulsion system opens up revolutionary NASA Mission scenarios for future interplanetary and interstellar spacecraft. The unique features of this concept with respect to future space travel opportunities are as follows: ability to implement high energy density chemical detonations or ICF microfusion bursts as the impulsive diamagnetic plasma source; high power density system characteristics constrain the size, weight, and cost of the vehicle architecture; provides inductive storage pulse power with a very short pulse rise time; multimegajoule energy bursts/terawatt power bursts; compact pulse power driver for low-impedance dense plasma devices; utilization of low cost HTSC material and casting technology to increase magnetic flux conservation and inductive energy storage; improvement in chemical/nuclear-to-electric energy conversion efficiency and the ability to generate significant levels of thrust with very high specific impulse; potential for developing a small, lightweight, low cost, self-excited integrated propulsion and power system suitable for space stations, planetary bases, and interplanetary and interstellar space travel; potential for attaining specific impulses approaching 10 (exp 6) seconds, which would enable missions to the outer planets within ten years and missions at interstellar distances within fifty years.
Litchford, Ron J.↗
Interstellar PAH in the Laboratory and in Space. What have we Learned from the New Generation of Laboratory and Observational Studies?
Polycyclic Aromatic Hydrocarbons (PAHs) are an important and ubiquitous component of carbon-bearing materials in space. PAHs are the best-known candidates to account for the IR emission bands (UIR bands) and PAH spectral features are now being used as new probes of the ISM. PAHs are also thought to be among the carriers of the diffuse interstellar absorption bands (DIBs). In the model dealing with the interstellar spectral features, PAHs are present as a mixture of radicals, ions and neutral species. PAH ionization states reflect the ionization balance of the medium while PAH size, composition, and structure reflect the energetic and chemical history of the medium. A major challenge for laboratory astrophysics is to reproduce (in a realistic way) the physical conditions that exist in the emission and/or absorption interstellar zones. An extensive laboratory program has been developed at NASA Ames to assess the physical and chemical properties of PAHs in such environments and to describe how they influence the radiation and energy balance in space and the interstellar chemistry. In particular, laboratory experiments provide measurements of the spectral characteristics of interstellar PAH analogs from the ultraviolet and visible range to the infrared range for comparison with astronomical data. This paper will focus on the recent progress made in the laboratory to measure the direct absorption spectra of neutral and ionized PAHs in the gas phase in the near-UV and visible range in astrophysically relevant environments. These measurements provide data on PAHs and nanometer-sized particles that can now be directly compared to astronomical observations. The harsh physical conditions of the IS medium - characterized by a low temperature, an absence of collisions and strong VUV radiation fields - are simulated in the laboratory by associating a molecular beam with an ionizing discharge to generate a cold plasma expansion. PAH ions are formed from the neutral precursors in an isolated environment at low temperature (of the order of 100 K). The spectra of neutral and ionized PAHs are measured using the high sensitivity methods of cavity ring down spectroscopy (CRDS). These experiments provide unique information on the spectra of free, cold large carbon molecules and ions in the gas phase. Intrinsic band profiles and band positions of cold gas-phase PAHs can now be measured with high-sensitivity spectroscopy and directly compared to the astronomical data. The electronic bands measured for ionized PAH are found to be intrinsically broad (about 20 cm(sup -1)) while the bands associated with the neutral precursors are narrower (of the order of 2 - 10 cm(sup -1)). The laboratory data are discussed and compared with recent astronomical spectra of large and narrow DIBs and with the spectra of circumstellar environments of selected carbon stars and the implications for the interstellar PAH population are derived. Preliminary results also show that carbon nanoparticles are formed during the short residence time of the precursors in the plasma.
Salama, Farid↗
Human factors issues for interstellar spacecraft
Developments in research on space human factors are reviewed in the context of a self-sustaining interstellar spacecraft based on the notion of traveling space settlements. Assumptions about interstellar travel are set forth addressing costs, mission durations, and the need for multigenerational space colonies. The model of human motivation by Maslow (1970) is examined and directly related to the design of space habitat architecture. Human-factors technology issues encompass the human-machine interface, crew selection and training, and the development of spaceship infrastructure during transtellar flight. A scenario for feasible instellar travel is based on a speed of 0.5c, a timeframe of about 100 yr, and an expandable multigenerational crew of about 100 members. Crew training is identified as a critical human-factors issue requiring the development of perceptual and cognitive aids such as expert systems and virtual reality.
Cohen, Marc M.↗
Enabling a Near-Term Interstellar Probe with the NASA's Space Launch System
No abstract available
Stough, Robert↗
Man's future in space
Studies evaluating potential operational and commercial uses of space are being conducted, taking into account astronomy, astrophysics, manned bases and laboratories in earth orbit, space colonization, terrestrial communications, space processing and manufacturing, interstellar probes, planetary exploration, and the use of space for terrestrial energy supply. The present status in the exploration of the solar system is examined, giving attention to Jupiter, Venus, Mars, and Mercury. A brief outline of the development of human colonies on Mars is presented.
Freitag, R. F.↗
Potentials of surfaces in space
The subject of surface potentials on natural and artificial bodies in space is reviewed with particular emphasis on recent developments. Following a brief survey of work done up to the early 1970s on the charging of astrophysical objects in interstellar and interplanetary space and spacecraft charging, the various charging mechanisms in space are examined, including the collection of plasma particles, photoemission, and secondary electron emission by electron impact and ion impact, and the effects on charging of nonisotropic plasmas, wakes, and environmental magnetic and electric fields are considered. The concept of equilibrium potential is discussed, along with differential charging, potential barriers and discharge processes. The measurement of spacecraft potentials is then considered, and recent work on spacecraft potential modification and control by active and passive means is presented. Finally, astrophysical applications where charging effects may be important are discussed, and areas for further work are indicated.
Whipple, E. C.↗
Condensation of solids in space. Isotope fractionation in the model system C-O
The reported chemical fractionation of a single isotope O-16 under simulated space conditions provides the first experimental proof for the hypothesis that the oxygen isotopic anomaly (and other similar anomalies) seen in meteorites is a product of chemical fractionation in interstellar or circumstellar space. Work proposed on this subject was discontinued because a peer review determined that such effects could not possibly exist and that continued support of this project would be a wasted effort. A bibliography is included of articles generated during research in this area.
Arrhenius, G.↗
Biological and physiological rhythms
Circadian rhythms, particularly that of sleep and wakefulness, are discussed. The sleep-wakefulness experiences of astronauts during several space missions are described, and predictions are made for future space activities, including Mars missions, interstellar flight, and life on permanent space stations.
Strughold, H.↗
Website for the Astrochemistry Laboratory, Astrophysics Branch, Space Sciences Division
The Astrochemistry Laboratory in the Astrophysics Branch (SSA) of the Space Sciences Division at NASA's Ames Research Center specializes in the study of extraterrestrial materials and their analogs. The staff has pioneered laboratory studies of space environments including interstellar, cometary, and planetary ices, simulations of the so-called 'Unidentified' Infrared Emission Bands and Diffuse Interstellar Bands using PAHs (Polycyclic Aromatic Hydrocarbons) and PAH-related materials, and has extensive experience with low-temperature spectroscopy and astronomical observation. Important discoveries made by the Astrochemistry Group include: (1) The recognition that polycyclic aromatic hydrocarbons and their ions are common in space; (2) The identification of a major fraction of the known molecular species frozen in interstellar/pre-cometary ices; (3) The recognition that a significant fraction of the carbon in the interstellar medium is carried by both microdiamonds and organic materials; (4) The expansion of the types of molecules expected to be synthesized in interstellar/pre-cometary ices. These could be delivered to the early Earth (or other body) and influence the origin or early evolution of life.
Sandford, Scott↗
Voyager Interstellar Mission (VIM)
The DSN (Deep Space Network) mission support requirements for the Voyager Interstellar Mission (VIM) are summarized. The general objectives of the VIM are to investigate the interplanetary and interstellar media and to continue the Voyager program of ultraviolet astronomy. The VIM will utilize both Voyager spacecraft for the period from January 1990 through December 2019. The mission objectives are outlined and the DSN support requirements are defined through the presentation of tables and narratives describing the spacecraft flight profile; DSN support coverage; frequency assignments; support parameters for telemetry, control and support systems; and tracking support responsibility.
Rudd, R.↗
Spaceport operations for deep space missions
Space Station Freedom is designed with the capability to cost-effectively evolve into a transportation node which can support manned lunar and Mars missions. To extend a permanent human presence to the outer planets (moon outposts) and to nearby star systems, additional orbiting space infrastructure and great advances in propulsion system and other technologies will be required. To identify primary operations and management requirements for these deep space missions, an interstellar design concept was developed and analyzed. The assembly, test, servicing, logistics resupply, and increment management techniques anticipated for lunar and Mars missions appear to provide a pattern which can be extended in an analogous manner to deep space missions. A long range, space infrastructure development plan (encompassing deep space missions) coupled with energetic, breakthrough level propulsion research should be initiated now to assist in making the best budget and schedule decisions.
Holt, Alan C.↗