Triton, Pluto, Centaurs, and Trans-Neptunian Bodies

The diverse populations of icy bodies of the outer Solar System (OSS) give critical information on the composition and structure of the solar nebula and the early phases of planet formation. The two principal repositories of icy bodies are the Kuiper belt or disk, and the Oort Cloud, both of which are the source regions of the comets. Nearly 1000 individual Kuiper belt objects have been discovered; their dynamical distribution is a clue to the early outward migration and gravitational scattering power of Neptune. Pluto is perhaps the largest Kuiper belt object. Pluto is distinguished by its large satellite, a variable atmosphere, and a surface composed of several ices and probable organic solid materials that give it color. Triton is probably a former member of the Kuiper belt population, suggested by its retrograde orbit as a satellite of Neptune. Like Pluto, Triton has a variable atmosphere, compositionally diverse icy surface, and an organic atmospheric haze. Centaur objects appear to come from the Kuiper belt and occupy temporary orbits in the planetary zone; the compositional similarity of one well studied Centaur (5145 Pholus) to comets is notable. New discoveries continue apace, as observational surveys reveal new objects and refined observing techniques yield more physical information about specific bodies.     

CIR Morphology, Turbulence, Discontinuities, and Energetic Particles

Corotating interaction regions (CIRs) in the middle heliosphere have distinct morphological features and associated patterns of turbulence and energetic particles. This report summarizes current understanding of those features and patterns, discusses how they can vary from case to case and with distance from the Sun and possible causes of those variations, presents an analytical model of the morphological features found in earlier qualitative models and numerical simulations, and identifies aspects of the features and patterns that have yet to be resolved. This revised version was published online in August 2006 with corrections to the Cover Date.     

Ion engine grids: Function,main parameters,issues, configurations,geometries, materials and fabrication methods

Ion optics are crucial components of ion thrusters and the study of the different ion extraction solutions used since the beginning of the electric propulsion era is essential to understand the evolution of ion engines. This work describes ion engine grids' main functions, parameters and issues related to thermal expansion and sputter erosion, and then introduces a review of ion optics used for significant launched and tested ion thrusters since 1970. Configurations, geometries, materials and fabrication methods are analyzed to understand when typical ion thrusters use two or three grids, what are the thicknesses and aperture sizes of the screen, accelerator and decelerator grids, why molybdenum and carbon-based materials such as pyrolytic graphite and carbon–carbon are the best available options for ion optics and what is the manufacturing method for each material.     

A survey of the outer planets Jupiter,Saturn, Uranus,Neptune, Pluto,and their satellites

A survey of current knowledge about Jupiter, Saturn, Uranus, Neptune, Pluto, and their satellites is presented. The best available numerical values are given for physical parameters, including orbital and body properties, atmospheric composition and structure, and photometric parameters. The more acceptable current theories of these bodies are outlined with thorough referencing offering access to the details. The survey attempts to cover the literature through May 1, 1972. Prepared Under Contract No. NAS7-100 National Aeronautics and Space Administration.     

Decisions, endings, and new beginnings

The Washington Watch column examines NASA shuttle developments, airline pilot age issues, development of a personnel recovery vehicle, and includes an obituary for retired Air Force General Bernard Schriever, remembered as an air and space pioneer. The discussion of NASA shuttle developments reports on the space shuttle flight schedule and NASA's ability to deliver hardware to the International Space Station, funding levels and equipment development schedules related to President Bush's mandate to visit Mars, a report on the space program by the American Academy of Arts and Sciences, and top-level management changes at NASA. The discussion of airline pilot age issues examines efforts to change mandatory retirement requirements. The discussion of personnel recovery vehicles reports on development of an aircraft designed to rescue survivors during combat search and rescue missions.     

System Worth, System Effectiveness, Integrated Logistics Support, and Maintainability

The system worth or cost effectiveness concept covers the measure of a system in terms of total dollar value. System worth encompasses the elements of system effectiveness (a quantitative measure of a system's technical ability) as well as cost. One of the elements of system effectiveness is maintainability. Maintainability is an effective mechanism for the accomplishment of planned maintenance during the early design and development phases of a system. Planned maintenance is an element of integrated logistics support. The intent of this paper is to outline the basic elements associated with system worth, system effectiveness, and integrated logistics support, to outline the interrelation-ships of these concepts, and to cover the discipline of maintainability as an element of each concept.     

The Contributions of Comets to Planets, Atmospheres, and Life: Insights from Cassini-Huygens, Galileo, Giotto, and Inner Planet Missions

Comets belong to a group of small bodies generally known as icy planetesimals. Today the most primitive icy planetesimals are the Kuiper Belt objects (KBOs) occupying a roughly planar domain beyond Neptune. KBOs may be scattered inward, allowing them to collide with planets. Others may move outward, some all the way into the Oort cloud. This is a spherical distribution of comet nuclei at a mean distance of ～50,000 AU. These nuclei are occasionally perturbed into orbits that intersect the paths of the planets, again allowing collisions. The composition of the atmosphere of Jupiter—and thus possibly all outer planets—shows the effects of massive early contributions from extremely primitive icy bodies that must have been close relatives of the KBOs. Titan may itself have a composition similar to that of Oort cloud comets. The origin and early evolution of its atmosphere invites comparison with that of the early Earth. Impacts of comets must have brought water and other volatile compounds to the Earth and the other inner planets, contributing to the reservoir of key ingredients for the origin of life. The magnitude of these contributions remains unknown but should be accessible to measurements by instruments on spacecraft.     

Collapse,equilibrium, and fragmentation of rotating,adiabatic clouds

Numerical calculations of the collapse of adiabatic clouds from uniform density and rotation initial conditions show that when restricted to axisymmetry, the clouds form either near-equilibrium spheroids or rings. Rings form in the collapse of low thermal energy clouds and have = T/ ¦W¦ 0.43. When the axisymmetric constraint is removed and an initial m=2 density variation is introduced, clouds either collapse to form near-equilibrium ellipsoids or else fragment into binary systems through a bar phase. Ellipsoids form in the collapse of high thermal energy clouds and have 3 0.27. The results are consistent with the critical values of for instabilities in Maclaurin spheroids, and suggest that protostellar clouds may undergo a dynamic fragmentation in the nonisothermal collapse regime.National Academy of Sciences — National Research Council Resident Research Associate.     

Caution, contention, and consolidation

The Washington Watch column provides an overview of NASA's cautious approach to the launch of Space Shuttle Discovery STS-114, contention between the Air Force and administration about production of the F/A-22 Raptor aircraft, and consolidation among U.S. airline companies.     

Electric field measurements in the solar wind,bow shock,magnetosheath, magnetopause,and magnetosphere

Electric field measurements are reported at 11 magnetopause crossings that occurred during a single in-bound ISEE-1 satellite pass near a local time of 1030. In combination with magnetic field data, these measurements show the existence of electric field components tangential to the actual magnetopause in the frame of rest of the magnetopause on every crossing of the current carrying layers associated with the 11 magnetopause traversals. These tangential electric field components were oriented with respect to the magnetopause sheet currents such that there was an electrical power dissipation of between 30 and 110 W km^-2 on 10 of the 11 crossings. These results are in agreement with requirements of reconnection theories. Histograms of the normal electric field components and of the orientation, velocity, and thickness of the current carrying layer are presented. Suggestions of the existence of a parallel electric field in the magnetosheath near the magnetopause and of propagation of large amplitude waves along the magnetopause are also made.     

Lunar Ranging, Gravitomagnetism, and APOLLO

The technique of lunar laser ranging (LLR) has for many decades contributed to cutting-edge tests of the fundamental nature of gravity. These include the best tests to date of the strong equivalence principle, the time-rate-of-change of the gravitational constant, gravitomagnetism, the inverse square law, and preferred frame effects. The phenomenologies of each are briefly discussed, followed by an extended discussion of gravitomagnetism. Finally, the new APOLLO project is summarized, which achieves range precision as low as one millimeter.     

ICP-AES法测定纯铜中的Bi,Sb,As,Fe,Ni,Pb,Sn,Zn,Ag的方法

研究了ICP-AES法测定纯铜中的Bi,Sb,As,Fe,Ni,Pb,Sn,Zn和Ag等9个元素的分析方法.进行了基体元素铜对9个分析元素的光谱干扰研究,选择了合适的分析谱线,同时测定了分析方法的检出限.     

The capital, energy, and time economics of an automated, on-demandtransportation system

Many transit and rail planners believe that the only way to decrease the capital and operating cost of rail and transit systems is to decrease the size and weight of the vehicles. The authors discuss the requirements of such a downsized transportation system and the benefits to be gained by decreasing the size of the operational vehicles. Not only can the capital and operating cost of the system be dramatically decreased, but the operational requirements of a system involving the use of smaller vehicles permits its use as an on-demand system, further increasing system utility to the passenger and system operator. The capital cost, energy economics, and the economics of the CyberTran transportation system are reviewed     

Aircraft with outboard horizontal stabilizers,history, current status,development potential

The potential of using outboard horizontal stabilizers (OHS) to reduce aircraft drag, and hence improve fuel economy, was investigated historically, experimentally and theoretically. The feasibility of OHS configurations on the basis of the structural stress levels expected was also studied. The findings of the work showed that from simple, low Reynolds number, wind-tunnel tests, at a wing-chord-based Reynolds number of approximately 6×10⁴ and also from theoretical analyses for a higher Reynolds number of 9×10⁶, lift/drag (L/D) value increases in the region of 40–50% for wing and tail surfaces can be expected relative to corresponding values for conventional aircraft. When account is taken of fuselage and tail-support boom drag, the expected overall L/D increase is in the region of 30–35%. The analytical stress-level work showed that contrary to what, on a first thought basis, might be expected, there were no major stress problems. Flight tests at the University of Calgary, and by others elsewhere, employing radio-controlled, powered, model aircraft (i.e. UAVs) showed that aircraft of the OHS type were easily controlled in flight and were stable. An examination was made of additional areas that may contribute yet further to the development of the OHS concept.     

A hardware-efficient, multirate, digital channelized receiverarchitecture

An approach is presented to realizing a digital channelized receiver for signal intercept applications that provides a hardware efficient implementation of a uniform filter bank in which the number of filters K is greater than the decimation factor M. The proposed architecture allows simple channel arbitration logic to be used and provides reliable instantaneous frequency measurements, even in adjacent channel crossover regions. In the proposed implementation of the filter bank, K is related to M by K=FM where F is an integer. It is shown that the optimum selection of F allows the instantaneous frequency measurement to be made in the channel crossover region and the arbitration function to be based solely on the instantaneous frequency measurement. The development of a filter bank structure which combines the flexibility of the short-time Fourier transform (STFT) with the implementation efficiency of the polyphase filter bank decomposition, meeting these requirements and leading to a hardware-efficient implementation, is presented     

Modeling of Venus, Mars, and Titan

Increased computer capacity has made it possible to model the global plasma and neutral dynamics near Venus, Mars and Saturn??s moon Titan. The plasma interactions at Venus, Mars, and Titan are similar because each possess a substantial atmosphere but lacks a global internally generated magnetic field. In this article three self-consistent plasma models are described: the magnetohydrodynamic (MHD) model, the hybrid model and the fully kinetic plasma model. Chamberlain and Monte Carlo models of the Martian exosphere are also described. In particular, we describe the pros and cons of each model approach. Results from simulations are presented to demonstrate the ability of the models to capture the known plasma and neutral dynamics near the three objects.     

Chemistry,accretion, and evolution of Mars

The high FeO concentrations measured by VIKING for the Martian soils correspond to all probability to a FeO-rich mantle. In general, the VIKING XRF-data indicate a mafic crust with a considerably smaller degree of fractionation compared to the terrestrial crust.In recent years evidence has been collected which points towards Mars being the parent body of SNC-meteorites and, hence, these meteorites have become a valuable source of information about the chemistry of Mars. Using element correlations observed in SNC-meteorites and general cosmochemical constraints, it is possible to estimated the bulk composition of Mars. Normalized to Si and Cl, the mean abundance value for the elements Ga, Fe, Na, P, K, F, and Rb in the Martian mantle is found to be 0.35 and thus exceeds the terrestrial value by about a factor of two. Aside pressure effects and the H₂O poverty, the high P and K content of the Martian mantle may lead to magmatic processes different from those on Earth.The composition of the Earth's mantle can successfully be described by a two component model. Component A: highly reduced and almost free of all elements more volatile than Na; component B: oxidized and containing all elements in Cl-abundances including volatile elements. The same two components can be used as building blocks for Mars, if one assumes that, contrary to the inhomogeneous accretion of the Earth, Mars accreted almost homogeneously. The striking depletion of all elements with chalcophile character indicates that chemical equilibrium between component A and B was achieved on Mars which lead to the formation of significant amounts of FeS which, on segregation, extracted the elements according to their sulphide-silicate partition coefficients. While for the Earth a mixing ratio AB = 8515 was derived, the Mars ratio of 6040 reflects the higher concentrations of moderately volatile elements like Na, K, and sulphur on Mars. A homogeneous accretion of Mars could also explain the obvious low abundances of water and primordial rare gases.     

Artificial hearts, batteries, and electric vehicles

New battery applications ranged from an implanted battery that powers an artificial heart, to powering a seismic sensor behind an oil-well drilling bit as it grinds through rock looking for oil-bearing structure. These applications require high reliability that justifies the cost of thorough qualification testing, production control, acceptance testing of every cell, and tracking every cell by its serial number through its lifetime. Electric vehicle developments ranged from electric scooters for commuting to work in Europe to electric cars connected to the electric grid when not being driven. Availability of their battery energy for carrying load peaks is so valuable that the electric utility being supported could offer to replace the vehicles batteries whenever they wear out, with no cost to the car owner.     

Auroral Radio Emissions, 1. Hisses, Roars, and Bursts

The Earth's auroral electrons produce copious non-thermal radio emissions of various types, including auroral kilometric radiation (AKR), whistler mode auroral hiss, mode conversion radiation such as auroral roar and MF-burst, and possibly HF/VHF emissions. In some cases, mechanisms have been identified and quantitatively described, whereby the energy of the auroral electrons is converted into electromagnetic radiation. In many other cases, the radiation mechanism, or the relative significance of several possible mechanisms, remains uncertain. This review covers fairly comprehensively experimental and theoretical research on types of auroral radiation other than AKR, concentrating on emissions with frequency higher than about 1kHz and treating only emissions which are unique to the auroral zone. The review covers both ground-based and in-situ observations. It covers a wide range of theoretical approaches, emphasizing those which at present appear most important for producing non-AKR auroral radiations.