Radiant ignition of a combustible solid with gas-phase exothermicity

An asymptotic analysis is presented for the ignition of a solid fuel that gasifies endothermically then reacts exothermically in the gas phase through a one-step Arrhenius process. The endothermic gasification was analyzed in an earlier paper; the present paper employs those results in treating the gas-phase reaction. It is shown that depending on values of the chemical parameters, the gas-phase ignition reaction may begin either at the time that gasification begins or during the later stage of transport-controlled gasification. In the former case, results for the gas-phase ignition time are similar to those for condensed-phase ignitions. In the latter case, a mixing layer develops in the gas-phase and moves away from the surface, the exothermic reaction being negligible until thermal runaway occurs somewhere within the mixing layer. Both early-time and late-time ignitions within the mixing layer are analyzed by solving partial differential equations derived from perturbations for large activation energies and a small ratio of gas to solid thermal responsivity. The theory serves to indicate how ignition by gas-phase reactions may be distinguished experimentally from ignition by condensed-phase or heterogenous reactions.     

Influence of the Solar Cycle on the General Circulation of the Stratosphere and Upper Troposphere

The record of dynamical structure reveals a systematic variation that operates coherently with the 11-yr variation of UV irradiance. Involving periods shorter than 5 years, the systematic variation reflects the influence of the QBO on the polar-night vortex. It has the same basic structure as interannual changes associated with the residual mean circulation of the stratosphere. A signature of the solar cycle also appears in the direct correlation to solar flux, as recovered through regression of the entire monthly record. That signature, however, is sharply enhanced around solstice, when the residual circulation is active, and during extremal phases of the QBO. In the tropics, the solar signature follows, throughout the year, from a decadal modulation in the frequency of the QBO. The modulation is manifested to either side of the QBO’s mean frequency, in two spectral peaks where the QBO dwells: one at (24 months)⁻¹, reflecting a Biennial Oscillation (BO), and another at (36 months)^-1. Intrinsic to the QBO, those peaks are separated from its mean frequency by ∼11 years⁻¹.Through the QBO’s residual circulation, the decadal modulation introduces anomalies in the subtropics, with symmetry about the equator. Accompanying anomalous temperature in the subtropics is a stronger signature over the winter pole. Discovered by Labitzke and van Loon 1988, that solar signature reflects anomalous downwelling of the Brewer-Dobson circulation. It is shown to follow through the BO, which is intrinsic to the QBO and its modulation of the polar-night vortex.     

Multipath Effects on an Azimuthal Monopulse System

The first topic considered is an analysis of the conditions under which the conventional definition of length of the glistening surface, as given by Beckmann and Spizzichino, is not valid. For some conditions, significant amounts of incoherent scattered power can be received from areas beyond the conventional length. A second topic is the investigation of the effect on azimuthal angular tracking accuracy due to such scattering factors as shadowing, surface height distribution, standard deviation in surface height ?, surface correlation length T, unevenness and inhomogeneity of the terrain, antenna heights, and signal polarization. A number of interesting results have been observed. The amount of additional incoherent power not included under the conventional definition depends on the ratio ?/T, except for the case where both transmitter and receiver are very close to the surface. The trends in the behavior of the glistening surface are similar for vertical or horizontal polarization, for Gaussian or exponential surface height distributions, and for different signal frequencies in the S-band to L-band range.     

The human/robot interface

The use of telerobotic technology in space exploration is examined. Early aspirations for anthropomorphic designs and advances in the field are reviewed. The application of human factors engineering to robotics design and the human-machine interface are examined. New strategies in design and automation are presented.     

Experimental Study of the Structures of Macroparticles in the Dust Plasma under Microgravity Conditions onboard the MirOrbital Complex

The dynamics of formation of the ordered structures of charged macroparticles under microgravity conditions is investigated. The experimental observations of the behavior of an ensemble of macroparticles were carried out onboard the Mirspace station. The analysis and comparison of results of experimental and theoretical investigations allow us to conclude that under microgravity conditions the formation of elongated, ordered structures of macroparticles, charged by solar radiation, is possible.     

Coronal Mass Ejections

This workshop summary tries to distill the key difficulties and questions in the art of (I)CME physics and strategies to address them. (I)CMEs are multi-dimensional, multi-parameter, and multi-scale phenomena related to the solar dynamo, corona, and heliosphere. This workshop illustrates the immense progress made in describing and modeling these spectacular energetic solar events, but also shows clear shortcomings in our understanding of them.     

A concept for NASA's Mars 2016 astrobiology field laboratory

The Mars Program Plan includes an integrated and coordinated set of future candidate missions and investigations that meet fundamental science objectives of NASA and the Mars Exploration Program (MEP). At the time this paper was written, these possible future missions are planned in a manner consistent with a projected budget profile for the Mars Program in the next decade (2007-2016). As with all future missions, the funding profile depends on a number of factors that include the exact cost of each mission as well as potential changes to the overall NASA budget. In the current version of the Mars Program Plan, the Astrobiology Field Laboratory (AFL) exists as a candidate project to determine whether there were (or are) habitable zones and life, and how the development of these zones may be related to the overall evolution of the planet. The AFL concept is a surface exploration mission equipped with a major in situ laboratory capable of making significant advancements toward the Mars Program's life-related scientific goals and the overarching Vision for Space Exploration. We have developed several concepts for the AFL that fit within known budget and engineering constraints projected for the 2016 and 2018 Mars mission launch opportunities. The AFL mission architecture proposed here assumes maximum heritage from the 2009 Mars Science Laboratory (MSL). Candidate payload elements for this concept were identified from a set of recommendations put forth by the Astrobiology Field Laboratory Science Steering Group (AFL SSG) in 2004, for the express purpose of identifying overall rover mass and power requirements for such a mission. The conceptual payload includes a Precision Sample Handling and Processing System that would replace and augment the functionality and capabilities provided by the Sample Acquisition Sample Processing and Handling system that is currently part of the 2009 MSL platform.     

A Modification of the Method of Transporting Trajectory

Further development of an approximate method for optimizing a flight with an ideally controlled small thrust is proposed. The method is based on the employment of the transporting trajectory and considered in [1–3]. A detailed analysis of the means of improving the accuracy of this method suggested in [2, 3] is carried out, and the solution is presented in finite form. The proposed approach is applied to the flights making flybys of many celestial bodies. In the case of small bodies the solution is also obtained in finite form. A numerical example is considered confirming the high efficiency of this method.