Analysis of laser extracted volatiles in carbonaceous chondrites

It is scientifically important to understand the composition of volatile compounds from interplanetary dust particles (IDPs) because they may be related to the primordial inventory of planetary materials which were necessary to provide environments conducive to the formation of life. The use of a laser microprobe to measure volatiles in IDPs was evaluated. Because primitive meteorites are thought to be closely related to IDPs, carbonaceous chondrites were used for the evaluation. Three sets of experiments were performed to determine the volatiles released from potential substrate materials, to analyze the volatiles released from matrices of bulk samples of carbonaceous chondrites, and to analyze volatiles released from approx. 100 to 200 micron meteorite particles to simulate IDPs. Aluminum appeared to be the best choice of substrate material. Mass ratios between carbonaceous chondrite matrices of Allende and Murchison show fair reproducibility with somewhat high uncertainties. Particles from the Orgueil, Murchison, and Allende meteorites produced measurable quantities of volatiles that appear to have mass spectra comparable to the bulk matrices

Wavelet encoding and variable resolution progressive transmission

Progressive transmission is a method of transmitting and displaying imagery in stages of successively improving quality. The subsampled lowpass image representations generated by a wavelet transformation suit this purpose well, but for best results the order of presentation is critical. Candidate data for transmission are best selected using dynamic prioritization criteria generated from image contents and viewer guidance. We show that wavelets are not only suitable but superior when used to encode data for progressive transmission at non-uniform resolutions. This application does not preclude additional compression using quantization of highpass coefficients, which to the contrary results in superior image approximations at low data rates

Electron microscopic observations of hydrogen implantation in ilmenites

Hydrogen ion beams were found to form submicrometer, bumpy textures on the surface of ilmenite grains. From this effect, it is believed that similar bumpy textures seen on lunar ilmenite, pyroxene, and olivine grains are likely to be caused by solar wind irradiation. As a consequence, the concentration of bumpy textured grains may be a useful index of surface maturity for lunar soils. An attempt was made to search for grains with these bumpy textures in interplanetary dust and lunar and meteoritic regolith breccias in order to obtain information about the duration of their exposure to the solar wind. Solar wind irradiation was simulated on natural, terrestrial ilmenite. Hydrogen ion beams were directed at small grains and polished sections which were then examined by electron microscopy

Particle track measurements in lunar regolith breccias

Particle track measurements have been reported for 25 (5 percent) of the regolith breccias in the collection; they have been reported for 16 breccias (30%) in the reference suite. The most frequently reported measurement for these 25 breccias is the maximum surface exposure age of the compacted rock (48% of the published breccia measurements). Information on the nature of the precompaction regolith is given for 9 rocks (36%) and on the nature of the compaction event for 6 rocks (24%). Most of the breccias appear to have simple post compaction surface exposure histories (89%). From the few track density frequency distributions (7) that are available and inferring from the low exposure ages of these rocks (75% were younger than 10 to the 6th years), it appears that most of these breccias are amenable to studies which separate the contemporary surface exposure age from information about the precompaction regolith. If the number of immature submature precompaction soils (6 out of 10 of the breccias for which appropriate data are available) represents many regolith breccias, then it is inferred that regolith breccias may sample the deeper, less reworked materials in the lunar soil and compliment the samples available from the returned cores

Testing of models of VVH particle sources and propagation

For comparisons between theoretical and observed charge spectra of the VVH particles to be meaningful, at least two conditions must be met. First, charge resolution must be adequate to separate important groups of nuclei, and there should be no significant systematic errors in the charge scale developed. Second, there must be adequate rejection of slower particles of smaller Z, which have been observed in several flights. Within these conditions, it has been shown that observed features of the charge spectrum are not accidents of the analysis but reflect real variations in the relative abundances that must be explained by any successful model

Managing the Transition to Climate Stabilization

This paper builds upon recent work by the US Climate Change Science Program (CCSP). Among its products, the CCSP developed new emission projections for the major man-made greenhouse gases, explored the effects of emission limits on the energy system, and calculated the costs of various stabilization constraints to the economy. This paper applies one of the models used for that analysis to explore the sensitivity of the results to three potentially critical factors: the stabilization level, the policy design, and the availability and costs of low- to zero-emitting technologies. The major determinant of costs is likely to be something over which we have little control - Mother Nature. The choice of stabilization level will reflect our understanding of the science of global climate change. We have little control over many of the key bio-geophysical processes which, to a major extent, will determine what constitutes dangerous anthropogenic interference with the climate system. We consider two limits on radiative forcing, corresponding to stabilizing CO2 concentrations at approximately 450 ppmv and 550 ppmv. These levels have been chosen because of the fundamentally different nature of the challenge posed by each. In the case of the lower concentration limit, emission reductions will be required virtually immediately and annual GDP losses to the US could approach 5%. With the higher concentration limit, the pressure for a sharp reduction in near-term emissions is not as great. This offers some potential to reduce GDP losses. Indeed, we find that depending upon the concentration limit, implementing market mechanisms which take advantage of 'where' and 'when' flexibility can markedly reduce GDP losses, perhaps by as much as an order of magnitude. However, for a variety of reasons, our ability to realize such savings may be compromised. One possible impediment relates to the proximity to the target. If the limit is imminent, flexibility will be greatly reduced. The nature of the coalition and our willingness to permit 'borrowing' emission rights from the future will also affect the magnitude of the potential savings. As a result, the reduction in GDP losses from where and when flexibility may turn out to be only a small fraction of what has been previously estimated. Fortunately, the biggest opportunity for managing costs may come from something over which we do have considerable control. We find that investments in climate friendly technologies can reduce GDP losses to the US by a factor of two or more. At present, we have insufficient economically competitive substitutes for high carbon emitting technologies. The development of low- to zero-emitting alternatives will require both a sustained commitment on the part of the public sector upstream in the R&D chain and incentives for the private sector to bring the necessary technologies to the marketplace. Aside from helping to assure that environmental goals are met in an economically efficient manner, climate policy can also serve as an enabler of new technologies. By recognizing the acute shortage of low-cost substitutes, the long lead times required for development and deployment, and the market failures that impede technological progress, climate policy can play an important role in reducing the long-term costs of the transition.