First stage identification of syntactic elements in an extra-terrestrial signal

By investigating the generic attributes of a representative set of terrestrial languages at varying levels of abstraction, it is our endeavour to try and isolate elements of the signal universe, which are computationally tractable for its detection and structural decipherment. Ultimately, our aim is to contribute in some way to the understanding of what ‘languageness’ actually is. This paper describes algorithms and software developed to characterise and detect generic intelligent language-like features in an input signal, using natural language learning techniques: looking for characteristic statistical “language-signatures” in test corpora. As a first step towards such species-independent language-detection, we present a suite of programs to analyse digital representations of a range of data, and use the results to extrapolate whether or not there are language-like structures which distinguish this data from other sources, such as music, images, and white noise.     

The solar wind interaction with the geomagnetic field

A review is presented of the interaction of the solar wind with the magnetic field of the earth. The material is developed primarily from an observational point of view. The early observations are covered through late 1963, with primary emphasis on the sunward interaction region. The historical review of the early results is discussed in terms of the significant contributions of each satellite observation and in the light of our present concept of the solar wind-geomagnetic field interaction. Subsequent to 1963 the observations tend to overlap such that a strictly historical treatment is not tractable and the material is presented from a phenomenological approach. The daytime and night-time hemispheres are covered separately in terms of the significant and separable phenomena which dominate the structure and dynamics of these two regions. Satellite and deep space probe data are compared with relevant theory. Further observational eflorts needed to improve our understanding of the details of the solar wind-geomagnetic field interaction are also discussed.     

Prediction of solar particle event proton doses using early dose rate measurements

A methodology for predicting solar particle event doses using Bayesian inference is being developed. As part of this development, we have tested criteria for categorization of new solar particle events (SPE) using calculated asymptotic doses and dose rates for the 22 SPEs that occurred in 2001. In 9 out of 22 events, our criteria for categorization would have over-predicted the range of asymptotic doses in which the tested events would have fallen. In two cases, our methodology under-predicted the dose range in which the event would have fallen. In order to better predict a new event's group category and thus, to better restrict the Bayesian inference predictive model parameter space, we have reexamined our dose rate criteria for categorization of new events. We report the updating of the grouping criteria using data from the 22 SPEs of 2001, as well as five additional SPEs. Using the revised grouping criteria, we present an analysis of group categorization prediction results for the first ten SPEs of 2002.     

Oxidant enhancement in martian dust devils and storms: storm electric fields and electron dissociative attachment

Laboratory studies, numerical simulations, and desert field tests indicate that aeolian dust transport can generate atmospheric electricity via contact electrification or "triboelectricity." In convective structures such as dust devils and dust storms, grain stratification leads to macroscopic charge separations and gives rise to an overall electric dipole moment in the aeolian feature, similar in nature to the dipolar electric field generated in terrestrial thunderstorms. Previous numerical simulations indicate that these storm electric fields on Mars can approach the ambient breakdown field strength of approximately 25 kV/m. In terrestrial dust phenomena, potentials ranging from approximately 20 to 160 kV/m have been directly measured. The large electrostatic fields predicted in martian dust devils and storms can energize electrons in the low pressure martian atmosphere to values exceeding the electron dissociative attachment energy of both CO2 and H2O, which results in the formation of the new chemical products CO/O- and OH/H-, respectively. Using a collisional plasma physics model, we present calculations of the CO/O- and OH/H- reaction and production rates. We demonstrate that these rates vary geometrically with the ambient electric field, with substantial production of dissociative products when fields approach the breakdown value of approximately 25 kV/m. The dissociation of H2O into OH/H- provides a key ingredient for the generation of oxidants; thus electrically charged dust may significantly impact the habitability of Mars.