Spatial fragmentation of solar flare plasma and beams

The observational and theoretical arguments for spatial fragmentation of the bulk of the thermal and non-thermal components of solar flare plasma are summarised. Observational aspects considered include XUV filling factors, EUV centre to limb variations, andH impact polarisation. Theoretical points addressed are the high flare inductance and beam/return current closure at the acceleration site.A high degree of beam/plasma filamentation implies strong transverse temperature gradients so that cross-field conduction must be included in energy transport modelling. Preliminary results are described for a simple two-component model.     

Space at ESOF 2012

Over 4200 delegates attended the fifth Euroscience Open Forum (ESOF), held in Dublin from 11 to 15 July 2012, with papers covering the gamut of scientific research, applications and policy contributed by Nobel laureates, including James Watson and Jules Hoffmann, internationally recognized but ‘local’ figures such as Mary Robinson, Jocelyn Bell Burnell and Bob Geldof, ‘celebrity’ scientists like Marcus du Sautoy and Craig Venter and a range of other major researchers. Space was also represented, with keynotes by the NASA administrator and ESA's Director of Science and Robotic Exploration. This report summarizes and discusses the space-related proceedings.     

Implementation of an ESA delta-DOR capability

This paper describes the implementation of delta-DOR (delta-differential one-way ranging) receivers within the ESA Deep Space ground station network. Delta-DOR provides very accurate plane-of-sky measurements of spacecraft position which complement existing line-of-sight ranging and Doppler measurements. We discuss how this technique has been adapted and implemented at the two ESA deep-space ground stations using existing equipment and infrastructure. These new capabilities were added by writing new software modules for the standard ESA digital receiver (the intermediate frequency modem system—IFMS). With these upgrades the receiver has the ability to record accurately timetagged signals from up to eight IF sub-channels. These sub-channels can have bandwidths of 50 kHz–2 MHz with a sample quantization of 1–16 bits per component. The IF samples are stored locally for subsequent retrieval over a WAN by the correlator facility at ESOC.     

Pulse Repetition Frequency Discriminator with Complete Harmonic Suppression

A method for selective pulse-train discrimination based on pulse repetition frequency (PRF) is presented. The technique permits acceptance of a pulse train with a desired PRF while rejecting all others, including those with pulse rates harmonically related to the desired one.     

Positive psychological effects of space missions

Being in space is a powerful experience that can have an enduring, positive impact on the psychological well-being of astronauts and cosmonauts. We sought to examine the frequency, intensity and distribution of such salutogenic experiences among persons who have flown in space, using a questionnaire we developed based on the scientific literature and first person accounts. All participants reported positive effects of being in space, but the degree of change varied widely, and some experiences were particularly common. Three of our five predicted attitude-behavior relationships were supported by the data. Response patterns did not vary according to demographics or time in space. Cluster analysis yielded two groups of participants. One group was generally more reactive and also placed a higher priority on perceptions of space than did the other group. We conclude that positive experiences are common among space travelers and seem to cluster into meaningful patterns that may be consequential for Mars missions. We consider the possible selection, training, and monitoring issues raised by our findings.     

The proximity fuze

The ballistic accuracy and range of guns in 1914 was adequate for shooting at aircraft, but the method of aiming had not evolved beyond 1871 and was incapable of dealing with the small size, high speed, and agility of the airplane. It was realized that direct hits by projectiles could not be expected except by machine gun and automatic cannon, so the high explosive shells of heavier guns would have to be detonated through the time fuzes used for shrapnel. Pointing the gun and cutting the fuze required accurate location of the target and calculation of where it would be when the shell completed its flight. Of the inaccuracies in causing a shell to explode near an airplane, that of the fuze, especially the accurate determination of the flight time, was by far the worst. The development of a solution to this problem, a fuze that felt the influence of the plane in some manner, is reviewed     

Observability, Eigenvalues, and Kalman Filtering

In higher order Kalman filtering applications the analyst often has very little insight into the nature of the observability of the system. For example, there are situations where the filter may be estimating certain linear combinations of state variables quite well, but this is not apparent from a glance at the error covariance matrix. It is shown here that the eigenvalues and eigenvectors of the error covariance matrix, when properly normalized, can provide useful information about the observability of the system.