Escaping near-relativistic electron beams from the solar corona

Processes in the solar corona are prodigious accelerators of energetic ions, and electrons. The angular distribution, composition, and spectra of energetic particles observed near Earth gives information on the acceleration mechanisms. A class of energetic particle observations particularly useful in understanding the solar acceleration is the near-relativistic impulsive beam-like electron events. During five years of operation the Advanced Composition Explorer (ACE) has measured well over 400 electron events. Approximately 25% of these electron events are impulsive beam-like events that are released onto interplanetary field lines predominantly from western solar longitudes. We extend our initial 3 year study during the rise to solar maximum (Haggerty and Roelof, 2002; Simnett et al., 2002) to a five year statistical analysis of these beam-like energetic electron events in relationship to optical flares, microwave emission, soft X-ray emission, metric and decametric type-III radio bursts, and coronal mass ejections.     

The asymmetrical growth of otoliths in fish is affected by hypergravity.

Size and asymmetry (size difference between the left and the right side) of inner ear otoliths of larval cichlid fish were determined after a long-term stay at moderate hypergravity conditions (3g; centrifuge), in the course of which the animals completed their ontogenetic development from hatch to freely swimming. Both the normal morphogenetic development as well as the timely onset and gain of performance of the swimming behaviour was not impaired by the experimental conditions. However, both utricular and saccular otoliths (lapilli and sagittae, respectively) were significantly smaller after hyper-g exposure as compared to parallely raised 1g control specimens. The asymmetry of sagittae was significantly increased in the experimental animals, whereas the respective asymmetry con-cerning lapilli was pronouncedly decreased in comparison to the 1g controls. These findings suggest, that the growth and the development of bilateral asymmetry of otoliths is guided by the environmental gravity vector.     

Productivity and food value of Amaranthus cruentus under non-lethal salt stress.

Stress effects from the accumulation of metal salts may pose a problem for plants in closed biological systems such as spacecraft. This work examined the effects of salinity on growth, photosynthesis and carbon allocation in the crop plant, Amaranthus. Plants were germinated and grown in modified Hoagland's solution with NaCl concentrations of 0 to 1.0%. Plants received salt treatments at various times in development to assess effects on particular life history phases. For Amaranthus cruentus, germination, vegetative growth, flowering, seed development and yield were normal at salinities from 0 to 0.2%. Inhibition of these phases increased from 0.2 to 0.4% salinity and was total above 0.5%. 1.0% salinity was lethal to all developmental phases. Onset of growth phases were not affected by salinity. Plants could not be adapted by gradually increasing salinity over days or weeks. Water uptake increased, while photosynthetic CO2 uptake decreased with increasing salinity on a dry weight basis during vegetative growth. Respiration was not affected by salinity. After flowering, respiration and photosynthesis decreased markedly, such that 1.0% NaCl inhibited photosynthesis completely. Protein levels were unchanged with increasing salinity. Leaf starch levels were lower at salinities of 0.5% and above, while stem starch levels were not affected by these salinities. The evidence supports salt inhibition arising from changes in primary biochemical processes rather than from effects on water relations. While not addressing the toxic effects of specific ions, it suggests that moderate salinity per se need not be a problem in space systems.     

Optimum Steady State Position, Velocity, and Acceleration Estimation Using Noisy Sampled Position Data

A one-dimensional tracking filter based on the Kalman filtering techniques for tracking of a dynamic target such as an aircraft is discussed. The target is assumed to be moving with constant acceleration and is acted upon by a plant noise which perturbs its constant acceleration motion. The plant noise accounts for maneuvers and/or other random factors. Analytical results for estimating optimum steady state position, velocity, and acceleration of the target are obtained.     

User issues and Earth observation data policy

The second workshop of the EOPOLE project was held in Cosenza, Italy, 10–12 May 1999, organised by Microwave Consultant Engineering (MiCE). Its purpose was to address the user issues related to Earth observation data policy. This report presents the main conclusions of the workshop. The different approaches among lead departments within national governments emerged as one of the main areas of which users in Europe need to be aware.     

Adaptive pulse compression via MMSE estimation

Radar pulse compression involves the extraction of an estimate of the range profile illuminated by a radar in the presence of noise. A problem inherent to pulse compression is the masking of small targets by large nearby targets due to the range sidelobes that result from standard matched filtering. This paper presents a new approach based upon a minimum mean-square error (MMSE) formulation in which the pulse compression filter for each individual range cell is adaptively estimated from the received signal in order to mitigate the masking interference resulting from matched filtering in the vicinity of large targets. The proposed method is compared with the standard matched filter and least-squares (LS) estimation and is shown to be superior over a variety of stressing scenarios.     

Near infrared studies of the massive X-ray binary 2S 0114+65

We present near-infrared spectroscopy of the massive X-ray binary 2S 0114+650. These observations covering the spectral range 1.08–2.35 μm span the region where Paschen and Brackett series recombination lines of hydrogen are expected to be seen, namely, Paβ , Brγ and Br 10–17 lines. The absence of any of these lines in emission supports earlier inferences that the optical component in 2S 0114+650 is unlikely to be a Be star but rather a B type supergiant. Near-IR photometry gives J = 8.78, H = 8.53 and K = 7.96; these values show marginal variations from earlier reported measurements.     

Multiband echo tomography of Sco X-1

We present preliminary results of a simultaneous X-ray/optical campaign of the prototypical LMXB Sco X-1 at 1–10 Hz time resolution. Lightcurves of the high excitation Bowen/HeII emission lines and a red continuum at λ_c  6000 Å were obtained through narrow interference filters with ULTRACAM, and these were cross-correlated with simultaneous RXTE X-ray lightcurves. We find evidence for correlated variability, in particular when Sco X-1 enters the Flaring branch. The Bowen/HeII lightcurves lag the X-ray lightcurves with a light travel time which is consistent with reprocessing in the companion star while the continuum lightcurves have shorter delays consistent with reprocessing in the accretion disc.     

A technique for estimating the probability of radiation-stimulated failures of integrated microcircuits in low-intensity radiation fields: Application to the Spektr-R spacecraft

In developing radio-electronic devices (RED) of spacecraft operating in the fields of ionizing radiation in space, one of the most important problems is the correct estimation of their radiation tolerance. The “weakest link” in the element base of onboard microelectronic devices under radiation effect is the integrated microcircuits (IMC), especially of large scale (LSI) and very large scale (VLSI) degree of integration. The main characteristic of IMC, which is taken into account when making decisions on using some particular type of IMC in the onboard RED, is the probability of non-failure operation (NFO) at the end of the spacecraft’s lifetime. It should be noted that, until now, the NFO has been calculated only from the reliability characteristics, disregarding the radiation effect. This paper presents the so-called “reliability” approach to determination of radiation tolerance of IMC, which allows one to estimate the probability of non-failure operation of various types of IMC with due account of radiation-stimulated dose failures. The described technique is applied to RED onboard the Spektr-R spacecraft to be launched in 2007.