Radiation protection standards in space.

Radiation protection standards for the individual exposed to ionizing radiation in his/her daily work have evolved over more than 50 years since the first recommendations on limits by the NCRP and the ICRP. Initial standards were based on the absence of observable harm, notably skin erythema, but have since been modified as other concerns, such as leukemia and genetic effects, became more important. More recently, the general carcinogenic effect of radiation has become the principal concern at low doses. Genetic effects are also of concern in the younger individual. Modern radiation protection practices take both of these risks into account. Quantification of these risks improves as new information emerges. The study of the Japanese survivors of the atomic bombs continues to yield new information and the recent revisions in the dosimetry are about to be completed. The special circumstances of space travel suggest approaches to limits not unlike those for radiation workers on the ground. One approach is to derive a career limit based on the risks of accident faced by many nonradiation workers in a lifetime. The career limit can be apportioned according to the type of mission. The NCRP is considering this and other approaches to the specification of radiation standards in space.     

Radio emission from EA eclipsing binaries: Evidence for kilogauss early- and late-type stars

Space Science Reviews -     

Theoretical model of HZE particle fragmentation by hydrogen targets.

The fragmenting of high energy, heavy ions (HZE particles) by hydrogen targets is an important, physical process in several areas of space radiation research. In this work quantum mechanical optical model methods for estimating cross sections for HZE particle fragmentation by hydrogen targets are presented. The cross sections are calculated using a modified abrasion-ablation collision formalism adapted from a nucleus-nucleus collision model. Elemental and isotopic production cross sections are estimated and compared with report measurements for the breakup of neon, sulphur, and iron, nuclei at incident energies between 400 and 910 MeV/nucleon. Good agreement between theory and experiment is obtained.     

Balloon observation of the 1983 solar eclipse in Indonesia

A balloon observation of the total solar eclipse on 11 June 1983 was carried out as a cooperative work between Japanese and Indonesian teams. The observation was a photo-polarimetry of the F corona in both visual and near-infrared regions.The balloon of 15,000-m³ with a payload of 150-kg was launched at 7^h13^m on 11 June from Watukosek Balloon Base in East Java. Observation at an altitude of 30.5-km was successfully made during the totality (11^h28～32^m) at a position of ～40-km east-south-east from Jogjakarta.As a preliminary result, an excess in infrared brightness has been found near the position of 3.8R_⊙ west from the sun, which may be due to thermal emission from a high-temperature dust cloud located around the sun.     

Mortality and morphological anomalies related to the passage of cosmic heavy ions through the smallest flowering aquatic plant Wolffia arrhiza

Radiobiological effects of single cosmic heavy ions on individual, actively metabolizing test organisms, plants of Wolffia arrhiza, have been explored in an experiment flown aboard the Russian Biosatellite 10. Mortality induced during space flight, population dynamics during subsequent cultivation, and morphological anomalies occurring in the plants of these cultures were investigated. Correlation of these effects with the passage of a heavy ion was achieved by inserting monolayers of plants in a stack of surrounding plastic nuclear track detectors (BIO-STACK). Enhanced initial mortality and delayed decline of induced anomalies have been significantly associated with the passage of single heavy ions, in particular if ions penetrated the budding region of the plants. The prolonged persistence of anomalies in filial generations as an indication of delayed genetic damage has been detected for the first time as the consequence of the hit by a single heavy ion. Regarding radiation protection of space crew during prolonged missions, especially outside the magnetosphere, this appears to be a significant finding.     

Development of digital interactive processing system for NOAA satellites AVHRR data

The paper discusses the digital image processing system for NOAA/AVHRR data including Land applications — configured around VAX 11/750 host computer supported with FPS 100 Array Processor, Comtal graphic display and HP Plotting devices; wherein the system software for relational Data Base together with query and editing facilities, Man-Machine Interface using form, menu and prompt inputs including validation of user entries for data type and range; preprocessing software for data calibration, Sun-angle correction, Geometric Corrections for Earth curvature effect and Earth rotation offsets and Earth location of AVHRR image have been accomplished. The implemented image enhancement techniques such as grey level stretching, histogram equalization and convolution are discussed. The software implementation details for the computation of vegetative index and normalized vegetative index using NOAA/AVHRR channels 1 and 2 data together with output are presented; scientific background for such computations and obtainability of similar indices from Landsat/MSS data are also included. The paper concludes by specifying the further software developments planned and the progress envisaged in the field of vegetation index studies.     

A compact dopplergraph/magnetograph suitable for space-based measurements of solar oscillations and magnetic fields

A compact Dopplergraph/magnetograph placed in a continuous solar-viewing orbit will allow us to make major advancements in our understanding of solar internal structure and dynamics. An international program is currently being conducted at JPL and Mt. Wilson to develop such an instrument. By combining a unique magneto-optical resonance filter with CID and CCD cameras we have been able to obtain full- and partial-disk Dopplergrams and magnetograms. Time series of the velocity images are converted into k-ω power spectra which show clear- the solar nonradial p-mode oscillations. Magnetograms suitable for studying the long-term evolution of solar active regions have also been obtained with this instrument. A flight instrument based on this concept is being studied for possible inclusion in the SOHO mission.     

A mean level adaptive detector using nonconcurrent data

Convergence results for a mean level adaptive detector (MLAD) are presented. The MLAD consists of an adaptive matched filter (for spatially correlated inputs) followed by a mean level detector (MLD). The optimal weights of the adaptive matched filter are estimated from one batch of data and applied to a statistically independent batch of nonconcurrent data. The threshold of the MLD is determined from the resultant data. Thereafter a candidate cell is compared against this threshold. Probabilities of false alarm and detection are derived as a function of the threshold factor, the order of the matched filter, the number of independent samples per channel used to calculate the adaptive matched filter weights, the number of samples used to set the MLD threshold, and the output signal-to-noise power ratio of the optimal matched filter. A number of performance curves are shown and discussed     

The x-ray experiment on-board the “astron”

This paper describes the X-ray instrumentation, its capabilities and preliminary results which have been obtained for first two months operation.     

On mapping a tracking algorithm onto parallel processors

The problem of mapping the tasks of a multitarget tracking algorithm onto parallel computing architectures to maximize speedup is considered. An asymptotically optimal mapping algorithm is developed and applied to study the effects of task granularity and processor architectures on the speedup. From the simulation results, it is concluded that task granularity and the parallelization of clustering and global hypotheses formation stages of the tracking algorithm are major determinants of speedup