Soviet-Indian research of cosmic radiation by high altitude balloons

The report presents some results on the cosmic radiation intensity research carried out with the high-altitude balloons for the period of 1977–1979. The intensity of gamma-radiation with the energy above 40 MeV was measured in two balloon flights at an altitude of 4–7 g/cm² of residual atmosphere in the vicinity of the geomagnetic equator. A temporal analysis of the intensity to discover fluctuations with periods in the range of 4–60 min was made. Quasi-periodic fluctuations of gamma-radiation intensity with 5 min periods, amplitude ～20% and duration of several hours were discovered. Possible mechanisms of such fluctuation appearance are discussed.The report gives the results of measuring downward, upward and horizontal electron fluxes in the vicinity of the equator. The obtained data and the data provided by satellites are compared. The report discusses the prospects of further joint Soviet-Indian research of cosmic gamma-radiation.     

Determination of Failure Thresholds in Hybrid Navigation

A systematic approach for the determination of failure thresholds for hybrid navigation systems is described. Cost functions which reflect the importance assigned to the consequences of false and missed alarms are minimized. The false alarm probability is obtained as a function of the threshold magnitude by observing the statistical behavior of the instrument outputs in the normal operating mode. The missed alarm probability is obtained by determining the sensitivity of navigation error performance to instrument error sources. Two cost functions are considered. To illustrate this method, failure detection and identification (FDI) thresholds are determined for the Space Shuttle Approach and Landing Test flight.     

Performance of a blood chemistry analyzer during parabolic flight

We have tested the performance of the VISION System Blood Analyzer, produced by Abbott Laboratories, during parabolic flight on a KC-135 aircraft (NASA 930). This fully automated instrument performed flawlessly in these trials, demonstrating its potential for efficient, reliable use in a microgravity environment. In addition to instrument capability, we demonstrated that investigators could readily fill specially modified test packs with fluid during zero gravity, and that filled test packs could be easily loaded into VISION during an episode of microgravity.     

Ultimate IR Horizon Sensor

The accuracy of presently available IR horizon sensors is not sufficient to meet the stringent attitude sensing and control requirements for future remote sensing and meteorological satellites. The different sources of error in a horizon sensor are analyzed. The accuracy of the sensor is presently limited by the detector noise. Use of HgCdTe in place of an immersed bolometer detector, which is used in conventional horizon sensors eliminates many of the errors. Hence, it is possible to design an ultimate IR horizon sensor whose accuracy is limited only by the uncertainty of the Earth horizon. Comparison of performances of the two types of detectors for horizon sensing is given and possible configurations of sensor using this detector are discussed.     

Shock waves in water foams

Propagation of shock waves in tubes filled with water foams is studied using pressure gauges. Low amplitude shock waves consist of a precursor which propagates at a velocity slightly less than the acoustic velocity in the gas, and of a main compression wave which propagates slower than the precursor. Stronger shock waves have a single front. Maximum pressure rise in the incident and reflected shock waves cannot be calculated using one-dimensional conservation equations at the shock front. It is suggested that the flow of the liquid in foam cells has to be taken into account in order to predict the behavior of shock waves in foams. The nature of the gas which fills the cells is shown to have a strong effect on the quenching of blast waves in foams.     

A retarding potential analyzer for rocket experiments

A Retarding Potential Analyzer (RPA) is designed using a micro-channel plate in front of the collector as a flow amplifier, which makes it possible to detect ion species with very low concentration (<0,5 cm.^?3). A technique is described for using the micro-channel plate at abnormally high pressure (>0.01 N/m²). This allows the precise determination of the mass composition of the low ionosphere. An adaptive retarding potential consisting of 2048 steps is used to increase the sensitivity. This retarding potential is applied in the range where dI/dU ≠ 0. The sensor is hermetically sealed and opens on command.     

Energy deposition rates by charged particles measured during the energy budget campaign

Measurements of the precipitation of electrons and positive ions (in the keV to MeV range) detected aboard eight rockets launched from Northern Scandinavia are reported together with corresponding satellite data. The downgoing integral fluxes indicate the temporal fluctuations during each flight. Height profiles of the energy deposition into the atmosphere at different levels of geomagnetic disturbance are given.     

Some recent advances in energetic ion mass spectrometry

New techniques are being developed which will extend the capability of spacecraft-borne ion mass spectrometers into previously unexplored momentum regimes. These instruments include time-of-flight mass spectrometers and large laboratory class spectrometers suitable for Spacelab applications. Their characteristics, strengths and weaknesses are reviewed.     

Hydrodynamic shock wave formation in the solar chromosphere and corona during flares

Basic mechanisms of the hydrodynamic shock wave formation in the solar atmosphere during flares are considered. Hydrodynamic plasma flows during flares arise due to fast energy release which is accumulated in the magnetic field of currents in the solar atmosphere. Shock waves arise as a result of rapid heating of the chromospheric upper layers from accelerated particles or heat fluxes. Powerful hydrodynamic phenomena can also arise due to explosive current sheet disruption in the region of strong magnetic field reconnection. Fundamental questions of shock wave formation and propagation in a non-homogeneous emitting solar atmosphere are discussed.An invited paper presented at STIP Workshop on Shock Waves in the Solar Corona and Interplanetary Space, 15–19 June, 1980, Smolenice, Czechoslovakia.