Biological UV dosimeters in simulated space conditions.

Polycrystalline uracil thin layers participate in the phage and uracil response (PUR) experiment, assigned to the biological dosimetry of the extraterrestrial solar radiation on the International Space Station (ISS). In ground based experiments (experiment verification tests), the following space parameters were simulated and studied: temperature, vacuum and short wavelength UV (UV-C, down to 200 nm) radiation. The closed uracil samples proved to be vacuum-tight for 7 days. In the tested temperature range (from -20 to +40 degrees C) the uracil samples are stable. The kinetic of dimer formation (dimerization) and reversion (monomerization) of uracil dimers due to short wavelength UV radiation was detected, the monomerization efficiency of the polychromatic deuterium lamp is higher than that of the germicidal lamp. A mathematical model describing the kinetic of monomerization-dimerization was constructed. Under the influence of UV radiation the dimerization-monomerization reactions occur simultaneously, thus the additivity law of the effect of the various wavelengths is not applicable.     

Features of rotational motion of a spacecraft descending in the Martian atmosphere

Angular motion at atmospheric entry is studied in the paper for a spacecraft with a bi-harmonic moment characteristic. Special attention is given to the case when the spacecraft possesses two stable balanced positions, and, hence, it can oscillate in dense atmospheric layers in the ranges of small or large angles of attack. The averaged equations of spacecraft motion are derived, which allow one to increase the speed of calculations by several orders of magnitude. A real example is presented, which concerns a spacecraft specially designed for descending in the Martian atmosphere.     

Coronal radio-sounding detection of a CME during the 1997 Galileo solar conjunction

Frequency fluctuations of the Galileo S-band radio signal were recorded nearly continuously during the spacecraft’s solar conjunction from December 1996 to February 1997. A strong propagating disturbance, most probably associated with a coronal mass ejection (CME), was detected on 7 February when the radio ray path proximate point was on the west solar limb at about 54 solar radii from the Sun. The CME passage through the line of sight is characterized by a significant increase in the fluctuation intensity of the recorded frequency and by an increase in the plasma speed from about 234 km s⁻¹ up to about 755 km s⁻¹. These velocity estimates are obtained from a correlation analysis of frequency fluctuations recorded simultaneously at two widely-separated ground stations. The density turbulence power spectrum is found to steepen behind the CME front. The Galileo radio-sounding data are compared with SOHO/LASCO observations of the CME in the corona and with WIND spacecraft data near the Earth’s orbit.     

The MELISSA pilot plant facility as as integration test-bed for advanced life support systems.

The different advances in the Micro Ecological Life Support System Alternative project (MELISSA), fostered and coordinated by the European Space Agency, as well as in other associated technologies, are integrated and demonstrated in the MELISSA Pilot Plant laboratory. During the first period of operation, the definition of the different compartments at an individual basis has been achieved, and the complete facility is being re-designed to face a new period of integration of all these compartments. The final objective is to demonstrate the potentiality of biological systems such as MELISSA as life support systems. The facility will also serve as a test bed to study the robustness and stability of the continuous operation of a complex biological system. This includes testing of the associated instrumentation and control for a safe operation, characterization of the chemical and microbial safety of the system, as well as tracking the genetic stability of the microbial strains used. The new period is envisaged as a contribution to the further development of more complete biological life support systems for long-term manned missions, that should be better defined from the knowledge to be gained from this integration phase. This contribution summarizes the current status of the Pilot Plant and the planned steps for the new period.     

Simplified Solution for a Class of Fading Memory Filters

A fading memory filter is a least squares estimator (LSE) thatapplies an exponentially decaying weight to past measurements.When compared with a standard Kalman filter, its key advantagesare asymptotic stability and reduced sensitivity to modeling errors.This paper derives a simple solution for a class of fading memoryfilters, resulting in a reduction in computational complexity. Steadystate filter solutions are obtained for second-and third-order filtersused in a global positioning system (GPS) receiver for high dynamicvehicles.     

Cloudiness over the Eastern Equatorial Pacific for summer 1983 from geostationary satellite data

The extraordinary El-Nino event of 1982–83 started to fade out in the late spring of 1983. However the sea surface temperature of the Eastern Equatorial Pacific still remained warmer than normal in the following summer. To investigate the characteristics of this late transition phase of the 1982–83 El-Nino, the GOES-West satellite data of July and August of 1983 are analyzed. The outgoing longwave radiation field and the distribution of cloudiness, which was derived by using a new threshold technique, are obtained. The longwave radiation field is compared to monthly average climatic indices commonly used at the Climatic Analysis Center. The results of cloud analysis showed some interesting features during the decaying phase of the 1982–83 El-Nino. The diurnal variation of cloudiness indicates that total cloud amounts decrease from 8 GMT to 20 GMT over most of the area. This overall study demonstrates preliminary results of the International Satellite Cloud Climatology Project of the World Climate Research Program.     

Connection between the discrete auroral structures drifting equatorward during the substorm expansion phase and the energetic particle injections at the geostationary orbit

The formation of an auroral bulge with a bright dynamical arc at its polar boundary is one of the main manifestations of the magnetospheric substorm expansion phase at the ionospheric level. At the same time, the region of discrete aurora broadens not only polewards but equatorwards as well. The discrete forms of auroras moving equatorwards form a dynamical equatorial boundary of the auroral bulge shifting together with them. The paper presents a spatial-time comparison of the drifting discrete auroras to the injection of energetic particles at the geostationary orbit. It is shown that bursts in the fluxes of energetic particles at the LANL geostationary satellites located in the same sector of MLT correspond to the majority of drifting discrete auroral structures observed by the all-sky camera. In the cases when the bursts in the fluxes are absent, the minimum latitude reached by the auroral structures at the equatorward drift is higher than the ionospheric projection of the geostationary orbit. A possible relation of the drifting discrete auroras to the plasma stream jets in the plasma sheet is discussed.     

Crew autonomy for deep space exploration: Lessons from the Antarctic Search for Meteorites

Future piloted missions to explore asteroids, Mars, and other targets beyond the Moon will experience strict limitations on communication between vehicles in space and control centers on Earth. These limitations will require crews to operate with greater autonomy than any past space mission has demonstrated. The Antarctic Search for Meteorites (ANSMET) project, which regularly sends small teams of researchers to remote parts of the southern continent, resembles a space mission in many ways but does not rely upon a control center. It provides a useful crew autonomy model for planners of future deep space exploration missions. In contrast to current space missions, ANSMET gives the crew the authority to adjust competing work priorities, task assignments, and daily schedules; allows the crew to be the primary monitor of mission progress; demands greater crew accountability for operational errors; requires the crew to make the most of limited communication bandwidth; adopts systems designed for simple operation and failure recovery; and grants the crew a leading role in the selection and stowage of their equipment.     

Instrumentation for investigation of the depth-dose distribution by the Liulin-5 instrument of a human phantom on the Russian segment of ISS for estimation of the radiation risk during long term space flights.

Described is the Liulin-5 experiment and instrumentation, developed for investigation of the space radiation doses depth distribution in a human phantom on the Russian Segment of the International Space Station (ISS). Liulin-5 experiment is a part of the international project MATROSHKA-R on ISS. The experiment MATROSHKA-R is aimed to study the depth dose distribution at the sites of critical organs of the human body, using models of human body-anthropomorphic and spherical tissue-equivalent phantoms. The aim of Liulin-5 experiment is long term (4-5 years) investigation of the radiation environment dynamics inside the spherical tissue-equivalent phantom, mounted in different places of the Russian Segment of ISS. Energy deposition spectra, linear energy transfer spectra, flux and dose rates for protons and the biologically-relevant heavy ion components of the galactic cosmic radiation will be measured simultaneously with near real time resolution at different depths of the phantom by a telescope of silicon detectors. Data obtained together with data from other active and passive dosimeters will be used to estimate the radiation risk to the crewmembers, verify the models of radiation environment in low Earth orbit, validate body transport model and correlate organ level dose to skin dose. Presented are the test results of the prototype unit. The spherical phantom will be flown on the ISS in 2004 year and Liulin-5 experiment is planned for 2005 year.     

Performance limits of sensor-scheduling strategies in electronic support

The case is considered in which a frequency-agile receiver (FAR) for electronic support (ES) attempts to intercept radar emissions over a wide search bandwidth. It was recently shown [1,2] that a random strategy exists in which the expected intercept time can be made arbitrarily close to linear as a function of the scan period of the radar. Can a deterministic strategy be devised in which a similar linear relationship exists for the maximum intercept time? By applying the celebrated arithmetic results of van der Waerden [3] and Szemeredi [4], we show that no such strategy is possible.