Determination of the Microacceleration Quasisteady Component onboard the International Space Station

A comparison of two methods of determination of the microacceleration quasisteady component arising onboard the International Space Station was performed. In the first method the acceleration was calculated using the relative motion of the station reconstructed on the basis of telemetry data. The second method was a direct measurement of the microacceleration by a low-frequency accelerometer and a smoothing of the data obtained. The used measurements were made by the American accelerometer MAMS. The above comparison can theoretically be used to refine the position of the station center of mass relative to its body.     

Microperturbations on the <Emphasis Type="Italic">International Space Station</Emphasis> during physical exercises of the crew

The results of a preliminary analysis of microperturbations on the International Space Station during physical exercises of the crew are presented. The goal of this paper is to identify the parameters of perturbations when physical exercises are performed. The results of measurements by sensors of microaccelerations of both Russian and American segments during physical exercises in the service module of the Russian segment are analyzed.     

Uncontrollable Rotational Motion of the Mir Orbital Station

The results of determining the rotational motion of the Mir orbital station are presented for four long segments of its unmanned uncontrolled flight in 1999–2000. The determination was carried out using the data of onboard measurements of the Earth's magnetic field intensity. These data, taken for a time interval of several hours, were jointly processed by the least squares method with the help of integration of the equations of station motion relative to its center of mass. As a result of this processing, the initial conditions of motion and the parameters of the mathematical model used were evaluated. The technique of processing is verified using the telemetry data on angular velocity of the station and its attitude parameters. Two types of motion were applied on the investigated segments. One of them (three segments) presents a rotation around the axis of the minimum moment of inertia. This axis executes small oscillations with respect to a normal to the orbit plane. Such a motion was used for the first time on domestic manned orbital complexes. The second type of motion begins with a biaxial rotation which, in a few weeks, goes over into a motion very similar to the rotation around the normal to the orbit plane, but around the axis of the maximum moment of inertia.     

The Mode of Gravitational Orientation for the International Space Station

The results of the determination of the uncontrolled attitude motion of the International Space Station during its unmanned flight in 1999 are presented. The data of onboard measurements of three components of the angular velocity are used for this determination. These data covering an interval of slightly less than one orbit were jointly processed by the least squares method, by integrating the equations of motion of the station relative to its center of mass. As a result of this processing, the initial conditions of the motion and the parameters of the mathematical model used were estimated. The actual motion of the station has been determined for 20 such intervals during April–November. Throughout these intervals, the station rotated about the axis of the minimum moment of inertia, the latter executing small oscillations relative to the local vertical. Such a mode, known as the mode of gravitational orientation of a rotating satellite or the mode of generalized gravitational orientation, was planned before the flight. The measurements were made to verify it. The quasistatic component of the microaccelerations aboard the station is estimated for this mode.     

Experimental investigation of the modes of operation of uncontrolled attitude motion of the Progress spacecraft

Results of in-flight tests of three modes of uncontrolled attitude motion of the Progress spacecraft are described. These proposed modes of experiments related to microgravity are as follows: (1) triaxial gravitational orientation, (2) gravitational orientation of the rotating satellite, and (3) spin-up in the plane of the orbit around the axis of the maximum moment of inertia. The tests were carried out from May 24 to June 1, 2004 onboard the spacecraft Progress M1-11. The actual motion of this spacecraft with respect to its center of mass, in the above-mentioned modes, was determined by telemetric information about an electric current tapped off from solar batteries. The values of the current obtained during a time interval of several hours were processed jointly using the least squares method by integration of the equations of the spacecraft’s attitude motion. The processing resulted in estimation of the initial conditions of motion and of the parameters of mathematical models used. For the obtained motions the quasi-static component of microaccelerations was computed at a point onboard, where installation of experimental equipment is possible.     

Instrumentation and data systems for high-time resolution study of space plasma shocks

This paper deals with the principal methods of achieving high-time resolution measurements for the study of fine structure of shocks and other discontinuities in space plasmas. In the measurements of ion energy spectra, we have obtained the time resolution about 1s.In the Soviet-Czechoslovak INTERSHOCK project we will obtain temporal resolution better than 0.1s in the measurement of the main plasma parameters. This will be obtained with the multichannel energy spectrometer and the on-board data acquisition and processing system triggered by the shock signature. This system controls the data sampling rate from some scientific instruments and switches on a high-sampling rate near the shock. The method implies detecting a shock by means of on-board processing of magnetic field and plasma parameters. The algorithm for this detection uses both parameters separately as well as in combinations.     

Experimental and mathematical models for small aqueous closed ecosystems with spatially separated components.

Experimental and theoretical models of closed "autotroph-heterotroph" (chlorella-yeast, chlorella-protozoa) ecosystems with spatially separated components have been created and studied. The chart of flows and interaction of components of gas-closed "chlorella-yeast" system have formed the basis describe mathematically the functioning of the given system, experimental results have been found to agree with computer solution of the problem in terms of quality. Investigation of the experimental model of the "producer-consumer" trophic chain demonstrated the role of protozoa in nitrogen turnover. "Production-decomposition" and "production-grazing-decomposition" cycle models has been theoretically analyzed and compared. The predator has been shown to be a more intensive mineralizer than the reducer component.     

Measurement of Vibration Microaccelerations onboard the Mir Orbital Station Using the VM-09 System of Accelerometers

The results of processing the data of measurements of microaccelerations, carried out onboard the Mir orbital station using the Russian VM-09 system of accelerometers, are described. The system was developed by the Composite Research-Production Association. The sensitivity of this system was 10^–4 m/s²; its frequency band had limits from a few tenths of a hertz up to 100 Hz. The measurements were carried out in the real-time mode of data transmission to the Earth, when the orbital station flew over the telemetry data receiving point. The instrument's sampling rate was 200 measurements per second, and the length of a continuous run of measurements did not exceed 10 min. The following problems are considered in the paper: (1) isolation of cyclic trends from the measurement data; (2) estimation of spectral density of the data component with a continuous spectrum; and (3) low-frequency filtration of the measurement data     

Uncontrolled Attitude Motion of the Orbital Station MIR in the Last Months of Its Flight

The results of determination of the uncontrolled attitude motion of the orbital station MIR on four prolonged segments of its unmanned flight in 2000 and 2001 are presented. The determination was carried out on the basis of the data of onboard measurements of the Earth's magnetic field. The data obtained on a time interval of several hours were processed jointly by the least squares method by integration of the equations of motion of the station with respect to its center of mass. The processing resulted in the estimation of the initial conditions of the motion and of the parameters of the mathematical model used. Several types of regular motion were observed on sufficiently prolonged time intervals on the studied segments. Some of these motions were planned; others were established spontaneously.     

Determination of the Quasistatic Component of Microaccelerations at the MirStation

We describe the determination of the quasistatic component of microaccelerations, as it was done during the space experiments with the instruments DACON and ALICE-2. This component was calculated using the telemetric information related to the motion of the station with respect to its center of mass. The information consists of the values of the station angular velocity vector and the quaternion which specifies its orientation, determined at discrete instants of time. The quaternion is determined with a step of about 1 min, the angular velocity with a step of about 10 s. The information is used in the following manner. At first, the quaternion components corresponding to some time interval are smoothed by splines. Then, employing the obtained splines and kinematic equations, the angular velocity and acceleration of the station are calculated on this interval. Finally, the microacceleration is calculated as a function of time at the point of the location of the instrument. The data of measurements of the angular velocity are used for the purpose of control. As a rule, the available telemetric information allows one to find the quasi-static component for the entire time interval of carrying out the experiment. Examples of determination of this component for some experiments are presented. A comparison with the results of calculating the microacceleration quasistatic component by other methods is made.