Bursts of geomagnetic pulsations in the frequency range 0.2-5 Hz excited by large changes of the solar wind pressure

We present the results of studying the magnetospheres’s response to sharp changes of the solar wind flow (pressure) based on observations of variations of the ions flux of the solar wind onboard the Inreball-1 satellite and of geomagnetic pulsations (the data of two mid-latitude observatories and one auroral observatory are used). It is demonstrated that, when changes of flow runs into the magnetosphere, in some cases short (duration ~ < 5 min) bursts of geomagnetic pulsations are excited in the frequency range Δf~ 0.2–5 Hz. The bursts of two types are observed: noise bursts without frequency changes and wide-band ones with changing frequency during the burst. A comparison is made of various properties of these bursts generated by pressure changes at constant velocity of the solar wind and by pressure changes on the fronts of interplanetary shock waves at different directions of the vertical component of the interplanetary magnetic field.     

Relative occurrence rate and geoeffectiveness of large-scale types of the solar wind

We investigate the relative occurrence rate for various types of the solar wind and their geoeffectiveness for magnetic storms with Dst < —50 nT. Both integrated effect for the entire time 1976–2000 and variations during this period of 2.5 cycles of solar activity are studied As raw data for the analysis we have used the catalog of large-scale types of the solar wind for the period 1976-2000 (see ftp://ftp.iki.rssi.ru/omni/) created by us with the use of the OMNI database (http://omni.web.gsgc.nasa.gov) [1] and described in detail in [2]. The average annual numbers of different type of events are as follows: 124 ±81 for the heliospheric current sheet (HCS), 8 ±6 for magnetic clouds (MC), 99 ±38 for Ejecta, 46 ±19 for Sheath before Ejecta, 6 ±5 for Sheath before MC, and 63 ±15 for CIR. The measurements that allowed one to determine a source in the solar wind were available only for 58% of moderate and strong magnetic storms (with index Dst < —50 nT) during the period 1976–2000. Magnetic clouds (MC) are shown to be the most geoeffective (~61%). The CIR events and Ejecta with Sheath region are three times less geoeffective (~20–21 %). Variations of occurrence rate and geoeffectiveness of various types of the solar wind in the solar cycle are discussed.     

ESA’s process for the identification and assessment of high-risk conjunction events

ESA’s Space Debris Office provides an operational service for the assessment of collision risks of ESA satellites. Currently, the ENVISAT and ERS-2 missions in low Earth orbits are covered by this service. If an upcoming high-risk conjunction event is predicted based on analysis of Two-Line Element (TLE) data from the US Space Surveillance Network, then independent tracking data of the potential high-risk conjunction object are acquired to improve the knowledge of its orbit. This improved knowledge and the associated small error covariances derived from the orbit determination process scale down the position error ellipsoid at the conjunction epoch. Hence, for the same miss-distance, in most cases an avoidance manoeuvre can be suppressed with an acceptable residual risk.     

The space situational awareness program of the European Space Agency

The organization principles of constructing the European system of warning about dangerous situations in the outer space are considered in the paper.     

Compact high-sensitivity accelerometer-seismometer

Design of a three-axial accelerometer-seismometer, constructed on the basis of two-coordinate sensors (sensitive elements) of high and low accelerations, is considered in the paper. This instrument is applied for gravi-inertial measurements. Basic characteristics of the instrument are described, as well as the technique and results of its standardization.     

Mathematical modeling of cruciform parachute deployment

A problem of cruciform parachute deployment is considered. The process of deployment is simulated using the present-day numerical methods in the continuum mechanics, that is, the method of concentrated masses and the method of vortex frames. The calculation results are compared with the experimental data.     

Estimation of the determination accuracy of orbit parameters of the apophis asteroid from measurement results

An analysis of the existing astrometric and radar observations of the Apophis asteroid is performed. On the basis of this analysis, characteristics of future measurements of the asteroid orbit and limitation on their conduction are accepted. A proposed launching of a spacecraft to the asteroid in order to obtain high-accuracy measurements of its distance and radial velocity is also considered. Trajectories of the flight to the asteroid in 2012–2022 are studied. Estimates of the accuracy of the Apophis position determination at various sets of both available and planned measurements at various numbers of determined parameters are obtained. The method of estimating accuracy is similar to that used in [1] for the Vega project.     

The high-latitude ionosphere structure on 22 March, 1979 magnetic storm from multi-satellite and ground-based observation

Variations in the high-latitude ionosphere structure during March 22, 1979 geomagnetic storm are examined. Electron density Ne and temperature Te from the Cosmos-900 satellite, NmF2, Ne and He⁺ from the ISS-b satellite, precipitation of soft electrons from the Intercosmos-19 satellite, and the global picture of the auroral electron precipitation from the DMSP, TIROS and P78 satellites are used. These multi-satellite databases allow us to investigate the storm-time variations in the locations of the following ionospheric structures: the day-time cusp, the equatorial boundary of the diffuse auroral precipitation (DPB), the main ionospheric trough (MIT), the day-time trough, the ring ionospheric trough (RIT) and the light ions trough (LIT). The variations in NmF2, Ne, He⁺ and Te in the high-latitude ionosphere for the different local time sectors are analyzed also. The features of the high-latitude ionospheric response to a strong magnetic storm are described.