Nanosatellites and micro systems technology — capabilities, limitations and applications

In recent years Micro Systems Technology (MST) was introduced to manufacture miniaturized components for satellite subsystems, like small sensors, valves, micromotors, antennas and many more. These components can be used to build a new class of satellites weighing considerably less than 10 kg, with the capabilities comparable to present microsatellites. With the possibility of cheap mass production of such nanosatellites new applications become possible. However, the construction of very small satellites is connected with problems concerning launch, orbit control and, deorbiting. Furthermore the reduction of size creates certain limits for power consumption, data rates and optical resolutions which have to be carefully considered.     

SCIAMACHY limb measurements of NO2, BrO and OClO. Retrieval of vertical profiles: Algorithm,first results,sensitivity and comparison studies

The Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY) measures scattered sun light also in limb viewing mode (i.e. tangential to Earth’s surface and its atmosphere), which allows determining vertical profiles of atmospheric trace gases. First results on the retrieval of NO₂, BrO and OClO profiles from the SCIAMACHY Limb measurements are presented and compared to independent satellite and balloon borne observations.     

GNSS-R concept extended by a fine orbit tuning

Small changes in semimajor axis of the orbits selected for the GNSS-R [R as Reflectometry] satellites, so-called fine orbit tuning, known from the ESA’s Gravity and steady-state Ocean Circulation Explorer mission, can dramatically increase the number of nadir and off-nadir reflecting points and, in turn, can enhance the capability of the concept of bistatic altimetry (GNSS Reflectometry) without additional costs. The application of our suggestion is feasible for a satellite which will be equipped by thrusters for the orbit keeping. During the mission lifetime several orbit tunings are feasible, just to transfer from one to another orbit. Then we can study short-periodic or longer-periodic features, according to scientific goals defined for the mission. The shortest cycles (few days), corresponding to the required revisit time (defined by ESA), may be subcycles of much longer cycles (repeat periods).     

Investigations on modern carbon materials in the Boris Kidrič Institute,Vinča

Modern carbon materials which have been objects of research at the Boris Kidri? Institute, Vin?a involve high-performance carbon fibres from PAN precursor, carbon-fibre-reinforced phenolic and epoxy resins, carbon-carbon composites, pyrolytic carbons deposited at 1500–2450 K both pure and containing small amounts of B, Si, P or U, and carbon felt from viscose rayon precursor. Investigations relevant to carbon fibres comprise a study of processes during air oxidation of PAN fibres and an extensive research of low-temperature SO₂-treatment of PAN fibres, which has resulted in a model of the structure stabilization and shows that this stabilization can be successfully applied for the preparation of high-performance carbon fibres. Extensive investigations of codeposition of carbon and small amounts of B, Si, P and U suggest that B, Si and P enter the pyrocarbon lattice substitutionally and produce important changes in properties of the product. B, Si and U act as graphitizing catalysts, the effect being most pronounced for Si. The fabrication technology of the carbon fibres, carbon-fibre-reinforced-plastics and of pyrolytic carbon has been developed on a laboratory scale.     

The distributions of positions of Minimal Orbit Intersection Distances among Near Earth Asteroids

This paper presents the distributions of the positions of the Minimal Orbit Intersection Distances (MOID) among three subgroups of the Near Earth Asteroids (NEAs). This includes 683 Atens, 4185 Apollos and 3538 Amors which makes over 15 millions combinations of the pairs of orbits. The results which are obtained in this analysis show very interesting distributions of positions of the MOIDs and circumstances of close approaches of the asteroids and emphasize influence of different orbital elements on these distributions.