LEO trajectory modeling is a fundamental aerospace capability and has applications in many areas of aerospace, such as maneuver planning, sensor scheduling, re-entry prediction, collision avoidance, risk analysis, and formation flying. Somewhat surprisingly, modeling the trajectory of an object in low Earth orbit is still a challenging task. This is primarily due to the large uncertainty in the...

German Aerospace Agency (DLR), Fraunhofer FOKUS.cats, and Tesat-Spacecom have designed a future multimedia ATMbased LEO satellite network. Part of the development was an adaptive MAC and FEC scheme which are presented in this paper. The MAC protocol reduces contention while the FEC scheme guarantees a maximum ATM cell error rate of 10−6 even in the presence of rain. FEC and MAC were implemented...

Measuring greenhouse gas (GHG) profiles with global coverage and high accuracy and vertical resolution in the upper troposphere and lower stratosphere (UTLS) is key for improved monitoring of GHG concentrations in the free atmosphere. In this respect a new satellite mission concept adding an infrared-laser part to the already well studied microwave occultation technique exploits the joint propa...

Abstract The tracking and data relay satellite (TDRS) in geosynchronous orbit (GEO) can provide ranging communication services for user spacecraft low Earth (LEO) through the inter‐satellite link (ISL). time delay of TDRS ISL transponder differs from its pre‐launch state changes due to complex space environment, adding significant errors spacecraft's determination based on four‐way data. author...

The paper describes the protocol definition within the framework of the Project "Transport Protocol and Resource Management for Mobile Satellite Networks", funded by the European Space Agency ESA) and carried out by an Italian group composed of Marconi Mobile, CNIT and Etnoteam. In more detail, the Project is aimed at designing, implementing and testing a protocol stack adapted to the specific ...

the aim of this research was to study the in vitro effect of lavandula officinalis (leo) and origanum vulgare (oeo) essential oils on rumen fermentation using a concentrate type substrate (cts) and roughage type substrate (rts). six mehraban ewes were divided into 2 groups and fed a concentrate type or roughage type diet, and used as rumen fluid donors. each essential oil (eo) was evaluated sep...

We present an analytical model for computing call-blocking probabilities in a low earth orbit (LEO) satellite network that carries voice calls. Both satelliteand earth-fixed constellations with interorbit links and handoffs are considered. In this model, we assume a single beam per satellite. Also, we assume that call arrivals are Poisson with a fixed arrival rate that is independent of the geo...

Low Earth Orbit (LEO) satellite networks are characterized by topology variations. Although space segment topology varies periodically, connections of mobile stations (MS’s) to the satellite network alter stochastically. As a result the quality of service delivered to users may degrade. Different procedures have been proposed either as part of a resource allocation mechanism or as part of an en...