In the near future low earth orbit (LEO) satellite communication networks will partially substitute for fixed terrestrial multimedia networks especially in sparsely populated areas. Unlike fixed terrestrial networks, ongoing calls may be dropped if satellite channels are shadowed. Therefore, in most LEO satellite communication networks more than one satellite need to be simultaneously visible i...

The invariant manifolds of libration point orbits (LPOs) in the Sun-Earth/Moon system are used to construct lowenergy transfers from Low Earth Orbits (LEOs) to geosynchronous orbits. A maneuver is performed in LEO to insert onto a stable manifold trajectory of an LPO. The spacecraft travels to the host LPO and then follows an unstable manifold trajectory back to a geosynchronous orbit, where an...

With the completion of Chinese BeiDou Navigation Satellite System (BDS), world has begun to enjoy Positioning, Navigation, and Timing (PNT) services four Global Systems (GNSS). In order improve GNSS performance expand its applications, Low Earth Orbit (LEO) Enhanced (LeGNSS) is being vigorously advocated. Combined with high-, medium-, low- earth orbit satellites, it can in terms determination, ...

In a Low Earth Orbit (LEO) satellite mobile multimedia system, the multiple access scheme should be capable of supporting the necessary features that would facilitate the provision of multimedia services. Wideband Code Division Multiple Access (WCDMA) is an attractive multiple access scheme for mobile multimedia communications based on LEO satellites. In this paper, the performance of WCDMA sys...

Since 2011, massive stranding of the brown algae Sargassum has regularly affected coastal waters West Caribbean, Brazil, and Africa, leading to heavy environmental socio-economic impacts. Ocean color remote sensing observations as performed by sun-synchronous satellite sensors such MODIS (NASA), MERIS (ESA), or OLCI (ESA/Copernicus) are used provide quantitative assessments coverage through cal...

Transatmospheric vehicles (TAVs), with aerodynamic properties similar to conventional aircraft, have the promise of flying into space and delivering payloads into low earth orbit (LEO). A key distinguishing feature between TAVs and aircraft is propulsion. Jet engines or pure air-breathing propulsion systems cannot provide the thrust levels needed to ascend into space. Traditional rockets overco...

This letter characterizes the contact angle distribution based on condition that relay low earth orbit (LEO) satellite is in communication range of both ground transmitter and receiver. As one core distributions stochastic geometry-based routing analysis, analytical expression Cumulative Distribution Function (CDF) conditional derived. Furthermore, applied to analyze inaccessibility common sate...

Within the German-Indonesian Tsunami Early Warning System project GITEWS (Rudloff et al., 2009), a feasibility study on a future tsunami detection system from space has been carried out. The Global Navigation Satellite System Reflectometry (GNSS-R) is an innovative way of using reflected GNSS signals for remote sensing, e.g. sea surface altimetry. In contrast to conventional satellite radar alt...

The aim of this work is to create a tool that can simulate the transmission of both connectionoriented and connection-less traffic over a constellation of LEO/MEO (Low Earth Orbit/ Medium Earth Orbit) satellites. We hope to provide a performance evaluation of various constellation access techniques and routing policies. The simulator, named GaliLEO, will be written in Java and will integrate re...

A three-dimensional ray tracing model with aiming algorithms for global positioning system (GPS) signal is proposed to make simulations conform to the realistic radio occultation (RO) signal propagation. The two aiming algorithms used in this study ensure the initial and end point ray trajectories are located in the prescribed region. In past studies, the ray tracing techniques applied to the R...