scholarly journals Geocentric Spherical Surfaces Emulating the Geostationary Orbit at Any Latitude with Zenith Links

2020 ◽  
Vol 12 (1) ◽  
pp. 16 ◽  
Author(s):  
Emilio Matricciani
Keyword(s):  
Free Space ◽  
Orbital Plane ◽  
Low Earth Orbit ◽  
Service Area ◽  
Geostationary Orbit ◽  
Earth Orbit ◽  
Tropospheric Propagation ◽  
Geostationary Earth Orbit ◽  
Constellation Design ◽  
Spherical Surfaces

According to altitude, the orbits of satellites constellations can be divided into geostationary Earth orbit (GEO), medium Earth orbit (MEO), and low Earth orbit (LEO) constellations. We propose to use a Walker star constellation with polar orbits, at any altitude, to emulate the geostationary orbit with zenith paths at any latitude. Any transmitter/receiver will be linked to a satellite as if the site were at the equator and the satellite at the local zenith. This constellation design can have most of the advantages of the current GEO, MEO, and LEO constellations, without having most of their drawbacks. Doppler phenomena are largely minimized because the connected satellite is always seen almost at the local zenith. The extra free-space loss, due to the fixed pointing of all antennas, is at most 6 dBs when the satellite enters or leaves the service area. The connections among satellites are easy because the positions in the orbital plane and in adjacent planes are constant, although with variable distances. No steering antennas are required. The tropospheric propagation fading and scintillations are minimized. Our aim is to put forth the theoretical ideas about this design, to which we refer to as the geostationary surface (GeoSurf) constellation.

A Comparative Study of Satellite Orbits as Low Earth Orbit (LEO) and Geostationary Earth Orbit (GEO)

2015 ◽  
Vol 6 (2) ◽  
Author(s):  
Sandeep Vishwakarma ◽  
Aradhana S. Chauhan ◽  
Shoeba Aasma
Keyword(s):  
Satellite Orbit ◽  
Low Earth Orbit ◽  
Geostationary Orbit ◽  
Earth Orbit ◽  
Satellite Orbits ◽  
Satellite Systems ◽  
Broadcast Television ◽  
Television Use ◽  
Gps System ◽  
Orbiting Systems

It is known facts that satellites are used to receive the signal at geostationary orbit by remaining stationary above a particular point on the Earth. The orbit that is chosen for a satellite depends upon its application. Those used for direct broadcast television use geostationary orbit. Many communication satellites similarly use geostationary orbit. Other satellite systems used for satellite phones use Low Earth orbiting systems. Similarly, satellite systems used for navigation like Nav-star or Global Positioning (GPS) system occupy a relatively Low Earth Orbit. There are also many other types of satellites : Weather satellites Research satellites and many others. Each will have its own type of orbit depending upon its application. The actual satellite orbit that is chosen will depend on factors including its function, and the area of serving. At some instances, the satellite orbit may be as low as 100 miles (160 km) for a Low Earth Orbit (LEO), whereas others may be over 22 000 miles (36000 km) high as in the case of a Geostationary Orbit (GEO). The satellite may even has an elliptical rather than a circular orbit.

Orbital transfer vehicle (OTV) system sizing study for manned GEO satellite servicing

2016 ◽  
Vol 120 (1226) ◽  
pp. 573-599 ◽  
Author(s):  
B. Chudoba ◽  
G. Coleman ◽  
L. Gonzalez ◽  
E. Haney ◽  
A. Oza ◽  
...  
Keyword(s):  
Low Earth Orbit ◽  
Geostationary Orbit ◽  
Earth Orbit ◽  
Orbital Transfer ◽  
Geo Satellite ◽  
Satellite Servicing ◽  
Geo Satellites ◽  
Kennedy Space ◽  
Cost Factors ◽  
Concept Of Operations

ABSTRACTIn an effort to quantify the feasibility of candidate space architectures for astronauts servicing Geosynchronous Earth Orbit (GEO) satellites, a conceptual assessment of architecture-concept and operations-technology combinations has been performed. The focus has been the development of a system with the capability to transfer payload to and from geostationary orbit. Two primary concepts of operations have been selected: (a) Direct insertion/re-entry (Concept of Operations 1 – CONOP 1); (b) Launch to low-earth orbit at Kennedy Space Center inclination angle with an orbital transfer to/from geostationary orbit (Concept of Operations 2 – CONOP 2). The study concludes that a capsule and de-orbit propulsion module system sized for the geostationary satellite servicing mission is feasible for a direct insertion/re-entry concept of operation CONOP 1. Vehicles sized for CONOP 2 show overall total mass savings when utilising the aero-assisted orbital transfer vehicle de-orbit propulsion module options compared to the pure propulsive baseline cases. Overall, the consideration of technical, operational and cost factors determine if either the aero-assisted orbital transfer vehicle concepts or the re-usable/expendable ascent/de-orbit propulsion modules is the preferred option.

scholarly journals Feasibility Analysis Of Free Space Earth To Satellite Optical Link In Tropical Region

2012 ◽  
Vol 12 (5) ◽  
Author(s):  
Norhanis Aida M. Nor ◽  
Md. Rafiqul Islam ◽  
Wajdi Al-Khateeb
Keyword(s):  
Electromagnetic Interference ◽  
Free Space ◽  
Elevation Angle ◽  
Rain Attenuation ◽  
Low Earth Orbit ◽  
Feasibility Analysis ◽  
Free Space Optics ◽  
Tropical Region ◽  
Earth Orbit ◽  
Space Optics

Free Space Optics (FSO) becomes a great attention because of the chances in transmitting data up to 2.5Gbps. There are a lot of advantages offered by FSO such as easily deployment with saving time and cost and no electromagnetic interference. In spite of the advantages, FSO has an uncontrolled drawback which is highly sensitive to atmospheric phenomena because uses air as tranmission medium. Current studies and researches are only focusing on FSO terrestrial link with short path length and based on data from temperate region. Therefore, this paper is aiming to provide feasibility analysis of FSO link from earth to satellite especially Low Earth Orbit (LEO) based on atmospheric data in tropical region. The analysis will include the losses from geometrical attenuation, absorption, scintillation, haze attenuation, and rain attenuation. ABSTRAK: Ruang Bebas Optik (Free Space Optics (FSO)) mendapat perhatian kerana kebolehannya memancarkan data pada kelajuan tinggi. Di sebalik kelebihannya, FSO amat sensitif terhadap fenomena atmosfera kerana ia menggunakan udara sebagai perantara transmisi. Penyelidikan dan kajian terkini hanya memfokus kepada jalinan darat FSO dengan kepanjangan jarak pendek dan bergantung kepada kawasan tenang.  Oleh itu, kertas ini menyasarkan untuk memberikan analisis kebolehlaksanaan  jalinan FSO dari bumi ke satelit terutamanya Orbit Rendah Bumi (Low Earth Orbit (LEO)) bergantung kepada data atmosfera di kawasan tropika. Analisa termasuklah kehilangannya akibat pengecilan geometri, penyerapan, kelipan, pelemahan jerebu dan pelemahan hujan.KEYWORDS:  feasibility; Free Space Optics; availability; atmospheric attenuation; beam divergence angle; elevation angle

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