Orbital pass: Difference between revisions
I'm sorry, but this introduces multiple inaccuracies. 1) It's called a "pass", never prefixed like that, 2) They aren't just orbital vehicles (think Voyagers), and 3) Availability isn't just determined by the horizon, but by slant attenuation/diffusion near the horizon |
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{{short description|event during which a spacecraft can be viewed from a specified ground location}} |
{{short description|event during which a spacecraft can be viewed from a specified ground location}} |
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[[File:SpaceStation STS132 Tampa.JPG|thumb|Visible pass of the [[International Space Station]] and [[Space Shuttle Atlantis|Space Shuttle ''Atlantis'']] over Tampa, Florida, on mission [[STS-132]], May 18, 2010 (five-minute exposure)]] |
[[File:SpaceStation STS132 Tampa.JPG|thumb|Visible pass of the [[International Space Station]] and [[Space Shuttle Atlantis|Space Shuttle ''Atlantis'']] over Tampa, Florida, on mission [[STS-132]], May 18, 2010 (five-minute exposure)]] |
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A '''pass''', in [[spaceflight]] and [[satellite communications]], is the period in which a [[satellite]] or other [[spacecraft]] is above the [[Horizontal coordinate system|local horizon]] and available for [[radio]] communication with a particular [[ground station]], [[satellite receiver]], or relay satellite (or, in some cases, for visual sighting). The beginning of a pass is |
A '''pass''', in [[spaceflight]] and [[satellite communications]], is the period in which a [[satellite]] or other [[spacecraft]] is above the [[Horizontal coordinate system|local horizon]] and available for [[radio]] communication with a particular [[ground station]], [[satellite receiver]], or relay satellite (or, in some cases, for visual sighting). The beginning of a pass is ''acquisition of signal''; the end of a pass is ''loss of signal''.<ref name=NLSA/> The point at which a spacecraft comes closest to a ground observer is the ''time of closest approach''.<ref name=NLSA/> |
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==Timing and duration== |
==Timing and duration== |
Revision as of 02:24, 25 May 2020
A pass, in spaceflight and satellite communications, is the period in which a satellite or other spacecraft is above the local horizon and available for radio communication with a particular ground station, satellite receiver, or relay satellite (or, in some cases, for visual sighting). The beginning of a pass is acquisition of signal; the end of a pass is loss of signal.[1] The point at which a spacecraft comes closest to a ground observer is the time of closest approach.[1]
Timing and duration
The timing and duration of passes depends on the characteristics of the orbit a satellite occupies, as well as the ground topography and any occulting objects on the ground (such as buildings), or in space (for planetary probes, or for spacecraft using relay satellites).[2] An observer directly on the ground track of the satellite will experience the greatest ground pass duration.[3] Path loss is greatest toward the start and end of a ground pass,[4] as is Doppler shifting for Earth-orbiting satellites.[5]
Satellites in geosynchronous orbit may be continuously visible from a single ground station, whereas satellites in low Earth orbit only offer short-duration ground passes[3] (although longer contacts may be made via relay satellite networks such as TDRSS). Satellite constellations, such as those of satellite navigation systems, may be designed so that a minimum subset of the constellation is always visible from any point on the Earth, thereby providing continuous coverage.[2]
Prediction and visibility
A number of web-based and mobile applications produce predictions of passes for known satellites.[6] In order to be observed with the naked eye, a spacecraft must reflect sunlight towards the observer; thus, naked-eye observations are generally restricted to twilight hours, during which the spacecraft is in sunlight but the observer is not. A satellite flare occurs when sunlight is reflected by flat surfaces on the spacecraft. The International Space Station, the largest artificial satellite of Earth, has a maximum apparent magnitude of –5.9,[7] brighter than the planet Venus.[8]
See also
- Ground track, the path on the surface of the Earth directly below a satellite
References
- ^ a b "AOS, TCA, and LOS". Northern Lights Software Associates. Retrieved 17 November 2015.
- ^ a b Wood, Lloyd (July 2006). Introduction to satellite constellations: Orbital types, uses and related facts (PDF). ISU Summer Session. Retrieved 17 November 2015.
- ^ a b Del Re, Encrico; Pierucci, Laura (eds.). Satellite Personal Communications for Future-generation Systems. Springer. p. 19. ISBN 1447101316. Retrieved 17 November 2015.
- ^ Richharia, Madhavendra (2014). Mobile Satellite Communications: Principles and Trends (Second ed.). Wiley. pp. 106–107. ISBN 1118810066. Retrieved 17 November 2015.
- ^ Montenbruck, Oliver; Eberhard, Gill (2012). Satellite Orbits: Models, Methods, and Applications. Springer. p. 229. ISBN 3642583512. Retrieved 17 November 2015.
- ^ Dickinson, David (July 11, 2013). "How to Spot and Track Satellites". Universe Today. Retrieved 17 November 2015.
- ^ "ISS Information - Heavens-above.com". Heavens-above. Retrieved 2007-12-22.
- ^ "HORIZONS Web Interface". Solar System Dynamics. Jet Propulsion Laboratory. Retrieved 13 July 2016.