Editing Geosynchronous orbit (section)

=== Elliptical and inclined geosynchronous orbits ===

[[File:Qzss-45-0.09.jpg|left|thumb|A quasi-[[zenith]] satellite orbit]]

Many objects in geosynchronous orbits have eccentric and/or inclined orbits. Eccentricity makes the orbit elliptical and appear to oscillate E-W in the sky from the viewpoint of a ground station, while inclination tilts the orbit compared to the equator and makes it appear to oscillate N-S from a groundstation. These effects combine to form an [[analemma]] (figure-8).<ref name="smad"/>{{rp|122}}

Satellites in elliptical/eccentric orbits must be tracked by steerable [[ground station]]s.<ref name="smad"/>{{rp|122}}

====Tundra orbit====
{{main|Tundra orbit}}

The Tundra orbit is an eccentric geosynchronous orbit, which allows the satellite to spend most of its time dwelling over one high latitude location. It sits at an inclination of 63.4°, which is a [[frozen orbit]], which reduces the need for [[orbital station-keeping|stationkeeping]].<ref name="scs">{{cite book|url=https://books.google.com/books?id=PEsmLaDXzvsC&q=tundra&pg=PT110 |section=2.2.1.2 Tundra Orbits |isbn=978-1-119-96509-1 |title=Satellite Communications Systems: Systems, Techniques and Technology|last1=Maral |first1=Gerard |last2=Bousquet |first2=Michel |date=2011-08-24|publisher=John Wiley & Sons }}</ref> At least two satellites are needed to provide continuous coverage over an area.<ref name="jenkin">{{cite conference|title=Tundra Disposal Orbit Study |surname1=Jenkin |given1=A.B. |surname2=McVey |given2=J.P. |surname3=Wilson |given3=J.R. |surname4=Sorge |given4=M.E. |date=2017 |publisher=ESA Space Debris Office|conference=7th European Conference on Space Debris|url=https://conference.sdo.esoc.esa.int/proceedings/sdc7/paper/328|access-date=2017-10-02|archive-url=https://web.archive.org/web/20171002121240/https://conference.sdo.esoc.esa.int/proceedings/sdc7/paper/328|archive-date=2017-10-02|url-status=dead}}</ref> It was used by the [[Sirius XM Satellite Radio]] to improve signal strength in the northern US and Canada.<ref name="Sirius Launch">{{cite web
  | title=Sirius Rising: Proton-M Ready to Launch Digital Radio Satellite Into Orbit
  | url=http://www.americaspace.com/2013/10/18/sirius-rising-proton-m-ready-to-launch-digital-radio-satellite-into-orbit/
  | website=AmericaSpace
  | access-date=8 July 2017
  | date=2013-10-18
  | archive-url=https://web.archive.org/web/20170628043459/http://www.americaspace.com/2013/10/18/sirius-rising-proton-m-ready-to-launch-digital-radio-satellite-into-orbit/
  | archive-date=28 June 2017
  | url-status=live
  }}</ref>

====Quasi-zenith orbit====
The [[Quasi-Zenith Satellite System]] (QZSS) is a four-satellite system that operates in a geosynchronous orbit at an inclination of 42° and a 0.075 eccentricity.<ref>{{citation |title=Interface Specifications for QZSS |version=version 1.7 |url=http://qz-vision.jaxa.jp/USE/is-qzss/index_e.html |date=2016-07-14 |author=Japan Aerospace Exploration Agency |pages=7–8 |url-status=dead |archive-url=https://web.archive.org/web/20130406032030/http://qz-vision.jaxa.jp/USE/is-qzss/index_e.html |archive-date=2013-04-06}}</ref> Each satellite dwells over [[Japan]], allowing signals to reach receivers in [[urban canyons]] then passes quickly over Australia.<ref>{{cite web |url=http://qzss.go.jp/en/technical/technology/orbit.html |title=Quasi-Zenith Satellite Orbit (QZO) |access-date=2018-03-10 |archive-url=https://web.archive.org/web/20180309194252/http://qzss.go.jp/en/technical/technology/orbit.html |archive-date=2018-03-09 |url-status=live}}</ref>