View source for Quasi-Zenith Satellite System

{{Short description|Japanese regional navigation satellite system}}
{{Use American English|date=October 2021}}
{{Use dmy dates|date=October 2021}}
{{Infobox navigation satellite system
| name               = Quasi-Zenith Satellite System
| image              = [[File:QZSS logo.png|frameless]]
| country            = Japan
| type               = Civilian
| status             = Operational
| operator           = Quasi-Zenith Satellite System Services Inc. / [[Cabinet Office (Japan)|Cabinet Office]]
| coverage           = Regional
| precision          = {{abbr|PNT|Positioning, Navigation and Timing Service}} <10 m (public)<br>{{abbr|SLAS|Sub-meter Level Augmentation Service}} <1 m (public)<br>{{abbr|CLAS|Centimeter Level Augmentation Service}} <10 cm (public)

| satellites_nominal = 7
| satellites_current = 4
| first_launch       = 11 September 2010
| last_launch        = 26 October 2021
| launch_total       = 5

| regime             = 3x [[geosynchronous orbit|GSO]]

| cost               = [[JPY]] 170 billion
| website            = {{url|http://qzss.go.jp/en/}}
}}

[[File:Qzss-45-0.09.jpg|thumb|upright=1.0|Quasi-[[Zenith]] satellite orbit]]
[[File:Qzss-01-120s2.gif|thumb|upright=1.0|QZSS animation, the "Quasi-Zenith/[[tundra orbit]]" plot is clearly visible.]]

The {{Nihongo|'''Quasi-Zenith Satellite System''' ('''QZSS''')|準天頂衛星システム|juntenchō eisei shisutemu|lead=yes}}, also known as {{nihongo3|"guidance"|みちびき|'''Michibiki'''}}, is a four-satellite [[regional satellite navigation system]] and a [[GNSS augmentation#Satellite-based augmentation system|satellite-based augmentation system]] developed by the [[Japanese government]] to enhance the United States-operated [[Global Positioning System]] (GPS) in the [[Asia-Pacific|Asia-Oceania]] regions, with a focus on Japan.<ref>{{Cite web |url=http://qzss.go.jp/en/technical/technology/orbit.html |title=Quasi-Zenith Satellite Orbit (QZO) |access-date=10 March 2018 |archive-url=https://web.archive.org/web/20180309194252/http://qzss.go.jp/en/technical/technology/orbit.html |archive-date=9 March 2018 |url-status=live}}</ref> The goal of QZSS is to provide highly precise and stable positioning services in the Asia-Oceania region, compatible with GPS.<ref>{{cite web |title=[Movie] Quasi-Zenith Satellite System "QZSS" |url=http://qzss.go.jp/en/overview/downloads/movie_qzss.html |website=Quasi-Zenith Satellite System(QZSS) |access-date=19 July 2017 |archive-url=https://web.archive.org/web/20170715000523/http://qzss.go.jp/en/overview/downloads/movie_qzss.html |archive-date=15 July 2017 |url-status=live}}</ref> Four-satellite QZSS services were available on a trial basis as of 12 January 2018,<ref>{{cite news |url=http://qzss.go.jp/en/overview/notices/trial-qzs4_180112.html |title=Start of QZS-4 Trial Service |publisher=Quasi-Zenith Satellite System (QZSS) |access-date=2 May 2018 |archive-url=https://web.archive.org/web/20180810205031/http://qzss.go.jp/en/overview/notices/trial-qzs4_180112.html |archive-date=10 August 2018 |url-status=live}}</ref> and officially started on 1 November 2018.<ref name="gpsworld">{{Cite web |url=https://www.gpsworld.com/japans-qzss-service-now-officially-available/ |title=Japan's QZSS service now officially available |date=26 November 2018 |access-date=11 January 2019}}</ref> A satellite navigation system independent of GPS is planned for 2023 with seven satellites.<ref>{{Cite web |title=Japan mulls seven-satellite QZSS system as a GPS backup |url=https://spacenews.com/japan-mulls-seven-satellite-qzss-system-as-a-gps-backup/ |publisher=SpaceNews |access-date=10 August 2019 |date=15 May 2017}}</ref><ref>{{Cite web |last1=Kriening |first1=Torsten |title=Japan Prepares for GPS Failure with Quasi-Zenith Satellites |url=https://spacewatch.global/2019/01/japan-prepares-for-gps-failure-with-quasi-zenith-satellites/ |publisher=SpaceWatch.Global |date=23 January 2019 |access-date=10 August 2019}}</ref> In May 2023 it was announced that the system would expand to eleven satellites.<ref>{{Cite web |url=https://asia.nikkei.com/Business/Aerospace-Defense-Industries/Japan-plans-expansion-of-homegrown-GPS-network-to-11-satellites |title=Japan plans expansion of homegrown GPS network to 11 satellites |first=Satoshi |last=Kawahara |date=8 May 2023 |work=Nikkei Asia}}</ref>

== History ==
In 2002, the Japanese government authorized the development of QZSS, as a three-satellite regional [[time transfer]] system and a [[GNSS augmentation#SatelliteBasedAugmentationSystem|satellite-based augmentation system]] for the United States operated [[Global Positioning System]] (GPS) to be receivable within Japan. A contract was awarded to Advanced Space Business Corporation (ASBC), that began concept development work, and [[Mitsubishi Electric]], [[Hitachi]], and GNSS Technologies Inc. However, ASBC collapsed in 2007, and the work was taken over by the Satellite Positioning Research and Application Center (SPAC), which is owned by four Japanese government departments: the [[Ministry of Education, Culture, Sports, Science and Technology]], the [[Ministry of Internal Affairs and Communications]], the [[Ministry of Economy, Trade and Industry]], and the [[Ministry of Land, Infrastructure, Transport and Tourism]].<ref name="ASM2">{{Cite web |url=http://www.aprsaf.org/data/aprsaf15_data/csawg/CSAWG_6d.pdf |title=Service Status of QZSS |date=12 December 2008 |access-date=7 May 2009 |url-status=dead |archive-url=https://web.archive.org/web/20110725134531/http://www.aprsaf.org/data/aprsaf15_data/csawg/CSAWG_6d.pdf |archive-date=25 July 2011}}</ref>

The first satellite "Michibiki" was launched on 11 September 2010.<ref>{{Cite web |url=http://www.jaxa.jp/press/2010/09/20100911_h2af18_e.html |title=Launch Result of the First Quasi-Zenith Satellite "MICHIBIKI" by H-IIA Launch Vehicle No. 18 |publisher=JAXA |date=11 September 2010 |access-date=12 December 2011 |archive-url=https://web.archive.org/web/20120320030026/http://www.jaxa.jp/press/2010/09/20100911_h2af18_e.html |archive-date=20 March 2012 |url-status=live}}</ref> Full operational status was expected by 2013.<ref name="ASM">{{Cite web |url=http://www.asmmag.com/news/qzss-in-2010 |title=QZSS in 2010 |date=7 May 2009 |publisher=Asian Surveying and Mapping |access-date=7 May 2009}}{{dead link|date=December 2011}}</ref><ref name="GPSWorld_TheSystem_Nov07">{{Cite web |url=http://www.gpsworld.com/gnss-system/the-system-november-2007-4187 |title=GNSS All Over the World |publisher=GPS World Online |date=1 November 2007 |access-date=12 December 2011 |url-status=dead |archive-url=https://web.archive.org/web/20110823064320/http://www.gpsworld.com/gnss-system/the-system-november-2007-4187|archive-date=23 August 2011}}</ref> In March 2013, Japan's Cabinet Office announced the expansion of QZSS from three satellites to four. The US$526 million contract with Mitsubishi Electric for the construction of three satellites was scheduled for launch before the end of 2017.<ref>http://www.spaceflightnow.com/news/n1304/04qzss/ {{Webarchive |url=https://web.archive.org/web/20130411121927/http://www.spaceflightnow.com/news/n1304/04qzss/ |publisher=Spaceflight Now |title=Japan to build fleet of navigation satellites |access-date=5 April 2013}}</ref> The third satellite was launched into orbit on 19 August 2017,<ref>{{Cite web |url=https://spaceflightnow.com/2017/08/19/japan-launches-navigation-satellite-after-week-long-delay/ |title=Launch Schedule |access-date=20 August 2017 |archive-url=https://web.archive.org/web/20180809111944/https://spaceflightnow.com/2017/08/19/japan-launches-navigation-satellite-after-week-long-delay/ |archive-date=9 August 2018 |url-status=live}}</ref> and the fourth was launched on 10 October 2017.<ref>{{Cite web |url=https://spaceflightnow.com/launch-schedule/ |title=Launch Schedule |publisher=Spaceflight Now |access-date=20 August 2017 |archive-url=https://web.archive.org/web/20180816161152/https://spaceflightnow.com/launch-schedule/ |archive-date=16 August 2018 |url-status=live}}</ref> The basic four-satellite system was announced as operational on 1 November 2018.<ref name="gpsworld"/>

{{As of|2024}}, an eleven-satellite configuration is under consideration, which would provide redundancy for single-satellite failure.<ref>{{Cite web |url=https://www8.cao.go.jp/space/qzs/houshin/houshin2024.pdf |language=ja |title=National Space Policy Secretariat |script-title=ja:衛星測位に関する取組方針 2024 |publisher=Cabinet Office, Government of Japan |date=12 June 2024}}</ref>

== Orbit ==
QZSS uses one [[Geostationary orbit|geostationary satellite]] and three satellites in [[Tundra orbit|Tundra]]-type highly inclined, slightly [[elliptical orbit|elliptical]], [[geosynchronous orbit]]s. Each orbit is 120° apart from the other two. Because of this inclination, they are not geostationary; they do not remain in the same place in the sky. Instead, their ground traces are asymmetrical figure-8 patterns ([[analemma]]s), designed to ensure that one is almost directly overhead (elevation 60° or more) over Japan at all times.

The nominal [[orbital elements]] are:
{|class="wikitable"
|+ QZSS satellite Keplerian elements (nominal)<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|publisher=JAXA |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>
|-
| [[Epoch (astronomy)|Epoch]] || 26 December 2009, 12:00 [[Coordinated Universal Time|UTC]]
|-
| [[Semimajor axis]] (''a'') || {{cvt|42164|km}}
|-
| [[Eccentricity (orbit)|Eccentricity]] (''e'') || 0.075 ± 0.015
|-
| [[Inclination]] (''i'') || 43° ± 4°
|-
| [[Right ascension of the ascending node]] (''Ω'') || 195° (initial)
|-
| [[Argument of perigee]] (''ω'') || 270° ± 2°
|-
| [[Mean anomaly]] (''M''<sub>0</sub>) || 305° (initial)
|-
| Central longitude of ground trace || 135° E ± 5°
|}

Planned seven satellites constellation consists of four Quasi-Zenith Orbit (QZO) satellites, two geostationary (GEO) satellites, and one quasi-geostationary (slight incline and eccentricity) orbit satellite.<ref name="space20190123">{{Cite web |url=https://www8.cao.go.jp/space/comittee/dai76/siryou2.pdf |language=ja |script-title=ja:準天頂衛星の７機体制に向けた開発について |publisher=Cabinet Office, Government of Japan |date=23 January 2019 |access-date=4 March 2024}}</ref>

== Satellites ==
{| class="wikitable sortable"
|-
! Name !! Launch date !! Launch Vehicle !! Status !! Notes
|-
| QZS-1 (Michibiki-1) || 11 September 2010 || [[H-IIA]] 202 ||{{no|Replaced by QZS-1R}} || Experimental. Lacks MADOCA and PTV signals. Acting as spare since March 2022.<ref>NAQU 2022059, accessible via {{cite web |title=NAQU Message |url=https://sys.qzss.go.jp/dod/en/naqu.html |website=Quasi-Zenith Satellite System (QZSS) |language=en}}</ref> Decommissioned on 15 September 2023.<ref>{{cite web |url=https://qzss.go.jp/en/overview/notices/qzs1_230915.html |title=
Suspension of QZS-1 all operations |work=Quasi-Zenith Satellite System |date=15 September 2023 |access-date=16 September 2023}}</ref>
|-
| QZS-2 (Michibiki-2) || 1 June 2017 || H-IIA 202 || {{yes|Operational}} || Improved solar panels and increased fuel
|-
| QZS-3 (Michibiki-3) || 19 August 2017 || H-IIA 204 || {{yes|Operational}} || Heavier design with additional S-band antenna on [[geostationary orbit]] at 127° E<ref name="space20190123"/>
|-
| QZS-4 (Michibiki-4) || 10 October 2017 || H-IIA 202 ||{{yes|Operational}} || Improved solar panels and increased fuel
|-
| [[QZS-1R]] (Michibiki-1R) || 26 October 2021 || H-IIA 202 ||{{yes|Operational}} || Replacement for QZS-1.<ref name=cao-fy02>{{cite web|url=https://www8.cao.go.jp/space/plan/plan2/kaitei_fy02/kaitei_fy02.pdf|title=宇宙基本計画工程表 (令和2年6月29日)|trans-title=Space Plan Schedule (2020 June 29)|page=54|publisher=Cabinet Office (Japan)|date=29 June 2020|access-date=6 December 2020|language=ja}}</ref>
|-
| QZS-5 (Michibiki-5)  || [[Fiscal year#Japan|JFY]]2025 || [[H3 (rocket)|H3]]-22S || {{Planned}} || <ref name="mynavi20241127">{{cite web |url=https://news.mynavi.jp/techplus/article/20241127-3072703/ |language=ja |script-title=ja:準天頂衛星「みちびき」6号機の機体公開。7機体制で日本独自の測位実現へ前進 |publisher=Mynavi Corporation |date=27 November 2024 |access-date=27 November 2024}}</ref>
|-
| QZS-6 (Michibiki-6)  || 2 February 2025 || H3-22S || {{yes|Launched on 2 February 2025 <ref>{{cite web | url=https://www.youtube.com/watch?v=uZkj9FkYMyQ&ab_channel=JAXA%7C%E5%AE%87%E5%AE%99%E8%88%AA%E7%A9%BA%E7%A0%94%E7%A9%B6%E9%96%8B%E7%99%BA%E6%A9%9F%E6%A7%8B | title=「みちびき6号機」（準天頂衛星）／H3ロケット5号機打上げライブ中継 | website=[[YouTube]] | date=2 February 2025 }}</ref>}} || Geostationary at 90.5° E<ref name="space20190123"/><ref name=mit-qzss>{{Cite web |last=Ryan |first=Dorothy |url=https://news.mit.edu/2020/lincoln-laboratory-designing-payload-integrate-japanese-satellites-1203 |title=Lincoln Laboratory is designing a payload to integrate on Japanese satellites |publisher=MIT |date=3 December 2020 |access-date=6 December 2020 |quote=The laboratory is working with the Japanese National Space Policy Secretariat and Mitsubishi Electric Company to integrate state-of-the-art sensors on the newest satellites in the QZSS constellation, QZS-6 and QZS-7, which are scheduled for launch in 2023 and 2024, respectively.}}</ref><ref name="mynavi20241127" />
|-
| QZS-7 (Michibiki-7) || JFY2025 || H3 ||{{Planned}} || Quasi-geostationary around 190° E<ref name="space20190123"/><ref name=mit-qzss/>
|}

{{multiple image
| align     = left
| direction = horizontal
| width     = 250
| header    = Animation of QZSS
| image1    = Animation of QZSS's orbit around Earth.gif
| caption1  = Around the Earth - Oblique view
| image2    = Animation of QZSS's orbit around Earth - Polar view.gif
| caption2  = Around the Earth - Polar view
| image3    = Animation of QZSS's orbit - Earth fixed.gif
| caption3  = [[ECEF|Earth fixed frame]] - Equatorial view, front
| image4    = Animation of QZSS's orbit - Earth fixed - side view.gif
| caption4  = [[ECEF|Earth fixed frame]] - Equatorial view, side
| footer    = {{legend2| RoyalBlue | Earth}}{{·}}{{legend2| Cyan | QZS-1 }}{{·}}{{legend2| Gold |QZS-2}}{{·}}{{legend2| Magenta|QZS-3}}{{·}}{{legend2| OrangeRed|QZS-4}}
}}
{{clear}}

== QZSS and positioning augmentation ==
[[File:GPSTest screenshot (2025).webp|thumb|Screenshot of GPSTest application showing a QZSS satellite and other GNSS satellites usage in [[South Tangerang]], [[Indonesia]] (2025)]]

The primary purpose of QZSS is to increase the availability of GPS in Japan's numerous [[urban canyon]]s, where only satellites at very high elevation can be seen. A secondary function is performance enhancement, increasing the accuracy and reliability of GPS-derived navigation solutions. The Quasi-Zenith Satellites transmit signals compatible with the GPS L1C/A signal, as well as the modernized GPS L1C, L2C signal and L5 signals. This minimizes changes to existing GPS receivers. Compared to standalone GPS, the combined system GPS plus QZSS delivers improved positioning performance via ranging correction data provided through the transmission of submeter-class performance enhancement signals L1-SAIF and LEX from QZSS. It also improves reliability by means of failure monitoring and system health data notifications. QZSS also provides other support data to users to improve GPS satellite acquisition. According to its original plan, QZSS was to carry two types of space-borne [[atomic clock]]s; a hydrogen maser and a rubidium (Rb) atomic clock. The development of a passive hydrogen maser for QZSS was abandoned in 2006. The positioning signal will be generated by a Rb clock and an architecture similar to the GPS timekeeping system will be employed. QZSS will also be able to use a [[Two-Way Satellite Time and Frequency Transfer]] (TWSTFT) scheme, which will be employed to gain some fundamental knowledge of satellite atomic standard behavior in space as well as for other research purposes.

=== Signals and services ===
The QZSS provides the following classes of public service:<ref>Quasi-Zenith Satellite System Performance Standard PS-QZSS-003 (Mar.17, 2022)</ref>

* The PNT (Positioning, Navigation and Timing) service complements the signals used by the GPS, essentially acting as extra satellites. The QZSS satellites sync their clocks with GPS satellites. The service broadcasts at frequency bands L1C/A, L1C, L2C, and L5C, the same as GPS.<ref name=":0">{{Cite book |last=Jeffrey |first=Charles |url=https://www.worldcat.org/oclc/1036065024 |title=An introduction to GNSS: GPS, GLONASS, Galileo and other Global Navigation Satellite Systems |date=2010 |publisher=NovAtel |isbn=978-0-9813754-0-3 |edition=1st |location=Calgary |oclc=1036065024}}</ref>
* The SLAS (Sub-meter Level Augmentation) service provides a form of [[GNSS augmentation]] for GPS interoperable with other GPS-SBAS systems. The principle of operation is similar to that of, e.g. [[Wide Area Augmentation System]]. It transmits on L1.<ref name=":0" />
* The CLAS (Centimeter Level Augmentation) service provides high-precision positioning compatible with the higher-precision E6 service of [[Galileo (satellite navigation)|Galileo]]. The band is referred to as L6 or LEX, for "experimental".<ref name=":0" />
* The MADOCA-PPP (Multi-GNSS Advanced Orbit and Clock Augmentation – [[Precise Point Positioning]]) service is a L6 augmentation service independent from CLAS.
* The DC Report (Satellite Report for Disaster and Crisis Management) service broadcasts on L1S and provides information on floods and earthquakes.

The other classes of service are not publicly available:
* The PTV (Positioning Technology Verification) service broadcasts on L5S. The documentation only describes a "null" message type.
* The Q-ANPI (QZSS Safety Confirmation Service) is an authorized short message service.

=== QZSS timekeeping and remote synchronization ===
Although the first generation QZSS timekeeping system (TKS) will be based on the Rb clock, the first QZSS satellites will carry a basic prototype of an experimental crystal clock synchronization system. During the first half of the two-year in-orbit test phase, preliminary tests will investigate the feasibility of the atomic clock-less technology which might be employed in the second generation QZSS.

The mentioned QZSS TKS technology is a novel satellite timekeeping system which does not require on-board atomic clocks as used by existing navigation satellite systems such as [[BeiDou]], [[Galileo (satellite navigation)|Galileo]], [[Global Positioning System]] (GPS), [[GLONASS]] or [[Indian Regional Navigation Satellite System|NavIC]] system. This concept is differentiated by the employment of a synchronization framework combined with lightweight steerable on-board clocks which act as transponders re-broadcasting the precise time remotely provided by the time synchronization network located on the ground. This allows the system to operate optimally when satellites are in direct contact with the ground station, making it suitable for a system like the Japanese QZSS. Low satellite mass and low satellite manufacturing and launch cost are significant advantages of this system. An outline of this concept as well as two possible implementations of the time synchronization network for QZSS were studied and published in ''Remote Synchronization Method for the Quasi-Zenith Satellite System''<ref name="TAP_dissertation">{{Cite web |url=http://unsworks.unsw.edu.au/fapi/datastream/unsworks:4274/SOURCE02 |title=Remote Synchronization Method for the Quasi-Zenith Satellite System |archive-url=https://web.archive.org/web/20110307191142/http://unsworks.unsw.edu.au/fapi/datastream/unsworks:4274/SOURCE02 |url-status=dead |archive-date=7 March 2011 |author=Fabrizio Tappero |date=April 2008 |type=PhD thesis|access-date=10 August 2013}}</ref> and ''Remote Synchronization Method for the Quasi-Zenith Satellite System: study of a novel satellite timekeeping system which does not require on-board atomic clocks''.<ref name="TAP_QZSS">{{Cite book |title=Remote Synchronization Method for the Quasi-Zenith Satellite System: study of a novel satellite timekeeping system which does not require on-board atomic clocks |author=Fabrizio Tappero |publisher=VDM Verlag |isbn=978-3-639-16004-8 |date=24 May 2009}}</ref>{{non-primary source needed|date=November 2019}}

{{multiple image
| align     = left
| direction = horizontal
| width     = 240
| header    = Comparison of [[Tundra orbit]], QZSS orbit and [[Molniya orbit]] - equatorial view
| image1    = Animation of Tundra and QZSS orbit - front view.gif
| caption1  = Front view
| image2    = Animation of Tundra and QZSS orbit - side view.gif
| caption2  = Side view
| image3    = Animation of Tundra and QZSS orbit - ECEF - front view.gif
| caption3  = [[ECEF|Earth fixed frame]], Front view
| image4    = Animation of Tundra and QZSS orbit - ECEF - side view.gif
| caption4  = [[ECEF|Earth fixed frame]], Side view
| footer    = {{legend2| OrangeRed | Tundra orbit}}{{·}}{{legend2|Lime| QZSS orbit}}{{·}}{{legend2|Cyan|Molniya orbit}}{{·}}{{legend2|RoyalBlue|Earth}}}}
{{clear}}

== References ==
{{Reflist}}

== See also ==
{{Portal|Spaceflight}}
* [[Multi-functional Satellite Augmentation System]] (MSAS)
* [[Inclined orbit]]
* [[Tundra orbit]]

== Bibliography ==
* [https://web.archive.org/web/20061111095113/http://www.gpsworld.com/gpsworld/article/articleDetail.jsp?id=61200 Petrovski, Ivan G.  QZSS - Japan's New Integrated Communication and Positioning Service for Mobile Users.] GPS World Online. 1 June 2003
* [https://web.archive.org/web/20081206183659/http://www.space.com/spacenews/archive04/budgetarch_090704.html Kallender-Umezu, Paul. Japan Seeking 13 Percent Budget Hike for Space Activities.] Space.com 7 September 2004
* [https://web.archive.org/web/20110614022238/http://www.navcen.uscg.gov/pdf/cgsicMeetings/47/%5B24%5Dqzzmsas.pdf QZSS / MSAS Status] Kogure, Satoshi. Presentation at the 47th Meeting of the Civil Global Positioning System Service Interface Committee (CGSIC) 25 September 2007


== External links ==
* [http://www.qzss.jp/en/ Government Of Japan QZSS site]
* [https://web.archive.org/web/20070519164026/http://qzss.jaxa.jp/ JAXA QZSS site]{{in lang|ja}}
* [https://web.archive.org/web/20100817162351/http://qz-vision.jaxa.jp/ JAXA MICHIBIKI data site] {{in lang|ja}}
* [https://web.archive.org/web/20160624075904/http://qz-vision.jaxa.jp/USE/en/ JAXA MICHIBIKI data site, English subsite]
* [http://www.jaxa.jp/projects/sat/qzss/index_e.html JAXA Quasi-Zenith Satellite-1 "MICHIBIKI"] {{Webarchive |url=https://web.archive.org/web/20130122080817/http://www.jaxa.jp/projects/sat/qzss/index_e.html |date=22 January 2013}}
* [http://www.jaxa.jp/countdown/f18/index_e.html JAXA MICHIBIKI Special Site]
* [http://www.navipedia.net/index.php/QZSS ESA Navipedia QZSS article]

{{Satellite navigation systems}}
{{Satellite constellations}}
{{Time signal stations}}
{{Japanese space program}}

[[Category:Navigation satellite constellations]]
[[Category:Satellite-based augmentation systems]]
[[Category:Space program of Japan]]
[[Category:Spacecraft launched by H-II rockets]]