# Astro-G
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{{Short description|Cancelled radio satellite}}
{{Infobox spaceflight
| name = ASTRO-G
| names_list = VSOP-2
| operator = [JAXA](/source/JAXA)
| mission_type = [Radio astronomy](/source/Radio_astronomy)
| mission_duration = Cancelled
| orbit_reference = [Geocentric](/source/Geocentric_orbit) (planned)
| orbit_periapsis = {{cvt|1000|km|mi}}
| orbit_apoapsis = {{cvt|25000|km|mi}}
| apsis = gee
| programme = ['''ASTRO''' program](/source/JAXA)
| previous_mission = [Akari](/source/Akari_(satellite)) (ASTRO-F)
| next_mission = [Hitomi](/source/Hitomi_(satellite)) (ASTRO-H)
}}
'''ASTRO-G''' (also known as '''VSOP-2''', and very rarely called '''VSOP-B''') was a planned [radio telescope](/source/radio_telescope) [satellite](/source/satellite) by [JAXA](/source/JAXA). It was expected to be launched into elliptic orbit around Earth (apogee height 25,000 km, perigee height 1,000 km).[{{Cite news|script-title=ja:電波天文衛星「アストロＧ」|date = May 10, 2007|url = http://www.yomiuri.co.jp/science/news/20070510ik21.htm|archive-url = http://archive.today/2013.08.28-014951/http://web.archive.org/web/20070513081506/http://www.yomiuri.co.jp/science/news/20070510ik21.htm|url-status = dead|archive-date = August 28, 2013|trans-title=Radio astronomy satellite "Astro G"|work = [Yomiuri Shimbun](/source/Yomiuri_Shimbun)|language = ja}}]
==History==
Astro-G was selected in February 2006 against the competition of a proposed new X-Ray astronomy mission ([NeXT](/source/Hitomi_(satellite))) and a proposed [solar sail](/source/solar_sail) mission to Jupiter.
Funding started from FY 2007 with a budget of 12 billion yen, around 100 million US dollars.
It was planned to be launched in 2012 but technical difficulty with the dish antenna as well as budget constraints led to putting development on hold for fiscal year 2010.[{{cite web|url = http://www.cao.go.jp/sasshin/oshirase/pdf/nov17-am-shiryo/3-34.pdf|script-title = ja:事業番号3-34|language = ja|access-date = March 9, 2010|archive-url = https://web.archive.org/web/20091122143128/http://www.cao.go.jp/sasshin/oshirase/pdf/nov17-am-shiryo/3-34.pdf|archive-date = November 22, 2009|url-status = dead}}][{{cite web |url=http://www.mext.go.jp/component/b_menu/other/__icsFiles/afieldfile/2010/01/19/1289012_012.pdf |script-title=ja:10-1．平成22年度予算案の概要 |language=ja |access-date=March 9, 2010|archive-url = https://web.archive.org/web/20110722235535/http://www.mext.go.jp/component/b_menu/other/__icsFiles/afieldfile/2010/01/19/1289012_012.pdf|archive-date = July 22, 2011|url-status = live|year = 2010|trans-title=FY 2010 Overview of budget: Strengthening of research and development capabilities}}] Eventually the project was canceled in 2011 for the increased cost and the difficulty of achieving science goals.[{{cite web |url=http://www.isas.jaxa.jp/j/topics/topics/2011/0824_sac.shtml |title=電波天文衛星（ASTRO‐G）の状況について（報告資料） |language=ja |publisher=[Japan Aerospace Exploration Agency](/source/Japan_Aerospace_Exploration_Agency) |date=August 24, 2011 |access-date=February 5, 2012|archive-url = https://web.archive.org/web/20120226223138/http://www.isas.jaxa.jp/j/topics/topics/2011/0824_sac.shtml|archive-date = February 26, 2012|url-status = live}}][{{cite web |url=http://www.mext.go.jp/b_menu/shingi/uchuu/016/gijiroku/1312923.htm |script-title=ja:平成23年宇宙開発委員会（第35回） 配付資料 |language=ja |publisher=Ministry of Education, Culture, Sports, Science and Technology |date=November 30, 2011 |access-date=February 5, 2012 |archive-date=June 24, 2017 |archive-url=https://web.archive.org/web/20170624163746/http://www.mext.go.jp/b_menu/shingi/uchuu/016/gijiroku/1312923.htm |url-status=dead }}]
It was planned to feature a 9 m diameter dish antenna to observe in 8, 22 and 43 GHz bands, and was to be used in combination with ground radio telescopes to perform [Very Long Baseline Interferometry](/source/Very_Long_Baseline_Interferometry).[{{Cite journal|last=Saito|first=Hirobumi|last2=Sakai|first2=Shin-ichiro|last3=Higuchi|first3=Ken|last4=Kishimoto|first4=Naoko|last5=Takeuchi|first5=Hiroshi|last6=Yoshihara|first6=Keisuke|last7=Asaki|first7=Yoshiharu|last8=Tsuboi|first8=Masato|last9=Murata|first9=Yasuhiro|last10=Kobayashi|first10=Hideyuki|date=2010|title=Advanced Space Technologies in Space Science Missions - Space VLBI Mission ASTRO-G Project as an Example -|url=https://www.jstage.jst.go.jp/article/tastj/8/ists27/8_ists27_To_4_33/_article/-char/ja/|journal=Transactions of the Japan Society for Aeronautical and Space Sciences, Aerospace Technology Japan|volume=8|issue=ists27|pages=To_4_33–To_4_41|doi=10.2322/tastj.8.To_4_33|doi-access=free|url-access=subscription}}] It was expected to achieve ten times higher resolution and ten times higher sensitivity than its predecessor [HALCA](/source/HALCA).
==Science targets==
Key science :
*Jet structure, collimation and acceleration regions
*Structure of accretion disks around AGN
*Structure of magnetic fields in protostars
Other science targets:
*Galactic masers in star-forming region
*Extragalactic Megamasers
*Radio quiet quasars
*X-ray binaries, SNR, gravitational lenses etc.
==See also==
*[HALCA](/source/HALCA)
*[Spektr-R](/source/Spektr-R)
==References==
{{reflist}}
==External links==
* [https://web.archive.org/web/20150917051847/http://www.isas.jaxa.jp/e/enterp/missions/astro-g/index.shtml ASTRO-G] - [Japan Aerospace Exploration Agency](/source/Japan_Aerospace_Exploration_Agency) - [Institute of Space and Astronautical Science](/source/Institute_of_Space_and_Astronautical_Science)
** [http://www.vsop.isas.jaxa.jp/vsop2/ VSOP-2 Project]
*{{webarchive |url=https://web.archive.org/web/20120320060155/http://vsop.mtk.nao.ac.jp/2010/index-eng.html |date=March 20, 2012 |title=VSOP-2 Home Page }} - [National Astronomical Observatory of Japan](/source/National_Astronomical_Observatory_of_Japan)
{{Japanese space program}}
{{Space observatories}}
Category:Satellites of Japan
Category:Cancelled space telescopes
Category:Radio telescopes
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Adapted from the Wikipedia article [Astro-G](https://en.wikipedia.org/wiki/Astro-G) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Astro-G?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.