Editing H-II Transfer Vehicle (section)

== Design ==
[[File:H-II Transfer Vehicle diagram.jpg|left|thumb|Structure]]
[[File:HTV from inside 02 - cropped and rotated.jpg|thumb|left|The inside view of the Pressurised Logistics Carrier section of HTV-1.]]
[[File:ISS-26 HTV-2 Exposed Pallet grappled by Canadarm2.jpg|thumb|left|The Canadarm2 removing unpressurised payload from HTV-2.]]
[[File:HTV-1 close-up view.jpg|left|thumb|The four main thrusters. Smaller attitude control thrusters can be seen at the right side of this view of HTV-1.]]

The HTV is about {{convert|9.8|m}} long (including maneuvering thrusters at one end) and {{convert|4.4|m}} in diameter. Total mass when empty is {{convert|10500|kg}}, with a maximum total payload of {{convert|6000|kg}}, for a maximum launch weight of {{convert|16500|kg}}.<ref name=jaxa2007>{{cite web|title=H-II Transfer Vehicle "KOUNOTORI" (HTV)|url=http://www.jaxa.jp/projects/rockets/htv/design_e.html |publisher=Japan Aerospace Exploration Agency|year=2007|access-date=2010-11-11|url-status=dead|archive-url=https://web.archive.org/web/20101116044853/http://www.jaxa.jp/projects/rockets/htv/design_e.html
|archive-date=2010-11-16}}</ref>

The HTV is comparable in function to the [[Roscosmos|Russian]] [[Progress (spacecraft)|Progress]], the [[European Space Agency|ESA]] [[Automated Transfer Vehicle|ATV]], the [[SpaceX]] [[SpaceX Dragon 2|Cargo Dragons]], and the [[Cygnus (spacecraft)|Cygnus spacecraft]], all of which bring supplies to the ISS. Like the ATV, the HTV carries more than twice the payload of the Progress, but is launched less than half as often. Unlike Progress spacecraft, Cargo Dragon 2's and ATV's which use the [[Androgynous Peripheral Attach System|docking ports]] automatically, HTVs and American Dragon 1 approach the [[International Space Station|ISS]] in stages, and once they reach their closest parking orbit to the ISS, crew [[Grapple fixture|grapple]] them using the robotic arm [[Mobile Servicing System|Canadarm2]] and berth them to an open [[Common Berthing Mechanism|berthing port]] on the [[Harmony (ISS module)|''Harmony'']] module.<ref>{{cite conference|last=Fujimoto|first=Nobuyoshi |url=http://www.aprsaf.org/data/aprsaf17_data/DAY1-seu_0950-Kibo_Utilization_Status.pdf|title=Kibo Utilization Status Update|conference=17th Session of the Asia Pacific Regional Space Agency Forum |archive-url=https://web.archive.org/web/20120317080738/http://www.aprsaf.org/data/aprsaf17_data/DAY1-seu_0950-Kibo_Utilization_Status.pdf|archive-date=17 March 2012|date=23–26 November 2010|access-date=20 June 2019}}</ref>

The HTV has an external payload bay which is accessed by the robotic arm after it has been berthed to the ISS. New payloads can be moved directly from the HTV to ''[[Kibō (ISS module)|Kibō]]'''s exposed facility. Internally, it has eight [[International Standard Payload Rack]]s (ISPRs) in total which can be unloaded by the crew in a [[shirt-sleeve environment]]. After the retirement of [[NASA]]'s [[Space Shuttle]] in 2011, HTVs became the only spacecraft capable of transporting ISPRs to the ISS. The [[SpaceX Dragon]] and [[Northrop Grumman Innovation Systems|Northrop Grumman]] [[Cygnus (spacecraft)|Cygnus]] can carry resupply cargo bags but not ISPRs.{{citation needed|date=December 2016}}

The intent behind the HTV's modularized design was to use different module configurations to match different mission requirements.<ref name="miki2010">{{cite journal
|url=https://www.mhi.co.jp/technology/review/pdf/e471/e471058.pdf|title=Development of the H-II Transfer Vehicle (HTV)|journal=Mitsubishi Heavy Industries Technical Review|volume=47|issue=1|first1=Yoichiro |last1=Miki|first2=Naohiko|last2=Abe|first3=Koichi|last3=Matsuyama|first4=Kazumi|last4=Masuda|first5=Nobuhiko|last5=Fukuda|first6=Hiroshi|last6=Sasaki|date=March 2010|publisher=Mitsubishi Heavy Industries |url-status=live|archive-url=https://web.archive.org/web/20150720201230/https://www.mhi.co.jp/technology/review/pdf/e471/e471058.pdf|archive-date=2015-07-20}}</ref> However, to reduce the development cost it was decided to fly the mixed PLC/ULC configuration only.<ref name="miki2010"/>

To control the HTV's attitude and perform the orbital maneuvers such as rendezvous and reentry, the craft has four 500-N-class main thrusters and twenty-eight 110-N-class attitude control thrusters. Both use bipropellant, namely [[monomethylhydrazine]] (MMH) as fuel and [[mixed oxides of nitrogen]] (MON3) as oxidizer.<ref name="IAC">{{cite conference|last1=Matsuo|first1=Shinobu|last2=Miki|first2=Yoichiro |last3=Imada|first3=Takane|last4=Nakai|first4=Shunichiro|url=https://arc.aiaa.org/doi/10.2514/6.IAC-05-C4.1.03|title=The Design Characteristics of the HTV Propulsion Module|location=[[Fukuoka]], Japan |conference=56th [[International Astronautical Congress]]|date=17–21 October 2005|access-date=20 June 2019|doi=10.2514/6.IAC-05-C4.1.03|url-access=subscription}}</ref> HTV-1, HTV-2, and HTV-4 use [[Aerojet]]'s 110 N R-1E, [[Space Shuttle]]'s [[vernier engine]], and the 500 N based on the [[Apollo spacecraft]]'s [[R-4D]].<ref name="IAC"/> Later HTVs use 500 N class [[BT-4 (rocket engine)|HBT-5]] thrusters and 120 N class HBT-1 thrusters made by Japanese manufacturer [[IHI Corporation|IHI Aerospace Co., Ltd]].<ref>{{cite web|url=http://iss.jaxa.jp/htv/mission/htv-3/library/presskit/htv3_presskit.pdf|title=宇宙ステーション補給機「こうのとり」3号機（HTV3）ミッションプレスキット|language=ja|date=June 20, 2012|access-date=2012-06-24|url-status=live|archive-url=https://web.archive.org/web/20121031141116/http://iss.jaxa.jp/htv/mission/htv-3/library/presskit/htv3_presskit.pdf|archive-date=October 31, 2012}}</ref> The HTV's four spherical propellant tanks usually carry about 2 tonnes of propellant (the maximum capacity is 2432&nbsp;kg<ref name="IAC"/>).

After the unloading process is completed, the HTV is loaded with waste and unberthed. The vehicle then deorbits and is destroyed during reentry, the debris falling into the [[Pacific Ocean]].<ref name=jaxa2007op>{{cite web|url=http://iss.jaxa.jp/en/htv/operation/|title=HTV Operations|author=JAXA|year=2007|access-date=2011-01-02|url-status=live |archive-url=https://web.archive.org/web/20110126091208/http://iss.jaxa.jp/en/htv/operation/|archive-date=2011-01-26}}</ref>