}}}}دلتای 4 گروهی از پنج سیستم پرتاب قابل مصرف در خانواده راکت های دلتا است که در اوایل دهه 2000 معرفی شدند. دلتا 4 که در اصل توسط بخش دفاع ، فضا و امنیت بوئینگ برای برنامه [[National Security Space Launch|NSSL]] طراحی شده بود ، در سال 2006 به یک محصول شرکت [[یونایتد لانچ آلاینس]] (معروف به ULA) تبدیل شد. دلتا 4 در اصل وسیله پرتاب نیروی هوایی ایالات متحده است ( محموله های نظامی USAF) ، اما همچنین برای پرتاب تعدادی محموله غیر نظامی دولت ایالات متحده و یک ماهواره تجاری استفاده شده است.
}}}}'''Delta IV''' is a group of five [[expendable launch system]]s in the [[Delta (rocket family)|Delta rocket family]] introduced in the early 2000s. Originally designed by [[Boeing]]'s Defense, Space and Security division for the [[National Security Space Launch|Evolved Expendable Launch Vehicle]] (EELV) program, the Delta IV became a [[United Launch Alliance]] (ULA) product in 2006. The Delta IV is primarily a launch vehicle for [[United States Air Force]] (USAF) military payloads, but has also been used to launch a number of United States government non-military payloads and a single commercial satellite.
The Delta IV originally had two main versions which allowed the family to cover a range of payload sizes and masses: the retired Medium (which had four configurations) and [[Delta IV Heavy|Heavy]]. As of 2019, only the Heavy remains active, with payloads that would previously fly on Medium moving to either the existing [[Atlas V]] or the forthcoming [[Vulcan (rocket)|Vulcan]]. Retirement of the Delta IV is anticipated in 2023.<ref name="SFN20200917">{{cite web|url=https://spaceflightnow.com/2020/09/17/ula-targeting-sept-26-for-next-delta-4-heavy-launch-attempt/|title=ULA targeting September 26 for next Delta 4-Heavy launch attempt|publisher=Spaceflight Now|date=17 September 2020|access-date=25 September 2020}}</ref>
Delta IV vehicles are built in the ULA facility in [[Decatur, Alabama]].<ref>{{cite press release|url=http://www.boeing.com/news/releases/2006/q4/061201a_nr.html|date=December 1, 2006|publisher=Boeing|title=Boeing and Lockheed Martin Complete United Launch Alliance Transaction|url-status=dead|archive-url=https://web.archive.org/web/20130502183612/http://www.boeing.com/news/releases/2006/q4/061201a_nr.html|archive-date=May 2, 2013}}</ref> Final assembly is completed at the launch site by ULA: at the [[horizontal integration facility]] for launches from [[Cape Canaveral Space Launch Complex 37|SLC-37B]] pad at [[Cape Canaveral Air Force Station|Cape Canaveral]] and in a similar facility for launches from [[Vandenberg Space Launch Complex 6|SLC-6]] pad at [[Vandenberg Air Force Base]].
