View source for Delta IV

{{short description|Retired expendable launch system in the Delta rocket family}}
{{about|the rocket|other uses|Delta 4 (disambiguation)}}
{{Use American English|date=January 2014}}
{{Use dmy dates|date=September 2020}}
{{Infobox rocket
| name           = Delta IV
| logo           = Delta logo.png
| logo_upright   = 0.3
| image          = Delta IV Medium Rocket DSCS.jpg
| caption        = Delta IV Medium launch carrying [[DSCS]] III-B6.

|function       = Orbital [[launch vehicle]]
|manufacturer   = [[United Launch Alliance]]
|country-origin = United States
|cpl            = {{US$|164+ million|link=yes}}<ref>{{Cite web |title=Surplus Missile Motors: Sale Price Drives Potential Effects on DOD and Commercial Launch Providers |url=http://www.gao.gov/products/GAO-17-609}}</ref>
|height         = {{cvt|63.0-70.7|m}}
|diameter       = {{cvt|5.1|m}}
|mass           = {{cvt|249500-733400|kg}}
|stages         = 2

|capacities= 
  {{Infobox rocket/payload
  |location    = [[Low Earth orbit|LEO]]
  |kilos       = {{cvt|11470-28790|kg}}<ref name=":1" />
  }}
  {{Infobox rocket/payload
  |location    = [[Geostationary transfer orbit|GTO]]
  |kilos       = {{cvt|4440-14220|kg}}
  }}
|family        = [[Delta (rocket family)]]
|comparable    = {{flatlist|
* [[Atlas V]]
* [[Falcon 9]]
* [[H-IIA]]
* [[Long March 5]]
* [[Proton-M]]
}}
|status        = Retired
|sites         = {{plainlist|
* [[Cape Canaveral Space Force Station|Cape Canaveral]], [[Cape Canaveral Space Launch Complex 37|SLC-37]]
* [[Vandenberg Space Force Base|Vandenberg]], [[Vandenberg Space Launch Complex 6|SLC-6]]
}}

|launches      = {{collapsible list
  |title=45<ref>{{Cite web |last=Kyle |first=Ed |title=Delta IV Launch Record |url=http://www.spacelaunchreport.com/delta4.html#delta4log |url-status=usurped |archive-url=https://web.archive.org/web/20220425022016/http://www.spacelaunchreport.com/delta4.html |archive-date=25 April 2022 |access-date=21 January 2023 |publisher=Space Launch Report}}</ref><ref>{{Cite web |last=Graham |first=William |date=24 September 2022 |title=Last West Coast Delta IV Heavy launches with NROL-91 |url=https://www.nasaspaceflight.com/2022/09/delta-iv-nrol-91/ |access-date=25 September 2022 |website=[[NASASpaceFlight]]}}</ref>
  | {{in5|3}} '''Medium''': 3
  | {{in5|3}} '''M+ (4,2)''': 15
  | {{in5|3}} '''M+ (5,2)''': 3
  | {{in5|3}} '''M+ (5,4)''': 8
  | {{in5|3}} '''Heavy''': 16
  }}
|success       = {{collapsible list
  |title=44
  | {{in5|3}} '''Medium''': 3
  | {{in5|3}} '''M+ (4,2)''': 15
  | {{in5|3}} '''M+ (5,2)''': 3
  | {{in5|3}} '''M+ (5,4)''': 8
  | {{in5|3}} '''Heavy''': 15
  }}
|fail          = 
|partial       = 1 (Heavy Demo)
|other_outcome = 
|first         = {{plainlist|
* '''Medium/M+:''' 20 November 2002 ([[Eutelsat W5]])
* '''Heavy:''' 21 December 2004 ([[List of USA satellites|USA-181]])
}}
|last= {{plainlist|
* '''Medium/M+:''' 22 August 2019 ([[USA-293]]/[[GPS satellite blocks|GPS III-2]])
* '''Heavy:''' 9 April 2024 ([[List of NRO launches|NROL-70]])
}}
|payloads      = {{flatlist|
* [[Geostationary Operational Environmental Satellite|GOES]]
* [[GPS Block IIF]]
* [[NROL|NRO classified payloads]]
* [[Wideband Global SATCOM|WGS]]
* [[Exploration Flight Test 1]]
* [[Parker Solar Probe]]
}}
|stagedata = 
  {{Infobox rocket/stage
  |type        = booster
  |diff        = Medium+
  |name        = [[Graphite-Epoxy Motor|GEM&nbsp;60]]
  |number      = 2{{efn|Medium+ (4,2) and Medium+ (5,2)}} or 4{{efn|Medium+ (5,4)}}
  |length      = <!-- length of a single booster in metres, use {{cvt}}, optional -->
  |diameter    = <!-- diameter of a single booster in metres, use {{cvt}}, optional -->
  |empty       = <!-- empty mass of a single booster in kilograms, use {{cvt}}, optional -->
  |gross       = {{cvt|74158|lb|kg|order=flip}}
  |propmass    = <!-- propellant mass carried by a single booster in kilograms, use {{cvt}}, optional -->
  |engines     = 
  |thrust      = {{cvt|826.6|kN|lk=on}}
  |total       = <!-- total thrust for all boosters in kN, use {{cvt}}, optional -->
  |SI          = {{Abbr|'''SL'''|at sea level}}: {{cvt|245|isp|lk=on}}
  |burntime    = 91 seconds
  |fuel        = [[Ammonium perchlorate composite propellant|AP]] / [[Hydroxyl-terminated polybutadiene|HTPB]] / [[Aluminium|Al]]
  }}
  {{Infobox rocket/stage
  |type        = booster
  |diff        = Heavy
  |name        = [[Common Booster Core|CBC]]
  |number      = 2
  |length      = <!-- length of a single booster in metres, use {{cvt}}, optional -->
  |diameter    = <!-- diameter of a single booster in metres, use {{cvt}}, optional -->
  |empty       = <!-- empty mass of a single booster in kilograms, use {{cvt}}, optional -->
  |gross       = {{cvt|226400|kg|lb}}
  |propmass    = <!-- propellant mass carried by a single booster in kilograms, use {{cvt}}, optional -->
  |engines     = 1{{nnbsp}}×{{nnbsp}}[[RS-68A]]
  |thrust      = {{cvt|705000|lbf|kN|order=flip}} (sea level)
  |total       = <!-- total thrust for all boosters in kN, use {{cvt}}, optional -->
  |SI          = {{Abbr|'''SL'''|at sea level}}: {{cvt|360|isp}}<br/>{{Abbr|'''vac'''|in vacuum}}: {{cvt|412|isp}}
  |burntime    = 242 seconds<ref name=":1" />
  |fuel        = [[LH2|LH<sub>2</sub>]] / [[LOX]]
  }}
  {{Infobox rocket/stage
  |type        = stage
  |diff        = 
  |stageno     = First
  |name        = [[Common Booster Core|CBC]]
  |number      = 2
  |length      = <!-- length of a single stage in metres, use {{cvt}}, optional -->
  |diameter    = <!-- diameter of a single stage in metres, use {{cvt}}, optional -->
  |empty       = <!-- empty mass of a single stage in kilograms, use {{cvt}}, optional -->
  |gross       = {{cvt|226,400|kg}}
  |propmass    = <!-- propellant mass carried by a single stage in kilograms, use {{cvt}}, optional -->
  |engines     = 1{{nnbsp}}×{{nnbsp}}[[RS-68A]]
  |thrust      = {{cvt|705,000|lbf|kN|order=flip}} (sea level)
  |SI          = {{Abbr|'''SL'''|at sea level}}: {{cvt|360|isp}}<br/>{{Abbr|'''vac'''|in vacuum}}: {{cvt|412|isp}}
  |burntime    = 245 seconds (328 seconds in Heavy configuration)<ref name=":1" />
  |fuel        = [[LH2|LH<sub>2</sub>]] / [[LOX]]
  }}
  {{Infobox rocket/stage
  |type        = stage
  |diff        = 
  |stageno     = Second
  |name        = [[Delta Cryogenic Second Stage|DCSS]]
  |number      = 1
  |length      = <!-- length of a single stage in metres, use {{cvt}}, optional -->
  |diameter    = <!-- diameter of a single stage in metres, use {{cvt}}, optional -->
  |empty       = <!-- empty mass of a single stage in kilograms, use {{cvt}}, optional -->
  |gross       = '''4-m''': {{cvt|24170|kg}}<br/>'''5-m''': {{cvt|30700|kg}}
  |propmass    = <!-- propellant mass carried by a stage in kilograms, use {{cvt}}, optional -->
  |engines     = 1{{nnbsp}}×{{nnbsp}}[[RL10|RL10-B-2]]
  |thrust      = {{cvt|110|kN|lbf}}
  |SI          = {{cvt|462|isp}}
  |burntime    = 850–1,125 seconds
  |fuel        = [[LH2|LH<sub>2</sub>]] / [[LOX]]
  }}
}}

'''Delta IV''' was a group of five [[expendable launch system]]s in the [[Delta (rocket family)|Delta rocket family]]. It flew 45 missions from 2002 to 2024. 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 was primarily a launch vehicle for [[United States Air Force]] (USAF) military payloads, but was also used to launch a number of United States government non-military payloads and a single commercial satellite. 

The Delta IV had two main versions which allowed the family to cover a range of payload sizes and masses: the Medium (which had four configurations) and [[Delta IV Heavy|Heavy]]. The final flight of Medium occurred in 2019. The final flight of Heavy was in April 2024.

Delta IV vehicles were built in the ULA facility in [[Decatur, Alabama]].<ref>{{Cite press release |title=Boeing and Lockheed Martin Complete United Launch Alliance Transaction |date=December 1, 2006 |publisher=Boeing |url=http://www.boeing.com/news/releases/2006/q4/061201a_nr.html |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 was 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 Space Force Base]].

== History ==
The latest evolutionary development of the [[Delta (rocket family)|Delta rocket family]], Delta IV was introduced to meet the requirements of the United States Air Force's (USAF) [[Evolved Expendable Launch Vehicle]] (EELV, now [[National Security Space Launch]] (NSSL)) program. While the Delta IV retains the name of the Delta family of rockets, major changes were incorporated. Perhaps the most significant change was the switch from kerosene to [[liquid hydrogen]] fuel, with new tankage and a new engine required.<ref>{{Cite web |last=Kelly |first=Emre |title=The last ever 'single stick' Delta IV scheduled to launch; here's what that means |url=https://www.floridatoday.com/story/tech/science/space/2019/08/15/united-launch-alliance-set-launch-last-ever-single-stick-delta-iv-rocket-cape-canaveral-florida/2008221001/ |access-date=2021-04-19 |website=Florida Today |language=en-US}}</ref><ref name="planner guide2013" />

During the Delta IV's development, a small variant was considered. This would have featured the [[Delta II]] second stage, an optional [[Thiokol]] [[Star (rocket stage)|Star 48B]] third stage, and the Delta II payload fairing, all atop a single [[Common Booster Core]] (CBC).<ref>[http://www.astronautix.com/lvs/delsmall.htm "Delta IV Small"] {{webarchive |url=https://web.archive.org/web/20061105183541/http://www.astronautix.com/lvs/delsmall.htm|date=2006-11-05}} Astronautix.com</ref> The Small variant was dropped by 1999.<ref>[http://space.skyrocket.de/doc_lau/delta-4.htm Gunter's Space page - Delta IV]</ref><ref>{{Cite press release |title=Boeing Signs agreement for Delta IV Integration Facility |date=January 28, 1999 |publisher=Boeing |url=http://www.boeing.com/news/releases/1999/news_release_990128b.html |url-status=dead |archive-url=https://web.archive.org/web/20121010230340/http://www.boeing.com/news/releases/1999/news_release_990128b.html |archive-date=October 10, 2012}}</ref>

In 2002, the Delta IV was first launched, with the [[RS-68]] becoming the first large [[liquid-propellant rocket]] engine designed in the United States since the [[RS-25|Space Shuttle main engine]] (SSME) in the 1970s.<ref name="slrdiv">{{Cite web |date=26 Apr 2021 |title=Space Launch Report: Delta IV Data Sheet |url=http://www.spacelaunchreport.com/delta4.html |url-status=usurped |archive-url=https://web.archive.org/web/20220406013823/http://www.spacelaunchreport.com/delta4.html |archive-date=6 Apr 2022}}</ref>

The [[L3 Technologies]] Redundant Inertial Flight Control Assembly (RIFCA) guidance system originally used on the Delta IV was common to that carried on the [[Delta II]], although the software was different because of the differences between the Delta II and Delta IV. The RIFCA featured six [[ring laser gyroscope]]s and [[accelerometer]]s each, to provide a higher degree of reliability.<ref>[http://www.l-3com.com/spacenav/space_and_nav/space_products/RIFCA-Trihex.htm "L-3 Space & Navigation's RIFCA Trihex"] {{webarchive|url=https://web.archive.org/web/20061015192521/http://www.l-3com.com/spacenav/space_and_nav/space_products/RIFCA-Trihex.htm|date=2006-10-15}}</ref>

[[Boeing]] initially intended to market Delta IV commercial launch services. However, the Delta IV entered the space launch market when global capacity was already much higher than demand. Furthermore, as an unproven design it had difficulty finding a market in commercial launches, and Delta IV launch costs are higher than comparable vehicles of the same era. In 2003, Boeing pulled the Delta IV from the commercial market, citing low demand and high costs. In 2005, Boeing stated that it sought to return the Delta IV to commercial service.<ref>{{Cite news |date=March 25, 2005 |title=Boeing's Delta IV may return to commercial launches |url=http://www.ocregister.com/ocr/2005/03/25/sections/business/business_nation/article_456341.php |url-status=dead |archive-url=https://web.archive.org/web/20061114073317/http://www.ocregister.com/ocr/2005/03/25/sections/business/business_nation/article_456341.php |archive-date=November 14, 2006 |publisher=Orange County Register}}</ref>

As of 2009, the USAF funded Delta IV EELV engineering, integration, and infrastructure work through contracts with Boeing Launch Services (BLS). On 8 August 2008, the USAF [[Space and Missile Systems Center]] increased the "cost plus award fee" contract with BLS for US$1.656 billion to extend the period of performance through the 30 September 2008 ([[Fiscal year|FY09]]). In addition, a US$557.1 million option was added to cover FY10.<ref name="Def_Contract_Aug2008">{{Cite web |date=8 August 2008 |title=DefenseLink Contracts for Friday, August 08, 2008 |url=http://www.defenselink.mil/contracts/contract.aspx?contractid=3837 |access-date=6 January 2009 |publisher=US Department of Defense}}</ref>

In February 2010, naturalized citizen Dongfan Chung, an engineer working with Boeing, was the first person convicted under the [[Economic Espionage Act of 1996]]. Chung passed on classified information on designs including the Delta IV rocket to China and was sentenced to 15 years.<ref>{{Cite news |last=Whitcomb |first=Dan |date=8 February 2010 |title=Ex-Boeing engineer gets 15 years in U.S. spy case |url=https://www.reuters.com/article/idUSN0821290920100208 |url-status=live |archive-url=https://web.archive.org/web/20100212070059/http://www.reuters.com/article/idUSN0821290920100208 |archive-date=12 February 2010 |work=Reuters}}</ref>

In March 2015, ULA announced plans to phase out the Delta IV Medium by 2018.<ref>{{Cite web |date=3 March 2015 |title=ULA Targets 2018 for Delta 4 Phase-out, Seeks Relaxation of RD-180 Ban |url=http://spacenews.com/ula-targets-2018-for-delta-4-phase-out-seeks-relaxation-of-rd-180-ban/ |access-date=2015-03-03 |publisher=SpaceNews.com}}</ref>

With the exception of the first launch, which carried the [[Eutelsat 33B|Eutelsat W5]] commercial communications satellite, all Delta IV launches have been paid for by the US government. In 2015, ULA stated that a [[Delta IV Heavy]] is sold for nearly US$400 million.<ref name="sfn-20150422">{{Cite news |last=Clark |first=Stephen |date=22 April 2015 |title=ULA needs commercial business to close Vulcan rocket business case |url=http://spaceflightnow.com/2015/04/22/ula-needs-commercial-business-to-close-vulcan-rocket-business-case/ |access-date=23 April 2015 |publisher=Spaceflight Now}}</ref>

=== RS-68A booster engine upgrade ===
The possibility of a higher performance Delta IV was first proposed in a 2006 [[RAND Corporation]] study of national security launch requirements out to 2020. A single [[National Reconnaissance Office]] (NRO) payload required an increase in the lift capability of the Delta IV Heavy.<ref>{{Cite web |last=Forrest McCartney |display-authors=etal |year=2006 |title=National Security Space Launch Report |url=https://www.rand.org/pubs/monographs/2006/RAND_MG503.pdf |publisher=RAND |pages=6–7}}</ref> Lift capacity was increased by developing the higher-performance [[RS-68#Variants|RS-68A]] engine,<ref>{{Cite press release |title=Three Pratt & Whitney Rocketdyne RS-68A Engines Power Delta IV Heavy Upgrade Vehicle on Inaugural Flight |url=http://www.prnewswire.com/news-releases/three-pratt--whitney-rocketdyne-rs-68a-engines-power-delta-iv-heavy-upgrade-vehicle-on-inaugural-flight-160868765.html |access-date=November 9, 2014 |website=prnewswire.com}}</ref> which first flew on 29 June 2012.<ref name="ULA-PR-Jun12">{{Cite press release |title=United Launch Alliance Upgraded Delta IV Heavy rocket successfully Launches Second Payload in Nine Days for the National Reconnaissance Office |date=2012-06-29 |publisher=United Launch Alliance |url=http://www.ulalaunch.com/site/pages/News.shtml#/109/ |access-date=2011-01-21 |url-status=dead |archive-url=https://web.archive.org/web/20131207160150/http://www.ulalaunch.com/site/pages/News.shtml#/109/ |archive-date=2013-12-07}}</ref> ULA phased out the baseline RS-68 engine with the launch of Delta flight 371 on 25 March 2015. All following launches used the RS-68A,<ref name="Spaceflight Now">{{Cite web |date=27 March 2015 |title=Delta 4 rocket evolving to upgraded main engine |url=http://spaceflightnow.com/2015/03/27/delta-4-rocket-evolving-the-upgraded-main-engine/ |access-date=28 March 2015 |publisher=Spaceflight Now}}</ref> and the engine's higher thrust allowed the use of a single standardized CBC design for all Delta IV Medium and M+ versions. This upgrade reduced cost and increased flexibility, since any standardized CBC could be configured for zero, two, or four [[solid-propellant rocket]] boosters. However, the new CBC led to a slight performance loss for most medium configurations.<ref>{{Cite web |date=15 June 2012 |title=New Delta 4 Engine Variant is Part of ULA Cost Cutting Strategy |url=http://www.spacenews.com/article/new-delta-4-engine-variant-part-ula-cost-cutting-strategy |website=spacenews.com}}</ref> The Delta IV Heavy required non-standard CBCs for the core and boosters.<ref>{{Cite web |date=March 2010 |title=Ongoing Launch Vehicle Innovation at United Launch Alliance |url=http://ulalaunch.com/site/docs/publications/ULA-Innovation-March-2010.pdf |archive-url=https://web.archive.org/web/20140328201054/http://ulalaunch.com/site/docs/publications/ULA-Innovation-March-2010.pdf |archive-date=2014-03-28 |access-date=July 13, 2014 |publisher=ULA}}</ref>

'''Payload capacities after RS-68A upgrade'''
{| class="wikitable sortable"
|- style="background:#ffdead;"
! Version
! Fairing
! CBCs
! SRBs
! Payload to [[Low Earth orbit|LEO]]
407&nbsp;km x 51.6°
! Payload to [[Geostationary transfer orbit|GTO]]
1800&nbsp;m/s residual
! Launches
|-
| Medium
| 4 m
| 1
| 0
| 8,510&nbsp;kg<ref name=":0">{{Cite web |title=Delta IV |url=http://www.spacelaunchreport.com/delta4.html |url-status=usurped |archive-url=https://web.archive.org/web/20100821062352/http://www.spacelaunchreport.com/delta4.html |archive-date=21 August 2010 |publisher=SpaceLaunchReport.com}}</ref>
| 4,440&nbsp;kg<ref name=":1">{{Cite web |date=June 2013 |title=Delta IV User's Guide |url=http://www.ulalaunch.com/uploads/docs/Launch_Vehicles/Delta_IV_Users_Guide_June_2013.pdf |archive-url=https://web.archive.org/web/20140710005717/http://www.ulalaunch.com/uploads/docs/Launch_Vehicles/Delta_IV_Users_Guide_June_2013.pdf |archive-date=2014-07-10 |access-date=July 10, 2014 |publisher=ULA}}</ref>
| 0
|-
| M+ (4,2)
| 4 m
| 1
| 2
| 12,000&nbsp;kg<ref name=":0" />
| 6,390&nbsp;kg<ref name=":1" />
| 2
|-
| M+ (5,2)
| 5 m
| 1
| 2
| 10,220&nbsp;kg<ref name=":0" />
| 5,490&nbsp;kg<ref name=":1" />
| 2
|-
| M+ (5,4)
| 5 m
| 1
| 4
| 12,820&nbsp;kg<ref name=":0" />
| 7,300&nbsp;kg<ref name=":1" />
| 4
|-
| Heavy
| 5 m
| 3
| 0
| 25,980 kg<ref name=":0" />
| 14,220 kg<ref name=":1" />
| 9
|}

'''Payload capacities with original RS-68'''
{| class="wikitable sortable"
!
Version
!
Fairing
!
CBCs
!
SRBs
!
Payload to [[Low Earth orbit|LEO]]

407&nbsp;km x 51.6°
!
Payload to [[Geostationary transfer orbit|GTO]]

1800&nbsp;m/s residual
!
Launches
|-
| Medium
| 4 m
| 1
| 0
| 8,800&nbsp;kg<ref name=":0" />
| 4,540&nbsp;kg<ref name=":2">{{Cite web |date=September 2007 |title=Delta IV Payload Planner's Guide |url=https://www.scribd.com/doc/16924978/Boeing-Delta-IV-Payload-Planners-Guide}}</ref>
| 3
|-
| M+ (4,2)
| 4 m
| 1
| 2
| 11,920&nbsp;kg<ref name=":0" />
| 6,270&nbsp;kg<ref name=":2" />
| 13
|-
| M+ (5,2)
| 5 m
| 1
| 2
| 10,580&nbsp;kg<ref name=":0" />
| 5,430&nbsp;kg<ref name=":2" />
| 1
|-
| M+ (5,4)
| 5 m
| 1
| 4
| 13,450&nbsp;kg<ref name=":0" />
| 7,430&nbsp;kg<ref name=":2" />
| 4
|-
| Heavy
| 5 m
| 3
| 0
| 22,980&nbsp;kg<ref name=":0" />
| 13,400&nbsp;kg<ref name=":2" />
| 7
|}
<nowiki>*</nowiki>Masses include a Payload Attach Fitting (240&nbsp;kg to 1,221&nbsp;kg depending on payload).<ref name=":1" />

=== Proposed upgrades that were not implemented ===
Possible future upgrades for the Delta IV included adding extra strap-on solid motors, higher-thrust main engines, lighter materials, higher-thrust second stages, more (up to eight) strap-on CBCs, and a cryogenic propellant cross feed from strap on boosters to the common core.<ref name="Growth">{{Cite web |title=Delta Launch 310 – Delta IV Heavy Demo Media Kit - Delta Growth Options |url=http://www.boeing.com/defense-space/space/delta/kits/d310_d4heavy_demo.pdf |url-status=dead |archive-url=https://web.archive.org/web/20121006021346/http://www.boeing.com/defense-space/space/delta/kits/d310_d4heavy_demo.pdf |archive-date=October 6, 2012 |publisher=Boeing}}</ref>

At one point, NASA planned to use Delta IV or Atlas V to launch the proposed [[Orbital Space Plane Program|Orbital Space Plane]],<ref>{{Cite web |last=Whitesides |first=Loretta Hidalgo |date=July 9, 2008 |title=Why NASA Isn't Trying to Human-Rate the Atlas V or Delta IV Rockets |url=https://www.wired.com/wiredscience/2008/07/why-nasa-isnt-t/ |publisher=Wired |quote="You could launch a smaller human vehicle on a current expendable rocket [...] In fact, before the Columbia disaster NASA teams were working on an Orbital Space Plane (OSP) designed to do just that".}}</ref> which eventually became the [[Crew Exploration Vehicle]] and then the [[Orion (spacecraft)|Orion]]. Orion was intended to fly on the [[Ares I]] launch vehicle, then the [[Space Launch System]] after Ares I was cancelled.

In 2009, [[The Aerospace Corporation]] reported on [[NASA]] results of a study to determine the feasibility of modifying Delta IV to be [[Human-rating certification|crew-rated]] for use in NASA [[human spaceflight]] missions. According to [[Aviation Week & Space Technology]] the study, "found that a Delta IV heavy [...] could meet NASA's requirements for getting humans to low Earth orbit".<ref>{{Cite web |last=Frank Morring, Jr. |date=June 15, 2009 |title=Study Finds Human-rated Delta IV Cheaper |url=http://www.aviationweek.com/aw/generic/story_channel.jsp?channel=space&id=news/Study061509.xml |publisher=Aviation Week}}{{Dead link|date=October 2023 |bot=InternetArchiveBot |fix-attempted=yes }}</ref>

A proposed upgrade to the Delta IV family was the addition of extra solid motors. The Medium+ (4,4) would have used existing mount points to pair the four GEM 60s of the M+ (5,4) with the upper stage and fairing of the (4,2). An M+ (4,4) would have had a GTO payload of {{cvt|7500|kg}}, a LEO payload of {{cvt|14800|kg}}, and could have been available within 36 months of the first order. It was also considered to add extra GEM 60s to the M+ (5,4), which would have required adding extra attachment points, structural changes to cope with the different flight loads, and launch pad and infrastructure changes. The Medium+ (5,6) and (5,8) would have flown with six and eight SRBs respectively, for a maximum of up to {{cvt|9200|kg}} to GTO with the M+ (5,8). The Medium+ (5,6) and (5,8) could have been available within 48 months of the first order.<ref>{{Cite web |date=September 2007 |title=Delta IV Payload Planners Guide |url=http://www.ulalaunch.com/site/docs/product_cards/guides/DeltaIVPayloadPlannersGuide2007.pdf |archive-url=https://web.archive.org/web/20110722081616/http://www.ulalaunch.com/site/docs/product_cards/guides/DeltaIVPayloadPlannersGuide2007.pdf |archive-date=2011-07-22 |publisher=ULA |pages=10–15, 16}}</ref>

=== Successors ===
The [[Vulcan Centaur]] is planned to replace the [[Atlas V]] and Delta IV rockets. Vulcan Centaur had been projected to enter service by 2023, using the [[BE-4]] [[methane]]-fueled rocket engine,<ref>{{Cite news |last=Mike Gruss |date=13 April 2015 |title=ULA's Next Rocket To Be Named Vulcan |url=http://spacenews.com/ulas-next-rocket-to-be-named-vulcan/ |publisher=Space News}}</ref><ref>{{Cite web |last=Roulette |first=Joey |date=10 October 2022 |title=United Launch Alliance's debut Vulcan mission slips to 2023 -CEO |url=https://www.reuters.com/lifestyle/science/united-launch-alliances-debut-vulcan-mission-slips-2023-ceo-2022-10-10/ |access-date=24 October 2022 |website=[[Reuters]]}}</ref> but the first Vulcan launched on 8 January 2024.<ref>{{Cite news |last=Belam |first=Martin |date=2024-01-08 |title=Nasa Peregrine 1 launch: Vulcan Centaur rocket carrying Nasa moon lander lifts off in Florida – live updates |url=https://www.theguardian.com/science/live/2024/jan/08/nasa-peregrine-1-launch-rocket-moon-latest-news-updates-live |access-date=2024-01-08 |work=the Guardian |language=en-GB |issn=0261-3077}}</ref> The Atlas V is expected to stay in service for a few years after Vulcan's inaugural launch, and the Delta IV Heavy was discontinued in April 2024.<ref>{{Cite news |last=Stephen Clark |date=19 August 2019 |title=ULA's second launch of the month scheduled for Thursday |url=https://spaceflightnow.com/2019/08/19/ulas-second-launch-of-the-month-scheduled-for-thursday/ |publisher=Spaceflight Now}}</ref>

== Delta IV Medium ==
The Delta IV Medium (also referred to as 'single stick'<ref>{{Cite web |last=Clark |first=Stephen |title=Final 'single stick' Delta 4-Medium rocket arrives at Florida launch pad – Spaceflight Now |url=https://spaceflightnow.com/2019/06/07/final-single-stick-delta-4-medium-rocket-arrives-at-florida-launch-pad/ |access-date=2020-11-01 |language=en-US}}</ref><ref>{{Cite web |last=Ray |first=Justin |title=Air Force assigns new Delta 4 rocket launch – Spaceflight Now |url=https://spaceflightnow.com/2015/09/10/air-force-assigns-new-delta-4-rocket-launch/ |access-date=2020-11-01 |language=en-US}}</ref>) was available in four configurations: Medium, Medium+ (4,2), Medium+ (5,2), and Medium+ (5,4).<ref name="NASA-SF_Last_med_DIV">{{Cite web |last=Gebhardt |first=Chris |date=2019-08-22 |title=Delta IV Medium's well-earned retirement with GPS finale |url=https://www.nasaspaceflight.com/2019/08/delta-iv-medium-retirement-gps-finale/ |access-date=2020-08-15 |publisher=NASASpaceFlight.com}}</ref>

The Delta IV Medium (Delta 9040) was the most basic Delta IV. It featured a single CBC and a modified [[Delta III]] second stage, with 4-meter liquid hydrogen and liquid oxygen tanks (called a [[Delta Cryogenic Second Stage]] (DCSS)) and a 4-meter payload fairing. The Delta IV Medium was capable of launching 4,200&nbsp;kg to [[geostationary transfer orbit]] (GTO). From Cape Canaveral, GTO is 1804&nbsp;m/s away from GEO. The mass of fairing and payload attach fittings have been subtracted from the gross performance.<ref name="planner guide2013">{{Cite web |date=June 2013 |title=Delta IV Launch Services User's Guide |url=http://www.ulalaunch.com/uploads/docs/Launch_Vehicles/Delta_IV_Users_Guide_June_2013.pdf |url-status=dead |archive-url=https://web.archive.org/web/20140710005717/http://www.ulalaunch.com/uploads/docs/Launch_Vehicles/Delta_IV_Users_Guide_June_2013.pdf |archive-date=2014-07-10 |access-date=2014-07-09 |publisher=United Launch Alliance |pages=2–10, 5-3}}</ref>

The Delta IV Medium+ (4,2) (Delta 9240) had the same CBC and DCSS as the Medium, but with the addition of two [[Orbital ATK]]-built 1.5-m (60-in) diameter [[solid rocket booster]] [[Graphite-Epoxy Motor]]s (GEM 60s) [[strap-on booster]]s to increase payload capacity to 6,150&nbsp;kg to GTO.<ref name="planner guide2013" />

The Delta IV Medium+ (5,2) (Delta 9250) was similar to the Medium+ (4,2), but had a 5-m–diameter DCSS and payload fairing for larger payloads. Because of the extra weight of the larger payload fairing and second stage, the Medium+ (5,2) could launch 5,072&nbsp;kg to GTO.<ref name="planner guide2013" />

The Delta IV Medium+ (5,4) (Delta 9450) was similar to the Medium+ (5,2), but used four GEM 60s instead of two, enabling it to lift 6,882&nbsp;kg to GTO.<ref name="planner guide2013" />

To encapsulate the satellite payload, a variety of different payload fairings were available. A stretched Delta III 4-meter diameter composite payload fairing was used on 4-meter Medium versions, while an enlarged, 5-meter diameter composite fairing was used on 5-meter Medium versions.<ref name=DeltaIVpayloadplanner/>

The Medium (4,2) version last flew on 22 August 2019, marking the retirement of the Delta IV Medium variants.<ref name="NASA-SF_Last_med_DIV" /><ref>{{Cite web |last=Berger |first=Eric |date=2019-08-22 |title=The last single-stick Delta rocket launched Thursday, and it put on a show |url=https://arstechnica.com/science/2019/08/the-last-single-stick-delta-rocket-launched-thursday-and-it-put-on-a-show/ |access-date=2020-08-06 |publisher=Ars Technica}}</ref>

== Delta IV Heavy ==
{{main|Delta IV Heavy}}
[[File:Delta-4H DSP-23 2.jpg|thumb|270px|right|Delta IV Heavy launching]]

The Delta IV Heavy (Delta 9250H) combines a {{cvt|5|m}} diameter DCSS and payload fairing with two additional CBCs. These are strap-on boosters which are [[Separation event|separated]] earlier in the flight than the center CBC. As of 2007, a longer 5 meter diameter composite fairing was standard on the Delta IV Heavy,<ref name="Growth" /> with an aluminum isogrid fairing also available. The aluminum trisector (three-part) fairing was built by [[Boeing]] and derived from a [[Titan IV]] fairing.<ref name="DeltaIVpayloadplanner">{{Cite web |date=September 2007 |title=Delta IV Payload Planners Guide |url=http://www.ulalaunch.com/site/docs/product_cards/guides/DeltaIVPayloadPlannersGuide2007.pdf |url-status=dead |archive-url=https://web.archive.org/web/20110722081616/http://www.ulalaunch.com/site/docs/product_cards/guides/DeltaIVPayloadPlannersGuide2007.pdf |archive-date=2011-07-22 |publisher=United Launch Alliance |pages=1–7}}</ref> The trisector fairing was first used on the [[Defense Support Program|DSP-23]] flight.<ref>[http://www.afspc.af.mil/library/factsheets/factsheet.asp?id=3643 US Air Force - EELV Fact Sheets] {{webarchive |url=https://web.archive.org/web/20140427031225/http://www.afspc.af.mil/library/factsheets/factsheet.asp?id=3643|date=April 27, 2014}}</ref> The Delta IV with the extended fairing is over {{cvt|62|m}} tall. The last launch took place on 9 April 2024, carrying the NROL-70 satellite, marking the conclusion of the Delta rocket family.

== Vehicle description ==
[[File:Delta rocket evolution.png|thumb|270px|right|upright=1.8|Delta IV evolution]]

=== Common Booster Core ===
{{main|Common Booster Core}}

Each Delta IV consists of at least one [[Common Booster Core]] (CBC). Each CBC is powered by one [[Aerojet Rocketdyne]] [[RS-68]] engine, which burns [[liquid hydrogen]] and [[liquid oxygen]].

On flights of the Medium, the RS-68 ran at 102% rated thrust for the first few minutes of flight, and then throttled down to 58% rated thrust before main engine cutoff.<ref>{{Cite web |date=June 9, 2005 |title=Delta IV GOES-N Launch Timeline |url=http://www.spaceflightnow.com/delta/d313/050609launchtimeline.html |publisher=Spaceflight Now}}</ref> On the Heavy, the main CBC's engine throttles down to 58% rated thrust around 50 seconds after liftoff, while the strap-on CBCs remain at 102%. This conserves propellant and allows the main CBC to burn after booster separation. After the strap-on CBCs separate, the main CBC's engine again throttles up to 102% before throttling back down to 58% prior to main engine cutoff.<ref>{{Cite web |date=December 1, 2004 |title=Delta IV Heavy Demo Launch Timeline |url=http://www.spaceflightnow.com/delta/d310/041201launchtimeline.html |publisher=Spaceflight Now}}</ref>

The RS-68 engine is mounted to the lower thrust structure of the CBC by a four-legged (quadrapod) thrust frame and enclosed in a protective composite conical thermal shield. Above the thrust structure is an [[Aluminium|aluminum]] [[isogrid]] (a grid pattern machined out of the inside of the tank to reduce weight) liquid hydrogen tank, followed by a [[Composite material|composite]] cylinder called the centerbody, an aluminum isogrid liquid oxygen tank, and a forward skirt. Along the back of the CBC is a cable tunnel to hold electrical and signal lines, and a feedline to carry the liquid oxygen to the RS-68 from the tank. The CBC is of a constant, {{cvt|5|m}} diameter.<ref name=slrdiv/>

=== Delta Cryogenic Second Stage ===
{{main|Delta Cryogenic Second Stage}}
[[File:Second stage of a Delta IV Medium rocket.jpg|thumb|270px|Delta IV 4-meter Cryogenic Second Stage]]

The upper stage of the Delta IV was the [[Delta Cryogenic Second Stage]] (DCSS). The DCSS was based on the [[Delta III]] upper stage but has increased propellant capacity. Two versions have been produced: a {{cvt|4|m}} diameter DCSS that was retired with the Delta IV Medium and a {{cvt|5|m}} diameter DCSS that remains in service with the Delta IV Heavy. The 4 m diameter version lengthened both Delta III propellant tanks, while the 5-meter version has an extended diameter liquid hydrogen tank and a further lengthened liquid oxygen tank. Regardless of the diameter, each DCSS is powered by one [[RL10|RL10B-2]] engine, with an extendable carbon-carbon nozzle to improve specific impulse.<ref>{{Cite web |date=September 2007 |title=Delta IV Payload Planners Guide |url=http://www.ulalaunch.com/site/docs/product_cards/guides/DeltaIVPayloadPlannersGuide2007.pdf |url-status=dead |archive-url=https://web.archive.org/web/20110722081616/http://www.ulalaunch.com/site/docs/product_cards/guides/DeltaIVPayloadPlannersGuide2007.pdf |archive-date=2011-07-22 |publisher=United Launch Alliance |pages=1-5 to 1-6}}</ref> Two different interstages are used to mate the first stage and DCSS. A tapering interstage that narrowed down from 5 m to 4 m diameter was used to mate the 4 m DCSS to the CBC, while a cylindrical interstage is used to mate the 5 m DCSS. Both interstages were built from composites and enclosed the liquid oxygen tank, with the larger liquid hydrogen tank making up part of the vehicle's outer mold line.<ref>{{Cite web |date=November 2006 |title=ATK Composite and Propulsion Technologies Help Launch Defense Weather Satellite |work=ATK |url=http://atk.mediaroom.com/index.php?s=25280&item=57724 |publisher=Alliant Techsystems}}</ref><ref>{{Cite web |date=November 2007 |title=ATK Propulsion Technologies Help Launch Boeing's Delta IV Heavy Rocket |url=http://www.atk.com/news-releases/atk-propulsion-technologies-help-launch-boeings-delta-iv-heavy-rocket/ |publisher=Alliant Techsystems}}</ref>

=== Launch sites ===
[[File:Delta IV Heavy rocket on launch pad.jpg|thumb|270px|First Delta IV Heavy with three [[Common Booster Core|CBCs]] prior to launch]]

Delta IV launched from either of two rocket [[Launch pad|launch complexes]]. Launches on the East coast of the United States used [[Cape Canaveral Space Launch Complex 37|Space Launch Complex 37]] (SLC-37) at the [[Cape Canaveral Air Force Station]]. On the West coast, polar-orbit and high-inclination launches used [[Vandenberg Space Force Base]]'s [[Vandenberg Space Launch Complex 6|Space Launch Complex 6]] (SLC-6).<ref name=DeltaIVLaunchFac/>

Launch facilities at both sites are similar. A [[Horizontal integration facility|Horizontal Integration Facility]] (HIF) is situated some distance from the pad. Delta IV CBCs and second stages to be mated and tested in the HIF before they are moved to the pad.<ref name=DeltaIVLaunchFac/> The partial horizontal rocket assembly of the Delta IV is somewhat similar to the [[Soyuz (rocket family)|Soyuz launch vehicle]], which is completely assembled horizontally. The [[Space Shuttle]]s, the past [[Saturn (rocket family)|Saturn launch vehicles]], and the [[Space Launch System]] are assembled and rolled out to the launch pad entirely vertically.{{citation_needed|date=August 2019}}

Movement of the Delta IVs among the various facilities at the pad was facilitated by rubber-tired Elevating Platform Transporters (EPTs) and various transport jigs. [[Diesel engine]] EPTs are used for moving the vehicles from the HIF to the pad, while electric EPTs are used in the HIF, where precision of movement is important.<ref name="DeltaIVLaunchFac">[http://www.boeing.com/defense-space/space/delta/flo_facilities_delta_IV.htm Delta IV Launch Facilities] {{webarchive |url=https://web.archive.org/web/20060703004057/http://boeing.com/defense-space/space/delta/flo_facilities_delta_IV.htm |date=2006-07-03}}</ref>

The basic launchpad structure includes a flame trench to direct the engine plume away from the rocket, lightning protection, and propellant storage. In the case of Delta IV, the vehicle was completed on the launch pad inside a building. This [[Service structure|Mobile Service Tower]] (MST) provides service access to the rocket and protection from the weather and is rolled away from the rocket on launch day. A crane at the top of the MST lifts the encapsulated payload to the vehicle and also attached the GEM 60 solid motors for Delta IV Medium launches. The MST is rolled away from the rocket several hours before launch. At Vandenberg, the launch pad also has a Mobile Assembly Shelter (MAS), which completely encloses the vehicle; at CCAFS, the vehicle is partly exposed near its bottom.<ref name=DeltaIVLaunchFac/>

Beside the vehicle is a Fixed Umbilical Tower (FUT), which has two (VSFB) or three (CCAFS) swing arms. These arms carry telemetry signals, electrical power, [[hydraulic]] fluid, environmental control air flow, and other support functions to the vehicle through umbilical lines. The swing arms retract at T-0 seconds once the vehicle is committed to launch.<ref name=DeltaIVLaunchFac/>

Under the vehicle is a Launch Table, with six Tail Service Masts (TSMs), two for each CBC. The Launch Table supports the vehicle on the pad, and the TSMs provide further support and fueling functions for the CBCs. The vehicle is mounted to the Launch Table by a Launch Mate Unit (LMU), which is attached to the vehicle by bolts that sever at launch. Behind the Launch Table is a Fixed Pad Erector (FPE), which used two long-stroke hydraulic pistons to raise the vehicle to the vertical position after being rolled to the pad from the HIF. Beneath the Launch Table is a flame duct, which deflects the rocket's exhaust away from the rocket or facilities.<ref name=DeltaIVLaunchFac/>

=== Vehicle processing ===
Delta IV CBCs and DCSSs are assembled at ULA's factory in [[Decatur, Alabama]]. They are then loaded onto the [[RS RocketShip|R/S ''RocketShip'']], a [[roll-on/roll-off]] cargo [[ship|vessel]], and shipped to either launch pad. There, they are offloaded and rolled into a HIF. For Delta IV Medium launches, the CBC and DCSS were mated in the HIF. For Delta IV Heavy launches, the port and starboard strap-on CBCs are also mated in the HIF.<ref name=DeltaIVassembly/>

Various tests are performed, and then the vehicle is rolled horizontally to the pad, where the Fixed Pad Erector (FPE) is used to raise the vehicle to the vertical position. At this time, the GEM 60 solid motors, if any are required, are rolled to the pad and attached to the vehicle. After further testing, the payload (which has already been enclosed in its fairing) is transported to the pad, hoisted into the MST by a crane, and attached to the vehicle. Finally, on launch day, the MST is rolled away from the vehicle, and the vehicle is ready for launch.<ref name="DeltaIVassembly">{{Cite web |date=December 1, 2004 |title=Delta IV prelaunch assembly |url=http://www.spaceflightnow.com/delta/d310/041201prelaunch.html |publisher=Spaceflight Now}}</ref>

== Launch history ==
{{clear left}}

{| class="wikitable sortable collapsible" style="margin: 1em 1em 1em 0";
! No.
! Date/Time<br/>([[UTC]])
! Type
! Serial no.
! Start place
! Payload
! Payload type
! Orbit
! Outcome
! Remarks
|-
| 1
| 20 November 2002<br/>22:39
| Medium+ (4,2)
| 293
| [[Cape Canaveral Air Force Station|CCAFS]], [[Cape Canaveral Space Launch Complex 37|SLC-37B]]
| [[Eutelsat 33B|Eutelsat W5]]
| Commercial [[communications satellite]]
| [[Geostationary transfer orbit|GTO]]
| {{Success}}
| First Delta IV launch.
|-
| 2
| 2003-03-11<br/>00:59
| Medium
| 296
| [[Cape Canaveral Air Force Station|CCAFS]], [[Cape Canaveral Space Launch Complex 37|SLC-37B]]
| USA-167 ([[Defense Satellite Communications System|DSCS-3 A3]])
| Military communications satellite
| GTO
| {{Success}}
| First Delta IV Medium launch.<br/>First USAF EELV mission
|-
| 3
| 2003-08-29<br/>23:13
| Medium
| 301
| [[Cape Canaveral Air Force Station|CCAFS]], [[Cape Canaveral Space Launch Complex 37|SLC-37B]]
| USA-170 ([[Defense Satellite Communications System|DSCS-3 B6]])
| Military communications satellite
| GTO
| {{Success}}
|
|-
| 4
| 2004-12-21<br/>21:50
| Heavy
| 310
| [[Cape Canaveral Air Force Station|CCAFS]], [[Cape Canaveral Space Launch Complex 37|SLC-37B]]
| [[DemoSat]]<ref>{{Cite web |date=2004-12-01 |title=The DemoSat payload |url=http://spaceflightnow.com/delta/d310/041201demosat.html |publisher=Spaceflight Now}}</ref> / [[3CS-1]] / [[3CS-2]]
| Demonstration payload
| [[Geosynchronous orbit|GSO]] (planned)
| {{Partial failure}}
|
* First Delta IV Heavy launch.
* Premature cutoff of CBCs.
* DemoSat reached incorrect orbit, [[3 Corner Satellite]] (3CS) failed to reach orbit.<ref>{{Cite web |last=Justin Ray |date=December 22, 2004 |title=Delta 4-Heavy hits snag on test flight |url=http://www.spaceflightnow.com/delta/d310/ |access-date=December 12, 2010 |publisher=Spaceflight Now}}</ref><ref>{{Cite web |last=Justin Ray |date=December 22, 2004 |title=Air Force says plenty of good came from Delta 4 test |url=http://www.spaceflightnow.com/delta/d310/041222update.html |access-date=December 12, 2010 |publisher=Spaceflight Now}}</ref>
|-
| 5
| 2006-05-24<br/>22:11
| Medium+ (4,2)
| 315
| [[Cape Canaveral Air Force Station|CCAFS]], [[Cape Canaveral Space Launch Complex 37|SLC-37B]]
| [[GOES 13]] (GOES-N)
| Weather satellite
| GTO
| {{Success}}
|
|-
| 6
| 2006-06-28<br/>03:33
| Medium+ (4,2)
| 317
| [[Vandenberg Air Force Base|VAFB]], [[Vandenberg AFB Space Launch Complex 6|SLC-6]]
| USA-184 ([[List of NRO launches|NROL-22]])
| [[Spy satellite|Reconnaissance satellite]]
| [[Molniya orbit|Molniya]]
| {{Success}}
| First Delta IV launch from Vandenberg.<ref>{{Cite web |last=Justin Ray |date=June 27, 2006 |title=New era of rocket launches begins at California base |url=http://www.spaceflightnow.com/delta/d317/ |access-date=December 12, 2010 |publisher=Spaceflight Now}}</ref>
|-
| 7
| 2006-11-04<br/>13:53
| Medium
| 320
| [[Vandenberg Air Force Base|VAFB]], [[Vandenberg Space Launch Complex 6|SLC-6]]
| USA-192 ([[Defense Meteorological Satellite Program|DMSP F17]])
| Military weather satellite
| [[Sun-synchronous orbit|SSO]]
| {{Success}}
| First Delta IV launch into a [[Low Earth orbit|LEO]]/SSO, last flight of Delta IV Medium.
|-
| 8
| 2007-11-11<br/>01:50
| Heavy
| 329
| [[Cape Canaveral Air Force Station|CCAFS]], [[Cape Canaveral Space Launch Complex 37|SLC-37B]]
| USA-197 ([[Defense Support Program|DSP-23]])
| Missile warning satellite
| GSO
| {{Success}}
| First Delta IV launch contracted by United Launch Alliance.<br/>Launch delayed due to damage to launch pad caused by a liquid oxygen leak.<ref>{{Cite web |last=Covault |first=Craig |date=March 9, 2007 |title=Delta Pad Damage Assessed After Fuel Leak |url=http://www.aviationweek.com/aw/generic/story.jsp?id=news/DELTA03097.xml&channel=space |url-status=dead |archive-url=https://web.archive.org/web/20070929092828/http://www.aviationweek.com/aw/generic/story.jsp?id=news%2FDELTA03097.xml&channel=space |archive-date=29 September 2007 |access-date=24 November 2009 |publisher=Aviation Week}}</ref>
|-
| 9
| 2009-01-18<br/>02:47<ref name="spaceflightnow_schedule">{{Cite web |title=Tracking Station - Worldwide launch schedule |url=http://www.spaceflightnow.com/tracking/index.html |url-status=dead |archive-url=https://web.archive.org/web/20130811033415/http://www.spaceflightnow.com/tracking/index.html |archive-date=2013-08-11 |access-date=2008-10-13 |publisher=Spaceflight Now}}</ref><ref name="MSDB">{{Cite web |last=Schaub |first=Michael B. |title=Mission Set Database |url=http://msdb.gsfc.nasa.gov/launches.php |url-status=dead |archive-url=https://web.archive.org/web/20090320221234/http://msdb.gsfc.nasa.gov/launches.php |archive-date=2009-03-20 |access-date=2008-10-13 |publisher=NASA GSFC/Honeywell TSI}} {{PD-notice}}</ref>
| Heavy
| 337
| [[Cape Canaveral Air Force Station|CCAFS]], [[Cape Canaveral Space Launch Complex 37|SLC-37B]]
| [[USA-202]] ([[List of NRO launches|NROL-26]])
| Reconnaissance satellite
| GSO
| {{Success}}<ref>{{Cite web |date=January 17, 2009 |title=First ULA Delta IV Heavy NRO Mission Successfully Lifts Off From Cape Canaveral |url=http://www.ulalaunch.com/site/pages/News.shtml#/29 |url-status=dead |archive-url=https://web.archive.org/web/20131207160150/http://www.ulalaunch.com/site/pages/News.shtml#/29 |archive-date=December 7, 2013 |access-date=December 12, 2010 |publisher=United Launch Alliance}}</ref>
|
|-
| 10
| 2009-06-27<br/>22:51<ref>{{Cite web |last=Harwood |first=William |date=June 27, 2009 |title=Delta 4 deploys an advanced weather observatory |url=http://www.spaceflightnow.com/delta/d342/ |publisher=Spaceflight Now}}</ref>
| Medium+ (4,2)
| 342
| [[Cape Canaveral Air Force Station|CCAFS]], [[Cape Canaveral Space Launch Complex 37|SLC-37B]]
| [[GOES 14]] (GOES-O)
| Weather satellite
| GTO
| {{Success}}<ref>{{Cite press release |title=NASA and NOAA's GOES-O Satellite Successfully Launched |date=June 27, 2009 |publisher=NASA KSC |url=http://www.nasa.gov/centers/kennedy/news/releases/2009/release-20090627.html |access-date=24 November 2009 |url-status=dead |archive-url=https://web.archive.org/web/20090629053451/http://www.nasa.gov/centers/kennedy/news/releases/2009/release-20090627.html |archive-date=29 June 2009}} {{PD-notice}}</ref>
|
|-
| 11
| 2009-12-06<br/>01:47<ref name="WGS-3">{{Cite web |last=Ray |first=Justin |date=2009-12-05 |title=New communications craft launched for U.S. military |url=http://www.spaceflightnow.com/delta/d346/ |access-date=2009-12-06 |publisher=Spaceflight Now}}</ref>
| Medium+ (5,4)
| 346
| [[Cape Canaveral Air Force Station|CCAFS]], [[Cape Canaveral Space Launch Complex 37|SLC-37B]]
| USA-211 ([[Wideband Global SATCOM|WGS-3]])
| Military communications satellite
| [[Geosynchronous Transfer Orbit|GTO]]
| {{Success}}<ref name="WGS-3" />
| First Delta IV Medium+ (5,4) launch.
|-
| 12
| 2010-03-04<br/>23:57
| Medium+ (4,2)
| 348
| [[Cape Canaveral Air Force Station|CCAFS]], [[Cape Canaveral Space Launch Complex 37|SLC-37B]]
| [[GOES 15]] (GOES-P)
| Weather satellite
| GTO
| {{Success}}<ref>{{Cite web |date=2010-03-04 |title=Teaming of Delta 4 rocket and GOES a sweet success |url=http://www.spaceflightnow.com/delta/d348/ |publisher=Spaceflight Now}}</ref>
|
|-
| 13
| 2010-05-28<br/>03:00
| Medium+ (4,2)
| 349
| [[Cape Canaveral Air Force Station|CCAFS]], [[Cape Canaveral Space Launch Complex 37|SLC-37B]]
| [[USA-213]] ([[GPS Block IIF|GPS IIF-1]])
| Navigation Satellite
| [[Medium Earth orbit|MEO]]
| {{Success}}<ref name="d349">{{Cite web |date=2010-05-28 |title=First-of-its-kind satellite for GPS launched into space |url=http://spaceflightnow.com/delta/d349/ |publisher=Spaceflight Now}}</ref>
|
|-
| 14
| 2010-11-21<br/>22:58<ref name=spaceflightnow_schedule/>
| Heavy
| 351
| [[Cape Canaveral Air Force Station|CCAFS]], [[Cape Canaveral Space Launch Complex 37|SLC-37B]]
| [[USA-223]] ([[List of NRO launches|NROL-32]])
| Reconnaissance satellite
| GSO
| {{Success}}<ref>{{Cite web |date=22 November 2010 |title=Huge rocket launches secret U.S. spy satellite |url=https://www.nbcnews.com/id/wbna40308294 |access-date=22 November 2010 |website=NBC News}}</ref>
|
|-
| 15
| 2011-01-20<br/>21:10
| Heavy
| 352
| [[Vandenberg Air Force Base|VAFB]], [[Vandenberg Space Launch Complex 6|SLC-6]]
| [[USA-224]] ([[List of NRO launches|NROL-49]])
| Reconnaissance satellite
| [[Low Earth Orbit|LEO]]
| {{Success}}<ref name="d352">{{Cite web |date=20 January 2011 |title=United Launch Alliance Launches First West Coast Delta IV Heavy Mission |url=http://www.ulalaunch.com/site/pages/News.shtml#/63 |url-status=dead |archive-url=https://web.archive.org/web/20131207160150/http://www.ulalaunch.com/site/pages/News.shtml#/63 |archive-date=7 December 2013 |access-date=21 January 2011 |publisher=United Launch Alliance}}</ref>
| First Delta IV Heavy launch from Vandenberg.<ref name=d352/>

|-
| 16
| 2011-03-11<br/>23:38<ref name=spaceflightnow_schedule/>
| Medium+ (4,2)
| 353
| [[Cape Canaveral Air Force Station|CCAFS]], [[Cape Canaveral Space Launch Complex 37|SLC-37B]]
| [[USA-227]] ([[List of NRO launches|NROL-27]])
| Reconnaissance satellite
| GTO
| {{Success}}<ref>{{Cite web |date=11 March 2011 |title=ULA Successfully launches Fourth NRO mission in Six months |url=http://www.ulalaunch.com/site/pages/News.shtml#/67/ |url-status=dead |archive-url=https://web.archive.org/web/20131207160150/http://www.ulalaunch.com/site/pages/News.shtml#/67/ |archive-date=7 December 2013 |access-date=12 March 2011 |publisher=United Launch Alliance}}</ref>
|
|-
| 17
| 2011-07-16<br/>06:41
| Medium+ (4,2)
| 355
| [[Cape Canaveral Air Force Station|CCAFS]], [[Cape Canaveral Space Launch Complex 37|SLC-37B]]
| [[USA-232]] ([[GPS Block IIF|GPS IIF-2]])
| Navigation Satellite
| MEO
| {{Success}}<ref>{{Cite web |date=16 July 2011 |title=United Launch Alliance Marks the 50th Successful GPS Launch for the Air Force with the Delivery of the GPS IIF-2 Mission to orbit |url=http://www.ulalaunch.com/site/pages/News.shtml#/73/ |url-status=dead |archive-url=https://web.archive.org/web/20131207160150/http://www.ulalaunch.com/site/pages/News.shtml#/73/ |archive-date=7 December 2013 |access-date=16 July 2011 |publisher=United Launch Alliance}}</ref>
|
|-
| 18
| 2012-01-20<br/>00:38
| Medium+ (5,4)
| 358
| [[Cape Canaveral Air Force Station|CCAFS]], [[Cape Canaveral Space Launch Complex 37|SLC-37B]]
| USA-233 ([[Wideband Global SATCOM|WGS-4]])
| Military communications satellite
| GTO
| {{Success}}
|
|-
| 19
| 2012-04-03<br/>23:12
| Medium+ (5,2)
| 359
| [[Vandenberg Air Force Base|VAFB]], [[Vandenberg Space Launch Complex 6|SLC-6]]
| [[USA-234]] ([[List of NRO launches|NROL-25]])
| Reconnaissance satellite
| LEO
| {{Success}}
| First flight in the Medium+ (5,2) version.
|-
| 20
| 2012-06-29<br/>13:15
| Heavy
| 360
| [[Cape Canaveral Air Force Station|CCAFS]], [[Cape Canaveral Space Launch Complex 37|SLC-37B]]
| [[USA-237]] ([[List of NRO launches|NROL-15]])
| Reconnaissance satellite
| [[Geosynchronous orbit|GSO]]
| {{Success}}
| First flight of the RS-68A engine.<ref name="ULA-PR-Jun12" />
|-
| 21
| 2012-10-04<br/>12:10
| Medium+ (4,2)
| 361
| [[Cape Canaveral Air Force Station|CCAFS]], [[Cape Canaveral Space Launch Complex 37|SLC-37B]]
| [[USA-239]] ([[GPS Block IIF|GPS IIF-3]])
| Navigation Satellite
| MEO
| {{Success}}<ref>{{Cite web |date=October 4, 2012 |title=Delta IV GPS IIIF-3 |url=http://www.spaceflight101.com/delta-iv-gps-iif-3-launch-updates.html |url-status=dead |archive-url=https://web.archive.org/web/20140715011938/http://www.spaceflight101.com/delta-iv-gps-iif-3-launch-updates.html |archive-date=July 15, 2014 |access-date=July 14, 2014 |website=Spaceflight 101}}</ref> 
| Upper stage ([[Delta Cryogenic Second Stage|DCSS]]) anomaly caused by fuel leak, payload still reached planned orbit.<ref>{{Cite web |date=December 7, 2012 |title=Atlas V green light after RL-10 is exonerated during Delta IV anomaly review |url=http://www.nasaspaceflight.com/2012/12/atlas-v-green-light-rl-10-exonerated-delta-iv-review/ |access-date=July 14, 2014 |publisher=NASASpaceflight.com}}</ref>
|-
| 22
| 2013-05-25<br/>00:27
| Medium+ (5,4)
| 362
| [[Cape Canaveral Air Force Station|CCAFS]], [[Cape Canaveral Space Launch Complex 37|SLC-37B]]
| [[USA-243]] ([[Wideband Global SATCOM|WGS-5]])
| Military communications satellite
| GTO
| {{Success}}<ref>{{Cite web |date=24 May 2013 |title=United Launch Alliance Launches Second Successful Mission for U.S. Air Force in Just Nine Days |url=http://www.ulalaunch.com/site/pages/News.shtml#/141/ |url-status=dead |archive-url=https://web.archive.org/web/20131207160150/http://www.ulalaunch.com/site/pages/News.shtml#/141/ |archive-date=7 December 2013 |access-date=25 May 2013 |publisher=United Launch Alliance}}</ref>
|
|-
| 23
| 2013-08-08<br/>00:29
| Medium+ (5,4)
| 363
| [[Cape Canaveral Air Force Station|CCAFS]], [[Cape Canaveral Space Launch Complex 37|SLC-37B]]
| [[USA-244]] ([[Wideband Global SATCOM|WGS-6]])
| Military communications satellite
| GTO
| {{Success}}<ref>{{Cite web |date=8 August 2013 |title=United Launch Alliance Successfully Launches Second Wideband Global SATCOM mission for U.S. Air Force in Less Than Three Months |url=http://www.ulalaunch.com/site/pages/News.shtml#/150/ |url-status=dead |archive-url=https://web.archive.org/web/20131207160150/http://www.ulalaunch.com/site/pages/News.shtml#/150/ |archive-date=7 December 2013 |access-date=8 August 2013 |publisher=United Launch Alliance}}</ref>
|
|-
| 24
| 2013-08-28<br/>18:03
| Heavy
| 364
| [[Vandenberg Air Force Base|VAFB]], [[Vandenberg Space Launch Complex 6|SLC-6]]
| [[USA-245]] ([[List of NRO launches|NROL-65]])
| Reconnaissance satellite
| LEO
| {{Success}}<ref>{{Cite web |date=28 August 2013 |title=National Reconnaissance Office Mission Successfully Launches on World's Largest Rocket, the Unite Launch Alliance Delta IV Heavy |url=http://www.ulalaunch.com/site/pages/News.shtml#/152/ |url-status=dead |archive-url=https://web.archive.org/web/20131207160150/http://www.ulalaunch.com/site/pages/News.shtml#/152/ |archive-date=7 December 2013 |access-date=29 August 2013 |publisher=United Launch Alliance}}</ref>
|
|-
| 25
| 2014-02-21<br/>01:59
| Medium+ (4,2)
| 365
| [[Cape Canaveral Air Force Station|CCAFS]], [[Cape Canaveral Space Launch Complex 37|SLC-37B]]
| [[USA-248]] ([[GPS Block IIF|GPS IIF-5]])
| Navigation Satellite
| MEO
| {{Success}}<ref>{{Cite web |date=20 February 2014 |title=United Launch Alliance Successfully Launches 25th Delta IV Mission Carrying Global Positioning System Satellite for the U.S. Air Force |url=http://www.ulalaunch.com/site/pages/News.shtml#/167/ |url-status=dead |archive-url=https://web.archive.org/web/20131207160150/http://www.ulalaunch.com/site/pages/News.shtml#/167/ |archive-date=7 December 2013 |access-date=21 February 2014 |publisher=United Launch Alliance}}</ref>
|
|-
| 26
| 2014-05-17<br/>00:03
| Medium+ (4,2)
| 366
| [[Cape Canaveral Air Force Station|CCAFS]], [[Cape Canaveral Space Launch Complex 37|SLC-37B]]
| [[USA-251]] ([[GPS Block IIF|GPS IIF-6]])
| Navigation Satellite
| MEO
| {{Success}}<ref>{{Cite web |date=16 May 2014 |title=United Launch Alliance Successfully Launches Second Global Positioning System Satellite for the U.S. Air Force in Less Than Three Months |url=http://www.ulalaunch.com/ula-successfully-launches-second-global.aspx?title=United+Launch+Alliance+Successfully+Launches+Second+Global+Positioning+System+Satellite+for+the+U.S.+Air+Force+in+Less+Than+Three+Months |url-status=dead |archive-url=https://web.archive.org/web/20140517151604/http://www.ulalaunch.com/ula-successfully-launches-second-global.aspx?title=United+Launch+Alliance+Successfully+Launches+Second+Global+Positioning+System+Satellite+for+the+U.S.+Air+Force+in+Less+Than+Three+Months |archive-date=17 May 2014 |access-date=17 May 2014 |publisher=United Launch Alliance}}</ref>
|
|-
| 27
| 2014-07-28<br/>23:28
| Medium+ (4,2)
| 368
| [[Cape Canaveral Air Force Station|CCAFS]], [[Cape Canaveral Space Launch Complex 37|SLC-37B]]
| [[Air Force Space Command|AFSPC-4]] ([[Space Based Space Surveillance|GSSAP]] #1/2 and [[Autonomous Nanosatellite Guardian for Evaluating Local Space|ANGELS]]) (USA-253/254/255)
| Space surveillance and technology demonstrator
| GEO
| {{Success}}<ref>{{Cite web |date=29 July 2014 |title=United Launch Alliance Marks 85th Successful Launch by Delivering Three Satellites into Orbit for the U.S. Air Force |url=http://www.ulalaunch.com/ULA-Delta-IV-Launches-AFSPC-4.aspx?title=United+Launch+Alliance+Marks+85th+Successful+Launch+by+Delivering+Three+Satellites+into+Orbit+for+the+U.S.+Air+Force+ |url-status=dead |archive-url=https://web.archive.org/web/20140805021058/http://www.ulalaunch.com/ULA-Delta-IV-Launches-AFSPC-4.aspx?title=United+Launch+Alliance+Marks+85th+Successful+Launch+by+Delivering+Three+Satellites+into+Orbit+for+the+U.S.+Air+Force+ |archive-date=5 August 2014 |access-date=29 July 2014 |publisher=United Launch Alliance}}</ref>
| First use of secondary payload adapter on a Delta rocket.
|-
| 28
| 2014-12-05<br/>12:05
| Heavy
| 369
| [[Cape Canaveral Air Force Station|CCAFS]], [[Cape Canaveral Space Launch Complex 37|SLC-37B]]
| [[Orion (spacecraft)|Orion MPCV]] [[Exploration Flight Test-1|EFT-1]]
| Uncrewed Capsule Test Flight
| MEO
| {{Success}}<ref>{{Cite web |date=6 December 2014 |title=United Launch Alliance Successfully Launches NASA's Orion Spacecraft on Critical Flight Test for Lockheed Martin |url=http://www.ulalaunch.com/ula-successfully-launches-orion.aspx?title=United+Launch+Alliance+Successfully+Launches+NASA%e2%80%99s+Orion+Spacecraft+on+Critical+Flight+Test+for+Lockheed+Martin |url-status=dead |archive-url=https://web.archive.org/web/20141208035358/http://www.ulalaunch.com/ula-successfully-launches-orion.aspx?title=United+Launch+Alliance+Successfully+Launches+NASA%e2%80%99s+Orion+Spacecraft+on+Critical+Flight+Test+for+Lockheed+Martin |archive-date=8 December 2014 |access-date=5 December 2014 |publisher=United Launch Alliance}}</ref>
|
|-
| 29
| 2015-03-25<br/>18:36
| Medium+ (4,2)
| 371
| [[Cape Canaveral Air Force Station|CCAFS]], [[Cape Canaveral Space Launch Complex 37|SLC-37B]]
| [[USA-260]] ([[GPS Block IIF|GPS IIF-9]])
| Navigation Satellite
| MEO
| {{Success}}<ref>{{Cite web |date=26 March 2015 |title=United Launch Alliance Successfully Launches Second Mission in Less than Two Weeks |url=http://www.ulalaunch.com/ula-launches-gpsiif9-for-US-Air-Force.aspx?title=United+Launch+Alliance+Successfully+Launches+Second+Mission+in+Less+than+Two+Weeks |url-status=dead |archive-url=https://web.archive.org/web/20180112160114/http://www.ulalaunch.com/ula-launches-gpsiif9-for-US-Air-Force.aspx?title=United+Launch+Alliance+Successfully+Launches+Second+Mission+in+Less+than+Two+Weeks |archive-date=12 January 2018 |access-date=26 March 2015 |publisher=United Launch Alliance}}</ref>
| Final launch with baseline [[RS-68]] engine.<ref name="Spaceflight Now" />
|-
| 30
| 2015-07-24<br/>00:07
| Medium+ (5,4)
| 372
| [[Cape Canaveral Air Force Station|CCAFS]], [[Cape Canaveral Space Launch Complex 37|SLC-37B]]
| [[USA-263]] ([[Wideband Global SATCOM|WGS-7]])
| Military communications satellite
| GTO
| {{Success}}<ref>{{Cite web |date=23 July 2015 |title=United Launch Alliance Successfully Launches WGS-7 |url=http://www.ulalaunch.com/ula-successfully-launches-wgs7.aspx |url-status=dead |archive-url=https://web.archive.org/web/20180112160116/http://www.ulalaunch.com/ula-successfully-launches-wgs7.aspx |archive-date=12 January 2018 |access-date=24 July 2015 |publisher=[[United Launch Alliance]]}}</ref>
|
|-
| 31
| 2016-02-10<br/>11:40
| Medium+ (5,2)
| 373
| [[Vandenberg Air Force Base|VAFB]], [[Vandenberg Space Launch Complex 6|SLC-6]]
| [[USA-267]] ([[List of NRO launches|NROL-45]])
| Reconnaissance satellite
| LEO
| {{Success}}<ref>{{Cite web |date=10 February 2016 |title=United Launch Alliance Successfully Launches NROL-45 Payload for the National Reconnaissance Office |url=http://www.ulalaunch.com/ula-successfully-launches-nrol45.aspx?title=United+Launch+Alliance+Successfully+Launches+NROL-45+Payload+for+the+National+Reconnaissance+Office&Category=1 |url-status=dead |archive-url=https://web.archive.org/web/20180112160138/http://www.ulalaunch.com/ula-successfully-launches-nrol45.aspx?title=United+Launch+Alliance+Successfully+Launches+NROL-45+Payload+for+the+National+Reconnaissance+Office&Category=1 |archive-date=12 January 2018 |access-date=29 March 2016 |publisher=United Launch Alliance}}</ref>
|
|-
| 32
| 2016-06-11<br/>17:51
| Heavy
| 374
| [[Cape Canaveral Air Force Station|CCAFS]], [[Cape Canaveral Space Launch Complex 37|SLC-37B]]
| [[USA-268]] ([[List of NRO launches|NROL-37]])
| Reconnaissance satellite
| GSO
| {{Success}}<ref>{{Cite web |date=11 June 2016 |title=United Launch Alliance Successfully Launches NROL-37 Payload for the National Reconnaissance Office |url=http://www.ulalaunch.com/ula-successfully-launches-nrol37.aspx |url-status=dead |archive-url=https://web.archive.org/web/20170629130523/http://www.ulalaunch.com/ula-successfully-launches-nrol37.aspx |archive-date=29 June 2017 |access-date=12 June 2016 |publisher=United Launch Alliance}}</ref><ref name="sfn-20160611">{{Cite news |last=Justin Ray |date=11 June 2016 |title=Triple-barrel Delta 4-Heavy launches national security satellite |url=http://spaceflightnow.com/2016/06/11/triple-barrel-delta-4-heavy-launches-national-security-satellite/ |access-date=12 June 2016 |publisher=Spaceflight Now}}</ref>
|
|-
| 33
| 2016-08-19<br/>04:52
| Medium+ (4,2)
| 375
| [[Cape Canaveral Air Force Station|CCAFS]], [[Cape Canaveral Space Launch Complex 37|SLC-37B]]
| [[Air Force Space Command Space Operations Squadron|AFSPC-6]] ([[Space Based Space Surveillance|GSSAP #3/4]]) (USA-270/271)
| Space surveillance
| GEO
| {{Success}}<ref>{{Cite web |date=19 August 2016 |title=United Launch Alliance Successfully Launches AFSPC-6 Mission for the U.S. Air Force |url=http://www.ulalaunch.com/ula-successfully-launches-afspc6.aspx?title=United+Launch+Alliance+Successfully+Launches+AFSPC-6+Mission+for+the+U.S.+Air+Force |url-status=dead |archive-url=https://web.archive.org/web/20180112160140/http://www.ulalaunch.com/ula-successfully-launches-afspc6.aspx?title=United+Launch+Alliance+Successfully+Launches+AFSPC-6+Mission+for+the+U.S.+Air+Force |archive-date=12 January 2018 |access-date=22 August 2016 |publisher=[[United Launch Alliance]]}}</ref>
|
|-
| 34
| 2016-12-07<br/>23:53
| Medium+ (5,4)
| 376
| [[Cape Canaveral Air Force Station|CCAFS]], [[Cape Canaveral Space Launch Complex 37|SLC-37B]]
| [[USA-272]] ([[Wideband Global SATCOM|WGS-8]])
| Military communications satellite
| GTO
| {{Success}}<ref>{{Cite web |date=7 December 2016 |title=United Launch Alliance Successfully Launches WGS-8 Mission for the U.S. Air Force |url=http://www.ulalaunch.com/ula-successfully-launches-wgs8.aspxtitle=United+Launch+Alliance+Successfully+Launches+WGS-8+Mission+for+the+U.S.+Air+Force |access-date=9 February 2017 |publisher=United Launch Alliance}}{{dead link|date=January 2018 |bot=InternetArchiveBot|fix-attempted=yes}}</ref>
|
|-
| 35
| 2017-03-19<br/>00:18
| Medium+ (5,4)
| 377
| [[Cape Canaveral Air Force Station|CCAFS]], [[Cape Canaveral Space Launch Complex 37|SLC-37B]]
| [[USA-275]] ([[Wideband Global SATCOM|WGS-9]])
| Military communications satellite
| GTO
| {{Success}}<ref>{{Cite web |date=18 March 2017 |title=United Launch Alliance Commemorates U.S. Air Force 70th Anniversary with Successful Launch of WGS-9 Mission |url=http://www.ulalaunch.com/ula-deltaiv-launches-wgs9.aspx |access-date=12 January 2017 |publisher=United Launch Alliance}}</ref>
|
|-
| 36
| 2018-01-12<br/>22:11
| Medium+ (5,2)
| 379
| [[Vandenberg Air Force Base|VAFB]], [[Vandenberg Space Launch Complex 6|SLC-6]]
| [[USA-281]] ([[List of NRO launches|NROL-47]])
| Reconnaissance satellite
| LEO
| {{Success}}<ref>{{Cite web |date=12 January 2018 |title=United Launch Alliance Successfully Launches NROL-47 Mission for the National Reconnaissance Office |url=http://www.ulalaunch.com/ula-successfully-launches-nrol47-mission.aspx |url-status=dead |archive-url=https://web.archive.org/web/20180113093321/http://www.ulalaunch.com/ula-successfully-launches-nrol47-mission.aspx |archive-date=2018-01-13 |access-date=12 January 2017 |website=United Launch Alliance}}</ref>
| Final flight of Delta IV M+ (5,2) variant.
|-
| 37
| 2018-08-12<br/>07:31
| Heavy
| 380
| [[Cape Canaveral Air Force Station|CCAFS]], [[Cape Canaveral Space Launch Complex 37|SLC-37B]]
| [[Parker Solar Probe]]
| Solar Probe
| Heliocentric
| {{Success}}
| First use of Delta IV Heavy with [[Star 48]]BV third stage (9255H).
|-
| 38
| 2019-01-19<br/>19:10
| Heavy
| 382
| [[Vandenberg Air Force Base|VAFB]], [[Vandenberg Space Launch Complex 6|SLC-6]]
| [[USA-290]] ([[List of NRO launches|NROL-71]])
| Reconnaissance satellite
| LEO
| {{Success}}
|
|-
| 39
| 2019-03-16<br/>00:26
| Medium+ (5,4)
| 383
| [[Cape Canaveral Air Force Station|CCAFS]], [[Cape Canaveral Space Launch Complex 37|SLC-37B]]
| [[USA-291]] ([[Wideband Global SATCOM|WGS-10]])
| Military communications satellite
| GTO
| {{Success}}
| Final flight of Delta IV M+ (5,4) variant.
|-
| 40
| 2019-08-22<br/>13:06
| Medium+ (4,2)
| 384
| [[Cape Canaveral Air Force Station|CCAFS]], [[Cape Canaveral Space Launch Complex 37|SLC-37B]]
| [[USA-293]] ([[GPS Block IIIA|GPS III-2]])
| Navigation Satellite
| MEO
| {{Success}}<ref name="nsf20190822">{{Cite web |last=Gebhardt |first=Chris |date=August 22, 2019 |title=Delta IV Medium's well-earned retirement with GPS finale |url=https://www.nasaspaceflight.com/2019/08/delta-iv-medium-retirement-gps-finale/ |access-date=August 22, 2019 |publisher=NASASpaceflight.com}}</ref>
| Final flight of the Delta IV Medium and the Delta IV M+ (4,2) variant.<ref name="nsf20190822" />
|-
| 41
| 2020-12-11<br/>01:09
| Heavy
| 385
| [[Cape Canaveral Space Force Station|CCSFS]], [[Cape Canaveral Space Launch Complex 37|SLC-37B]]
| [[USA-311]] ([[List of NRO launches|NROL-44]])
| Reconnaissance satellite
| GSO
| {{Success}}<ref>{{Cite web |last=Graham |first=William |date=10 December 2020 |title=ULA Delta IV Heavy successfully launches NROL-44 |url=https://www.nasaspaceflight.com/2020/12/ula-nrol-44-delta-iv-heavy/ |access-date=27 December 2020 |website=NASA Space Flight}}</ref>
|
|-
| 42
| 2021-04-26<br/>20:47
| Heavy
| 386
| [[Vandenberg Air Force Base|VAFB]], [[Vandenberg Space Launch Complex 6|SLC-6]]
| [[USA 314]] ([[List of NRO launches|NROL-82]])
| Reconnaissance satellite
| LEO
| {{Success}}<ref name="ula-nrol-82-post-launch">{{Cite web |title=United Launch Alliance Successfully Launches NROL-82 Mission to Support National Security |url=https://www.ulalaunch.com/about/news/2021/04/26/united-launch-alliance-successfully-launches-nrol-82-mission-to-support-national-security |access-date=26 April 2021 |website=ULA Launch}}</ref>
|
|-
| 43
| 2022-09-24<br/>22:25
| Heavy
| 387
| [[Vandenberg Air Force Base|VAFB]], [[Vandenberg Space Launch Complex 6|SLC-6]]
| [[USA 338]] ([[List of NRO launches|NROL-91]])
| Reconnaissance satellite
| LEO
| {{Success}}<ref name="ula-nrol-91-post-launch">{{Cite web |title=United Launch Alliance Successfully Launches National Security Mission with Nation's Proven Heavy Lift Vehicle |url=https://www.ulalaunch.com/about/news-detail/2022/09/25/united-launch-alliance-successfully-launches-national-security-mission-with-nation-s-proven-heavy-lift-vehicle |access-date=25 September 2022 |website=United Launch Alliance}}</ref>
| Final flight of Delta IV from [[Vandenberg Space Force Base|VSFB]]
|-
| 44
| 2023-06-22<br/>09:18
| Heavy
| 388
| [[Cape Canaveral Space Force Station|CCSFS]], [[Cape Canaveral Space Launch Complex 37|SLC-37B]]
| [[USA-345]] ([[List of NRO launches|NROL-68]])
| Reconnaissance satellite
| GSO
| {{Success}}<ref name="ula-nrol-68-post-launch">{{Cite web |title=United Launch Alliance Successfully Launches the Penultimate Delta IV Heavy Rocket |url=https://www.ulalaunch.com/about/news-detail/2023/06/22/united-launch-alliance-successfully-launches-the-penultimate-delta-iv-heavy-rocket |access-date=22 June 2023 |website=United Launch Alliance}}</ref>
|
|-
| 45
| 2024-04-09<br/>16:53
| Heavy
| 389
| [[Cape Canaveral Space Force Station|CCSFS]], [[Cape Canaveral Space Launch Complex 37|SLC-37B]]
| [[USA-353]] ([[List of NRO launches|NROL-70]])
| Reconnaissance satellite
| GSO
| {{Success}}<ref name="ula-nrol-70-post-launch">{{Cite web |title=Marking the End of an Era, United Launch Alliance Successfully Launches Final Delta IV Heavy Rocket |url=https://www.ulalaunch.com/about/news-detail/2024/04/09/marking-the-end-of-an-era-united-launch-alliance-successfully-launches-final-delta-iv-heavy-rocket |access-date=9 April 2024 |website=United Launch Alliance}}</ref>
| Final flight of the Delta IV rocket and of the whole [[Delta (rocket family)|Delta rocket family]].
|-
|}
=== Delta family launches by decade ===
* [[List of Thor and Delta launches (2000–2009)]]
* [[List of Thor and Delta launches (2010–2019)]]
* [[List of Thor and Delta launches (2020–2024)]]

=== Delta IV launches by configuration ===
* [[List of Delta IV launches]] (all variants, Medium and Heavy)
** [[List of Delta IV Medium launches]]
** [[List of Delta IV Heavy launches]]

=== Notable launches ===
[[File:Delta IV Medium 4,2+ launch with GOES-N.jpg|thumb|270px|GOES-N launch on a Medium+ (4,2)]]
[[File:Delta IV Medium+ (4,2) NROL-22 launch 1.jpg|thumb|270px|A unique aerial view of NROL-22 launch from SLC-6]]

The first payload launched with a Delta IV was the ''[[Eutelsat 33B|Eutelsat W5]]'' communications satellite. A Medium+ (4,2) from Cape Canaveral carried the communications satellite into [[geostationary transfer orbit]] (GTO) on 20 November 2002.{{citation_needed|date=August 2019}}

''Heavy Demo'' was the first launch of the Delta IV Heavy in December 2004 after significant delays due to bad weather. Due to [[cavitation]] in the propellant lines, sensors on all three CBCs registered depletion of propellant. The strap-on CBCs and then core CBC engines shut down prematurely, even though sufficient propellant remained to continue the burn as scheduled. The second stage attempted to compensate for the shutdown and burned until it ran out of propellant. This flight was a test launch carrying a payload of:
*''DemoSat'' {{spaced ndash}} 6020&nbsp;kg; an aluminum cylinder filled with 60 brass rods {{spaced ndash}} planned to be carried to GEO; however due to the sensor faults, the satellite did not reach this orbit.
*''NanoSat-2'', carried to [[low Earth orbit]] (LEO) {{spaced ndash}} a set of two very small satellites of 24 and 21&nbsp;kg, nicknamed ''Sparky'' and ''Ralphie'' {{spaced ndash}} planned to orbit for one day. Given the under-burn, the two most likely did not reach a stable orbit.<ref>{{Cite web |title=Delta 4-Heavy mission report |url=http://spaceflightnow.com/delta/d4h.html |publisher=Spaceflight Now}}</ref>

''NROL-22'' was the first Delta IV launched from [[Vandenberg Space Launch Complex 6|SLC-6]] at [[Vandenberg Space Force Base]] (VSFB). It was launched aboard a Medium+ (4,2) in June 2006 carrying a classified satellite for the U.S. [[National Reconnaissance Office]] (NRO).

''DSP-23'' was the first launch of a valuable payload aboard a Delta IV Heavy. This was also the first Delta IV launch contracted by the [[United Launch Alliance]], a joint venture between Boeing and [[Lockheed Martin]]. The main payload was the 23rd and final [[Defense Support Program]] missile-warning satellite, [[Defense Support Program|DSP-23]]. Launch from Cape Canaveral occurred on 10 November 2007.<ref>{{Cite web |last=Justin Ray |date=2007-11-11 |title=Delta 4-Heavy rocket fires away from Cape Canaveral |url=http://www.spaceflightnow.com/delta/d329/index.html |access-date=2008-05-28 |publisher=Spaceflight Now}}</ref>

''NROL-26'' was the first Delta IV Heavy EELV launch for the NRO. [[USA 202]], a classified [[reconnaissance satellite]], lifted off 18 January 2009.<ref>{{Cite press release |title=First ULA Delta IV Heavy NRO Mission Successfully Lifts Off From Cape Canaveral |date=January 17, 2009 |publisher=ULA |url=http://news.prnewswire.com/DisplayReleaseContent.aspx?ACCT=104&STORY=/www/story/01-17-2009/0004956494 |url-status=dead |archive-url=https://web.archive.org/web/20090216180905/http://news.prnewswire.com/DisplayReleaseContent.aspx?ACCT=104&STORY=%2Fwww%2Fstory%2F01-17-2009%2F0004956494 |archive-date=February 16, 2009}}</ref>

''[[NROL-32]]'' was a Delta IV Heavy launch, carrying a satellite for NRO. The payload is speculated to be the largest satellite sent into space. After a delay from 19 October 2010, the rocket lifted off on 21 November 2010.<ref>{{Cite web |date=2010-11-22 |title="Eavesdropper" satellite rides huge rocket from Florida: The US National Reconnaissance Office has launched what is reputed to be the largest satellite ever sent into space |url=https://www.bbc.co.uk/news/science-environment-11809457 |publisher=BBC}}</ref>

''NROL-49'' lifted off from Vandenberg AFB on 20 January 2011.<ref name="spaceflightnow_schedule" /> It was the first Delta IV Heavy mission to be launched out of Vandenberg. This mission was for the NRO and its details are classified.<ref>{{Cite web |last=Justin Ray |date=January 16, 2009 |title=Delta 337 Mission Status Center |url=http://www.spaceflightnow.com/delta/d337/status.html |publisher=Spaceflight Now}}</ref>

On 4 October 2012, a Delta IV M+ (4,2) experienced an anomaly in the upper stage's [[RL10|RL10B-2]] engine which resulted in lower than expected thrust. While the vehicle had sufficient fuel margins to successfully place the payload, a GPS Block IIF satellite [[USA-239]], into its targeted orbit, investigation into the glitch delayed subsequent Delta IV launches and the next Atlas V launch (AV-034) due to commonality between the engines used on both vehicles' upper stages.<ref>{{Cite web |last=Bergin |first=Chris |date=8 December 2012 |title=Home Forums L2 Sign Up ISS Commercial Shuttle SLS/Orion Russian European Chinese Unmanned Other Atlas V green light after RL-10 is exonerated during Delta IV anomaly review |url=http://www.nasaspaceflight.com/2012/12/atlas-v-green-light-rl-10-exonerated-delta-iv-review/ |access-date=December 9, 2014 |publisher=NASASpaceflight.com}}</ref> By December 2012, ULA had determined the cause of the anomaly to be a fuel leak (into the combustion chamber<ref>[https://spaceflightnow.com/delta/d361/investigation.html ''Investigation finds Delta 4 rocket engine issue'' December 2012]</ref>), and Delta IV launches resumed in May 2013. After two more successful launches, further investigation led to the delay of Delta flight 365 with the [[GPS Block IIF|GPS IIF-5]] satellite.<ref>{{Cite web |last=Gruss |first=Mike |date=21 Oct 2013 |title=Glitch on October 2012 Delta 4 Mission Is Behind GPS 2F-5 Launch Delay |url=http://www.spacenews.com/article/military-space/37792glitch-on-october-2012-delta-4-mission-is-behind-gps-2f-5-launch-delay |url-status=dead |archive-url=https://archive.today/20141209071311/http://www.spacenews.com/article/military-space/37792glitch-on-october-2012-delta-4-mission-is-behind-gps-2f-5-launch-delay |archive-date=9 December 2014 |access-date=December 9, 2014 |publisher=SpaceNews.com}}</ref> Originally scheduled to launch in October 2013, the vehicle lifted off on 21 February 2014.<ref>{{Cite web |date=21 Feb 2014 |title=United Launch Alliance Successfully Launches 25th Delta IV Mission Carrying Global Positioning System Satellite for the U.S. Air Force |url=http://www.ulalaunch.com/site/pages/News.shtml#/167/ |url-status=dead |archive-url=https://web.archive.org/web/20131207160150/http://www.ulalaunch.com/site/pages/News.shtml#/167/ |archive-date=7 December 2013 |access-date=21 Feb 2014 |publisher=United Launch Alliance}}</ref>

A Delta IV Heavy launched the [[Orion spacecraft]] on an uncrewed test flight, [[Exploration Flight Test 1|EFT-1]], on 5 December 2014.<ref name="nsfeft1ffr">{{Cite web |last=Bergin |first=Chris |date=30 October 2014 |title=EFT-1 Orion completes assembly and conducts FRR |url=http://www.nasaspaceflight.com/2014/10/eft-1-orion-assembly-conduts-frr/ |access-date=November 8, 2014 |publisher=NASASpaceflight.com}}</ref> The launch was originally planned for 4 December 2014, but high winds and valve issues caused the launch to be rescheduled for 5 December 2014.<ref>[http://aviationweek.com/blog/delta-iv-issues-winds-scrub-orions-exploration-flight-test-1-debut "Delta IV issues, Winds Scrub Orion's Exploration Flight Test-1 Debut"]. Aviation Week, December 4, 2014</ref>

On August 12, 2018, another Delta IV Heavy launched the [[Parker Solar Probe]] on a mission to explore or "touch" the outer corona of the Sun.<ref>{{Cite web |title=First milestones accomplished on NASA's newly-launched Parker Solar Probe |url=https://spaceflightnow.com/2018/08/19/first-mission-milestones-accomplished-on-nasas-newly-launched-parker-solar-probe/ |access-date=August 22, 2018 |website=spaceflightnow.com}}</ref>

The second [[GPS Block III]] satellite was launched with the final Delta IV Medium+ (4,2) configuration rocket on 22 August 2019.<ref name="nsf20190822"/>

The final flight from Vandenberg of the Delta IV Heavy launched the [[List of NRO launches|NROL-91]] mission in September 2022.

The final flight from Cape Canaveral of the Delta IV Heavy and of the Delta rocket family took place in April 2024 carrying the [[List of NRO launches|NROL-70]] mission.

== See also ==
{{Portal|Spaceflight}}
* [[Comparison of orbital launchers families]]
* [[Comparison of orbital launch systems]]
* [[Advanced Cryogenic Evolved Stage]]
* [[Expendable launch system]]
* [[List of launch vehicles]]

== Notes ==
{{notelist}}

== References ==
{{reflist}}

== External links ==
{{Commons|Delta (rocket)}}
* [https://web.archive.org/web/20130426223044/http://www.ulalaunch.com/site/pages/Products_DeltaIV.shtml Delta IV Launch Vehicle page on United Launch Alliance site]
* [https://web.archive.org/web/20060928205134/http://www.boeing.com/defense-space/space/delta/delta4/delta4.htm Boeing's Delta IV Rocket page]
* [http://space.skyrocket.de/doc_lau/delta-4.htm Delta IV information on Gunter's Space page]
* [https://web.archive.org/web/20110524124727/http://www.boeing.com/defense-space/space/delta/kits/d310_d4heavy_demo.pdf Boeing press kit for Heavy Demo launch, 2005]
* [https://web.archive.org/web/20051119145351/http://www.floridatoday.com/!NEWSROOM/newsgraphics/122104rocket.jpg Comparison of Delta IV Heavy with Space Shuttle]
* [http://www.educatedearth.net/video.php?id=4538 First Vandenberg Delta IV Heavy launch video] via EducatedEarth.
* Bates, Jason. [http://www.space.com/spacenews/businessmonday_041206.html Boeing's Delta IV Heavy Gets Ready for its Close-Up], Space News, 2004-12-06.
* [https://web.archive.org/web/20120616140529/http://www.pw.utc.com/products/pwr/propulsion_solutions.asp Rocketdyne Space Page]
* [https://web.archive.org/web/20091125094600/http://www.astronautix.com/lvs/deltaiv.htm Delta IV page on Astronautix.com]

{{United Launch Alliance}}
{{Orbital launch systems}}
{{US launch systems}}
{{Thor and Delta rockets}}
{{USAF Weapons}}

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[[Category:Delta (rocket family)]]
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