Vulcan Centaur is a two-stage-to-orbit, heavy-lift launch vehicle that is under development by the United Launch Alliance (ULA) since 2014 with a initial flight expected in 2021. It is principally designed to meet the launch demands of the US government's National Security Space Launch (NSSL) program for use by the United States Space Force and US intelligence agencies for national security satellite launches.
Vulcan is ULA's first launch vehicle design; it adapts and evolves technologies that were developed for the Atlas V and Delta IV rockets of the USAF's EELV program. The first-stage propellant tanks have the same diameter as the Delta IV Common Booster Core but will contain liquid methane and liquid oxygen propellants rather than the Delta IV's liquid hydrogen and liquid oxygen.
Vulcan's upper stage is the Centaur V, an upgraded variant of the Common Centaur, the world’s first high-energy upper-stage the Centaur III variant. As of 2021[update], the Centaur V is used on the Atlas V. The RL-10CX, a version of the RL-10 engine with a nozzle extension, will be used on the Vulcan Centaur Heavy. ULA flies Centaur in either a single-engine or dual-engine configuration, leading to additional capability to satisfy launch demands. Previous plans, in which the Centaur V would eventually be upgraded with Integrated Vehicle Fluids technology to become the Advanced Cryogenic Evolved Stage (ACES), were canceled in 2020. Vulcan is intended to undergo the human-rating certification process to allow the launch of crewed craft such as the Boeing CST-100 Starliner or a future version of the Sierra Nevada Dream Chaser spaceplane.
The Vulcan booster has a 5.4 m (18 ft) outer diameter to support the Blue Origin BE-4 engines' liquid methane fuel. In September 2018, after a competition with the Aerojet Rocketdyne AR1, the BE-4 was selected to power Vulcan's first stage.
Up to six Northrop Grumman GEM-63XL solid rocket boosters (SRB)s can be attached to the first stage in pairs, providing additional thrust during the first part of the flight and allowing the six-SRB Vulcan Centaur Heavy to launch a higher-mass payload than the most-capable Atlas V 551 or Delta IV Heavy rockets.
The Vulcan Centaur will have a four-character designation for each configuration, in which the first character represents the first stage of the vehicle; Vulcan is designated with the letter "V". The second character shows the upper stage; Centaur is designated "C". The third letter represents the number of SRBs attached to the Vulcan; "0","2","4" or "6". The final character represents the payload-fairing length configuration, which is indicated by "S" (Standard; 15.5 m, 51 ft) or "L" (Long; 21.3 m, 70 ft). For example, "VC6L" would represent a Vulcan first stage, a Centaur upper stage, six SRBs and a long-configuration fairing. The single-core Vulcan Heavy will have a Vulcan first stage, a Centaur upper stage with RL10CX engines with a nozzle extension and six SRBs.
As of November 2019, the Vulcan Centaur payload figures are as follows:
|Version||SRBs||Payload mass to…|
|Vulcan Centaur VC0||0||10,600 kg (23,400 lb)||9,000 kg (20,000 lb)||8,300 kg (18,300 lb)||2,900 kg (6,400 lb)|
|Vulcan Centaur VC2||2||18,500 kg (40,800 lb)||16,100 kg (35,500 lb)||15,000 kg (33,000 lb)||7,600 kg (16,800 lb)||2,600 kg (5,700 lb)|
|Vulcan Centaur VC4||4||23,900 kg (52,700 lb)||21,000 kg (46,000 lb)||19,500 kg (43,000 lb)||10,800 kg (23,800 lb)||4,800 kg (10,600 lb)|
|Vulcan Centaur VC6||6||27,200 kg (60,000 lb)||25,300 kg (55,800 lb)||23,200 kg (51,100 lb)||13,600 kg (30,000 lb)||6,500 kg (14,300 lb)|
|Vulcan Centaur Heavy||6||27,200 kg (60,000 lb)||26,200 kg (57,800 lb)||24,000 kg (53,000 lb)||14,400 kg (31,700 lb)||7,200 kg (15,900 lb)|
|NSSL requirement||6,800 kg (15,000 lb)||17,000 kg (37,000 lb)||8,165 kg (18,000 lb)||6,600 kg (14,600 lb)|
Payload to low-Earth orbit (LEO) is for a 200 km (120 mi) circular orbit at a 28.7 degree inclination; payload to the International Space Station is for a 407 km (253 mi) circular orbit at 51.6 degree inclination; payload to polar LEO is for a 200 km (120 mi) circular orbit at 90 degree inclination. These capabilities are driven by the need to meet NSSL requirements with room for future growth.[how?]
By early 2014 it was clear[to whom?] ULA would have to develop a new launch vehicle to replace its existing Atlas V fleet. The Atlas V booster uses a Russian RD-180 engine, which led to a push to replace the RD-180 with a U.S. designed and built engine during the Ukrainian crisis of 2014. ULA's reliance on foreign hardware to launch critical, national security spacecraft was also seen as controversial and undesirable. In June 2014, ULA issued formal study contracts to several U.S. rocket engine suppliers. ULA was also facing competition from SpaceX, which was considered to affect ULA's core national security market of U.S. military launches. By July 2014, the United States Congress was debating whether to legislate a ban on future use of the RD-180.
In September 2014, ULA announced it had entered into a partnership with Blue Origin to develop the BE-4 liquid oxygen (LOX) and liquid methane (CH4) engine to replace the RD-180 on a new, first-stage booster, which ULA expected to start flying by 2019. ULA had consistently referred to Vulcan as a "next generation launch system" into early 2015.
At the time of the 2015 announcement, ULA proposed an incremental approach to rolling out the new rocket and its technologies. Vulcan deployment was expected to begin with a new first stage that was based on the Delta IV's fuselage diameter and production process, and initially expected to use two BE-4 engines or the AR1 as an alternative. The initial second stage was planned to be the Atlas V's Common Centaur and Centaur III with its existing RL10 engine. A later upgrade, the Advanced Cryogenic Evolved Stage (ACES), was conceptually planned for full development in the late 2010s and to be introduced a few years after Vulcan's first flight. ULA also announced a design concept for reuse of the Vulcan booster engines, thrust structure and first stage avionics,which could be detached as a module from the propellant tanks after booster engine cutoff; the module would re-enter the atmosphere under an inflatable heat shield. Neither the ACES second stage nor the SMART reuse for the first stage became funded development projects by ULA as of 2019[update], even though ULA stated the "first stage propulsion module accounts for around 65% of Vulcan Centaur’s costs".
Through the first several years, the ULA board of directors made quarterly funding commitments to Vulcan Centaur development. As of October 2018[update], the U.S. government had committed approximately US$1.2 billion in a public–private partnership to Vulcan Centaur development and future funding was dependent on ULA securing an NSSL contract.
By March 2016, the United States Air Force (USAF) had committed up to US$202 million of funding for Vulcan development. ULA had not yet estimated the total cost of development but CEO Tory Bruno noted "new rockets typically cost $2 billion, including $1 billion for the main engine". In April 2016, ULA Board of Directors member and President of Boeing's Network and Space Systems (N&SS) division Craig Cooning expressed confidence in the possibility of further USAF funding of Vulcan development.
In March 2018, Tory Bruno said the Vulcan-Centaur had been "75 percent privately funded" up to that point.[quantify] In October 2018, following a request for proposals and technical evaluation, ULA was awarded $967 million to develop a prototype Vulcan launch system as part of the National Security Space Launch program. Other providers Blue Origin and Northrop Grumman Innovation Systems were awarded $500 million and $792 million in development funding, with detailed proposals and a competitive selection process to follow in 2019. The USAF's goal with the next generation of Launch Service Agreements was to desist from "buying rockets" and move to acquire services from launch service providers but U.S. government funding of launch vehicle development continued.
Path to production
In September 2015, it was announced BE-4 rocket engine production would be expanded to increase production capacity for testing. The following January, ULA was designing two versions of the Vulcan first stage; the BE-4 version has a 5.4-meter (18 ft) diameter to support the use of less-dense methane fuel. In late 2017, the upper stage was changed to the larger and heavier Centaur V, and the launch vehicle was renamed Vulcan Centaur. The single-core Vulcan Centaur will be capable of lifting "30% more" than a Delta IV Heavy, meeting the NSSL requirements.
In May 2018, ULA announced the selection of Aerojet Rocketdyne's RL10 engine for the Vulcan Centaur upper stage. That September, ULA announced the selection of the Blue Origin BE-4 engine for Vulcan's booster. That October, the USAF released an NSSL launch service agreement with new requirements, delaying Vulcan's initial launch to April 2021, after an earlier postponement to 2020.
On 8 July 2019, CEO Tory Bruno released images of two Vulcan qualification test articles—the liquefied natural gas tank and thrust structure—on Twitter. The following day, Peter Guggenbach, the CEO of RUAG Space, released an image of a Vulcan payload attachment fitting. On 31 July the same year, two images of the mated LNG tank and thrust structure were similarly released. On 2 August the same year, Blue Origin released on Twitter an image of a BE-4 engine at full power on a test stand. On 6 August, the first two parts of Vulcan's mobile launcher platform (MLP) were transported to the Spaceflight Processing Operations Center (SPOC) near SLC-40 and SLC-41, Cape Canaveral, Florida. The MLP was fabricated in eight sections and will move at 3 mph (4.8 km/h) on existing rail dollies and stand 183 ft (56 m) tall. On 12 August, ULA submitted Vulcan Centaur for phase 2 of the USAF's launch services competition. As of February 2020, the tankage for the second operational rocket was under construction in the ULA factory in Decatur, Alabama.
As of October 2019, the first launch of Vulcan was planned for July 2021, and in June 2020, ULA said it could be earlier and announced a target launch date of early 2021. On 7 August 2020, the United States Space Force awarded ULA 60% of all National Security Space Launch payloads from 2022 to 2027. That December, ULA postponed BE-4 engine delivery to mid-2021 and said the Vulcan's first launch would not happen before the end of 2021. The following February, ULA shipped the first completed Vulcan core booster to Florida for pathfinder tests ahead of the Vulcan's debut launch.
On 14 August 2019, ULA won a commercial competition when it was announced the second Vulcan certification flight would be SNC Demo-1, the first of six Dream Chaser CRS-2 flights awarded to ULA. Launches are planned to begin in 2022 and will use the four-SRB Vulcan configuration. On 19 August, it was announced Astrobotic Technology selected ULA to launch their Peregrine lander on the first Vulcan certification flight. Peregrine is planned to launch in late 2021 from SLC-41 at Cape Canaveral Space Force Station on a mission to the lunar surface.
Since the formal announcement in 2015, ULA has spoken of several technologies that would extend the Vulcan launch vehicle's capabilities. These include enhancements to the first stage to make the most expensive components potentially reusable and enhancements to the second stage to increase its long-term mission duration to operate for months in Earth orbit cislunar space.
ACES upper stage with Integrated Vehicle Fluids
The ACES upper stage, which was described as fueled with liquid oxygen (LOX) and liquid hydrogen (LH2), and powered by up to four rocket engines with the engine type yet to be selected, was a conceptual upgrade to the Vulcan's upper stage at the time of the announcement in 2015. This stage could subsequently be upgraded to include the Integrated Vehicle Fluids technology that could allow the upper stage a much longer in-orbit life of weeks rather than hours. The ACES upper stage was eventually canceled.
The Sensible Modular Autonomous Return Technology (SMART) reuse concept was also announced during the initial April 2015 unveiling. The booster engines, avionics, and thrust structure would be detached as a module from the propellant tanks after booster engine cutoff. The module would descend through the atmosphere under an inflatable heat shield. After parachute deployment, a helicopter would capture the module in mid-air. ULA estimated this technology would reduce the cost of the first stage propulsion by 90%, and 65% of the total first-stage cost. By 2020, ULA has not announced firm plans to fund, build and test this engine-reuse concept, though in late 2019 they stated they were "still planning to eventually reuse Vulcan’s first-stage engines".
|Date and time,
|Q4 2021 ||VC2S||SLC-41||Peregrine lander||Selenocentric||Astrobotic Technology|
|NET 2022 ||VC4L||SLC-41||SNC Demo-1||LEO (ISS)||NASA (CRS)|
|2022 and on ||VC4L||SLC-41||Dream Chaser||LEO (ISS)||NASA (CRS)|
|5 more launches on contract.|
|Q1 2022 ||TBA||TBA||USSF-51||TBA||US Space Force|
|First launch for United Launch Alliance under National Security Space Launch.|
|Q2 2023 ||VC4X||SLC-41||USSF-112||"High-energy orbit"||US Space Force|
|Q3 2023 ||VC4X||SLC-41||USSF-87||"High-energy orbit"||US Space Force|
|2023 ||TBA||SLC-41||USSF-106 / NTS-3 ||GEO||US Space Force|
- Clark, Stephen. "ULA needs commercial customers to close Vulcan rocket business case". Spaceflight Now. Archived from the original on June 5, 2020. Retrieved April 22, 2015.
- Shalal, Klotz, Andrea, Irene. "'Vulcan' rocket launch in 2019 may end U.S. dependence on Russia". Reuters. Archived from the original on June 5, 2020. Retrieved April 13, 2015.
- "Vulcan Centaur Cutaway Poster" (PDF). ULA. November 2019. Retrieved April 14, 2020.
- Peller, Mark. "United Launch Alliance" (PDF). Archived from the original (PDF) on April 12, 2016. Retrieved March 30, 2016.
- "Rocket Rundown – A Fleet Overview" (PDF). United Launch Alliance. November 2019. Archived (PDF) from the original on December 13, 2019. Retrieved April 14, 2020.
- Clark, Stephen (October 12, 2015). "ULA selects launch pads for new Vulcan rocket". Spaceflight Now. Archived from the original on October 14, 2015. Retrieved October 12, 2015.
- Bezos' Blue Origin to deliver first flight-ready rocket engines next summer, Reuters, December 17, 2020, accessed 20 December 2020.
- @ToryBruno (July 1, 2019). "Vulcan is configurable with 0 to 6 SRBs. 2 fairing lengths, the longer, 70 ft fairing having a massive 11,000 cuft (317cu-m) payload volume" (Tweet) – via Twitter.
- Rhian, Jason. "ULA selects Orbital ATK's GEM 63/63XL SRBs for Atlas V and Vulcan Boosters". Spaceflight Insider. Archived from the original on January 11, 2016. Retrieved September 25, 2015.
- "United Launch Alliance Selects Aerojet Rocketdyne's RL10 Engine". ULA. May 11, 2018. Archived from the original on May 12, 2018. Retrieved May 13, 2018.
- "Aerojet Rocketdyne RL10 Propulsion System" (PDF). Aerojet Rocketdyne. Archived (PDF) from the original on June 29, 2019. Retrieved June 29, 2019.
- Neal, Mihir (June 8, 2020). "Vulcan on track as ULA eyes early-2021 test flight to the Moon". Archived from the original on June 9, 2020. Retrieved June 9, 2020.
- Gruss, Mike (April 13, 2015). "ULA's Vulcan Rocket To be Rolled out in Stages". SpaceNews. Retrieved April 17, 2015.
- Foust, Jeff (September 11, 2020). "ULA studying long-term upgrades to Vulcan". Retrieved April 28, 2021.
Peller described ACES as a concept that ULA is no longer actively pursuing.CS1 maint: discouraged parameter (link)
- Foust, Jeff (September 11, 2020). "ULA studying long-term upgrades to Vulcan". SpaceNews. Retrieved March 2, 2021.
- Tory Bruno. ""@A_M_Swallow @ULA_ACES We intend to human rate Vulcan/ACES"". Twitter.com. Retrieved August 30, 2016.
- de Selding, Peter B. (March 16, 2016). "ULA intends to lower its costs, and raise its cool, to compete with SpaceX". SpaceNews. Retrieved March 19, 2016.
Methane rocket has a lower density so we have a 5.4 meter design outside diameter, while drop back to the Atlas V size for the kerosene AR1 version.
- "United Launch Alliance Building Rocket of the Future with Industry-Leading Strategic Partnerships". September 28, 2018. Archived from the original on September 28, 2018. Retrieved September 28, 2018.
- Jason Rhian (September 23, 2015). "ULA selects Orbital ATK's GEM 63/63 XL SRBs for Atlas V and Vulcan boosters". Spaceflight Insider. Archived from the original on January 11, 2016. Retrieved September 25, 2015.
- @ToryBruno (July 1, 2019). "No. Vulcan SRBs come in pairs" (Tweet) – via Twitter.
- "United Launch Alliance Unveils America's New Rocket – Vulcan: Innovative Next Generation Launch System will Provide Country's Most Reliable, Affordable and Accessible Launch Service". ULA. April 13, 2015. Archived from the original on June 5, 2020. Retrieved April 14, 2020.
- "Vulcan Centaur". www.ulalaunch.com. Archived from the original on February 25, 2021. Retrieved March 3, 2021.
- "Vulcan Centaur Cutaway Poster" (PDF). ULAlaunch.com. ULA.
- Space and Missile Systems (October 5, 2018). "EELV LSA RFP OTA". Archived from the original on February 3, 2019. Retrieved June 22, 2019.
table 10 of page 27
- Ferster, Warren (September 17, 2014). "ULA To Invest in Blue Origin Engine as RD-180 Replacement". Space News. Retrieved September 19, 2014.
- Gruss, Mike (April 24, 2015). "Evolution of a Plan : ULA Execs Spell Out Logic Behind Vulcan Design Choices". Space News. Retrieved April 25, 2015.
- Clark, Stephen (April 22, 2015). "ULA needs commercial business to close Vulcan rocket business case". Spaceflight Now. Archived from the original on October 26, 2015. Retrieved April 23, 2015.
- Fleischauer, Eric (February 7, 2015). "ULA's CEO talks challenges, engine plant plans for Decatur". Decatur Daily. Archived from the original on June 12, 2017. Retrieved April 17, 2015.
- Avery, Greg (October 16, 2014). "ULA plans new rocket, restructuring to cut launch costs in half". Denver Business Journal. Archived from the original on March 15, 2017. Retrieved April 17, 2015.
- Ray, Justin (April 14, 2015). "ULA chief explains reusability and innovation of new rocket". Spaceflight Now. Archived from the original on April 17, 2015. Retrieved April 17, 2015.
- Henry, Caleb (November 20, 2019). "ULA gets vague on Vulcan upgrade timeline". SpaceNews. Retrieved June 20, 2020.
- Gruss, Mike (March 10, 2016). "ULA's parent companies still support Vulcan … with caution". SpaceNews. Retrieved March 10, 2016.
- Erwin, Sandra (October 10, 2018). "Air Force awards launch vehicle development contracts to Blue Origin, Northrop Grumman, ULA". SpaceNews.com. Retrieved July 28, 2020.
- Host, Pat (April 12, 2016). "Cooning Confident Air Force Will Invest In Vulcan Development". Defense Daily. Archived from the original on April 22, 2016. Retrieved April 13, 2016.
- Erwin, Sandra (March 25, 2018). "Air Force stakes future on privately funded launch vehicles. Will the gamble pay off?". SpaceNews. Archived from the original on August 21, 2015. Retrieved June 24, 2018.
- "Boeing, Lockheed Differ on Whether to Sell Rocket Joint Venture". Wall Street Journal. September 10, 2015. Archived from the original on April 15, 2017. Retrieved September 12, 2015.
- ToryBruno (President & CEO of ULA). "Vulcan Heavy?". Reddit.com. Retrieved April 12, 2018.
- Tribou, Richard (May 11, 2018). "ULA chooses Aerojet Rocketdyne over Blue Origin for Vulcan's upper stage engine". Orlando Sentinel. Archived from the original on May 13, 2018. Retrieved May 13, 2018.
- "United Launch Alliance Building Rocket of the Future with Industry-Leading Strategic Partnerships – ULA Selects Blue Origin Advanced Booster Engine for Vulcan Centaur Rocket System" (Press release). United Launch Alliance. September 27, 2018. Archived from the original on October 6, 2018. Retrieved October 5, 2018.
- Johnson, Eric M.; Roulette, Joey (September 27, 2018). "Jeff Bezos' Blue Origin to supply engines for Vulcan rocket". Reuters. Archived from the original on September 28, 2018. Retrieved September 28, 2018.
- Foust, Jeff (October 25, 2018). "ULA now planning first launch of Vulcan in 2021". SpaceNews. Archived from the original on March 29, 2020. Retrieved November 11, 2018.
- @jeff_foust (January 18, 2018). "Tom Tshudy, ULA: with Vulcan we plan to maintain reliability and on-time performance of our existing rockets, but at a very affordable price. First launch mid-2020" (Tweet) – via Twitter.
- Foust, Jeff. "ULA now planning first launch of Vulcan in 2021" Archived March 29, 2020, at the Wayback Machine. Space News, October 25, 2018.
- @ToryBruno (July 8, 2019). "I spy a Vulcan booster LNG qualification tank just finished and heading off to structural testing..." (Tweet) – via Twitter.
- @ToryBruno (July 8, 2019). "How do you get over a million pounds of thrust from a pair of BE4 rocket engines efficiently into the rest of the rocket? With a ultra high performance thrust structure. Here's Vulcan's on its way to structural testing" (Tweet) – via Twitter.
- @PeterGuggenbach (July 9, 2019). "Flying saucer at Area 51? Nope! Our first out-of-autoclave Payload Attach Fitting (PAF), produced on a 360-degree mold, is headed to the oven in our @RUAGSpace Decatur, Alabama facility. This PAF will be used on the @ULALaunch #VulcanCentaur" (Tweet) – via Twitter.
- @ToryBruno (July 31, 2019). "Look at that beautiful bird! This first Vulcan booster is heading off to structural qual testing to verify Vulcan's advanced design and manufacturing tech. Super proud of our Decatur team. #MadeInAlabama. #ULArocketStars @ulalaunch" (Tweet) – via Twitter.
- @ToryBruno (July 31, 2019). "Here's another shot of the Vulcan Structural Test qual booster to give you a size comparison. Mighty Atlas on the left. Great Vulcan on the right. A new class of space launch vehicle; the single-core heavy #TheBeast" (Tweet) – via Twitter.
- @blueorigin (August 2, 2019). "BE-4 continues to rack up time on the test stand. Here's a great shot of our full power engine test today #GradatimFerociter" (Tweet) – via Twitter.
- @ToryBruno (August 6, 2019). "Mighty Atlas is not the only thing rolling at the Cape today. Check the new Vulcan MLP arrival" (Tweet) – via Twitter.
- @ULAlaunch (August 6, 2019). "The MLP will transport #VulcanCentaur Vertical Integration Facility to SLC-41 using heritage undercarriage dollies used for Titan III, Titan IV and #AtlasV and will move at 3 mph. #VulcanCentaur" (Tweet) – via Twitter.
- "Vulcan Centaur Rocket on Schedule for First Flight in 2021: ULA Submits Proposal for U.S. Air Force's Launch Services Competition". www.ULAlaunch.com. ULA. August 12, 2019. Archived from the original on August 12, 2019. Retrieved August 12, 2019.
- Sandlin, Destin (February 29, 2020). "How Rockets Are Made (Rocket Factory Tour - United Launch Alliance) - Episode 231". YouTube. Archived from the original on March 7, 2020. Retrieved March 7, 2020.
- Wall, Mike. "SpaceX Falcon 9 Rocket Will Launch Private Moon Lander in 2021"Archived October 4, 2019, at the Wayback Machine Space.com 2 October 2019 Quote: "But Peregrine will fly on a different rocket, United Launch Alliance's Vulcan Centaur, which is still in development. The 2021 Peregrine mission will be the first for both the lander and its launch vehicle".
- "Contracts for August 7, 2020". U.S. DEPARTMENT OF DEFENSE. Retrieved August 9, 2020.
- "Three rockets depart factory aboard RocketShip". ULA Launch: blog. United Launch Alliance. February 4, 2021.
- "SNC Selects ULA for Dream Chaser® Spacecraft Launches: NASA Missions to Begin in 2021". ULALaunch. August 14, 2019. Archived from the original on August 14, 2019. Retrieved August 14, 2019.
- "Astrobotic Selects United Launch Alliance Vulcan Centaur Rocket to Launch its First Mission to the Moon". ULALaunch. August 19, 2019. Archived from the original on August 19, 2019. Retrieved August 19, 2019.
- "America, meet Vulcan, your next United Launch Alliance rocket". Denver Post. April 13, 2015. Archived from the original on April 17, 2015. Retrieved April 17, 2015.
- "Vulcan on track as ULA eyes early-2021 test flight to the Moon". NASASpaceFlight.com. June 8, 2020. Archived from the original on June 9, 2020. Retrieved June 9, 2020.
- Pietrobon, Steven (August 27, 2019). "United States Commercial ELV Launch Manifest". Archived from the original on March 4, 2019. Retrieved August 27, 2019.
- "Cargo Dream Chaser solidifies ULA deal by securing six Vulcan Centaur flights". NASASpaceFlight.com. August 14, 2019. Archived from the original on March 3, 2020. Retrieved June 9, 2020.
- @TGMetsFan98 (August 7, 2020). "The first three NSSL Phase 2 launches have also been awarded. ULA will launch USSF-51 in Q2 of FY2022 and USSF-106 in Q4 of FY2022. SpaceX will launch USSF-67 in Q4 of FY2022. No word on launch sites or launch vehicles for those missions" (Tweet) – via Twitter.
- Clark, Stephen (March 10, 2021). "ULA, SpaceX split military launch contract awards". Spaceflight Now. Retrieved March 19, 2021.
- Erwin, Sandra (March 9, 2021). "Space Force awards ULA, SpaceX contracts for four national security missions". Space News. Retrieved March 19, 2021.
- Erwin, Sandra (April 28, 2021). "Air Force NTS-3 navigation satellite to launch in 2023". SpaceNews. Retrieved April 28, 2021.
- Erwin, Sandra (September 15, 2020). "Air Force Research Laboratory's NTS-3 satellite to launch on ULA's Vulcan". SpaceNews. Retrieved September 18, 2020.
|Wikimedia Commons has media related to Vulcan (rocket).|
- Official ULA Vulcan page
- xTTkrxVR_20 ISPCS 2015 Keynote, Mark Peller, Program Manager of Major Development at ULA and Vulcan Program Manager discusses Vulcan, October 8, 2015. Key discussion of Vulcan is at 12:20 point in video.
- 7a758ea8_0 A current ULA Vulcan with 5.4 m Centaur image