Vulcan continues path to its maiden launch as ULA turns 15

by Lee Kanayama

On December 14, 2006, a Delta II rocket launched from VAFB (Vandenberg Air Force Base) SLC-2 (Space Launch Complex 2) on the NROL-21 mission. This launch marked the first mission for ULA (United Launch Alliance) and the beginning of its 15-year history.

The Delta rocket family has three more launches before being phased out with the Vulcan-Centaur rocket. Delta has seen an extensive history with operations of nearly 65 years and operating in two different countries. Delta started its life in two different rockets during the late 1950s.

Vanguard and Thor-Delta:

Delta began from the Thor and Vanguard rockets. Thor was an IRBM (intermediate-range ballistic missile) developed by the Douglas Aircraft Company. The goal of Thor was to create a deployable missile with a range of ~2,820 km and the ability to be air-transported by a Douglas C-124.

Thor was a single-stage rocket utilizing the Rocketdyne LR-79 kerosene/LOX (liquid oxygen) engine. The missile was 2.4 meters in diameter.

On January 25, 1957, the first Thor rocket attempted to launch from the–at the time–CCAFS (Cape Canaveral Air Force Station) SLC-17B. Just after liftoff, Thor lost thrust and fell back on the pad. Following four more unsuccessful launches, including the first from SLC-17A, Thor’s first successful launch was on September 20, 1957.

By 1963, the Thor rocket was retired as a missile and was solely a space launch vehicle. The final Thor IRBM was launched in 1975.

On October 4, 1957, the world changed with the launch of the first artificial Earth satellite, Sputnik 1. The United States accelerated its plans to place a US-built satellite in orbit. President Eisenhower called upon the Vanguard rocket to place the first US satellite in orbit.

Vanguard started with the US Naval Research Laboratory intended to launch the first artificial satellite. At the end of the program in 1959, 11 Vanguard rockets were launched with only three successful launches.

Vanguard was a three-stage rocket. The second stage used an Aerojet AJ10 hypergolic engine and was called Able. The third stage was a solid propellant motor named Altair. Able and Altair were then used with the Thor and Atlas rockets. Able and Altair were primarily used with Thor.

In April 1958, the Thor-Able was launched for the first time. On August 17, 1958, Thor-Able launched the Pioneer 0 mission. While unsuccessful, it was the first attempt to reach beyond Earth orbit by any country. In October 1958, Thor-Able launched NASA’s Pioneer 1, the first mission under the newly formed agency. This began the long partnership between NASA and Thor.

Following the launch of Pioneer 2 in November 1958, the Thor-Able received minor upgrades until its last flight in April 1960 with NASA’s TIROS 1.

In May 1960, a new upper stage named Delta launched with NASA’s Echo 1. Derived from Able, Delta used a reignitable version of the AJ10 engine with cold gas thrusters to allow inflight restarts. This new combination named Thor-Delta would be used for many NASA missions.

Following the retirement of the Thor-Delta, Delta would take over as the primary name. Delta A would be the first of the Delta family.

Delta B was the first Delta rocket to enter operational status. It was the first to get upgrades to reach GTO (Geosynchronous transfer orbit). It most notably carried NASA’s Syncom 2, the first satellite to enter Geosynchronous orbit.

Delta D was the first Delta to use solid rocket motors to boost performance. It introduced the Thrust Augmented Delta first stage, MB-3-III engine, and Castor boosters to Delta. The rocket carried the Syncom 3 satellite, which was the first to enter geostationary orbit.

Delta L was the first to introduce a new first stage called LTT (Long Tank Thor), using the MB-3-III engine. It also introduced the Castor-2 boosters to Delta.

In 1967, Douglas Aircraft merged with McDonnell Aircraft to form the McDonnell Douglas Corporation. The company used the Delta lettering system until 1972 with Delta-N. A new four-digit numbering system was used to show what version of the Delta rocket was used.

The first Delta to use the new numbering system was the Delta 0100 series of rockets. The 0100 rockets include the Delta 0300 and 0900. These were used five times from 1972 to 1973.

The 1000 series introduced the ELTT (Extended Long Tank Thor) with the MD-3-III. Delta P was introduced with Delta 1000, which used the Lunar Module Descent Engine derived TR-201 rocket engine. Delta 1000 series was used from 1972 to 1975.

Launch of Delta-2914 from SLC-17A with Symphonie-2. (Credit: NASA)

From 1975 to 1992, Japan launched 24 Japanese-built, Thor-derived rockets. N-I and N-II (Nippon I & II) were the first two orbital liquid-fueled rockets launched by Japan. H-I (Hydrogen I) was the first Japanese rocket to use hydrogen. These rockets used Japanese-built Thor-derived hardware for manly the first stage and boosters. Except for one partial failure on the N-I, all  other flights were successful.

H-II was the first Japanese liquid-fueled rocket to not use any Thor-derived hardware, but it was not the last time Japan was involved with Delta.

Delta continued with the Delta 2000 and 3000 series. Both introduced the Rocketdyne RS-27 engine while using the ELTT. The RS-27 was an updated version of the H-1 engine used on the Saturn 1/1B. The 3000 series saw the introduction of the Castor 4 boosters as well as the Delta-K upper stage.  Both still used the Delta-P upper stage, with the 3000 the final rocket to use it. The two were introduced in 1974 and 1975.

On April 12, 1981, Space Shuttle Columbia launched for the first time which was thought to mark the end of expendable rockets. As a reusable system, the Space Shuttle was designed to make access to space cheaper and more frequent. The Space Shuttle became the US’s primary launch vehicle.

In October 1981, Delta 2000 series was retired leaving the 3000 as the sole available Delta. In May 1986, the first Delta launch in 16 months, carrying the GOES-G satellite, failed a little over a minute after liftoff when the RS-27 main engine shut down early due to poor quality control on the wiring in the stage.

Beginning in 1987 following the Space Shuttle Challenger disaster, McDonnell Douglas with the US Air Force developed a new upgraded version of the Delta rocket. With the Shuttle being phased back out of commercial/expendable launch services, the new version of the launcher, named Delta II, would be used to launch the next-generation GPS (Global Positioning System) Block II satellites.

Delta II/III and Boeing era:

On February 14, 1989, Delta II saw its maiden flight with the GPS-II-1 satellite. Named the 6000 series, the first stage used an EELTT (Extra-Extended Long Tank Thor) with the RS-27 engine and nine upgraded Castor-4A boosters. The Delta-K is the only upper stage used for Delta II. The Delta II also had the option to fly with an optional third stage; it could use a Star-48B or a Star-37FM. Delta II could use three newly developed payload fairings.

Following the first launch of Delta II, the final Delta 3000 was launched in March 1989. Using a combination of parts from older Deltas and Delta II, the Delta 4000 and 5000 were created.

Two Delta 4000 were launched in 1989 and 1990. This version used the ELTT but with the MB-3-III engine. Both the 4000 and 5000 used Delta II’s Castor-4A along with the Delta-K upper stage. The Delta 5000 had only one launch in 1989. It used the ELTT but used the RS-27.

The Delta II 6000 series of rockets would fly 16 times. Delta II 7000 series would soon take over as the primary Delta. On November 26, 1990, the first Delta II 7000 series was launched with GPS-IIA-1.

Delta 7326 launches Deep Space 1 for NASA from SLC-17A in October 1998. (Credit: NASA)

The first stage on the 7000 was the same EELTT but with a new upgraded Rocketdyne RS-27A. It would also use a new set of solid boosters. Known as the GEM (Graphite Epoxy Motors), these boosters allowed for more thrust while cutting weight. GEMs use a graphite-epoxy and composite motor outer casing. The boosters used on the Delta II are the GEM-40s.

By 1994, 43 Delta IIs were launched. In August 1995, during the Koreasat 1 mission, one of the ground-lit boosters failed to separate causing a lower than expected speed. Koreasat 1 made it to orbit but with a lowered lifespan.

The Delta II quickly returned to flight in November 1995 with the launch of the RADARSAT-1/Surfsat-1. This launch was the first time a Delta II launched from VAFB.

Unfortunately, Delta II saw its only failure on January 17, 1997. A Delta II lifted off from SLC-17A with the GPS-IIR-1 satellite. About 12 seconds after the liftoff, the Delta II exploded raining debris everywhere.

The failure was attributed to one of the GEM-40 casings. The failure of one of the casings led to a split-second chain reaction that destroyed the vehicle and payload. A fix was made to check the casings from any damage made during transport and or testing.

Delta II quickly returned to flight in May 1997, with the first set of satellites for the Iridium constellation from SLC-2.

In 1997, McDonnell Douglas merged with long-time rival, Boeing. Boeing would take over as Delta’s manufacturer. Before the merger took place, McDonnell Douglas began work on a new Delta rocket to reach the newer demand of bigger comsats.

As a part of the Delta 8000 series, also known as the Delta III, this rocket was made to upgrade Delta’s capacity to GTO. Minus the RS-27A first stage engine, nearly the entire rocket was different from the Delta II. To support the first stage, GEM-46, also known as GEM LDXL (Large Diameter Extended Length) solid boosters were used.

The second stage saw the biggest change with the use of hydrolox propellant. Called the DCSS (Delta Cryogenic Second Stage), it was four meters in diameter and used the RL10B-2 engine. Japan made the four-meter hydrogen and kerosene tanks. Delta III used SLC-17B.

On August 27, 1998, the first Delta III launched with the Galaxy 10 satellite. Just before the ground-lit GEM-46 boosters were to burn out and separate from the rocket 75 seconds after liftoff, a sudden large downward pitch caused the break up of the rocket. The rocket and payload were lost.

The failure was traced back to a failure of the control system due to a higher than expected roll oscillation. A software change was made to the control system to fix the issue.

On May 5, 1999, the second Delta III launched with the Orion 3 satellite. The rocket was able to reach LEO. As the satellite was targeting GTO, the DCSS reignited for a second burn. Seconds after, it shutdown early. This left the second stage and spacecraft in an orbit they could not recover from. The mission was a failure.

It was later found that the failure was caused by a breach of the combustion chamber of the RL10. The failure caused a massive setback to the Delta III program. With the satellite market beginning to crash, Delta III lost several customers following the failure. Boeing did continue work for one more Delta III launch, but a new rocket was already in the works.

The Delta IV begins:

1994 saw the beginning of the EELV (Evolved Expendable Launch Vehicle) program to provide the US military with affordable and reliable access to space. Boeing began work on a new rocket for EELV called the Delta IV. Boeing with the Delta IV and Lockheed Martin with its Atlas V rocket won EELV contracts.

While called Delta, the Delta IV used little to no Thor-derived hardware. It was a part of the 9000 series.

The five-meter diameter first stage used the new Rocketdyne Hydrolox RS-68 engine.  The Delta IV design took the DCSS from Delta III and introduced a five-meter diameter version of the upper stage.

Two Delta IV rocket delivered to the Horizontal Integration Facility at SLC-37B, while the first Delta IV Heavy awaits for launch. (Credit: NASA)

The Delta IV would be the first Delta rocket that would not launch from SLC-17. It launched from SLC-37B, which was used for the Saturn I rocket. At Vandenberg, it would use the SLC-6 launch site.

On August 23, 2000, the final Delta III launched with a mass simulator. The flight’s goal was to test the DCSS for the Delta IV rocket and test the limit of Delta III. The mass simulator, named Delta Mission Flight Three, was 4.3 tons.

The Delta III successfully reached orbit and conducted its second burn. The mission was targeting an orbit of 180 km by 23,404 km but only reached 20,694 km.

It was found due to the weather conditions at launch, slight deviations were caused to the flight profile. The orbit reached was still within the allowable margin of error, and the flight was considered a success.

Due to the lack of planned flights, the Delta III program was canceled. Many payloads and parts that were planned for Delta III were moved to Delta II and IV. An unused DCSS from Delta III was put on display at the Discovery Cube in Santa Ana, California.

By late 2002, the Delta IV was ready to launch for the first time. On November 20, 2002, a Delta IV M+ (4,2) launched the Eutelsat 5W satellite on its maiden flight. This was Delta IV’s only commercial launch.

In June and July 2003, Delta II successfully launched the MER (Mars Exploration Rovers) A and B rovers. The launch of MER-B “Opportunity” was the first of the Delta II Heavy configuration. Delta II Heavy used the GEM-46 boosters that were used on Delta III.

Before 2004, the Titan IV was the US Air Force’s primary heavy-lift launcher. The rocket was already costly and was not as reliable as Atlas or Delta. When the EELV started both the Atlas V and Delta IV had concepts to replace the Titan IV. The Delta IV was selected, and the Delta IV Heavy was born.

The first stage of the Delta IV is called the CBC (Common Booster Core) and can be used in two main configurations. The CBC can be used as the first/core stage or used with nosecones as boosters.  Delta IV Heavy uses three CBCs, two boosters and a single core stage. The second stage of Delta IV Heavy uses the five-meter DCSS.

The first Delta IV Heavy launched on December 21, 2004. It carried a 6t DemoSat to a direct GSO along with a set of satellites called 3CSat (Three Corner Satellite). The 3CSat project was a set of satellites designed and built by undergrad college students.

Delta IV Heavy approaches booster engine cutoff. (Credit: Mack Crawford for NSF/L2)

During the flight, cavitations in the propellent lines caused the three CBCs to shutdown early, causing the initial parking orbit to be at 105 km. The 3Csats separated in the parking orbit and reentered sooner than expected. The DCSS continued to GSO but due to low fuel, it didn’t reach GSO. The flight was, however, considered a partial success as it proved the overall Delta IV Heavy rocket.

A Delta IV M+ (4,2) launched in June 2006 with the NROL-22 mission, as the first time a Delta IV launched from SLC-6 at Vandenberg.

ULA era and Delta’s end:

With both the Atlas and Delta families in the competition in EELV and the commercial market shrinking, Boeing and Lockheed Martin entered an agreement to create a joint venture in 2005. Named United Launch Alliance, the joint venture was made to lower the cost of both rocket families to the U.S. government and also to end litigation between the two companies.

The company was founded on December 1, 2006. ULA would offer the Atlas V, Delta II, and Delta IV rockets to customers. The formation of ULA would allow the construction and operation of the Atlas and Delta families under one company.

ULA quickly began launching rockets, as on December 14, 2006, a Delta II launched from SLC-2 with the NROL-21 mission.

Delta II continued to launch NASA and GPS missions under the ULA name. In August 2007, Delta II launched the Phoenix Mars lander. This would be the last time a Delta II launched a mission to Mars–but it was the first for ULA.

On August 17, 2009, Delta II launched the GPS-IIR-21/GPS-2RM-8. This mission was the last time a Delta II launched a GPS satellite as well as the last rocket to launch from SLC-17A.

In September 2011, a Delta II Heavy launched the GRAIL (Gravity Recovery and Interior Laboratory) A and B lunar orbiters. This launch would be the final time a Delta II Heavy launched and the final Delta launched from SLC-17. After this launch, SLC-17 was retired and returned to the Air Force.

In July 2012, NASA selected the Delta II to launch SMAP (Soil Moisture Active Passive), the OCO-2 (Orbiting Carbon Observatory-2), and the JPSS-1 satellites. In February 2013, NASA selected Delta II to launch the ICESat-2 (Ice, Cloud, and land Elevation) satellite; these were the last Delta IIs ordered. On July 2, 2014, Delta II launched OCO-2.

Delta IV Heavy launches the Orion EFT-1 mission. (Credit: ULA)

Before 2014 ended, on December 5, a Delta IV Heavy launched on one of Delta’s most important missions. The objective of the EFT-1 (Exploration Flight Test) mission was to launch the first orbital flight test of NASA’s Orion crew spacecraft. The purpose of the mission was an initial flight test of the overall design of the Orion spacecraft and test the spacecraft’s heatshield in a high-energy reentry.

The Delta IV Heavy had the Orion crew module and a service module simulator attached to the five-meter DCSS along with an inert launch abort system. It successfully lifted the Orion into orbit. The Orion crew module then separated from the Delta and simulator and successfully splashed down in the Pacific Ocean after a four and a half hour mission.

The Orion spacecraft will launch on top of an SLS (Space Launch System) rocket for the Artemis missions. The initial Block 1 version of SLS will use the ICPS (Interim Cryogenic Propulsion Stage), which is a modified version of the five-meter DCSS.  Block 1 with ICPS will be used on the first three SLS missions.

On January 31, 2015, the final Delta II with three SRBs (732x) launched from SLC-2 with the SMAP spacecraft. August 2018 saw a Delta IV Heavy with a Star-48BV third stage carry the Parker Solar Probe to “touch” the Sun. In November 2017, the final Delta II with nine SRBs (792x) launched the JPSS-1 satellite.

On September 15, 2018, the final Delta II launched using four SRBs (742x). The Delta II carried the ICESat-2 spacecraft.

The final Delta II marked the end of an era. With Delta IV not using any Thor-derived hardware, the ICESat-2 mission was the last time a Thor-derived rocket was launched. Delta II flew from 1989 to 2018. The final launch was the 155th overall launch and the 100th consecutive successful launch of the Delta II.

The Delta II left a legacy by supporting over 50 NASA missions including Mars Pathfinder, Stardust, and Messenger. It also launched 49 GPS satellites over three GPS-II generations. The final Delta II was put on display at the Kennedy Space Center Visitor Complex in 2021.

On August 22, 2019, a Delta IV M+ (4,2) launched the GPS-III-2 satellites to orbit, marking the last Delta IV Medium and the last GPS launch on Delta.

Currently, three Delta IV Heavy rockets are left. NROL-91 will be the final mission to launch from SLC-6, it will fly NET 2022. NROL-70 will launch from SLC-37B in 2024 and will be the final Delta rocket to launch. Delta’s final launch will mark the end of Delta’s over 60-year legacy.

Vulcan begins:

Vulcan-Centaur is ULA’s next-generation rocket with more performance and at a cheaper cost. Vulcan is also an answer to the issues Atlas and Delta have. Atlas V uses the Russian RD-180 engine, which will not be used on US military missions starting 2023. The Delta IV is costly to operate, with costs as high as 300 million US dollars.

Vulcan began development in 2014 with its announcement in 2015. Vulcan would take the lessons learned from the Delta and Atlas programs to make Vulcan as reliable as possible.

The maiden flight of Vulcan is currently set to launch in Summer 2022. Once in operation, Vulcan will replace the Delta IV and Atlas V rockets. Vulcan will be capable of lifting 30% more mass to GTO than Delta IV.

The Vulcan rocket will be 5.4-meters in diameter, similar to Delta IV’s five-meters. Vulcan is a two-stage rocket with up to six GEM-63XL solid boosters. GEM-63XL boosters are upgraded versions of the GEM boosters used on Delta IV and Atlas V. The first stage will use two Blue Origin BE-4 methalox engines. The second stage is a Centaur V using two RL10C-1-1 engines.

Centaur V’s pair of RL-10 engines burn toward orbit on a co-manifested Vulcan mission. (Credit: Mack Crawford for NSF/L2)

Vulcan is one of the U.S. government’s NSSL (National Security Space Launch) Phase 2 providers. In 2020, it was selected to launch 60% of all NSSL missions from 2022 to 2027. Its first USSF mission is the USSF-67 mission in 2023.

2019 saw a test article built for Vulcan’s first stage to complete qualifications. Vulcan will use SLC-41, the same pad used by the Atlas V. The MLP (Mobile Launch Platform) for Vulcan was nearly completed in the same year, with testing of the MLP in 2020.

Vulcan’s PTT (Pathfinding Tanking Test) booster was delivered to CCSFS via ULA’s RocketShip in February 2021.

The PTT is fitted with two pathfinder BE-4 engines. The goal of testing with the PTT is to help validate Vulcan launch operations and procedures and familiarize the ULA launch team with Vulcan. In February 2021, the PTT was lifted onto the MLP for the first time. From there the MLP and PTT were put in the SPOC (Spaceflight Operation Center) for storage as Atlas V continued operations.

On August 30, 2021, the MLP and PTT were on the pad and fueled up with only LOX. The same test was conducted on September 21, but with Methane instead. The final testing for the PTT was completed on October 5, when both LOX and Liquid Methane were loaded onto the propellant tanks. This test was the first demonstration of Vulcan’s full countdown until just prior to first-stage engine ignition.

The PTT will be replaced on MLP with the first flightworthy Vulcan first stage. Vulcan will continue further testing on the pad, including a FRF (Flight-Readiness Firing) of its BE-4s. The BE-4s are currently in qualification testing before being delivered to ULA in 2022. The PTT stage will be outfitted with its own flight-ready BE-4s and will be used on its own mission.

Vulcan PTT undergo tank testing. (Credit: ULA)

Since 2020, many Atlas Vs have tested components that will be used on Vulcan. In November 2020, Atlas V launched the NROL-101 mission using the GEM-63s. During the SBIRS-GEO 5 mission, Atlas V used the RL10C-1-1 which will be used on Vulcan.

ULA’s most recent mission, STP-3 (Space Test Program 3) used the first OoA (Out-of-Autoclave) fairings. The OoA fairings are cheaper and lighter to make than the older fairing used on Atlas V. Vulcan will use a more evolved version of the OoA fairings.

STP-3 was the first operational mission of the GPS enhanced navigation. This navigation system improves the accuracy of the Atlas V and will be used on the SLS ICPS.

The first Vulcan using two GEM-63XLs will launch Astrobotic’s Peregrine lander. A second Vulcan, using four GEM-63XLs, will launch Sierra Space’s Dream Chaser to resupply the ISS. Vulcan will continue to launch Dream Chaser for six missions to the ISS.

(Lead image: render of a pair of GEM-63XLs separating from Vulcan during launch. Credit: Mack Crawford for NSF/L2) 

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