ULA ready for inaugural Vulcan flight

by Sawyer Rosenstein

United Launch Alliance (ULA) is preparing for the inaugural flight of its new Vulcan rocket from Space Launch Complex (SLC) 41 at the Cape Canaveral Space Force Station in Florida. Liftoff is currently scheduled for Jan. 8, 2024, at 2:18 AM EST (07:18 UTC).

Onboard this first flight will be Astrobotic’s Peregrine lunar lander, part of NASA’s Commercial Lunar Payload Services (CLPS) initiative and the Artemis program.

Vulcan Rocket

The Vulcan Centaur will replace the Delta IV family of rockets, which has one remaining flight in 2024, and ULA’s workhorse Atlas V, of which all remaining rockets have been purchased by and assigned to customers.

This also marks ULA’s first new launch vehicle in its fleet since the company was formed in 2006.

The Vulcan rocket stands 61.6 meters (202 feet) tall with a consistent diameter of 5.4 meters (18 feet). The company offers two different-length payload fairings, something it had also done with Atlas V. These include a 15.5-meter (51-foot) “short” fairing and a 21.3-meter (70-foot) “long” fairing. The short fairing will be used on this flight.

The Vulcan first stage is lifted into the Vertical Integration Facility (VIF) for processing. (Credit: ULA)

The first stage booster of the vehicle is made of aluminum orthogrid tanks that hold over 450 tonnes of liquid oxygen and liquid natural gas – the latter of which is nearly pure liquid methane. This is ULA’s first methalox vehicle – or vehicle that uses liquid oxygen as an oxidizer and a form of methane, in this case natural gas, as fuel.

The stage is powered by two BE-4 engines developed by Blue Origin. Each engine outputs 2.45 meganewtons (550,000 pounds) of thrust at sea level. Additional thrust is available with the use of GEM 63XL solid rocket boosters (SRBs) manufactured by Northrop Grumman Space Systems. Vulcan is available with either zero, two, four, or six SRBs. Vulcan’s inaugural flight will feature two mounted SRBs.

The GEM-63XL boosters are constructed out of a graphite-epoxy composite with the throttle profile pre-formed into the propellant grain. Standing 21.8 meters (71.8 feet) tall, each booster produces a peak vacuum thrust of 2.04 meganewtons (460,000 pounds).

A GEM 63XL solid rocket booster is mounted to Vulcan’s first stage. (Credit: ULA)

Centaur Second Stage

Following the depletion of the SRBs and the first stage, the core will separate from the Centaur V second stage. While the Centaur stage can trace its roots back to 1958, Vulcan marks the first redesign of the fully cryogenic Centaur since 2002.

The Centaur V, which will fly on Vulcan, compared to the Atlas V’s Centaur III. (Credit: ULA)

Powered by liquid hydrogen and liquid oxygen, the 5.4-meter (18-foot) diameter Centaur V is powered by two RL-10 engines from Aerojet Rocketdyne. Capable of multiple relights, the stage has a maximum thrust of 213.5 kilonewtons (48,000 lbs).

Centaur Anomaly

During a propellant loading and tank pressurization test at NASA’s Marshall Space Flight Center on March 29, 2023, a test article of the Centaur V upper stage was destroyed after a hydrogen leak ignited.

A different Centaur upper stage, which at that point was attached to and ready to fly aboard this inaugural Vulcan launch, was sent back to the company’s manufacturing facility in Decatur, Alabama following the explosion.

According to ULA CEO Tory Bruno, a leak formed near the top of the tank dome, releasing hydrogen for four and a half minutes into an enclosed space. Bruno says it then found an ignition source, causing a large fireball.

An additional stainless-steel ring was added to help strengthen that area. To help the launch campaign progress, the Centaur V slated for Vulcan’s third flight was instead modified and shipped via barge to the launch site and will fly on flight one.

Vulcan’s Launch Campaign

In 2015, ULA announced its plans to slowly introduce a new launch vehicle which we now know as Vulcan. Later that year, it announced it would do away with the Russian-designed RD-180 engines used aboard Atlas in place of the BE-4s, which were designed to burn liquid methane and liquid oxygen.

BE-4 engine as seen during the Flight Readiness Firing. (Credit: ULA)

The original design for the second stage was to use the current Centaur III and later upgrade to the much larger and more capable Advanced Cryogenic Evolved Stage (ACES). The ACES concept was eventually shelved, and in 2017, the company decided to instead create a single second stage, incorporating design elements from both Centaur III and ACES.

In 2019, it was announced that the first flight would take place no earlier than July 2021 with Peregrine as the payload.

In December 2020, ULA stated the BE-4 engines for the flight wouldn’t be delivered until mid-2021, further delaying the flight. Then, Astrobotic announced that it would need more time to work on the vehicle because of the COVID-19 pandemic, delaying the launch into 2022 before pushing further to 2023.

ULA was also waiting on the qualification of the first-stage engine which, according to the Government Accountability Office, was experiencing technical difficulties.

A pathfinder first stage made it to SLC-41 in early 2021 for first-stage cryogenic testing. After additional testing, the Vulcan booster for the first flight was on the pad in June 2023 for a six-second “flight readiness firing” of its BE-4 engines.

The vehicle was rolled back to the Vertical Integration Facility (VIF) where it was integrated with the Centaur upper stage in November 2023.

In December 2023, the vehicle attempted a wet dress rehearsal (WDR), however, Bruno noted that ground-side leaks interfered with completing the test, saying he wanted to see a full WDR before flight one. That full WDR was completed successfully just days later.

Vulcan’s payload fairing, with the payloads already inside, is placed atop the rocket. (Credit: ULA)

Finally, the payload was integrated with the launch vehicle on Dec. 20, 2023, marking the first fully stacked flight-ready Vulcan Centaur.

CERT-1 Payloads

Astrobotic’s Peregrine Mission One is set to be one of the first US landers on the Moon since Apollo 17 in December 1972.

Astrobotic is one of 14 CLPS contractors. The goal is to conduct scientific experiments to better understand the Moon before the landing of the first astronauts of the Artemis program on Artemis III.

The Peregrine lander prior to encapsulation inside the fairing. Credit: ULA

The Peregrine lander, following launch aboard Vulcan, is scheduled to land in February 2024 at a lunar feature called Sinus Viscositatis near the largest dark spot on the near side of the Moon. The site was chosen as NASA calls it a “geologic enigma.” The area, a region of mare that is made of a basaltic lava flow, is just outside of the Gruithuisen Domes, or a set of large domes which are not basaltic.

“The Domes are suspected to have been formed by a sticky magma rich in silica, similar in composition to granite,” NASA said in a release. “On Earth, formations like these need significant water content and plate tectonics to form, but without these key ingredients on the Moon, lunar scientists have been left to wonder how these domes formed and evolved over time.”

Image of the Gruithuisen Domes at Peregrine’s landing site as seen from the Lunar Reconnaissance Orbiter. (Credit: NASA/GSFC/Arizona State University)

Aboard the lander will be five NASA payloads aimed at collecting data on possible water molecules just underground, on the surface, and in the lunar exosphere. Additional onboard experiments will study how solar radiation interacts with the lunar surface to prepare for when humans arrive.

That will be done with the help of different spectrometers to gather the data. In addition, a laser retroreflector array will be placed on the surface. Similar to the reflectors left on the lunar surface by Apollo crews, this collection of eight retroreflectors allows for laser ranging.

The reflections can then be used to measure distance as a permanent marker on the Moon. In all, the lander will carry 20 different payloads.

The Laser Retroreflector Array payload. (Credit: NASA/GSFC)

The secondary payload is part of Celestis Memorial Spaceflights. The deep space Voyager mission is known as the Enterprise flight.

This includes a capsule that, once released, will launch itself towards interplanetary space. According to Celestis, this includes, “…specially manufactured and inscribed individual flight capsules containing cremated remains, complete human genome individual DNA samples, and names and messages of well-wishers from around the globe.”

The “crew” includes Star Trek creator Gene Roddenberry and his wife Majel, the DNA of their son Eugene “Rod” Roddenberry, James Doohan, DeForest Kelley, Nichelle Nichols, and the DNA of her son Kyle Johnson.

Flight Profile

Vulcan’s configuration for this launch is known as VC2S. The V stands for Vulcan with C standing for Centaur. The 2 is the number of SRBs, and the S is the payload fairing length, meaning this will be using the short fairing length as opposed to the long fairing, which would be notated with an L.

The first major step will be loading propellants onto the vehicle, which includes the liquid natural gas and liquid oxygen for the first stage and the liquid hydrogen and liquid oxygen for the second stage. For this first flight, ULA has not released the exact timings and procedures for how this will occur.

The flight profile for the Cert-1 mission. (Credit: ULA)

At T-5 seconds, the BE-4 engines ignite, followed by liftoff at T+1 second before beginning its pitch maneuver.

After passing through max-Q, or maximum aerodynamic stress on the vehicle at T+1 minute 16 seconds, the SRBs will finish their portion of the flight. At T+1:50, the SRBs will be jettisoned. The first stage will continue burning until T+4:59 at which point booster engine cutoff, or BECO, will occur. That’s followed five seconds later by the separation of the first and second stages.

The vehicle coasts for an additional ten seconds before igniting the Centaur’s main engines at T+5 minute 15 seconds. This is then followed by payload fairing separation at T+5:23, exposing the payloads to space.

Centaur will continue firing until its first main engine cutoff at T+15 minutes 45 seconds.

That begins a coast phase until T+43 minutes 35 seconds when Centaur reignites for 4 minutes and 2 seconds for the second burn.

At T+50:26, the Peregrine lander, which is expected to be at an altitude of 490 kilometers and an inclination of 30.03 degrees, will separate.

One final 20-second burn of Centaur occurs at T+1:18:23, likely to dispose of the stage and ensure clearance from Peregrine. The official end of the mission is expected at T+4:24:44.

(Lead image: ULA’s first Vulcan rocket stands assembled inside the Vertical Integration Facility. Credit: ULA)

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