United Launch Alliance technicians in Cape Canaveral, Florida, partially disassembled the first Vulcan rocket to return the launch vehicle’s upper stage to its factory for reinforcements to its thin-steel fuel tank.
A test article of the Vulcan Centaur V rocket’s upper stage exploded on March 29 during a structural test at NASA’s Marshall Space Flight Center in Alabama. After an investigation that lasted nearly three months, ULA engineers determined that the upper stage already installed on the first Vulcan rocket rated to fly inside an aircraft hangar in Florida needed more work.
ULA hasn’t ruled out launching the company’s first new Vulcan rocket by the end of the year, but recovery from the test stand explosion in March eliminated any chance of getting a Vulcan off the ground this summer. It also means that the Vulcan missile won’t become operational for the US Army until sometime next year, after two “certification” flights to prove the vehicle’s performance and reliability.
The US Space Force is eager to put the Vulcan into service. The Pentagon selected ULA and SpaceX in 2020 to launch about 40 of the military’s most important surveillance, communications, and navigation satellites from 2022 to 2028. ULA won launch rights for about 60 percent of the missions, primarily using the new Vulcan rocket, with SpaceX taking the 40 percent. The remaining 100 are with the Falcon family of missiles.
The Vulcan missile will replace the Atlas and Delta launch vehicles flown by ULA, a 50-50 joint venture between Boeing and Lockheed Martin. There was only one Delta missile left in ULA’s inventory before retirement, and 19 more Atlas V launchers remained in ULA’s backlog. All of these missiles are already reserved for customers.
Gary Wentz, ULA’s vice president of government and commercial programs, confirmed previous reports from Ars that the first Vulcan launch is now targeted for no later than the fourth quarter of this year.
The Centaur V’s upper stage for Vulcan’s first launch has been detached from the Vulcan booster to prepare for shipment back to the factory, according to Jessica Ray, a spokeswoman for ULA.
In a statement, ULA described the work required on the Centaur V upper stage as “slight reinforcement at the top of the forward dome,” or the top of the liquid hydrogen tank. The changes will add power to the tank, which contains highly flammable fuel cooled to minus 423 degrees Fahrenheit (minus 253 degrees Celsius).
Wentz said the test stand explosion on March 29 was caused by liquid hydrogen leaking on the front bulkhead of the Centaur V upper stage.
“And then basically what happened is we got such a large concentration of hydrogen gas that it found an ignition source outside the car and ignited,” Wentz said.
“Ultra-thin, high-performance steel skin should be thicker near the top of the dome,” tweeted Tory Bruno, CEO of ULA. The steel walls of the Centaur’s upper-stage pressure-mounted fuel tanks are as thin as 0.02 inch, or half a millimeter, in places.
Wentz said the investigation concluded that the problem was “relatively easy” to solve. The production team at ULA is preparing another article to test the Centaur V at the factory in Decatur, Alabama, for a second attempt at ground testing that was cut short by the explosion in March.
The Vulcan booster and payloads are ready to go
Meanwhile, ULA’s launch crew at Cape Canaveral will also remove the Vulcan booster stage from its launch pad and store it horizontally in another hangar until the company is ready to resume launch preparations. ULA plans to launch a pair of Atlas V rockets this summer and fall from the same launch pad that Vulcan will use.
ULA aimed to launch its first Vulcan rocket in 2019 when the company announced the program in 2015. A development problem with the new BE-4 methane-fueled first-stage engines, designed by Jeff Bezos’ aerospace company Blue Origin, was responsible for most of the delay. In the inaugural Vulcan flight.
But now the first stage, with two BE-4 engines ready to fly, was ready for launch. ULA test fired the rocket at its launch pad in Florida on June 7, and the company says the “ready-to-fly launch” met all of the goals.
The main payload for the first Vulcan launch has also been completed and is in storage until trucking to Cape Canaveral. The rocket’s first flight will send a commercial lander built by Astrobotic to the moon with a suite of experiments and technical experimental payloads for NASA. Two test satellites of Amazon’s Kuiper broadband network will journey into space on the first Vulcan rocket.
It turns out that the problem holding Vulcan now is a part of the rocket with a design rooted in the early years of the Space Age. Centaur V is a larger, updated, twin-engine version of the Centaur upper stage, which has flown 268 missions since 1962.
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