Delta IV Heavy launch: Scrub of historic launch, next attempt to be determined

The wait will continue to see the powerful Delta IV Heavy rocket blast off on its retirement flight.

With minutes to go until the planned 2:45 p.m. target liftoff Thursday for the Delta IV Heavy and weather just at the edge of acceptable, the launch scrubbed. United Launch Alliance CEO Tory Bruno said winds exceeded the acceptable limit, causing a hold, and that was when a gaseous nitrogen pipeline ground pump failed. The pump provides pneumatic pressure to the launch vehicle systems.

ULA said they would do a 24-hour turnaround, and the launch was then planned for 1:37 p.m. Friday.

But Bruno later posted on X, formerly known as Twitter, that the "pump failed again ... Stand by."

Just before 8 p.m., ULA said they'd be standing down to continue to work on the pipeline.

"The team continues to troubleshoot the pipeline and more time is needed to instill confidence in the system," the company said in a statement. "We will continue to work with our customer to confirm our next launch attempt and a new date will be provided upon resolution."

There is launch attempt availability on Monday at 1:25 p.m., according to the Federal Aviation Administration, but it's unknown whether ULA will be ready for that launch window. Stay tuned to FLORIDA TODAY Space Team's coverage of this end-of-an-era flight.

The Delta IV Heavy, which is bound for retirement, will send a classified payload into orbit for the National Reconnaissance Office on the NROL-70 national security mission.

Cape Canaveral: Is there a launch today? Upcoming rocket launch schedule for SpaceX, NASA in Florida

2:47 p.m.: SCRUB. 24 hour turn around at earliest

It's a scrub. There will be a 24-hour turnaround at the earliest. No launch today. The teams have begun de-tanking the fuel from the Delta IV Heavy rocket.

HOLD HOLD HOLD

Launch was put on hold. Countdown clock will be reset. Stay tuned.

2:38 p.m. Go to launch of Delta IV Heavy on its final launch

Final launch check: GO for launch!

The launch vehicle is ready to launch.

Weather is green right now. If that changes as the team proceeds toward the final minutes of launch, we'll hear the launch control room call "Hold. Hold. Hold." That will stop the countdown and keep the rocket on the pad at Launch Complex 37.

But right now, we're green and heading toward a 2:45 p.m. liftoff on the final flight of the Delta IV Heavy.

2:35 p.m. 10 minutes to final launch of Delta IV Heavy

We're 10 minutes from launch of the final Delta IV Heavy rocket from Cape Canaveral Space Force Station Launch Complex 37. Launch target time is 2:45 p.m.

Weather remains near the limit acceptable for launch.

There is a longer window if needed but right now that 2:45 p.m. launch time remains the target.

2:30 p.m. Delta IV Heavy target launch 15 minutes away

Here are few things to keep in mind as we get closer to the target liftoff time at 2:45 p.m.

The countdown has proceeded smoothly other than weather concerns, and that's mainly wind at this point.

If we do get to launch today, the three RS-68A engines will fire at T- 5 Seconds to liftoff, giving off the thrust to push the three boosters off the pad. After liftoff, Delta IV Heavy will reach Maximum Dynamic Pressure (Max Q) at 1 minute and 20 seconds into the flight.

The crowds at Kennedy Space Center Visitor Complex are ready.

2:20 p.m. Winds still a concern for Delta IV Heavy launch

ULA says that Launch Weather Officer Mark Burger reported the current and forecast conditions are close to the threshold for acceptable criteria for the Delta IV Heavy liftoff at 2:45 p.m. today.

The team will continue to monitor the winds.

Stay tuned. At this point, no technical issues are being worked. It's all about the weather right now.

2:05 p.m. No tech issues being worked as Delta IV Heavy counts down

The Delta IV Heavy is counting down to its planned 2:45 p.m. liftoff. The one issue: weather.

Teams continue to monitor the weather.

Meanwhile, the Kennedy Space Center Visitor Complex is jam-packed. It took our reporter, Brooke Edwards, two hours to get in. Excitement is building as the launch time approaches.

2 p.m.: Delta IV Heavy launch won't produce sonic booms

What can you expect with the final Delta IV Heavy launch: a powerful rocket that should soar into the sky after seeming to emerge from a cloud of fire. There will be a rumble and depending on where you are and the wind, it could be loud.

But what you shouldn't be waiting for: sonic booms. There are no sonic booms with this launch.

Why not? The rocket’s boosters will fall back out to sea. They are not reusable unlike SpaceX launches where the boosters sometimes come back for a landing at the Cape, triggering the sonic booms. Want to know more about sonic booms, click here.

Countdown continuing for 2:45 p.m. planned launch.

1:45 p.m. One hour to planned final launch of Delta IV Heavy; winds a concern

Launch team has entered the planned, built-in T-minus 4 minutes hold and now will sync up with the target launch time of 2:45 p.m.

United Launch Alliance says this built-in hold is designed to give their teams a bit of margin to deal with any problems. Also during this time, the final readiness polls of the launch team and members of the mission management team will be performed.

Launch is still targeting a 2:45 p.m. blast off from Launch Complex 37 at Cape Canaveral Space Force Station. ULA said they are not working any technical issues but winds remain a concern.

1:30 p.m. Experienced launch director overseeing final Delta IV Heavy launch

United Launch Alliance has a launch director with more than a dozen missions under his belt in charge of today's final launch of the Delta IV Heavy.

His name is Tom Heter III. His father, Tom Heter II, worked on Atlas and Titan rockets.

Countdown toward the 2:45 p.m. liftoff is proceeding.

1:20 p.m. Delta IV Heavy launching from Cape's Launch Complex 37

The Delta IV Heavy will be launching from Cape Canaveral Space Force Station's Launch Complex 37.

It was constructed in 1963 and used for uncrewed Apollo missions aboard Saturn I and IB rockets. Then it became home to the triple-core Delta IV Heavy rocket.

While previous iterations of rockets in the Delta family began launching from this pad in the early 2000s, they've all since been retired.

SpaceX is interested in possibly taking over this launch pad for its massive Starship rocket.

Want to see where other rockets launch from on the Cape, here's a great guide below:

What launches where: Years after space shuttle retirement, Florida chases nearly 70 launches a year

1:15 p.m. ULA CEO on final Delta IV Heavy "bittersweet" launch

Tory Bruno, the CEO and president of ULA, reflected on the Delta IV Heavy's success during a Wednesday afternoon press conference.

“It’s a bittersweet moment for us. This is such an amazing piece of technology. Twenty-three stories tall. Half a million gallons of propellant. Two and a quarter million pounds of thrust. And the most metal of all rockets —setting itself on fire before it goes to space," said Bruno.

The countdown is proceeding as planned toward a 2:45 p.m. scheduled liftoff.

1:05 p.m. Traffic backed up around Cape ahead of Delta IV Heavy launch

Our photographer, Craig Bailey, who is out at the Cape for the launch said it's packed. Our Space Reporter Brooke Edwards is making her way to Kennedy Space Center Visitor Complex and said she's been stuck in traffic for awhile now.

Brevard County is crowded already with spring breakers from out of town, and our own public school students are on spring break this week, too.

Expect crowds at our beaches if you're going to watch. Here's a guide on where to go to see it. Scroll down for viewing locations.

1 p.m.: Weather is "green" now for final Delta IV Heavy launch

The weather is "green" now meaning there are no weather violations. That doesn't mean it's going to stay that way through the liftoff time. But we can hope!

ULA teams continue to make final preparations ahead of the planned 2:45 p.m. launch time.

"The standard post-fueling inspections of the rocket's outer thermal insulation is underway using launch pad cameras," ULA said. The cyrogenic tanks are covered with foam insulation to keep the fuel from warming up too quickly.

12:45 p.m: Two hours to final launch of Delta IV Heavy from Cape

We're two hours away from the final launch of the Delta IV Heavy. It's windy here on the Space Coast and weather remains the primary concern as the countdown proceeds.

With this flight, the storied Delta rocket program retires. It is being replaced by the Vulcan Centaur. The red-and-white Vulcan made its maiden flight from Cape Canaveral Space Force Station on January 8.

The Delta IV Heavy rocket first took to the skies over Cape Canaveral in 2004. Its first NRO mission from the Cape was in 2009.

The rocket today is, as ULA puts it, "loaded for launch." Weather still showing a "red" meaning no-go but there's time.

12:05 p.m. Weather currently "red" for launch but there's time to improve

The weather right now is currently "red" for launch which means no-go. But the launch target time is 2:45 p.m. so there's time to improve.

A cold front is moving through the Space Coast right now and that's what's causing the "red" weather conditions. Remember, there was only a 30 percent chance of acceptable weather for lift-off. The situation does improve if the launch moves to Friday to a 60 percent chance of good weather. But there's still plenty of time to hope for a liftoff today.

Noon: New liftoff time for Delta IV Heavy of 2:45 p.m.

From ULA: ULA Launch Director Tom Heter III has instructed the launch team to coordinate a new liftoff time of 2:45 p.m. EDT (1845 UTC) for the Delta IV Heavy rocket on the NROL-70 mission from Cape Canaveral.

11:50 a.m. Delta IV Heavy will launch secretive NRO mission

What's launching today on the Delta IV Heavy? We know it's a mission for the National Reconnaissance Office. Beyond that, not too much information has been released.

These are usual secretive missions. United Launch Alliance will be providing updates up to and throughout the launch but those will end with payload fairing separation at the request of the NRO.

What we do know is this mission has a cool emblem of a snow leopard. “The snow leopard illustrates the quiet strength with which we provide an advantage to the nation and its allies," the NRO said in a press release.

11:30 a.m. When Delta IV Heavy lifts off, get ready for massive power

The Delta IV Heavy has the reputation for being "the most metal of rockets" because it roars to life amid a blazing hydrogen fireball. It's a performance and today, if all things and especially weather cooperate, will be its final one.

The final step in the fueling operation is underway now, United Launch Alliance said. The team said they are loading 10,000 gallons of liquid hydrogen into the Delta Cryogenic Second Stage.

One thing to remember: the rocket uses three RS-68A main engines, which generate 2.1 million pounds of thrust at liftoff.

11:05 a.m. Liftoff time now targeting 2:03 p.m.

United Launch Alliance tweeted that we are now three hours from liftoff. A new liftoff time has been set at 2:03 p.m.

Weather remains the main concern.

11 a.m. Great White Shark and Delta IV Heavy?

In a pairing that makes sense, a massive great white shark pinged off Cape Canaveral this morning, according to OCEARCH scientists. The nearly 14-foot, 1,700-pound shark, nicknamed Mahone by OCEARCH, pinged in the waters southeast of Cape Canaveral at 5:45 a.m. Thursday.

A ping means the Smart Position and Temperature Transmitting Tag (SPOT) tag attached to the shark's dorsal fin broke the water's surface and transmitted location information to trackers.

10:40 a.m. "Go" to begin preparing Delta IV Heavy tanks for fueling

United Launch Alliance said the launch team has given a "go" to chilldown the three booster cores. This is the step needed before they can fill them with propellent.

This is the 16th and final flight of the Delta IV Heavy and the 45th Delta IV launch. Today's launch will truly be the end of an era.

10:30 a.m. Delta IV Heavy Countdown - Weather a concern

Weather remains the biggest concern today as the countdown ticks toward the final launch of the Delta IV Heavy. There is a 30 percent chance of favorable weather conditions.

The United Launch Alliance team is monitoring strong winds in the area from the passage of a cold front. Here's what they say are anticipating from the weather: some scattered clouds, good visibility, northwesterly winds 25 to 30 knots and temperatures in the low 70s.

For the latest news and launch schedule from Cape Canaveral Space Force Station and NASA's Kennedy Space Center, visit floridatoday.com/space.

Rick Neale is a Space Reporter at FLORIDA TODAY (for more of his stories, click here.) Contact Neale at 321-242-3638 or [email protected]. Twitter/X: @RickNeale1

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This article originally appeared on Florida Today: RECAP of ULA Delta IV Heavy rocket launch scrub: next attempt uncertain