The ULA heavy-lifter took off from pad 37B at Cape Canaveral Space Force Station at 8:09 p.m. EST on Dec. 10 (0109 GMT on Dec. 11) with a classified payload for the National Reconnaissance Office, the U.S. government’s spy satellite agency.

The Delta 4-Heavy’s three Aerojet Rocketdyne RS-68A main engines produced 2.1 million pounds of thrust, equivalent to 51 million horsepower, to power the launcher off the pad.

The rocket’s upper stage delivered the mission’s top secret cargo to its targeted orbit thousands of miles above Earth around six hours later. ULA confirmed the mission was a success.

The launch marked the 12th flight of a Delta 4-Heavy rocket since 2004, and the 41st flight of ULA’s Delta 4 rocket family overall.

Read our full report for details on the mission.

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Running more than three months late, a United Launch Alliance Delta 4-Heavy rocket took off Thursday and carried a U.S. government spy satellite into an orbit thousands of miles above Earth in the first mission from the newly-renamed Cape Canaveral Space Force Station.

The 235-foot-tall (71-meter) rocket lifted off from pad 37B at Cape Canaveral at 8:09 p.m. EST Thursday (0109 GMT Friday) with thrust from three hydrogen-fueled RS-68A engines producing 2.1 million pounds of thrust, equivalent to 51 million horsepower.

The orange and white launch vehicle — the most powerful in ULA’s fleet — soared into a starry sky over Florida’s Space Coast, targeting a trajectory toward the east from Cape Canaveral over the Atlantic Ocean.

A classified payload for the National Reconnaissance Office, owner of the U.S. government’s spy satellite fleet, was secured inside the Delta 4-Heavy’s nose cone for the rocket’s climb away from pad 37B.

The rocket’s three Aerojet Rocketdyne RS-68A engines steered the Delta 4-Heavy on an easterly course. The two side booster cores shut down and jettisoned to fall into the Atlantic ocean around four minutes after liftoff.

The Delta 4-Heavy’s center core stage throttled up its engine to full power after running in a fuel-saving partial thrust mode for the early minutes of the mission. Just before exhausting its propellant supply, the RS-68A center engine shut down and the core stage separated, leaving the second stage’s RL10 engine — also made by Aerojet Rocketdyne — to perform multiple firings to place the NRO’s newest spy satellite into orbit.

The launcher’s payload shroud separated about six-and-a-half minutes into the mission. The rest of the launch sequence occurred in secret due to a government-imposed new blackout intended to keep certain mission details under wraps — a standard practice for missions with NRO satellites.

ULA’s live broadcast ended at that point, and the company remained silent about the progress of the multi-hour launch sequence until around 2:20 a.m. EST (0720 GMT) Friday, when ULA issued a press release confirming a successful conclusion to the Delta 4-Heavy mission.

“We are honored to launch the first payload from the newly-renamed Cape Canaveral Space Force Station. I want to thank our mission partners for their collaboration and teamwork as we worked through technical challenges that culminated in the launch of this critical national security payload,” said Gary Wentz, ULA vice president of government and commercial programs.

The Florida launch base, formerly known as Cape Canaveral Air Force Station, was officially renamed Wednesday during a visit by Vice President Mike Pence. Nearby Patrick Air Force Base was also renamed as Patrick Space Force Base, and the two facilities are the first in the Defense Department to get a new Space Force designation.

The new names reflect the next step in the evolution of the U.S. Space Force, which was established nearly a year ago to take over most of the Air Force’s space operations.

“The Delta 4-Heavy again demonstrated its success as the nation’s proven heavy lift vehicle, through its unique capability to deliver this mission to orbit due to a combination of performance and fairing size,” Wentz said in a statement.

The NRO published no details about the payload on the Delta 4-Heavy mission, which officials designated NROL-44.

But independent analysts say publicly-known parameters such as the rocket’s capabilities, its launch azimuth, and the launch window suggested the Delta 4-Heavy was carrying a signals intelligence satellite into geosynchronous orbit more than 22,000 miles (nearly 36,000 kilometers) above Earth and closely hugging the equator.

Reaching such an orbit required the rocket to follow one of the most challenging flight profiles in the launch business, with three burns expected by the Delta’s upper stage to deploy its satellite payload at the targeted altitude.

Four previous Delta 4-Heavy launches in 2009, 2010, 2012 and 2016 followed similar trajectories after taking off from Cape Canaveral, each carrying a classified cargo for the National Reconnaissance Office. Independent analysts believe all delivered top secret NRO eavesdropping satellites to space.

In a “press kit” released before the launch, the NRO said the NROL-44 mission supports the agency’s “overall national security mission to provide intelligence data to the United States’ senior policy makers, the intelligence community and Department of Defense.”

But the satellite is likely related to the NRO’s fleet of “Advanced Orion” or “Mentor” signals intelligence stations flying in equatorial geosynchronous orbits. The Advanced Orion-series satellites began launching on Titan 4 rockets in 1995, following a pair of earlier NRO Orion payloads that launched in the 1980s on space shuttle missions.

The NRO began using Delta 4-Heavy rockets for the Advanced Orion missions in 2009, following the retirement of the Titan 4 booster.

Like the previous Delta 4-Heavy launches with Advanced Orion satellites, the launch time moved around four minutes earlier each day.

“The use of the Delta 4-Heavy, the eastward trajectory, and the four minute per day earlier time of liftoff, point to the launch of the eighth Advanced Orion satellite,” said Ted Molczan, an authoritative skywatcher who tracks satellite activity.k  “This signals intelligence spacecraft is so large, that when seen from Earth, it shines with the brightness of an 8th magnitude star, making it easily visible with small binoculars.”

Before the launch in 2010 of a suspected Advanced Orion satellite, then-director of the NRO Bruce Carlson called the payload the “the largest satellite in the world.” The satellites are believed to carry giant antennas that unfurl to a diameter of up to 100 meters, or 328 feet, once in space.

The antenna can likely be tuned to listen in on telephone calls, collect data transmissions, and eavesdrop on other communications among U.S. adversaries.

The geographic coverage area for the satellite launched Thursday night is unknown, but the Advanced Orion spacecraft span the world, flying at just the right altitude to orbit the Earth at the same rate the planet rotates. That allows the satellites to remain fixed over the same region of the planet.

It’s also not known whether the new satellite will replace an aging member of the Advanced Orion fleet, or expand the network’s coverage.

In that orbit, the satellite is expected to unfurl a giant football field-sized antenna to eavesdrop on telephone calls and other data traffic from U.S. adversaries.

The Advanced Orion satellites require the combination of the Delta 4-Heavy rocket’s lift capability, long-duration upper stage, and huge 65-foot-long (19.8-meter) trisector payload fairing.

ULA set Sept. 26 a 50-50 joint venture between Boeing and Lockheed Martin, first tried to launch the Delta 4-Heavy rocket and the NROL-44 mission in late August.

The launch company’s original launch date for the NROL-44 mission was Aug. 26, but the NRO requested a one-day delay before the countdown could begin. A  pneumatics issue prevented the rocket from launching Aug. 27, and the Aug. 29 countdown stopped when the automated launch sequencer detected a problem with a pressure regulator on the launch pad designed to flow helium gas to spin up rocket’s center engine for ignition.

ULA set Sept. 26 as the target launch date for the NROL-44 mission, but officials delayed the mission again to investigate a concern with the swing arm retraction system at the Delta 4-Heavy’s seaside launch complex at Cape Canaveral. The swing arms, which feed liquid propellants and conditioned air to the vehicle, are designed to quickly retract away from the rocket at liftoff.

Bad weather and a hydraulic leak in hardware associated with the launch pad’s mobile gantry forced ULA officials to call off a pair of launch attempts in late September.

Another launch attempt Sept. 30 was halted at T-minus 7 seconds, just before ignition of the rocket’s three hydrogen-fueled RS-68A main engines. Engineers traced that problem to a bad sensor reading involving a valve position inside one of the RS-68A engines.

While that problem was resolved, ULA encountered deeper issues with the swing arms at pad 37B.

Tory Bruno, ULA’s president and CEO, tweeted that technicians drained 2,000 gallons of oil from the hydraulic swing arm retraction system. Teams replaced several dozen valves and “several other important items” before recharging the system with fresh hydraulic fluid, Bruno tweeted.

“Mission success is the priority,” he added.

The repeated problems with different parts of the Delta 4-Heavy’s launch pad have raised questions about aging infrastructure at pad 37B, which was originally built to support Saturn rocket launches in the 1960s, then mothballed until Boeing took over the facility in the 1990s for the Delta 4 program.

Boeing built the towering mobile gantry for the Delta 4 rocket, along with a then-new fixed umbilical tower with the three huge retractable swing arms.

ULA is retiring the Delta 4 rocket family after four more launches — two more from Cape Canaveral and two from Vandenberg Air Force Base in California. The company’s next-generation Vulcan Centaur rocket, scheduled to debut in the second half of next year, will replace ULA’s existing Delta 4 and Atlas 5 launch vehicles.

Vulcan Centaur rockets will sell for a fraction of the price of a Delta or Atlas 5, according to ULA.

While SpaceX’s Falcon Heavy rocket is significantly less expensive and can lift heavier payloads into low orbits, the Delta 4-Heavy has demonstrated an ability to inject satellites directly into high-altitude circular geosynchronous orbits more than 22,000 miles (nearly 36,000 kilometers) above Earth.

The Delta 4-Heavy also has a larger payload fairing than the Falcon Heavy, and the mobile shelters at Cape Canaveral and Vandenberg allow ground crews to mate satellites to the rocket in a vertical orientation. SpaceX plans to offer an enlarged payload shroud on the Falcon Heavy and build a vertical integration hangar at the Kennedy Space Center to support future national security missions that can currently only fly on the Delta 4-Heavy.

The launch Thursday night was the 41st flight in the history of the Delta 4 rocket program, and the 12th to use the Delta 4-Heavy rocket configuration.

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United Launch Alliance’s live launch broadcast begins at 7:45 p.m. EST Thursday, Dec. 10 (0045 GMT Friday, Dec. 11).

United Launch Alliance is set to try again to launch a Delta 4-Heavy rocket and a classified U.S. government spy satellite Thursday after delays of more than three months caused by persistent issues with the mission’s launch pad.

The mission is set to take off at 6:15 p.m. EST (2315 GMT) Thursday from pad 37B at the newly-renamed Cape Canaveral Space Force Station in Florida. Forecasters predict near-ideal weather with a 90% chance of favorable conditions during the launch window Thursday evening.

The Florida launch base, formerly known as Cape Canaveral Air Force Station, was officially renamed Wednesday during a visit by Vice President Mike Pence. Nearby Patrick Air Force Base was also renamed as Patrick Space Force Base.

The new names reflect the next step in the evolution of the U.S. Space Force, which was established nearly a year ago to take over most of the Air Force’s space operations.

The Delta 4-Heavy rocket is set to haul a top secret payload into orbit for the National Reconnaissance Office, the U.S. government’s spy satellite agency. The mission is codenamed NROL-44.

ULA, a 50-50 joint venture between Boeing and Lockheed Martin, first tried to launch the Delta 4-Heavy rocket in late August.

The launch company’s original launch date for the NROL-44 mission was Aug. 26. A pneumatics issue prevented the rocket from launching Aug. 27, and the Aug. 29 countdown stopped when the automated launch sequencer detected a problem with a pressure regulator on the launch pad designed to flow helium gas to spin up rocket’s center engine for ignition.

The regulator for the center engine did not open, prompting the countdown’s computer controller to stop the countdown during thee engine startup sequence.

Bruno said that engineers refurbished and tested all three pressure flow devices at pad 37B before proceeding with another launch attempt.

ULA set Sept. 26 for the next launch attempt for the NROL-44 mission, but officials delayed the mission again to investigate a concern with the swing arm retraction system at the Delta 4-Heavy’s seaside launch complex at Cape Canaveral. The swing arms, which feed liquid propellants and conditioned air to the vehicle, are designed to quickly retract away from the rocket at liftoff.

Bad weather and a hydraulic leak in hardware associated with the launch pad’s mobile gantry forced ULA officials to call off a pair of launch attempts in late September.

Another launch attempt Sept. 30 was halted at T-minus 7 seconds, just before ignition of the rocket’s three hydrogen-fueled RS-68A main engines. Engineers traced that problem to a bad sensor reading involving a valve position inside one of the RS-68A engines.

While that problem was resolved, ULA encountered deeper issues with the swing arms at pad 37B. Three swing arms feeding propellants and conditioned air to the rocket and its satellite payload are designed to retract as the Delta 4-Heavy lifts off.

Tory Bruno, ULA’s president and CEO, tweeted that technicians drained 2,000 gallons of oil from the hydraulic swing arm retraction system. Teams replaced several dozen valves and “several other important items” before recharging the system with fresh hydraulic fluid, Bruno tweeted.

“Mission success is the priority,” he added.

The repeated problems with different parts of the Delta 4-Heavy’s launch pad have raised questions about aging infrastructure at pad 37B, which was originally built to support Saturn rocket launches in the 1960s, then mothballed until Boeing took over the facility in the 1990s for the Delta 4 program.

Boeing built the towering mobile gantry for the Delta 4 rocket, along with a then-new fixed umbilical tower with the three huge retractable swing arms.

ULA is retiring the Delta 4 rocket family after five more launches — three more from Cape Canaveral and two froom Vandenberg Air Force Base in California. The company’s next-generation Vulcan Centaur rocket, scheduled to debut in the second half of next year, will replace ULA’s existing Delta 4 and Atlas 5 launch vehicles.

While SpaceX’s Falcon Heavy rocket is significantly less expensive and can lift heavier payloads into low orbits, the Delta 4-Heavy has demonstrated an ability to inject satellites directly into high-altitude circular geosynchronous orbits more than 22,000 miles (nearly 36,000 kilometers) above Earth.

The maneuvers required for such an orbital injection take place over roughly six hours. While the payload on the NROL-44 mission is classified, independent analysts say publicly-known parameters such as the rocket’s capabilities, its launch azimuth, and the launch window suggest the Delta 4-Heavy is set to carry a signals intelligence satellite into geosynchronous orbit.

In that orbit, the satellite is expected to unfurl a giant football field-sized antenna to eavesdrop on telephone calls and other data traffic from U.S. adversaries.

The Delta 4-Heavy also has a larger payload fairing than the Falcon Heavy, and the mobile shelters at Cape Canaveral and Vandenberg allow ground crews to mate satellites to the rocket in a vertical orientation. SpaceX plans to offer an enlarged payload shroud on the Falcon Heavy and build a vertical integration hangar at the Kennedy Space Center to support future national security missions that can currently only fly on the Delta 4-Heavy.

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Follow Stephen Clark on Twitter: @StephenClark1.

United Launch Alliance engineers have resolved the problem that triggered an abort of a planned Delta 4-Heavy rocket launch Sept. 30, but the company said Friday it is continuing to evaluate a concern with the launch pad swing arm retraction system at Cape Canaveral.

ULA said the Delta 4-Heavy’s mission to launch a classified National Reconnaissance Office spy satellite will be postponed beyond next week.

The launch provider, a 50-50 joint venture between Boeing and Lockheed Martin, said Friday that the Delta 4-Heavy launch date was now “indefinite” on the Eastern Range, which oversees launch operations at Cape Canaveral Air Force Station.

“With continued emphasis on mission success, our team will continue to test and evaluate the swing arm retraction system prior to the launch of the Delta 4-Heavy,” ULA tweeted. “We will confirm a launch date as soon as possible.”

The #NROL44 launch date is now indefinite on the range. With continued emphasis on mission success, our team will continue to test and evaluate the swing arm retraction system prior to the launch of the #DeltaIVHeavy. We will confirm a launch date as soon as possible.

— ULA (@ulalaunch) October 16, 2020

The Delta 4-Heavy launch countdown was halted at T-minus 7 seconds Sept. 30, just before ignition of the rocket’s three hydrogen-fueled RS-68A main engines.

Tory Bruno, ULA’s president and CEO, tweeted Oct. 13 that the issue that caused the abort was “understood and resolved.”

“A sensor incorrectly reported that a valve in the RS-68A was not in the flight position,” Bruno tweeted. “We have implemented a change that will better verify its position.”

He added the ULA was “working through an issue with pad hydraulics” associated with the swing arm retraction system at the Delta 4 launch pad. Three swing arms feeding propellants and conditioned air to the rocket and its satellite payload are designed to retract as the Delta 4-Heavy lifts off.

“Fixing is always easy,” Bruno tweeted. “Making sure something stays fixed takes more work and lots of discipline.”

The countdown hold Sept. 30 was the second abort for the Delta 4-Heavy rocket in the final 10 seconds of a countdown. A launch attempt Aug. 29 was aborted at T-minus 3 seconds, after ignition of one of the rocket’s three RS-68A main engines.

ULA traced the problem uncovered Aug. 29 to a pressure regulator at the Delta 4’s launch pad at Cape Canaveral.

The Delta 4-Heavy mission, codenamed NROL-44, has suffered repeated delays over the last two months.

ULA has delayed the launch from its original target date of Aug. 26. A pneumatics issue prevented the rocket from launching Aug. 27, and the Aug. 29 countdown stopped when the automated launch sequencer detected a problem with a pressure regulator on the launch pad designed to flow helium gas to spin up rocket’s center engine for ignition.

The regulator for the center engine did not open, prompting the countdown’s computer controller to stop the countdown.

Bruno said that engineers refurbished and tested all three pressure flow devices at pad 37B before proceeding with another launch attempt.

ULA set Sept. 26 for the next launch attempt for the NROL-44 mission, but officials delayed the mission again to investigate a concern with the swing arm retraction system at the Delta 4-Heavy’s seaside launch complex at Cape Canaveral. The swing arms, which feed liquid propellants and conditioned air to the vehicle, are designed to quickly retract away from the rocket at liftoff.

Officials kicked off a countdown Monday afternoon for a launch opportunity just after midnight Tuesday. But the threat of lightning prevented ground crews from retracting the launch pad’s towering mobile gantry, which is needed to attach satellites in a vertical configuration on the pad, and also provides protection for the rocket before launch.

Storms again delayed rollback of the Mobile Service Tower on Tuesday, but the weather cleared in time to allow technicians to begin moving the gantry. Then a hydraulic leak interrupted the gantry rollback procedure, causing ULA to scrub another launch attempt.

The repeated problems with different parts of the Delta 4-Heavy’s launch pad have raised questions about aging infrastructure at pad 37B, which was originally built to support Saturn rocket launches in the 1960s, then mothballed until Boeing took over the facility in the 1990s for the Delta 4 program.

Boeing built the towering mobile gantry for the Delta 4 rocket, along with a then-new fixed umbilical tower with huge swing arms designed to pull away from the launcher as it climbs away from the pad.

ULA is retiring the Delta 4 rocket family after five more launches — three more from Cape Canaveral and two froom Vandenberg Air Force Base in California. The company’s next-generation Vulcan Centaur rocket, scheduled to debut in the second half of next year, will replace ULA’s existing Delta 4 and Atlas 5 launch vehicles.

While SpaceX’s Falcon Heavy rocket is significantly less expensive and can lift heavier payloads into low orbits, the Delta 4-Heavy has demonstrated an ability to inject satellites directly into high-altitude circular geosynchronous orbits more than 22,000 miles (nearly 36,000 kilometers) above Earth.

The maneuvers required for such an orbital injection take place over roughly six hours. While the payload on the NROL-44 mission is classified, independent analysts say publicly-known parameters such as the rocket’s capabilities, its launch azimuth, and the launch window suggest the Delta 4-Heavy is set to carry a signals intelligence satellite into geosynchronous orbit.

In that orbit, the satellite is expected to unfurl a giant football field-sized antenna to eavesdrop on telephone calls and other data traffic from U.S. adversaries.

The Delta 4-Heavy also has a larger payload fairing than the Falcon Heavy, and the mobile shelters at Cape Canaveral and Vandenberg allow ground crews to mate satellites to the rocket in a vertical orientation. SpaceX plans to offer an enlarged payload shroud on the Falcon Heavy and build a vertical integration hangar at the Kennedy Space Center to support future national security missions that can currently only fly on the Delta 4-Heavy.

ULA’s next Delta 4-Heavy rocket is scheduled to take off no earlier than December from Vandenberg. Bruno said ULA is reviewing maintenance and test procedures at the Delta 4 pads at Cape Canaveral and Vandenberg to ensure the facilities are ready to support the remaining Delta 4 flights.

“We are conducting a very detailed and comprehensive review of all of our preventative maintenance and pre-launch testing processes at the Delta pads and will make whatever improvements are indicated going forward,” Bruno tweeted last month.

The final Delta 4-Heavy rocket is scheduled to launch in 2023.

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Follow Stephen Clark on Twitter: @StephenClark1.

The rocket was set to blast off from Cape Canaveral with a U.S. government spy satellite at 11:54 p.m. EDT Wednesday (0354 GMT Thursday), but the countdown stopped at T-minus 7 seconds. ULA said the automated countdown sequencer controlling the rocket in the final moments before liftoff detected an “unexpected condition prior to the engine start sequence.”

“The team is currently reviewing all data and will determine the path forward,” ULA said in a statement.

Here’s a replay of the final seconds of the aborted Delta 4-Heavy countdown tonight.

This is the second abort inside T-minus 10 seconds for this mission.

Continuing coverage: https://t.co/gZCB2vhVYZ pic.twitter.com/Gt7Wf4Cgzb

— Spaceflight Now (@SpaceflightNow) October 1, 2020

It was the second abort for the Delta 4-Heavy rocket in the final 10 seconds of a countdown. A launch attempt Aug. 29 was halted at T-minus 3 seconds, after ignition of one of the rocket’s three RS-68A main engines.

ULA, a 50-50 joint venture between Boeing and Lockheed Martin, traced the problem uncovered Aug. 29 to a pressure regulator at the Delta 4’s launch pad at Cape Canaveral Air Force Station. Officials began assessing the cause of Wednesday night’s abort as the launch team “safed” the Delta 4-Heavy rocket and drained it of cryogenic propellant.

Tory Bruno, ULA’s president and CEO, tweeted after Wednesday night’s abort that the countdown automatically stopped after a “sensor reported a fault.” He added that the Delta 4’s automated safety system operated as intended.

“Bird and payload are safe and unharmed,” Bruno tweeted, referring to the launcher and the NRO spy satellite. He also confirmed that ignitors inside the rocket’s three Aerojet Rocketdyne RS-68A main engines were not figured, and the engine turbopumps were not “spun up” at the beginning of the ignition sequence.

“Mission safety first,” Bruno added.

We experienced an automated abort because a sensor reported a fault. Automated Safety System operated as intended. Bird and payload are safe and unharmed. Engine ROFI ignitors were not fired. Turbo pumps were not spun up. Mission safety first…

— Tory Bruno (@torybruno) October 1, 2020

The abort Wednesday night occurred after sparklers at the base of the rocket ignited to burn off any excess hydrogen gas around the vehicle before the engine startup sequence.

Bruno later tweeted it was too early to know how long engineers might need to investigate the cause of Wednesday night’s abort and ready the Delta 4-Heavy for another launch attempt. But the launch team was instructed to prepare for an “extended recycle,” suggesting officials did not anticipate another launch attempt this week.

In any event, it seemed likely early Thursday that the Delta 4-Heavy will remain grounded for at least several days, and perhaps longer. That would free up the military-run Eastern Range to support a pair of SpaceX Falcon 9 rockets slated to blast off from different pads on Florida’s Space Coast on Thursday and Friday.

A Falcon 9 launcher was being prepared for launch from pad 39A at NASA’s Kennedy Space Center at 9:17 a.m. EDT (1317 GMT) Thursday with SpaceX’s next 60 Starlink broadband satellites. A separate Falcon 9 rocket was standing on pad 40 at Cape Canaveral Air Force Station for launch at 9:43 p.m. EDT Friday (0143 GMT Saturday) with a GPS navigation satellite for the U.S. Space Force.

Read our earlier story for details on the Starlink and GPS missions.

The aborted countdown Wednesday night continued a series of delays for the Delta 4-Heavy mission, codenamed NROL-44.

ULA has delayed the launch from its original target date of Aug. 26. A pneumatics issue prevented the rocket from launching Aug. 27, and the Aug. 29 countdown stopped when the automated launch sequencer detected a problem with a pressure regulator on the launch pad designed to flow helium gas to spin up rocket’s center engine for ignition.

The regulator for the center engine did not open, prompting the countdown’s computer controller to stop the countdown.

Bruno said that engineers refurbished and tested all three pressure flow devices at pad 37B before proceeding with another launch attempt.

ULA set Sept. 26 for the next launch attempt for the NROL-44 mission, but officials delayed the mission again to investigate a concern with the swing arm retraction system at the Delta 4-Heavy’s seaside launch complex at Cape Canaveral. The swing arms, which feed liquid propellants and conditioned air to the vehicle, are designed to quickly retract away from the rocket at liftoff.

Officials kicked off a countdown Monday afternoon for a launch opportunity just after midnight Tuesday. But the threat of lightning prevented ground crews from retracting the launch pad’s towering mobile gantry, which is needed to attach satellites in a vertical configuration on the pad, and also provides protection for the rocket before launch.

Storms again delayed rollback of the Mobile Service Tower on Tuesday, but the weather cleared in time to allow technicians to begin moving the gantry. Then a hydraulic leak interrupted the gantry rollback procedure, causing ULA to scrub another launch attempt.

The repeated problems with different parts of the Delta 4-Heavy’s launch pad have raised questions about aging infrastructure at pad 37B, which was originally built to support Saturn rocket launches in the 1960s, then mothballed until Boeing took over the facility in the 1990s for the Delta 4 program.

Boeing built the towering mobile gantry for the Delta 4 rocket, along with a then-new fixed umbilical tower with huge swing arms designed to pull away from the launcher as it climbs away from the pad.

ULA is retiring the Delta 4 rocket family after five more launches — three more from Cape Canaveral and two froom Vandenberg Air Force Base in California. The company’s next-generation Vulcan Centaur rocket, scheduled to debut in the second half of next year, will replace ULA’s existing Delta 4 and Atlas 5 launch vehicles.

While SpaceX’s Falcon Heavy rocket is significantly less expensive and can lift heavier payloads into low orbits, the Delta 4-Heavy has demonstrated an ability to inject satellites directly into high-altitude circular geosynchronous orbits more than 22,000 miles (nearly 36,000 kilometers) above Earth.

The maneuvers required for such an orbital injection take place over roughly six hours. While the payload on the NROL-44 mission is classified, independent analysts say publicly-known parameters such as the rocket’s capabilities, its launch azimuth, and the launch window suggest the Delta 4-Heavy is set to carry a signals intelligence satellite into geosynchronous orbit.

In that orbit, the satellite is expected to unfurl a giant football field-sized antenna to eavesdrop on telephone calls and other data traffic from U.S. adversaries.

The Delta 4-Heavy also has a larger payload fairing than the Falcon Heavy, and the mobile shelters at Cape Canaveral and Vandenberg allow ground crews to mate satellites to the rocket in a vertical orientation. SpaceX plans to offer an enlarged payload shroud on the Falcon Heavy and build a vertical integration hangar at the Kennedy Space Center to support future national security missions that can currently only fly on the Delta 4-Heavy.

Space Force officials said last month that ULA’s next Delta 4-Heavy rocket was scheduled to take off no earlier than December from Vandenberg. Bruno said ULA is reviewing maintenance and test procedures at the Delta 4 pads at Cape Canaveral and Vandenberg to ensure the facilities are ready to support the remaining Delta 4 flights.

“We are conducting a very detailed and comprehensive review of all of our preventative maintenance and pre-launch testing processes at the Delta pads and will make whatever improvements are indicated going forward,” Bruno tweeted last month.

The final Delta 4-Heavy rocket is scheduled to launch in 2023.

Email the author.

Follow Stephen Clark on Twitter: @StephenClark1.

The 9-million-pound, 330-foot-tall mobile gantry began moving away from the Delta 4-Heavy rocket shortly after 3 p.m. EDT (1900 GMT) Wednesday. The structure moved along rail tracks to a park position around 300 feet northeast of the launch mount at Complex 37B.

The tower provided weather protection for the Delta 4-Heavy, and access to the launch vehicle for engineers and technicians, since the rocket’s rollout and erection at the launch pad last November. The tower stands around 330 feet tall, and measures 90 feet wide and 40 feet deep. It was built before the first Delta 4 launch in 2002.

The rollback of the Mobile Service Tower on Wednesday afternoon revealed the 235-foot-tall Delta 4-Heavy rocket for liftoff late Wednesday night. The triple-core rocket, built by United Launch Alliance, will carry a classified satellite into orbit for the National Reconnaissance Office, the U.S. government’s spy satellite agency.

The photos below show the retraction of the mobile gantry Wednesday. See our Mission Status Center for live countdown and mission coverage.

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Two SpaceX rockets are standing on launch pads several miles apart on Florida’s Space Coast awaiting launch opportunities Thursday and Friday, once an oft-delayed Delta 4-Heavy rocket from rival United Launch Alliance is able to blast off from Cape Canaveral with a top secret U.S. government spy satellite.

ULA has been trying to launch the Delta 4-Heavy rocket since late August, but a series of problems with the launch pad have kept the heavy-lifter on the ground. The mission will deploy a classified payload into a geosynchronous orbit more than 22,000 miles (nearly 36,000 kilometers) above Earth.

The Delta 4-Heavy flight, with its national security payload likely valued at more than $1 billion, has taken priority on the Space Force’s Eastern Range, which oversees launch scheduling from pads at Cape Canaveral Air Force Station and the neighboring Kennedy Space Center.

A pressure regulator failed at the launch pad during the Delta 4’s ignition sequence Aug. 29, prompting ULA to refurbish and retest equipment before setting up for a launch attempt Saturday, Sept. 26. ULA delayed the mission again to assess an issue with the hydraulic swing arm system at pad 37B, the Delta 4’s launch pad at Cape Canaveral.

Officials kicked off a countdown Monday afternoon for a launch opportunity just after midnight Tuesday. But the threat of lightning prevented ground crews from retracting the launch pad’s towering mobile gantry, which is needed to attach satellites in a vertical configuration on the pad and also provides protection for the rocket before launch.

Storms again delayed rollback of the Mobile Service Tower on Tuesday, but the weather cleared in time to allow technicians to begin moving the gantry. Then a hydraulic leak interrupted the gantry rollback procedure, causing ULA to scrub another launch attempt.

ULA is set to kick off its fifth countdown for the Delta 4-Heavy mission — codenamed NROL-44 — Wednesday afternoon. Clocks will be timed to tick down toward liftoff at 11:54 p.m. EDT Wednesday (0354 GMT Thursday).

Analysts believe the payload aboard the Delta 4-Heavy is a signals intelligence satellite with a giant deployable antenna designed to intercept voice and data traffic from U.S. adversaries.

Several SpaceX missions have been delayed by the Delta 4-Heavy’s ever-changing launch dates. A Falcon 9 launch with Argentina’s SAOCOM 1B radar observation satellite was delayed a month in August due to concerns about the rocket’s flight path near the Delta 4 pad, where the NRO’s high-value payload was sitting on top of the ULA rocket.

The SAOCOM 1B satellite was eventually cleared for flight Aug. 30 after military officials apparently waived their concerns, following the Delta 4-Heavy’s last-minute abort Aug. 29.

A Falcon 9 rocket and a U.S. Space Force Global Positioning System navigation satellite were supposed to go up Tuesday night from pad 40 at Cape Canaveral Air Force Station. But SpaceX has delayed the GPS mission this week in response to the scrubbed Delta 4-Heavy launch attempts.

SpaceX initially rescheduled the GPS launch for Wednesday night after the Delta 4 was delayed to Tuesday. After the Delta 4-Heavy’s scrub Tuesday, SpaceX announced the GPS launch would be pushed back to Friday, when there is a 15-minute launch window available opening at 9:43 p.m. EDT (0143 GMT Saturday).

The Falcon 9 will target an elliptical orbit to release the Lockheed Martin-built GPS 3 SV04 navigation satellite. The spacecraft will then maneuver into a circular orbit 12,550 miles (20,200 kilometers) above Earth to enter the GPS constellation providing worldwide positioning, navigation and timing services.

The launch of SpaceX’s next 60 Starlink broadband satellites has also been impacted by the shuffling schedule at the Cape Canaveral range.

The 60 Starlink satellites are flat-packed on top of a Falcon 9 rocket at pad 39A, located at NASA’s Kennedy Space Center a few miles north of pad 40 and pad 37B. SpaceX tried launching the Starlink mission Monday morning, but scrubbed the countdown less than a minute prior to liftoff due to unfavorable weather.

SpaceX plans to try again to launch the next 60 Starlink satellites Thursday at 9:17 a.m. EDT (1317 GMT). The Falcon 9 rocket will aim to deliver the 60 quarter-ton Internet satellites into a low-altitude orbit on the way to operating orbit 341 miles (550 kilometers) above Earth.

SpaceX has two sea-going landing platforms in the Atlantic Ocean several hundred miles northeast of Cape Canaveral for recovery of the reusable first stage boosters on the GPS and Starlink missions.

The ever-changing launch schedule on Florida’s Space Coast has been dizzying for space enthusiasts, space reporters, and other observers. Michael Ellis, director of SpaceX’s national security space launch division, said last week that it can also be stressful for launch teams.

“These things happen. We’re quite used to the bullwhip effect of new information coming,” Ellis said in a conference call with reporters Friday. “We’re able to handle it because we have such a strong partnership (with the range), and the communication is transparent.

“I’d be lying if I were to tell you that it isn’t sometimes stressful, but up to this point, we have two pads. We have teams dedicated to support simultaneous operations and we’re able to, with our partnership, work hand-in-hand with the Space Force.”

Brig. Gen. Doug Schiess, commander of the 45th Space Wing that oversees range operations at Cape Canaveral, said Friday that the range has improved its ability to handle the quickening pace of launches.

“I’ve been in the launch business for quite a while, and a lot of it was keeping things to ourselves,” Schiess said. “Recently, we’ve done a lot of work where we’re all in the same room together — ULA, SpaceX, and eventually others as they come to the Eastern Range — and we try to work through the schedule.”

The introduction of autonomous flight safety systems has helped range safety officials shorten the time needed between launches. The autonomous safety systems allow rockets to automatically terminate their flights if they fly off course, replacing destruct systems that rely on a manual command from a range safety officer.

SpaceX’s Falcon 9 rockets use autonomous safety systems. ULA’s Atlas 5 and Delta 4 rockets still use the older flight termination system design, but will transition to an automated design with the next-generation Vulcan Centaur rocket.

Because the military deems the NROL-44 payload of critical importance, the 45th Space Wing gives the Delta 4-Heavy three launch opportunities at a time. Most missions receive just two dates — a primary and backup opportunity — before having to submit a new request to the range.

“Because the Delta 4 had one launch date with two backups because of its importance, in the past we would not have given SpaceX the opportunity to launch (on one of the backup dates),” Schiess said.

Now the range gives SpaceX an opportunity to secure a date on a Delta 4 backup date. The launch opportunity is then contingent upon the Delta 4 actually launching, or at least delaying long enough to clear out of the way.

“I think that’s part of that collaboration, with the caveat that, ‘Hey, you can have this (date), but if this doesn’t go, we’re going to have to do something else,” Schiess said. “In the past we would not have done that. We would have said those three days are for Delta 4-Heavy, and you’re going to have to wait. So I think that’s part of that collaboration that we’re really trying to work to be able to get as many opportunities as possible.”

Ellis said SpaceX also prioritizes national security missions, such as the GPS launch, on its internal manifest when deciding when to find slots for the company’s own Starlink launches.

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United Launch Alliance’s live launch broadcast begins at 11:34 p.m. EDT on Wednesday, Sept. 30 (0334 GMT on Oct. 1).

Continuing a dizzying series of rescheduled launches from Florida’s Space Coast, poor weather at the Kennedy Space Center forced SpaceX to keep a Falcon 9 rocket and 60 Starlink broadband satellites on the ground Monday. The Starlink launch is expected to be delayed until Thursday, after a pair of national security missions are set to blast off from Cape Canaveral Tuesday.

SpaceX halted the Falcon countdown Monday around 30 seconds before a liftoff from pad 39A that was scheduled for an instantaneous launch window at 10:22 a.m. EDT (1422 GMT). The company’s launch conductor said the countdown stopped due to weather violations.

SpaceX did not immediately set a new target launch date, but sources said the next opportunity to launch the mission will be Thursday at around 9:17 a.m. EDT (1317 GMT).

Two rocket flights with U.S. national security payloads will take priority on the Eastern Range’s launch schedule at Cape Canaveral.

A United Launch Alliance Delta 4-Heavy rocket is set for liftoff at 12:02 a.m. EDT (0402 GMT) Tuesday from pad 37B at Cape Canaveral Air Force Station. Its mission, codenamed NROL-44, will deploy a classified cargo for the National Reconnaissance Office, the agency which owns the U.S. government’s spy satellites.

Assuming the Delta 4-Heavy gets off the ground early Tuesday, SpaceX will ready a separate Falcon 9 rocket and a GPS navigation satellite for liftoff from pad 40 at Cape Canaveral during a 15-minute window opening at 9:55 p.m. EDT Tuesday (0155 GMT Wednesday).

The three back-to-back launches — none directly related to the other — are planned from separate pads on the Space Coast.

The Delta 4-Heavy rocket — the most powerful in ULA’s fleet — was originally supposed to launch in late August with the NROL-44 mission. ULA scrubbed a launch attempt Aug. 27 to investigate an issue with a launch pad pneumatics system, then a computer sequencer commanded a hold just three seconds prior to liftoff Aug. 29 due to a failure in a pressure regulator associated with one of the rocket’s three hydrogen-fueled main engines.

The Aug. 29 countdown stopped after one of the rocket’s three RS-68A engines had ignited. ULA’s launch team announced the aborted countdown as a fireball erupted at the base of the rocket, a fiery feature normally observed during the Delta 4-Heavy’s engine startup sequence.

The rocket was later drained of cryogenic propellants, and ULA engineers traced the problem to a pressure regulator on the launch pad designed to flow helium gas to spin up rocket’s center engine for ignition. The regulator for the center engine did not open, prompting the countdown’s automated sequencer to stop the countdown.

Tory Bruno, ULA’s president and CEO, tweeted that engineers refurbished and tested all three pressure flow devices at pad 37B before proceeding with another launch attempt.

ULA set Sept. 26 for the next launch attempt for the NROL-44 mission, but officials delayed the mission again to investigate a concern with the swing arm retraction system at the Delta 4-Heavy’s seaside launch complex at Cape Canaveral. The swing arms, which feed liquid propellants and conditioned air to the vehicle, are designed to quickly retract away from the rocket at liftoff.

ULA announced early Monday that the Delta 4-Heavy rocket was on track for its launch opportunity just after midnight Tuesday, Florida time.

The 235-foot-tall (71.6-meter) Delta 4-Heavy rocket will arc toward the east from Cape Canaveral over the Atlantic Ocean, targeting a near-circular geosynchronous orbit more than 22,000 miles (nearly 36,000 kilometers) near the equator.

While the NRO has not disclosed any details about the Delta 4-Heavy’s payload, analysts believe it is likely a signals intelligence satellite with a giant antenna that will be unfurled in space to stretch as big as a football field. If the analysts are correct, the spacecraft will intercept telephone calls and data transmissions from U.S. adversaries.

The Falcon 9 rocket scheduled to blast off from pad 40 Tuesday night will loft the U.S. Space Force’s next Global Positioning System spacecraft, the fourth in the latest generation of GPS navigation satellites made by Lockheed Martin.

The GPS 3 SV04 spacecraft joins three previous Lockheed Martin-built GPS 3-series satellites launched in December 2018, August 2019, and June 30 of this year.

But the official weather forecast at Cape Canaveral is iffy for the NROL-44 and GPS missions Tuesday. There’s a 60 percent chance of good conditions for launch of the Delta 4-Heavy rocket early Tuesday, and just a 40 percent probability of acceptable weather for the Falcon 9 launch Tuesday night with the GPS satellite.

If the NROL-44 and GPS missions take off as scheduled, SpaceX could launch its Falcon 9 rocket from pad 39A Thursday with the next 60 Starlink satellites.

SpaceX has launched 715 Starlink satellites to date, and is nearing the halfway point in a series of missions since to place some 1,440 broadband relay stations into orbit to provide high-speed Internet services over most of the world.

SpaceX has regulatory approval from the Federal Communications Commission to launch up to 12,000 Starlink satellites for global broadband service, and SpaceX has signaled its intention to seek authority to put up another 30,000 Starlink platforms in the coming years.

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