A Delta IV rocket, carrying the Parker Solar Probe, lifts off from launch complex 37 at the Kennedy Space Center, Sunday, Aug. 12, 2018, in Cape Canaveral, Florida. The Parker Solar Probe will venture closer to the Sun than any other spacecraft and is protected by a first-of-its-kind heat shield and other innovative technologies that will provide unprecedented information about the Sun.

The scheduled launch of a rocket carrying a reconnaissance satellite into orbit from Vandenberg Air Force Base in Santa Barbara County that was originally scheduled for Friday and reset for Saturday was called off at T-minus 7 seconds due to a problem detected by the Terminal Countdown Sequencer Rack, according to United Launch Alliance.

The launch was not immediately rescheduled.

Prior launches from Vandenberg have created spectacular light displays over the Southern California and the southwestern United States.

The United Launch Alliance rocket was initially set to take off at 8:19 p.m. Friday, but roughly three hours before launch time, it was scrubbed due to "an issue with a redundant communication link between the control center and launch site.''

If liftoff had been successful Saturday, the launch would have been the second rocket to take off this week from Vandenberg AFB. Hawthorne-based SpaceX launched a Falcon 9 rocket from the base Monday, carrying 64 satellites into orbit.

The latest launch is being carried out by United Launch Alliance, a joint venture of Lockheed Martin and Boeing. ULA's Delta IV Heavy rocket will carry a secretive satellite for the U.S. National Reconnaissance Office.

"We are proud to launch this critical payload in support of our nation's national security mission,'' Gary Wentz, ULA vice president of government and commercial programs, said in a statement. "As the nation's premiere launch provider, the teams have worked diligently to ensure continued mission success, delivering our customer's payloads to the precise orbits requested.''

According to the company, the Delta IV Heavy rocket includes three Rocketdyne liquid hydrogen/liquid oxygen engines that can produce a combined 2.1 million pounds of thrust.

ULA has carried out 27 launches for the National Reconnaissance Office over the past 12 years.

Copyright City News Service</s>United Launch Alliance’s Delta IV Heavy rocket launched Saturday with the mysterious NROL-71 mission for the National Reconnaissance Office from SLC-6 at Vandenberg Air Force Base in California. A series of technical and weather-related scrubs hampered the launch attempts, prior to a lengthy stand down to fix a hydrogen leak that scrubbed the final attempt of 2017 with just seconds remaining in the count. With the issue fixed, the launch was realigned for January 19, with the window opening at 11:05 AM local time (19:05 UTC). Launch occurred slightly into the window at 11:10 AM local time.

Like most activities conducted by the United States National Reconnaissance Office (NRO), specifics of the NRO Launch 71 (NROL-71) mission were classified. The NRO is the organization that operates America’s fleet of reconnaissance and intelligence-gathering satellites, using a variety of spacecraft types and surveillance techniques to support national defense and security.

Despite the classified nature of their operations, a combination of information published by the NRO itself and other government sources, leaks and observation of the satellites’ orbits and behavior has allowed different groups of satellites to be characterized and their purpose determined. Analysis of hazard areas published for maritime and aviation safety in advance of every launch, combined with a comparison of the type of rocket to be used to those that have orbited previous satellites, allows most NRO satellites to be identified before they even leave the ground – although occasionally a mission will throw a curveball.

NROL-71 has proven one such mission. Before the launch time and hazard areas were published it was a safe bet that this launch would add a new member to the NRO’s fleet of KH-11, or Crystal, imaging satellites. Also formerly codenamed Kennen, Key Hole 11 (KH-11) spacecraft collect incredibly high-resolution images of the Earth’s surface and transmit them back to the ground for analysis. Originally developed in the 1970s, but upgraded over time, the KH-11 is among the largest satellites that the NRO operates and requires one of America’s most powerful rockets, the Delta IV Heavy, to place it into orbit.

The near-polar sun-synchronous orbits used by Crystal satellites dictate that they must be launched from California, as to launch from Florida would either require the rocket to fly – and potentially drop debris – over land, or to avoid this by making a dogleg maneuver which would affect its performance.

As Crystal is the only type of satellite to have launched aboard a Delta IV Heavy from the West Coast, the launch was widely expected to carry a replacement for the oldest satellite in the constellation. But instead of the south-westerly trajectory required to reach Crystal’s sun-synchronous orbit, hazard areas for the NROL-71 mission show that the rocket will follow a south-easterly track towards an orbit inclined at about 74 degrees. Aside from a 2010 technology demonstration mission, no US military satellite has operated in an orbit close to this inclination since 1971.

That 2010 mission was STPSat-2, which was flown in a 72-degree orbit by the Space Test Program to test sensors and data relay systems in space. It is unlikely to be related to the NROL-71 mission. Before 1971 a 75-degree orbit was used for a small proportion of the NRO’s fleet of KH-4 Corona imaging satellites as well as seven “heavy ferret” electronic signals intelligence (ELINT) satellites and two photoreconnaissance satellites of the short-lived KH-6 Lanyard project. The Soviet Union operated Zenit photoreconnaissance satellites in 73-degree orbits from 1966 until 1989, along with ELINT, calibration, communications and geodesy satellites in similarly-inclined orbits whose launches were continued by Russia until the early 2000s.

The use of a Delta IV Heavy means that the NROL-71 payload must either by too heavy to be deployed by any of the other rockets qualified to carry out the NRO’s most expensive and critical missions or destined for a sufficiently high orbit as to require the services of this behemoth rocket.

The only high orbits typically of value for reconnaissance are an elliptical Molniya orbit, which allows eavesdropping satellites to loiter over high latitudes for much of their time, and geostationary orbit. NROL-71 will target neither of these – Molniya orbits require a precise inclination of 63.4 degrees, while geostationary trajectories require that the rocket launch almost due East which is not practical from Vandenberg – meaning that its payload is likely a heavy satellite.

Despite the unusual orbit, a KH-11 is still a likely candidate for the identity of the NROL-71 payload. The less-inclined orbit could allow the satellite to spend more time over lower latitudes instead of passing over the polar oceans and icecaps. Not having the satellite in a sun-synchronous orbit would also allow it to view areas of interest at different times of the day with objects on the surface casting shadows in different directions. A Crystal in such an orbit could be intended to compliment the sun-synchronous element of the constellation, or may signal a move away from SSO for this program.

If NROL-71 does deploy a Crystal satellite, it will be the seventeenth such spacecraft to launch. The KH-11 was developed as a continuation to the long-running series of Key Hole satellites that had begun with early Corona imaging spacecraft in the 1950s. It was the first Key Hole not to use film capsules, downlinking images electronically instead of physically sending them back to Earth for processing.

The first KH-11, OPS 5705, was deployed by a Titan rocket in December 1976. Initially KH-11 operated alongside the film-return KH-8 Gambit and KH-9 Hexagon satellites, which provided high-resolution and wide-area imaging capabilities respectively, but eventually the new satellites assumed both of these roles.

The design of the Hubble Space Telescope was reportedly influenced by Crystal, with Hubble’s mirrors being designed to take advantage of production techniques – and possibly hardware – developed for the reconnaissance programme. The KH-11 satellites are also said to have similar proportions and appearance to Hubble.



Four distinct “blocks” of KH-11 satellites have been identified. The first two blocks consisted of five and four satellites respectively, launched aboard Titan III(34)D rockets. Block III was designed to be launched by the Space Shuttle, however following the loss of Challenger polar-orbit Shuttle missions were abandoned and the Titan IV rocket was developed instead. The most recent upgrade, Block IV, was first flown in 2001.

The fourteenth Crystal mission, NROL-20 or USA-186, was launched by the final Titan IV rocket and was expected to be the last KH-11 to fly. The National Reconnaissance Office had intended to procure a next-generation optical imaging satellite through its Future Imagery Architecture (FIA) program, but after this collapsed the agency purchased two additional KH-11s, built in part from leftover spares, to serve as a stopgap until a new system could be developed. When the first of these launched, aboard a Delta IV Heavy in 2011, its mission patch bore the Latin inscription “melior diabolus quem scies” – better the devil you know.

More recent rumors have suggested that the NRO has opted to buy a fifth generation of Crystal satellites instead of developing a replacement from scratch. These could incorporate more modern technologies and benefit from the increased performance of Delta IV over Titan IV to carry more fuel, which would allow them to maintain lower orbits than their predecessors. If NROL-71 is a KH-11, it will certainly be the first member of this new generation.

Another possibility is that NROL-71 may be a successor to the stealthy Misty imaging satellites that were launched in 1990 and 1999. Believed to be an offshoot of the Crystal series, the first Misty satellite was USA-53, deployed from Space Shuttle Atlantis during 1990’s STS-36 mission.

After deployment, USA-53 shed debris – leading to reports that it had failed – and maneuvered to a different orbit. During its lifetime, amateur observers lost track of – and subsequently rediscovered – Misty several times with the last sighting in 1997.

A second Misty, USA-144, was launched in May 1999 aboard a Titan IV(404)B. After deployment the satellite released a decoy and then disappeared – despite the efforts of the amateur satellite watching community, USA-144 was never found. It is unclear whether this spacecraft is still in orbit.

The Misty satellites operated in orbits with significantly lower inclination than Crystal: USA-53 used a 65-degree orbit and USA-144 was deployed into a 63-degree orbit, although its final destination is unknown. They are believed to be among the most expensive satellites ever launched, and development of a third Misty satellite was canceled in the mid-2000s due to the project’s cost.

Observations of the NROL-71 payload, which is expected to be named USA-289 once it reaches orbit, will likely reveal more about its identity and mission. A lack of observations could point towards it being another Misty satellite.

The Delta IV Heavy that was used for the NROL-71 mission is the heaviest rocket currently certified to carry out national security launches of this nature.

A two-stage vehicle, Delta IV consists of a Common Booster Core (CBC) first stage and a Delta Cryogenic Second Stage (DCSS), which both burn cryogenic propellant: liquid hydrogen and liquid oxygen.

It’s a beautiful day for remote camera setup here at historic SLC-6 (designed as a shuttle pad!). Delta IV Heavy is sitting ready to muscle NRO-71 into orbit tonight. @NASASpaceflight @ulalaunch @torybruno @NatReconOfc pic.twitter.com/OExMQ03CTz — Jack Beyer (@thejackbeyer) December 7, 2018

The rocket can be flown in five different configurations depending on the mass and dimensions of its payload and the target orbit. The smallest of these, the Delta IV Medium, used a four-meter diameter upper stage and no boosters, while three Medium+ versions – M+(4,2), M+(5,2) and M+(5,4) added two or four solid rocket motors and in the latter two cases a five-meter upper stage.

The Delta IV Heavy uses three Common Booster Cores strapped together, with the center core operating at partial thrust for much of its flight to extend its burn beyond that of the two outboard cores. It is the only version of the Delta that is expected to continue flying past the end of next year, as the Medium configuration has already been retired and the Medium+ versions of the rocket are being phased out. United Launch Alliance will instead focus on offering launch services in these classes with its Atlas V rocket, before introducing a new rocket – Vulcan – to replace both Atlas and Delta in the family.

The launch used the west-coast Delta IV launch pad, Space Launch Complex 6 (SLC-6) at Vandenberg Air Force Base. SLC-6 was originally developed in the 1960s for the Titan family of rockets, specifically to support the Manned Orbiting Laboratory (MOL) military space station. When MOL was canceled, SLC-6 was mothballed. It would later be reconstructed to support Space Shuttle missions to polar orbits, however risk reduction following the Challenger accident eliminated these plans and the complex once again went unused.

The first launch from SLC-6 finally came in August 1995, when Lockheed launched the first flight of the Lockheed Launch Vehicle 1 (LLV-1), which would later be named Athena. This launch failed, and while the next launch from the pad successfully placed NASA’s Lewis satellite into orbit the payload suffered an unrecoverable malfunction three days later. This, along with another launch failing in April 1999, led to a myth that the launch pad was cursed. The fourth and final Athena mission from SLC-6, in August 1999, successfully delivered a healthy satellite to orbit.

Boeing began converting SLC-6 for its Delta IV rocket in the early 2000s. Delta first used the complex in June 2006 and has made seven launches from Vandenberg prior to this mission, two of which have been in the Heavy configuration. This will be the first west-coast launch for a Delta IV Heavy with RS-68A engines, an upgraded version of the RS-68 Overall, this launch will be the thirty-eighth flight of Delta IV and the eleventh Heavy.

The NROL-71 launch began with the ignition of the RS-68A engines that power the three Common Booster Cores.

The starboard core ignited seven seconds before the scheduled liftoff, with the port and center boosters igniting two seconds later at T-5. This staggered ignition is intended to mitigate a fireball that can form around the rocket on startup as a result of hydrogen boiling off the rocket. Liftoff occurred at the zero mark in the countdown.

After pitching over onto a south-easterly azimuth of about 168 degrees, Delta IV passed through the area of maximum dynamic pressure – Max-Q – shortly before it reaches Mach 1 – the speed of sound – 82 seconds into the flight.

The three CBCs powered the rocket for the first three minutes and fifty-six seconds of the flight, with the port and starboard boosters burning at full thrust and the center core at partial thrust. When the two outboard cores depleted their propellant, their engines shut down, and the spent cores separated two seconds later.

Once the port and starboard boosters separated, the center core throttled up and burned at full power for most of the remaining two minutes of first-stage flight. Seven seconds after main engine cutoff (MECO), the first stage was jettisoned and the second stage entered its prestart sequence. The RL10B-2 engine ignited twelve seconds after stage separation. Eleven seconds later, Delta IV’s payload fairing separated from the nose of the rocket, exposing the payload to space for the first time.

Owing to the classified nature of this mission, United Launch Alliance has not published a timeline for mission events following fairing separation and as is normal for NRO flights all official coverage of the mission is expected to conclude at this point other than a press release confirming a successful launch some time after spacecraft separation.

The second stage will likely make a single burn, lasting around 12 minutes, before separating its payload into low Earth orbit. An additional launch hazard area to the northwest of Vandenberg suggests that the second stage will be deorbited into the Pacific shortly after separation.

The next launch for both United Launch Alliance and the Delta IV will be the Medium+(5,4) configuration will be used for the last time to loft a Wideband Global Satcom communications satellite for the US Air Force. The next Delta IV Heavy mission is expected to fly from Vandenberg in mid-2020.</s>United Launch Alliance will use a Delta IV Heavy rocket to launch the NROL-71 mission for the National Reconnaissance Office.

This will be 132nd mission for United Launch Alliance and ULA's second Delta IV Heavy launch in less than four months. It is the 382nd Delta launch since 1960, the 38th for a Delta IV rocket since 2002 and the 11th Delta IV Heavy.

This comes a day after SpaceX's successful launch on a mission to resupply the International Space Station.

Though the cargo-packed Dragon spacecraft made it safely to orbit and is scheduled to arrive at the ISS around 6 a.m. Saturday, the 156-foot-tall rocket stage did not share the same fate – instead of Landing Zone 1, it automatically targeted a wet landing in the Atlantic Ocean about two miles offshore.

USA TODAY will stream the Delta IV Heavy rocket launch live in the player above.</s>The launch of a massive rocket carrying out a mission for the U.S. agency responsible for spy satellites was called off just seconds ahead of liftoff on Saturday.

United Launch Alliance, a contractor for the U.S. National Reconnaissance Office (NRO), was expected to launch a Delta IV Heavy rocket carrying the NROL-71 mission from Vandenberg Air Force Base in California on Saturday evening.

The launch was initially delayed, then called off about 7.5 seconds before liftoff. The company said there was “an unexpected condition during terminal count.”

READ MORE: SpaceX says top secret spy satellite disappearing not its fault

“The team is currently reviewing all data and will determine the path forward. A new launch date will be provided when available,” ULA said.

A previous launch attempt was aborted on Friday due to an issue with a communication link between the control centre and launch site.

The NRO is responsible for developing, launching and operating U.S. intelligence satellites. It described the NROL-71 as a “national security payload designed, built and operated by the NRO.”</s>The launch of the Delta IV Heavy rocket, carrying a reconnaissance satellite, was called off on Saturday evening seven seconds before liftoff, United Launch Alliance (ULA) said. According to the company, the mission was put on hold due to “an unexpected condition” in one of the computing systems. The launch was supposed to take place at Vandenberg Air Force Base in California. The satellite was originally to be launched into space on Friday but that attempt was also abruptly called off due to a technical malfunction.</s>The countdown stopped 7 seconds before liftoff Saturday as a Delta IV Heavy rocket sat poised on its launch pad at Vandenberg Air Force Base for a second attempt to launch a spy satellite into orbit on behalf of the National Reconnaissance Office.

United Launch Alliance scrubbed a planned launch in the final seconds after detecting a problem, ULA said via Twitter. A previous attempt to launch the 233-foot-tall rocket on Friday was scrubbed about three hours before launch.

Small flames could be seen igniting at the base of the engines before they quickly disappeared The rocket remained still.

With favorable weather conditions, Saturday’s launch was originally slated for 8:06 p.m., but a brief stop in the countdown to troubleshoot a problem pushed the liftoff back to 8:15 p.m., the company said.

All systems were “go” until the countdown was halted just seven seconds before liftoff after a problem was detected, ULA said. The attempt was cancelled for the night, but it was not clear when ULA will try again.

The rocket carries a secret payload. It is set to deploy a classified satellite for the National Reconnaissance Office.

ULA is working in conjunction with the Air Force’s 30th Space Wing on the launch, dubbed NROL-71.</s>LOMPOC, Calif. — Just seconds before the planned liftoff of a Delta IV Heavy rocket with the NROL-71 payload for the National Reconnaissance Office, an automatic abort of the launch sequence was triggered.

With only a minor issue earlier in the countdown, the Dec. 8, 2018, launch attempt of United Launch Alliance’s Delta IV Heavy rocket seemed ready to fly with the classified NROL-71 payload at 8:15 p.m. PST (11:15 p.m. EST / 04:15 GMT Dec. 9) from Space Launch Complex 6 at Vandenberg Air Force Base.

However, just as the engines were about to start and excess hydrogen gas burn off began—a hold was called, which would ultimately scrub the launch.

“The launch of a United Launch Alliance Delta IV Heavy carrying the NROL-71 mission for the National Reconnaissance Office was scrubbed today due to an unexpected condition during terminal count at approximately 7.5 seconds before liftoff,” a ULA statement reads. “The team is currently reviewing all data and will determine the path forward.”

Within minutes, the launch team verified the rocket, launch pad and payload were in a safe configuration. Shortly thereafter, it was recommended that the 233-foot (71-meter) tall, triple-core rocket be emptied of its liquid oxygen and liquid hydrogen propellant.

This was the second attempt to get the NROL-71 mission off the ground (the first was on Dec. 7). ULA has not announced when its next launch attempt will occur. This was slated to be the company’s 38th Delta IV rocket (the 11th “Heavy” variant) since the vehicle’s debut in 2002.

Should the rocket launch before the end of the year, it will be the final flight for ULA in 2018, capping off with nine missions—five Atlas V’s, three Delta IV’s (two if NROL-71 is delayed to 2019) and the final flight of the venerable Delta II rocket.

Derek Richardson has a degree in mass media, with an emphasis in contemporary journalism, from Washburn University in Topeka, Kansas. While at Washburn, he was the managing editor of the student run newspaper, the Washburn Review. He also has a blog about the International Space Station, called Orbital Velocity. He met with members of the SpaceFlight Insider team during the flight of a United Launch Alliance Atlas V 551 rocket with the MUOS-4 satellite. Richardson joined our team shortly thereafter. His passion for space ignited when he watched Space Shuttle Discovery launch into space Oct. 29, 1998. Today, this fervor has accelerated toward orbit and shows no signs of slowing down. After dabbling in math and engineering courses in college, he soon realized his true calling was communicating to others about space. Since joining SpaceFlight Insider in 2015, Richardson has worked to increase the quality of our content, eventually becoming our managing editor. @TheSpaceWriter</s>If you would like to see more articles like this please support our coverage of the space program by becoming a Spaceflight Now Member . If everyone who enjoys our website helps fund it, we can expand and improve our coverage further.

A dramatic automatic abort 7.5 seconds before the planned liftoff of a United Launch Alliance Delta 4-Heavy rocket Saturday night kept the towering launcher on the pad at Vandenberg Air Force Base, California, with a top secret spy payload for the National Reconnaissance Office.

The 233-foot-tall (71-meter) rocket was counting down to launch at 8:15 p.m. PST Saturday (11:15 p.m. PST; 0415 GMT Sunday), but an automated sequencer detected a technical issue and triggered an abort.

“Hold hold hold,” a member of the ULA launch team declared on the countdown net.

A burst of flame appeared at the base of the rocket, a normal occurrence in the final seconds of a Delta 4 countdown as sparklers activate near the engines to burn off excess hydrogen gas before ignition, a measure aimed at eliminating the risk of a fireball or explosion.

It was not immediately clear whether any of the rocket’s three Aerojet Rocketdyne RS-68A main engines started their ignition sequences, but a statement later released by ULA said the computer-controlled countdown sequencer ordered an abort at T-minus 7.5 seconds.

In the statement, ULA said the abort was “due to an unexpected condition during terminal count at approximately 7.5 seconds before liftoff.

“The team is currently reviewing all data and will determine the path forward. A new launch date will be provided when available,” ULA said.

The Delta 4-Heavy is made up of three Delta 4 first stage boosters bolted together, each with an RS-68A engine burning liquid hydrogen and liquid oxygen propellants. ULA commands the three RS-68A engines to start in a staggered sequence, beginning with the starboard engine at T-minus 7 seconds, followed two seconds later by ignition of the center and port engines.

The timing of the abort at T-minus 7.5 seconds suggests the countdown stopped around a half-second before the first of the Delta 4-Heavy’s three main engines was supposed to ignite.

ULA’s launch team quickly “safed” the rocket, disarmed ordnance, and drained the Delta 4-Heavy of its supply of cryogenic propellants. The launch team did not set a new target launch date, but officials were instructed to plan for an extended turnaround after Saturday night’s scrub, and the Delta 4-Heavy flight was expected to be delayed at least a few days.

A similar cutoff in the final seconds of a Delta 4 countdown in 2010 resulted in a three-day slip to resolve the problem responsible for the abort — and replace the hydrogen burn-off sparklers on the pad — before the rocket successfully launched from Cape Canaveral with a GPS navigation satellite.

The upcoming mission from Vandenberg, located around 140 miles (225 kilometers) northwest of Los Angeles, is codenamed NROL-71 by the National Reconnaissance Office, which owns the U.S. government’s classified intelligence-gathering satellites. The NRO has not released any information about the spacecraft aboard the Delta 4-Heavy, but independent observers of NRO space launches believe the payload is heading for an unusual, high-inclination orbit, and is likely a new Keyhole-type high-resolution optical imaging satellite, with an Earth-pointing telescope capable of capturing extremely detailed imagery of sites around the world for review by government intelligence analysts.

The Delta 4-Heavy is ULA’s biggest rocket, and can loft up to 51,950 pounds (23,560 kilograms) of payload mass to a 120-mile-high (200-kilometer) low Earth orbit inclined 90 degrees to the equator.

The heavy-lift variant of the Delta 4 rocket has launched 10 times to date. The NROL-71 mission will be the 11th flight of a Delta 4-Heavy, and the 38th mission overall for the Delta 4 family since November 2002. It will also be ULA’s ninth and final launch of the year, following five Atlas 5 launches, a pair of Delta 4s, and the final liftoff of the company’s now-retired Delta 2 rocket.

A launch attempt for the NROL-71 mission Friday night was scrubbed after the Delta 4 team encountered a problem with a communications link between the control center and the rocket associated with the holdfire system.</s>The planned launch of a 233-foot-tall, 1.6-million-pound United Launch Alliance Delta IV rocket on Friday was delayed about three hours before it was set to blast off from Vandenberg Air Force Base with a top secret satellite, authorities said.

National Reconnaissance Office Launch 71, or NROL 71, was scheduled to lift off at 8:19 p.m., ULA said in a written statement.

But the company “scrubbed” the launch in favor of trying again 24 hours later, ULA said via Twitter.

The launch will be the private space launch company’s 132nd mission, and its second Delta IV Heavy launch in under four months. The mission is being flown in conjunction with the Air Force’s 30th Space Wing.

ULA plans to live stream the launch beginning 20 minutes before liftoff.</s>"The launch of #DeltaIVHeavy carrying the #NROL71 mission for the @NatReconOfc was scrubbed today due to an unexpected condition during terminal count. The team is reviewing all data and will determine the path forward. A new launch date will be provided when available," the company said on Twitter.

READ MORE: Delta II US Carrier Rocket With New Generation Satellite Lifts Off (VIDEO)

The launch was to be carried out at 20.15 local time Saturday (04.15 GMT Sunday) from the US Air Force Base Vanderberg in California.

The Delta IV rocket is the fourth generation of the Boeing Delta family of launch vehicles. The Delta IV was developed as part of the Evolved Expendable Launch Vehicle program to launch commercial satellites and US Air Force satellites.
The ULA launch of a Delta IV Heavy rocket carrying the NROL-71 mission is called off 7 seconds before liftoff time.