A United Launch Alliance Delta IV Heavy rocket launched from California’s Vandenberg Air Force Base Monday, carrying to orbit the classified NROL-82 payload for the National Reconnaissance Office. The launch occurred at 13:47 Pacific Daylight Time / 20:47 UTC.
Designated NRO Launch 82 (NROL-82), Monday’s Delta IV flight marked the first launch of the year for United Launch Alliance (ULA). Formed in 2006, ULA operates the Atlas and Delta vehicles that launch critical national security missions for the US military, as well as scientific spacecraft for NASA and commercial satellites.
The payload for Monday’s launch was classified, as is typical for National Reconnaissance Office (NRO) satellites. Despite this official secrecy, many details could still be inferred from what is public knowledge about this mission as well as images and documents that have previously been released — or leaked — into the public domain.
Delta IV Heavy is the most powerful rocket in ULA’s fleet and is only needed for the few payloads that are too heavy to fly on an Atlas V or the now-retired Medium+ configurations of the Delta IV. Such a payload would be either an exceptionally large satellite headed for low Earth orbit or a still-relatively-large spacecraft bound for a higher destination, such as direct insertion into geostationary orbit.
The choice of launch site at Vandenberg Air Force Base, California, ruled out geostationary orbit since launching from the west coast would require Delta IV to overfly the mainland United States, which is not permitted for safety reasons.
The only high class orbits regularly launched to from Vandenberg are the inclined, elliptical, Molniya orbits in which some of the NRO’s communications and signals intelligence satellites operate. These are typically lighter satellites well within the capabilities of the Atlas V, so this can be ruled out.
Another indication of the payload was the ground track that had been published for the early stages of Delta IV’s ascent. While the azimuth for most launches can be determined from notices to mariners and airmen as well as warning of hazard areas where spent boosters or rocket stages might fall downrange, for the NROL-82 mission ULA published a viewing guide that showed Delta IV taking a south-westerly track after its departure from Vandenberg.
This ruled out Molniya orbit, which would require a south-easterly trajectory, but was consistent with a Sun-synchronous orbit (SSO). SSO is a particular type of low Earth orbit inclined such that a satellite will always pass over a given point on Earth’s surface at the same local solar time. This means that the Sun will always illuminate the surface from the same angle whenever the satellite passes over that point.
Imaging and remote sensing satellites often use this type of orbit as it allows consistency between the images across multiple passes. Typical Sun-synchronous orbits follow a slightly retrograde, near-polar, track.
The NRO operates a fleet of Crystal imaging satellites — also known as KH-11, or formerly Kennen — in Sun-synchronous orbit. Said to resemble the Hubble Space Telescope, these very large satellites were developed in the 1970s to replace earlier spy satellites that relied on physically returning photographic film to Earth.
Crystal is an electro-optical spacecraft, meaning images are instead downlinked directly from the satellite — allowing a faster turnaround for intelligence gathered and removing the constraints that the limited supply of photographic film and return capsules previously placed on the lifespan of individual satellites.
Although the basic Crystal design is almost 50 years old, the satellites have undergone upgrades over the years, with at least five different “blocks” identified. The first Crystal satellites were launched from 1976, initially aboard Titan III(23)D rockets, moving to the Titan III(34)D in 1984 and then the Titan IV in 1992. The 14th Crystal satellite, USA-186 or NROL-20, was the payload of the final Titan launch in October 2005. At the time, the NRO expected this to be the last satellite of its kind, with the Future Imagery Architecture (FIA) program developing a more modern replacement.
While the FIA program led to the successful development of the Topaz radar imaging satellites, which entered service in 2010 and replaced the earlier Onyx spacecraft, the procurement of electro-optical spacecraft was more fraught. In 2005, the project was years behind schedule and more than $4 billion USD over budget. By 2009 the optical satellites had been cancelled altogether.
In their place, the Crystal satellites were brought back into production. The first of these, USA-224 or NROL-49, launched atop a Delta IV Heavy in January 2011. Its mission patch appeared to reference FIA’s failures, depicting a phoenix rising from the ashes and the Latin phrase “melior diabolus quen scies” — better the devil you know.
A second Crystal — USA-245 or NROL-65 — launched on a Delta IV Heavy in August 2013. These are two of only three Delta IV Heavy launches to have taken place from Vandenberg, with the third being NROL-71 with the USA-290 satellite in early 2019. NROL-71 placed a very large satellite into low Earth orbit in an unusual 73.5 degree orbit instead of the Sun-synchronous orbits used by Crystal satellites. It is unclear whether this was another Crystal in an atypical orbit, or part of a different — possibly related — program.
Hopefully this remote video gear will work like a charm like it did last time for ULA – Delta IV Heavy – NROL-71 launch in 2019. @NASASpaceflight @ulalaunch
— Jay L. DeShetler (@jdeshetler) April 26, 2021
The Crystals (assuming NROL-71 did not launch one into an odd orbit) operate within two Sun-synchronous orbital planes separated by about 50 degrees in right ascension of their ascending nodes. Each plane contains a single primary satellite, while older spacecraft which have been replaced in the primary role are moved to secondary positions, offset by several more degrees. The current primary satellites are USA-224 in the eastern plane and USA-245 on the western side of the constellation. These were launched in 2011 and 2013 respectively.
With Monday’s launch apparently targeting Sun-synchronous orbit, it appeared certain that the payload is another Crystal satellite. This was further reinforced by the target launch time being shortly before the Earth’s rotation carried Vandenberg into the path of the eastern plane. USA-224 is the older of the two principal Crystal satellites in orbit and is a prime candidate for replacement having been on orbit for just over 10 years — a few months longer than its own predecessor had been at the time of its launch.
Many of the capabilities of the Crystal satellites remain closely guarded secrets, although the world did see a glimpse of their capabilities in 2019 when then-President Donald Trump tweeted an image showing the aftermath of a failed Iranian satellite launch. The image — which satellite observers traced back to the USA-224 spacecraft based on its viewing angle and the time of pass derived from the position of shadows — showed the Iranian launch pad with such clarity that many initially thought it could not have come from a satellite.
Another clue pointing to a Crystal satellite as the NROL-82 payload was the mission patch, depicting an eagle wearing a World War II-era flight suit set against a background of the US flag and a starry sky. An F4U Corsair fighter aircraft can be seen in the background. The previous Crystal satellite launch likewise featured an eagle in camouflage.
For NROL-82, the NRO designed the patch as a tribute to Second World War Marine aviator and Medal of Honor recipient Gregory “Pappy” Boyington, with an inscription reading “tacitae libertatis custodemque”, Latin for “the silent guardian of liberty”.
The Delta IV Heavy rocket that carried out the NROL-82 mission was built at United Launch Alliance’s facility in Decatur, Alabama. Delta’s components left Decatur aboard ULA’s Rocketship transport vessel — formerly the Delta Mariner — in February 2020 and arrived in Vandenberg at the start of April, having travelled via a short stopover at Cape Canaveral and through the Panama Canal to reach the West Coast.
Following issues that plagued the previous Delta IV launch from Cape Canaveral, the launch pad at SLC-6 underwent upgrades over the last few months to improve its readiness for Monday’s launch, which ULA hoped would lead to the final stages of the launch campaign proceeding more smoothly than last year’s NROL-44 flight — which it did.
Delta was rolled out to SLC-6 on 15 February and raised into position the following day, a milestone in the launch campaign designated Launch Vehicle On Stand. The payload — already encapsulated in its protective fairing — arrived at the pad on 31 March and was lifted atop Delta IV using the launch pad’s overhead crane.
Space Launch Complex 6, the west coast home of the Delta IV, was originally built for Titan III launches in support of the Manned Orbiting Laboratory (MOL) program of the 1960s. This project, which would have seen US Air Force crews operating a small space station with scientific and reconnaissance capabilities, was cancelled before any launches took place and SLC-6 was mothballed.
It would later be rebuilt to host Space Shuttle launches to deploy military payloads into high-inclination orbits. After the loss of Challenger this, too, was abandoned as it was felt the missions were too risky and satellite deployments could be accomplished with expendable rockets. The complex was mothballed again, having still not supported a launch.
Really nice touch on the NROL-82 Delta IV Heavy from @ulalaunch. "Salute to our front-line medical workers! In harm's way to keep us healthy while we flight to keep America safe." @NASASpaceflight #NROL82 pic.twitter.com/75zNrhC6Nw
— Jack Beyer (@thejackbeyer) April 26, 2021
The first launches from SLC-6 finally came in the second half of the 1990s, when Lockheed Martin flew four small Athena rockets from the pad. The run of bad luck continued, however, as the first and third launches failed to reach orbit; while the second launch was successful, its payload — NASA’s Lewis satellite — malfunctioned a few days after launch and was declared a total loss.
With the advent of the US Air Force’s Evolved Expendable Launch Vehicle (EELV) program, now National Security Space Launch (NSSL), SLC-6 was selected as a launch site for the McDonnell Douglas entry which would become Delta IV. Boeing took over development of the Delta IV following a 1997 merger, and the rocket was selected for development alongside Lockheed Martin’s competing Atlas V product.
The launch complex was renovated for Delta IV operations, but many of the existing structures — such as the Mobile Service Tower and Mobile Assembly Shelter that enclose the pad — were retained.
Delta IV first flew from Vandenberg in June 2006. United Launch Alliance was formed in December 2006 when Boeing and Lockheed Martin combined their launch services divisions into a single company. ULA inherited the Atlas V from Lockheed Martin and the Delta II and Delta IV from Boeing.
Monday’s launch was the 42nd flight of Delta IV and the 13th mission for its Heavy configuration. The rocket had flight number Delta 386 — counting back to the first Thor-Delta launch in May 1960.
Each of the three Common Booster Cores that made up Delta 386’s first stage were powered by an Aerojet Rocketdyne RS-68A engine followed by an RL10B-2 engine powering the 5-meter diameter Delta Cryogenic Second Stage (DCSS). Both stages burned cryogenic propellant — liquid hydrogen and liquid oxygen.
Delta’s ignition sequence began at T-7 seconds before liftoff, with the ignition of the starboard RS-68A engine. The center and port core RS-68As ignited two seconds later. This helped manage the build-up of hydrogen around the rocket that occurred during RS-68A engine ignition, though a fireball can often be seen forming around the first stage of Delta IV rockets as they lift off.
About 10 seconds after liftoff, Delta began a pitch and yaw maneuver to establish itself on a south-westerly heading for the journey into orbit. The center core then throttled down its engine to a partial thrust mode during the early stages of flight, allowing the port and starboard boosters to do the heavy lifting.
As they approached cutoff, the port and starboard CBCs throttled down their engines to limit acceleration. After side core separation, the center core throttled up to full thrust as its engine continued to burn alone.
Shutdown of the center core’s engine, known as Booster Engine Cutoff, or BECO, marked the end of what was termed the “boost phase” of flight, with the second stage taking over to inject its payload into orbit.
United Launch Alliance is scheduled for its first launch of 2021 on Monday at 1:46 pm Pacific from Vandenberg Air Force Base with a Delta IV Heavy rocket. Onboard will be the classified NROL-82 mission.
— Michael Baylor (@nextspaceflight) April 26, 2021
The NROL-82 payload was contained within Delta IV’s payload fairing, which provided protection as the rocket climbed through the dense lower regions of Earth’s atmosphere. Delta IV Heavy can fly with a bisector fairing — one that separates into two pieces — made of composite materials, or a metallic trisector (three-piece) fairing. NROL-82 used the composite, bisector fairing.
After the second stage took over, the fairing was no longer needed and was jettisoned.
On national security missions, fairing separation is the point at which coverage of the launch and updates on its status cease. It is likely that the second stage continued to burn for about 12 minutes, inserting its payload directly into the planned deployment orbit without the need for a coast phase or circularisation burn.
Upon reaching orbit, the satellite was given a new public-facing name, likely USA-313. It will now begin on-orbit checkout and early operations.
United Launch Alliance’s previous mission was another Delta IV Heavy flight — NROL-44 from Cape Canaveral last December. The company’s next launch is currently expected in the middle of May, with an Atlas V deploying an SBIRS missile detection satellite out of the Cape.
The next launch from Vandenberg is currently unclear. The next launch with a confirmed date is NASA’s Landsat 9 spacecraft, due to lift off atop an Atlas V on 16 September.
However, the first flight of Firefly’s Alpha rocket, from the old Delta II pad at Space Launch Complex 2W, has been delayed from April but may still happen in the next few months while a rare outing for Northrop Grumman’s air-launched Pegasus-XL was previously slated to fly no earlier than May on a low-key mission for the Air Force.
The NRO’s next mission is NROL-111, which will fly aboard a small Minotaur I rocket — converted from a Minuteman missile — out of the Mid-Atlantic Regional Spaceport at Wallops Island, Virginia. This is currently scheduled for June.
(Lead image: Delta IV launching on NROL-82. Credit: Michael Baylor for NSF)
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