Screenshot from ULA Webcast of the launch of NROL-82. The cores roars to life in a sea of flames
Mission Rundown: ULA - Delta IV Heavy - NROL-82
Written: September 4, 2021 - Edit: November 29, 2022
What a big camera, you have?
United Launch Alliance’s Delta IV Heavy rocket launched on the first attempt from SLC-6 on California’s Vandenberg Air Force Base this Monday, carrying to a polar orbit the classified NROL-82 payload for the National Reconnaissance Office.
Designated NRO Launch 82 (NROL-82), Monday’s Delta IV ‘D386’ flight marked the first launch of the year for United Launch Alliance (ULA).
The webcast ended just before payload deployment per the customer request. The NRO has a contract with ULA to fly their large NROL satellites on Delta IV Heavy rockets.
This was the 13th launch of a Delta IV Heavy at 13:47 PDT on April 26, 2021.
The launch trajectory was consistent with a Sun-synchronous orbit (SSO). That particular type of low Earth orbit is 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.
Photo by USA-224 a KH-11/Crystal satellite of a failed Iranian rocket test. Published by Trump
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.
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.
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.
The NROL-82 Payload
Due to the NRO being a government agency, there is no publicly available information regarding the parameters and function of the NROL-82 satellite. It is also difficult to speculate on the purposes, size, mass, and function of the satellite. The NRO has chosen ULA because of their continuously successful and highly accurate launches for all customers.
Graphic speculation on what a KH-11 KENNEN spy satellite looks like. A small Huble telescope
Because of the chosen orbit, which is similar to a previous NROL mission 10 years earlier, it’s speculated that NROL-82 is a Blok 5 KH-11 Kennen/Chrystal satellite. KH-11 is a big Hubble-like earth observation satellite designated USA-314, and it is replacing the aging USA-224 launched on NROL-49 on January 11, 2011.
The Delta IV launch
Five seconds before the scheduled launch, Delta’s three RS-68A engines ignited. At this point, a fireball formed around the base of the rocket. This is caused by the engines igniting residual hydrogen that has boiled off from the rocket.
The process is well understood and harmless but has charred or set fire to the insulation on several previous flights.
Once the three engines had built up to full thrust, Delta IV Heavy lifted off to begin its mission. Liftoff occurred at the T-0 mark in the countdown when the thrust the rocket’s engines are generating exceeds the weight of the vehicle. For the first 9.4 seconds of flight, Delta climbed straight up, before initiating a pitch and yaw maneuver to place it on an easterly trajectory for the climb into orbit.
Shortly after this, the center core throttled down into partial-thrust mode, limiting loads on the vehicle early in the mission and conserving fuel so it can continue to burn after the side boosters separated.
One minute and 18.4 seconds into the mission, Delta reached Mach 1, the speed of sound. A second and a half later it passed through the area of maximum dynamic pressure – Max-Q – where it experienced peak mechanical stress from aerodynamic forces.
Three minutes and 56 minutes after liftoff, the two side boosters engines shut down, with the spent CBCs separating from the vehicle two seconds later. Around this time, the center core throttled back up to full thrust as it continued the boost phase of the mission. Its role in the flight ended with Booster Engine Cutoff, or BECO, at five minutes, 42.8 seconds mission elapsed time.
About six and a half seconds after BECO, the first and second stages separated, with the final CBC falling away from the rocket. The second stage RL10B-2 engine extended its deployable nozzle and initiated its pre-start sequence – with ignition coming 13 seconds after stage separation.
About 42 seconds after the second stage ignited, Delta’s payload fairing separated. The fairing is the nose cone of the rocket which protects the payload during ascent through Earth’s atmosphere and gives the rocket a consistent aerodynamic profile. Once the rocket reaches space, the fairing is no longer needed and can be discarded to reduce mass.
There are two different payload fairings that can be used on the Delta IV Heavy – a composite fairing which was designed for the Delta, and a metallic fairing made of aluminum which was inherited from the Titan IV. The launch will use the latter, which measures 19.8 meters (65 feet) in length.
After fairing separation, the mission will enter a media blackout.
The only likely official updates after this point will be a confirmation of mission success once the NROL-44 payload has separated from Delta IV Heavy. Given that the launch is targeting a geostationary orbit, this will not occur until six or seven hours after liftoff.
In this time, the DCSS upper stage can be expected to perform three burns. The first, which began after separation from the first stage, will continue for about seven minutes. This will establish the upper stage and its payload in their initial parking orbit.
Screenshot of the NROL-82 fairing separation. Note the DCSS is going 175.9 degree south
Based on the published flight profile of Delta IV Heavy’s initial demo mission – which was rumored to be simulating deployment of an Orion satellite – after coasting for a little under eight minutes, the rocket will fire its RL10 engine again for another eight-minute burn.
Now in geostationary transfer orbit, DCSS will coast for about five hours before commencing its final burn. This will last for about 3 minutes and 15 seconds, increasing the orbit’s perigee and decreasing its inclination to deploy its cargo directly into a circular geostationary orbit.
Following spacecraft separation, the DCSS will perform a collision avoidance maneuver to take itself out of the geostationary belt and minimize the risks of a future collision with a satellite. DCSS will then have used 1105 second burn time, so how much propellant can be left for a fourth disposal burn? 18 minutes 15 seconds equals 1105 seconds.
The Delta IV Heavy
One of the more powerful rockets currently in operation, the Delta IV Heavy has launched payloads including NROL satellites and the Parker Solar Probe, a mission to study the Sun. All 12 of the previous Delta IV Heavy launches have been successful.
Customers can choose between different payload fairing sizes to better optimize for their specific payload.
Screenshot of Delta Heavy IV split in its major parts. Note the spacecraft can be Hubble sized
The Delta IV Heavy is a 725,7 ton reliable heavy lift launch vehicle, meaning that it can take bigger and heavier payloads into orbit. It can launch up to 28,000 kg (61,000 lbs) to a 90 degree inclination Low Earth Orbit (LEO) and 14,000 kg (30,000 lbs) to a 27 degree inclination geostationary transfer orbit (GTO).
To accommodate payloads of all sizes, ULA offers two different payload fairing types with three heights both at 5 m (16 ft) in diameter. A 14 meter (47 ft) tall fairing and a 19.1 m (62.7 ft) tall fairing. As types go it's a three part fairing and a two part fairing.
The Delta IV Heavy first stage consists of three nearly identical 40.8 meter - 170 foot boosters strapped together. The Hydrogen and Oxygen tanks hold together 470 000 gallon of liquid propellant in 6 tanks measuring about 1 792 m3 in needed tank volume.
Each booster has one RS-68A engine also manufactured by Aerojet Rocketdyne. Together with DCSS and fairing they stand 71,6 meters - 235 feet tall on the launch pad.
The Hydrogen tanks hold 330 000 gallon of liquid Hydrogen chilled to -252,8 0C Celsius or -423 0F Fahrenheit in 3 tanks measuring about 1 254 m3 in estimated tank volume. The three Hydrogen tanks each hold at least 418 m3 cubic meter liquid Hydrogen.
The Oxygen tanks hold 120 000 gallon of liquid Oxygen chilled to below -182,96 0C Celsius or -297,33 0F Fahrenheit in 3 tanks measuring about 454,2 m3 in estimated tank volume. The three Oxygen tanks each hold at least 151,4 m3 cubic meter liquid Oxygen.
NROL-82 states that 120 000 gallons of liquid Oxygen is loaded. NROL-44 gave me these numbers. Second source found. Is 470 000 gallon of liquid propellant with DCSS +?
The first stage is infamously known for lighting itself on fire just before launch to burn off extra hydrogen. It does this because it needs to get rid of any hydrogen so it does not explode unintentionally during liftoff.
The hydrogen comes from the purging or chilling of the engines prior to ignition. The engine can’t handle the freezing chock of liquid Hydrogen and Oxygen and will split itself apart especially in the turbopump bearings. They will become brittle and shatter.
Each RS-68A engine has the capability to produce 3,160 kN (705,000 lbf) of thrust for a combined 9,420 kN of total thrust. The RS-68A engine has a specific impulse of 362 seconds and uses a combination of liquid hydrogen (LH2) and liquid oxygen (LOx).
During the flight, the center booster burned at a slightly slower throttle setting - 80% - than the two side boosters. This is because the Delta IV Heavy needs all three boosters in order to get enough velocity to pass through the thick parts of the atmosphere. However, after that, they are expended and jettisoned as to not carry any extra weight.
As the vacuum optimized second stage is very efficient, but not very powerful, the Delta IV Heavy burns its center booster longer than other rockets so the second stage will be able to put its payload into orbit.
Continuing up the rocket comes the second stage. The Delta Cryogenic Second Stage (DCSS) is powered by a single, vacuum optimized RL10B-2 engine. For its fuel, the DCSS uses liquid hydrogen (LH2) and for the oxidizer, liquid oxygen (LOX).
The LH2 tank - volume of 38 m3 holding 10 000 gallon LH2 - being on top, it has the job of supporting the payload and the payload fairing and is structurally separated from the other ‘half’ of DCSS. The clearly smaller LOX tank - volume of 23 m3 holding 6 000 gallon LOX - is suspended below it and is responsible for structurally supporting the RL10B-2 engine.
The RL10B-2 was originally built by Aerojet Rocketdyne and first flew in 1998. It has the capability to produce 110 kN (24,700 lbf) of thrust in a vacuum and has a specific impulse of 462 seconds. It will light up at least four times with 18 minutes 15 seconds of burn time and an unknown throttle setting during the mission.
In order to save costs and weight, the gimbal system uses electromagnetic actuators over normal hydraulics; this also increases reliability.
Photo of Delta IV Heavy in VIF. Sell a few seats in the side boosters nose cones. They would pay
Three common booster cores are seen here with an attached DCSS on the center core prior to the installing of the sealed fairing with NROL-82 inside. Three orange 40000 gallon LOX tanks are here side by side, while the top orange tank is the DCSS 10000 gallon LH2 liquid hydrogen tank.
The white interstage hides DCSS 6000 gallon LOX tank and the RL10B-2 engine.
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