Screenshot from ULA Webcast of the launch of NROL-47. SLC-6 was built to launch shuttles
Mission Rundown: ULA - Delta IV M+5,2 - NROL-47
Written: December 12, 2022
You don’t see, hear or talk about it.
United Launch Alliance launched a Delta IV rocket from Vandenberg Air Force Base, carrying the classified NROL-47 mission for the US National Reconnaissance Office. Following a scrub on Thursday, liftoff occurred on Friday at 22:10 UTC.
The NROL-47 Payload
NRO Launch 47, or NROL-47, is a national security payload that will be operated by the National Reconnaissance Office (NRO), an agency of the US Government tasked with operating the country’s fleet of reconnaissance satellites. The launch comes just five days after SpaceX launched another classified satellite – Zuma – to be operated by an undisclosed US government agency.
ZUMA failed to deploy being unable to be released from its Payload Adapter Fitting - PAF. SpaceX had handed over a PAF to the undisclosed US government agency and they didn’t manage to fit ZUMA to the release mechanism on the PAF. The blame was placed on the lack of vertical integration facility of SpaceX. ZUMA couldn’t be fitted lying down.
With details of most NRO missions being classified – including the design, specification and capabilities of the satellites, their missions, orbits and operations.
Despite this, amateur and professional observers have been able to infer many details from observation of the spacecraft and how they behave once in space, combined in some cases with classified information that has been leaked from government agencies and intelligence services.
Located on California’s western coast, Vandenberg Air Force Base allows launches to high-inclination and retrograde orbits that would be inaccessible from Cape Canaveral without overflying land. Low-inclination orbits, such as the equatorial geostationary orbit, are impractical to reach from Vandenberg.
NRO missions that normally use Vandenberg include optical imaging satellites, which use near-polar sun-synchronous orbits, radar imaging satellites which fly in retrograde orbits, orbiting the Earth from east to west, and signals intelligence satellites (SIGINT) in inclined low-Earth and elliptical Molniya orbits.
The trajectory takes the rocket further to the south than the rockets that carried Topaz satellites. Assuming the rocket does not perform a dog-leg maneuver to change its final orbit after clearing these hazard areas, this course would result in a lower-inclination orbit than the 123-degree orbits used by Topaz. Because the orbit is retrograde, this lower inclination means the satellite would pass over higher latitudes on the Earth’s surface.
The use of a retrograde orbit suggests that the satellite is still some form of radar imaging satellite – as there is little reason to put any other type of reconnaissance satellite into retrograde orbit. It is unclear why a different orbit is being used for NROL-47 – although this could be related to the 68-degree plane of the former Onyx constellation.
More details will likely emerge once NROL-47 arrives on orbit and begins to be tracked by the amateur community. Once in orbit, the satellite will be renamed. Most US military satellites are given sequentially-numbered designations beginning with a USA code. Zuma was assigned the designation USA-280, so NROL-47 will probably be USA-281.
The Delta IV M Rocket Launch
Delta IV is a two-stage rocket, with an all-cryogenic core vehicle – fuelled by liquid hydrogen propellant and liquid oxygen oxidizer. The first stage is a Common Booster Core (CBC), powered by a single RS-68A engine. In the Medium+(5,2) configuration this is augmented by two GEM-60 solid rocket motors.
About five and a half seconds before liftoff, Delta 379 lit its RS-68A engine. Once the count reached zero, the two booster rockets ignited, and the Delta IV began its ascent towards orbit. The rocket took about fifty seconds to reach a speed of Mach 1 – the speed of sound – and passed through the area of maximum dynamic pressure (Max-Q) about twelve seconds later.
The two GEM-60 motors burned for about 100 seconds before they burnt out. The spent casings were jettisoned ten seconds later. A reason for this is to ensure that the landing site of the SRB’s don’t hit anything man made - Oil Rigs.
Another more logical reason for this delayed jettison of the SRB’s is that the solid rocket propellant still is coughing up small but dangerous bursts of thrusts, which can cause serge forward to a midair collision with the common core booster.
After climbing above the dense lower layers of the atmosphere, Delta 379 shed its payload fairing around three and a half minutes after liftoff. This was the last event before the mission enters a blackout, with no further information being released about its progress except a brief statement later confirming the successful completion of the launch.
The CBC will likely continue to burn until about four minutes and six seconds into the flight. Six seconds after shutdown, the first and second stages will separate.
Delta’s second stage, the five-meter (16.4-foot) diameter version of the Delta Cryogenic Second Stage (DCSS), will begin to deploy the extendible nozzle of its RL10B-2 engine, with ignition coming about 13 seconds after separation.
Delta’s second stage, the five-meter (16.4-foot) diameter version of the Delta Cryogenic Second Stage (DCSS), will begin to deploy the extendible nozzle of its RL10B-2 engine, with full ignition burn coming on about 13 seconds after stage separation.
The timings of the upper DCSS burns are more mission-specific than earlier flight events and have not been published, however, the first burn is likely to be longer, typically around twelve-and-a-half minutes in duration, establishing an initial Earth parking orbit.
Following a coast phase, a much shorter second DCSS burn will circularize the orbit. This burn could take as little as fifteen seconds.
After deployment of NROL-47 in a speculative near circular orbit at an inclination of 108.6 degrees compared with the equator. A third deorbit burn is performed.
On SeeSat-L, a mailing list that contains a community of leading amateur satellite observers, Marco Langbroek has calculated a likely destination orbit for NROL-47 based on the launch hazard areas and additional NOTAMS that show that DCSS is expected to reenter off the coast of Antarctica about two hours and 23 minutes after launch.
His calculations have shown a near-circular orbit at an altitude of 1,500 kilometers (930 miles, 810 nautical miles) and an inclination of 108.6 degrees.
The use of a retrograde orbit suggests that the satellite is still some form of radar imaging satellite – as there is little reason to put any other type of reconnaissance satellite into retrograde orbit. It is unclear why a different orbit is being used for NROL-47 – although this could be related to the 68-degree plane of the former Onyx constellation.
A 108.6-degree orbit would give the satellite coverage of the same latitudes as a spacecraft in a 71.4-degree prograde orbit – allowing it to cover parts of the Earth’s surface that would not be visible to the four spacecraft already in orbit.
The 108.6 degree retrograde orbit keeps the Sun in a fixed position. The satellite follows the same time zone 22:00 UTC on descending north to south nodes and after passing the south pole in the time zone 10:00 UTC on ascending south to north nodes.
The 71.4 degree prograde orbit follows the Earth's rotation with the latitude. The satellite follows the same strip of land while keeping an eye on military targets every 90 minutes or so depending on the altitude of the orbit.
The Delta IV Medium rocket
United Launch Alliance’s Delta IV Medium +(5,2) rocket launched on the rocket type’s thirty-sixth flight, had flight number Delta 379 (D379). The Delta IV, which first flew in 2002, is one of the two types of Delta Evolved Expendable Launch Vehicles (EELVs) operated by ULA, along with the Atlas V.
ULA also operates the older Delta II rocket, which will be retired later this year. ULA has operated these three rockets since it was formed in December 2006 – with Delta II and Delta IV having been previously operated by Boeing and Atlas V originally developed by Lockheed Martin before the merger between the two companies.
This NROL-47 launch was the first Delta IV mission to use the newly developed United Launch Alliance’s Common Avionics system, a standardized avionics package designed to be used on both the Atlas V and Delta IV rockets.
By standardizing this component across their fleet, ULA aims to reduce costs and ensure a continued high level of reliability for both rockets. The NROL-47 mission was delayed from December in order to allow further checks to be carried out on the rocket’s new avionics.
Delta IV is a two-stage rocket, with an all-cryogenic core vehicle – fuelled by liquid hydrogen propellant and liquid oxygen oxidizer. The first stage is a Common Booster Core (CBC), powered by a single RS-68A engine. In the Medium+(5,2) configuration this is augmented by two GEM-60 solid rocket motors.
Delta’s second stage, the five-meter (16.4-foot) diameter version of the Delta Cryogenic Second Stage (DCSS), will begin to deploy the extendible nozzle of its RL10B-2 engine, with full ignition burn coming on about 13 seconds after stage separation.
The timings of the upper DCSS burns are more mission-specific than earlier flight events and have not been published, however, the first burn is likely to be longer, typically around twelve-and-a-half minutes in duration, establishing an initial Earth parking orbit.
Following a coast phase, a much shorter second DCSS burn will circularize the orbit. This burn could take as little as fifteen seconds. Depending on mission type, objectives and payload mass DCSS can make several more burns.
DCSS first burn always puts the payload into an elliptical orbit, second burn has either a transfer objective or is to circularize the high Earth orbit. The transfer burn happens usually on the equator line over Africa where a yaw turn will reduce the inclination of the orbit with the equator line from 28 to 16-8 degrees.
DCSS will perform a third 10 minute burn to raise the first orbit to a steep elliptical 10 hour long transfer orbit with the aim to reach a geostationary orbit at 35 500 km altitude. The size and mass of the payload now dictates whether or not the payload will be deployed 5 minutes after the third burn shutdown.
Eight ton - 8 000 kg payloads are left to find the way to their geostationary orbit under their own power with an apogee engine and its propellant of choice. Smaller payloads 2-3 ton - 2-3 000 kg can be inserted by DCSS in a geostationary orbit with a fourth burn.
Now all there is left is the fourth deorbit burn or the fifth graveyard burn. DCSS have by now used all of its propellant but 10-12 seconds. That burn time is used to get out of the payload's way so it won't interfere with its orbit.
The graveyard orbit will take about 25 000 years to decay down to Earth and the deorbit burn will lower the perigee to below ocean level or below the 100 Km Karman line, where air friction will brake its mach 25 speed for good.
Delta IV Medium 5,2 split in its major parts. The DCSS tank capacity isn’t know in details yet
Delta IV M stands 67 meters - 220 feet tall, weighs about 340 194 kg - 750 000 pounds and is launched with a thrust of more than 4.45 MN - 1 000 000 foot pounds.
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