Screenshot from ULA launch of WGS-9. It’s the end of the line. Mikey. You got nowhere to go but up
Mission Rundown: ULA - Delta IV M +5,4 - WGS-9
Written: December 21, 2022
All those military calls to Pentagon
United Launch Alliance’s third launch of 2017 is the first Delta IV launch carrying a Wideband Global Satcom spacecraft (WGS-9) into orbit Saturday. The lift off from Cape Canaveral Air Force Station occurred on March 18, 2017 at 20:18 local time (00:18 UTC on the next day), following a slight delay related to the Swing Arm system at the pad.
Saturday’s launch will deploy the ninth satellite of the US Air Force’s Wideband Global Satcom (WGS) constellation. WGS-9, which was purchased for the Air Force by a group of other nations in exchange for access to the WGS system, will join the eight satellites already in orbit which launched between 2007 and 2016.
The WGS-9 Payload
Built by Boeing, WGS satellites are based on the BSS-702 platform and designed for fourteen years of service. Each spacecraft is equipped with an Aerojet Rocketdyne R-4D-15 High Performance Apogee Thruster (HiPAT) to perform insertion into geosynchronous orbit and four Xenon-Ion Propulsion System (XIPS-25) thrusters for station keeping.
The WGS-9 satellite carries X and Ka-band transponders. The satellite will use a phased array antenna to provide eight jam-resistant X-band beams, while ten individual antennas will provide Ka-band beams. An additional X-band payload will be used to provide Earth coverage. The satellite can support 8.088 gigahertz of bandwidth, with an expected downlink speed of up to 11 Gbps.
The Delta IV M +5,4 Launch
Saturday’s launch began with ignition of the Delta IV RS-68A main engine, five seconds before the countdown reached zero. Burning liquid hydrogen and liquid oxygen, the RS-68A powers the Common Booster Core (CBC) that form’s Delta’s first stage. At the zero-second mark in the countdown, the four GEM-60 solid rocket motors ignited, and the rocket – whose mission number was Delta 377 – lifted off.
Seven seconds into its flight, Delta 377 began a series of pitch, yaw and roll maneuvers to place it on course for orbit. The rocket flew east downrange along an azimuth of 93.46 degrees, passing through the area of maximum dynamic pressure – Max-Q – 46.1 seconds after liftoff.
The solid rocket motors began to burn out 92.8 seconds after launch, with boosters three and four burning out 2.3 seconds ahead of boosters one and two. The two pairs of boosters separated eight seconds after their respective burnouts.
Three minutes and 14.6 seconds into the mission, the payload fairing separated from around the WGS-9 satellite at the nose of the rocket. By this point, the rocket cleared the lower regions of Earth’s atmosphere and the fairing was no longer needed to protect the spacecraft.
Flight path of WGS-9. Red zones are where 4 SRB’s, 2 fairings and the Atlas booster will land
The Common Booster Core completed its burn three minutes and 56.5 seconds after liftoff. The spent stage was jettisoned 6.6 seconds later. After stage separation, the second stage – a five-meter Delta Cryogenic Second Stage (DCSS) – deploy the extendible nozzle of its RL10B-2 engine ahead of ignition. The RL10B-2 ignited thirteen seconds after staging to begin its first burn.
The DCSS, which like the first stage burns liquid hydrogen and liquid oxygen, made two burns to deploy WGS-9 into its planned orbit, with a third burn after spacecraft separation to deorbit itself. The first burn was the longest, lasting fifteen minutes and 37.5 seconds, and established the rocket in an initial parking orbit. Nine minutes and 33 seconds after the first burn ended the second burn began, raising the apogee of Delta 377’s orbit. This burn lasted three minutes and 9.7 seconds.
Spacecraft separation occurred at 41 minutes, 45.6 seconds mission elapsed time, nine minutes and 10.3 seconds after the end of the second burn. WGS-9 was deployed into a supersynchronous transfer orbit with a perigee of 435 kilometers (270 miles, 235 nautical miles), an apogee of 44,372 kilometers (27,572 miles, 23,959 nautical miles) and an inclination of 27 degrees to the equator. From this orbit, the satellite will use its R-4D apogee motor to raise itself into geostationary orbit.
The second stage began its third and final ten-second deorbit burn twenty-nine minutes and 59 seconds after spacecraft separation.
This deorbit burn lowered its orbit’s perigee so that DCSS re-entered Earth’s atmosphere at the end of its first orbit.
Because of the orbit’s high apogee, the stage will take another eleven hours to complete this one revolution, while the Earth rotates underneath such that the stage will reenter over the western Pacific.
ULA states that the expected 44 g impact time for any debris surviving reentry will be twelve hours, twelve minutes and 9.6 seconds mission elapsed time.
The Delta IV Medium rocket
United Launch Alliance’s Delta IV Medium +(5,2) rocket launched on the rocket type’s thirty-fifth flight, had flight number Delta 377 (D377). 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 5,4 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.
Orbital ATK provided parts of the propulsion, composite and spacecraft technologies to enable the successful launch of both the United Launch Alliance (ULA) Delta IV rocket and the ninth Wideband Global SATCOM (WGS-9) satellite that was launched Saturday from Cape Canaveral Air Force Station, Florida.
For the Delta IV rocket, Orbital ATK provided four 60-inch diameter Graphite Epoxy Motors (GEM-60). The 53-foot-long solid rocket boosters burned for 90 seconds and provided more than 1.1 million pounds of thrust, more than the combined thrust of four 747 jet aircraft.
Orbital ATK produced the solid rocket motors at its Magna, Utah, facility, where it has manufactured 84 GEM-60s in support of the 36 Delta IV launches since 2002.
