Screenshot from ULA Webcast of the launch of GPS III SV02
Mission Rundown: ULA - Delta IV M4,2 - GPS III SV02
Written: September 12, 2021 - Edit December 3, 2022
Anyway I’ll find your way
The swansong flight for the Delta IV Medium+ from United Launch Alliance launched at 09:06 EDT - 13:06 UTC from Space Launch Complex 37B at the Cape Canaveral Air Force Station on a mission to place the second GPS III Satellite Vehicle number 2 - SV02 for the US Air Force into orbit.
GPS III SV02 launched on a Delta IV Medium+ (4,2) configuration vehicle, which included a 4-meter Payload Fairing and two Northrop Grumman solid rocket motors. The common booster core for Delta IV was powered by the RS-68A engine, and the Delta Cryogenic Second Stage was powered by the RL10B-2 engine, both supplied by Aerojet Rocketdyne.
For ULA’s Delta IV M+ configuration rocket, Northrop Grumman provided two 1,5 meter ~ 60 inch diameter GEM 60 motors. At 53 feet long, the boosters burned for 90 seconds and together provided more than 560,000 pounds of thrust.
Magellan will join the current GPS constellation comprised of 31 operational spacecraft, and will be the 21st M-Code-capable satellite added to the fleet. GPS satellites operate in Medium Earth Orbit at an altitude of approximately 20,200 km (12,550 miles) in six planes. Each satellite circles the Earth twice per day, providing the “Gold Standard” of position, navigation and timing services for billions of users worldwide.
GPS III, the newest generation of GPS satellites, brings new capabilities to users, including three times greater accuracy and up to eight times improved anti-jamming capabilities.
The GPS III SV02 Payload
At about 11:01 a.m. ET, Air Force and Lockheed Martin engineers at Lockheed Martin's Launch & Checkout Facility near Denver declared they had full control of GPS III Space Vehicle 02 (GPS III SV02) shortly after the satellite's separation from its United Launch Alliance (ULA) Delta IV rocket booster.
The satellite, nicknamed "Magellan" by the Air Force, began its rocket ride to space with a 09:06 EST launch on August 22, 2019 from Cape Canaveral Air Force Station.
GPS III SV02 is the second GPS III satellite designed and built by Lockheed Martin to help the Air Force modernize today's Global Positioning System (GPS) constellation with new technology and capabilities.
GPS III satellites provide 3x greater accuracy and up to 8x improved anti-jamming capabilities. GPS III also provides a new L1C civil signal, compatible with other international global navigation satellite systems, like Europe's Galileo.
Lockheed Martin is under contract to build up to 32 next-generation GPS III/IIIF satellites for the Air Force. Additional "IIIF" capabilities will begin being added at the 11th satellite. These will be a fully digital navigation payload, a Regional Military Protection capability, an accuracy-enhancing laser retroreflector array, and a Search & Rescue payload.
The GPS III Space Vehicle has been listed with two different mass numbers from two different sources. Everyday Astronaut Tim Dodd lists the mass as 4 400 kg, and the other source SpaceFlight Now lists it as 3 705 kg. A third source states that 2159 kg of oxidizer and fuel have been loaded on the Space Vehicle for insertion and station keeping uses.
Newton_V suspects that 4 400 kg ~ 9,700 lbs includes a PLA? or PAF - Payload Adaptor Fitting in the number. Somebody probably saw a total "Payload Systems Weight" quoted somewhere, not a separated SV mass. This means that 695 kg is tied up in the equipment to hold, battery power supply, radio contact holding and release mechanism of the GPS III Space Vehicle during launch and coast faze before deployment.
GPS III SV02 “Magellan” was loaded with 1452 kg ~ 3200.9 lbs of high-purity hydrazine (N2H4) and 707 kg ~ 1559.4 lbs of oxidizer (N204) on June 20, 2019.
The Air Force Second Space Operations Squadron (2SOPS) indicates that GPS III SV02, with military numbers SVN-75/PRN-52, will replace the previous older USA-168 GPS IIR SVN-45/PRN-21 in the D plane slot 3. The GLAN is (D-3, 11.37 degrees). source
The Delta IV M+4.2 rocket
The Delta IV M+ 4.2 rocket stands 63.1 meter - 207 feet tall on SLC-37B and will generate 5,78 MN - 1.3 million pounds of thrust of liftoff.
Graphic of Delta IV M+4.2 split in its major parts. The DCSS is 4 meter wide in this configuration
The Delta IV M+4.2 rocket gets filled with 165 000 gallons of liquid oxygen and liquid hydrogen in all four cryogenic tanks. All pipes and tanks holding cryogenic propellant must be chilled before the loading of liquid oxygen and liquid hydrogen can begin.
First stage gets filled with 110 000 gallons of liquid hydrogen. Then 40 000 gallons of liquid oxygen gets pumped into the first stage.
Continuing up the rocket comes the second stage. The 4 meter Delta cryogenic second stage - DCSS gets filled with 10 000 gallons of liquid hydrogen in the big tank and the smaller tank below it gets filled with 4 500 gallons of liquid oxygen. The Delta Cryogenic Second Stage (DCSS) is powered by a single, vacuum optimized RL10B-2 engine.
The DCSS uses liquid hydrogen (LH2) and liquid oxygen (LOX).
The LH2 tank - volume of 37.854 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 22.712 m3 holding 6 000 gallon LOX - is suspended below it and is responsible for structurally supporting the RL10B-2 engine.
LH2 weighs 70,85 grams per liter giving a mass of 2682 kilo of liquid hydrogen.
LOX weighs 1141 grams per liter giving a mass of 25914 kilo of liquid oxygen.
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 850 seconds of available burn time and an unknown throttle setting during the mission.
850 seconds is equivalent to a 14 minute 10 seconds of full burn time.
The 4 meter Delta cryogenic second stage - DCSS is 12.2 meter - 40 feet tall. DCSS has a diameter of 4 meters - 13 feet and has an empty weight of 2850 kg - 6280 pounds. Filled with propellant it weighs 24170 kg - 53290 pounds.
That leaves 21320 kg - 47010 pounds of liquid hydrogen (LH2), liquid oxygen (LOX), liquid hydrazine and gaseous Helium under pressure in the stage.
Installed between the propellant tanks there are 6-8 pressure vessels containing gaseous Helium under pressure to backfill the tanks and 150 kg (340 lb) of Hydrazine stored in a pair of bladder tanks to feed the rocket's RCS thrusters.
The numbers don’t add up. 28.5 tons of liquid hydrogen (LH2) and liquid oxygen (LOX) is mentioned but there is only room for 21.3 ton propellant according to wikipedia.
In order to save costs and weight, the gimbal system uses electromagnetic actuators over normal hydraulics; this also increases reliability.
Now all that’s missing is 500 gallon gaseous Helium under pressure to backfill the tanks and 150 kg (340 lb) of Hydrazine stored in a pair of bladder tanks to feed the rocket's RCS thrusters?
The RS-68A engine burns nearly a ton propellant a second - up to ? gallons a second
The RL-10B-2 rocket engine burns up to ? gallons a second
At stage separation it weighs only 10% of its lift off weight.
Technical details about the Delta IV M+ 4.2 rocket will end up here later.
Photo found on wikipedia of the DCSS under construction. This is the bigger 5 meter DCSS
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