Screenshot from ULA Webcast of the launch of GPS IIF-11. Sometimes the Sun shines just right
Mission Rundown: ULA - Atlas V 401 - GPS IIF-11
Written: January 6, 2023
Just find the bloody way
With its third launch of October, United Launch Alliance’s Atlas V rocket has successfully deployed the penultimate Block IIF Global Positioning System satellite. Liftoff from SLC-41 at Cape Canaveral AFB – rescheduled for Saturday, October 31, 2015 – occurred at the start of a 19 minute window that opened at 12:13 EDT (16:13 UTC).
The Atlas V that launched GPS IIF-11 had the tail number AV-060 and flew in the 401 configuration. Saturday’s launch is targeting an orbit at an altitude of 20,459 kilometers (12,713 statute miles, 11,047 nautical miles) and an inclination of 55 degrees.
Atlas V 401 flying with GPS IIF-11 along the eastern shoreline will pass Nova Scotia before reentry
The distance from Cape Canaveral to Atlas V’s final resting place in Davy Jones locker is measured to be about 2600 km ±100 km on Google Earth. However the fairings crash site isn’t marked on this map. It’s estimated to be about 1000 km ±100 km down range just past Cape Hatteras, North Carolina.
The GPS IIF-11 Payload
Initiated to provide precise location and navigational data to the US military, the GPS constellation is used worldwide for both civil and military purposes – and although Russia and China have developed their own global navigation systems in the GLONASS and Beidou constellations, with Europe continuing to develop its Galileo system, the majority of satellite navigation receivers rely upon GPS satellites.
The GPS Master Control Station, operated by the 50th Space Wing's 2nd Space Operations Squadron at Schriever Air Force Base, Colorado, is responsible for monitoring and controlling the GPS as a 24-satellite system, consisting of six orbital planes, with a minimum of four satellites per plane.
There are currently 39 vehicles in the GPS constellation.
Block IIF represents the final replenishment of the second-generation GPS constellation, with Friday’s payload, GPS IIF-11, the seventy-second GPS satellite to fly and the sixty-first member of the Block II GPS satellite constellation.
Each GPS satellite broadcasts a pseudo-random noise (PRN) signal encoded with a navigational message that contains the time, orbital properties of the satellite and information on the status of the constellation.
Each satellite is assigned a different PRN signal, with GPS IIF-11 expected to take on PRN-10 when it begins broadcasting. PRN-10 was last used by USA-175, a Block IIR-10 satellite which was launched in October 1993 and decommissioned last October, after 22 years in orbit, to make way for the launch of the previous Block IIF spacecraft.
Once it reaches orbit, GPS IIF-11 will be given a designation under the USA series, used to give a uniform designation to American military satellites. Recent designations have been assigned sequentially, so GPS IIF-11 will likely become USA-265.
The satellite is also known by its Space Vehicle Number (SVN) – it's like a production serial number within the GPS series, which is SVN-73. Fact data sheet.
The GPS launch history
The first Block II satellite launched on 14 February 1989, aboard the maiden flight of the Delta II rocket which would carry out a further forty-eight GPS missions over the following twenty-one years.
Block II was the first operational form of the Global Positioning System – the eleven Block I satellites launched by Atlas-E/F rockets between 1978 and 1985 were experimental spacecraft which paved the way for full deployment. The original Block II spacecraft – of which nine were launched – were 1,660-kilogram (3,660 lb) vehicles built by Rockwell.
Designed for seven and a half years of service, all nine launches took place between February 1989 and December 1990 using Delta II 6925-9.5 rockets.
The Block II was superseded by the enhanced Block IIA spacecraft, which were also produced by Rockwell and derived from the earlier satellites. Heavier, at a mass of 1,816 kg (4,004 lb), the spacecraft were able to operate and maintain accurate navigation signals without input from the ground for up to 180 days – increased from the fortnight that earlier satellites had been able to function autonomously.
Between the Block II and IIA vehicles, Rockwell completed a contract for the initial 28-satellite GPS constellation.
The first Block IIA satellite, USA-66, was the longest-lived spacecraft in the constellation achieving over 25 years of service. Launched atop Delta 200, the first flight of the 7000-series Delta II in November 1990, it was only retired from service on 25 January to make room in the constellation for the new spacecraft carried by Friday’s launch. As well as the first to launch, USA-66 was the final Block IIA satellite in service at the time of its decommissioning last Monday.
With the initial GPS constellation nearing completion, in 1997 the US Air Force began to launch Block II Replenishment, or Block IIR, satellites to augment and upgrade the constellation.
Block IIR satellites were built by Lockheed Martin, using the AS-4000 satellite bus, and were designed to provide a minimum of ten years’ service. Thirteen were launched between 1997 and 2004, with a further eight spacecraft being upgraded to the Block IIRM configuration and launched over the following five years.
The first Block IIR satellite, GPS IIR-1, launched atop a Delta II on 16 January 1997 but was lost seconds later when the structural failure of one of the rocket’s solid motors triggered the vehicle’s self-destruct. This was the only Block II spacecraft to be lost at launch.
Launched between 2005 and 2009, the eight Block IIRM satellites broadcast an additional military signal intended to be more resistant to jamming.
The first, GPS IIR-14(M) or GPS IIRM-1 (USA-183) was launched on 26 September 2005 and the last, GPS IIR-21(M) or GPS IIRM-8 (USA-206) flew on 17 August 2009. The Block IIRM spacecraft were the final GPS satellites to launch atop Delta II rockets, using the same 7925-9.5 configuration used since the Block IIA.
The penultimate IIRM spacecraft, USA-203, was equipped to broadcast an additional navigation signal, L5, as a demonstration ahead of the signal’s introduction with the Block IIF spacecraft.
In orbit, it was discovered that modifications made to the satellite to facilitate this test degraded its ability to broadcast regular navigation signals and as a result it never entered operational service.
Blocks IIR and IIRM were followed by the Boeing-developed Block IIF satellites. At the time of its inception in the mid-late 1990s, Block IIF was expected to consist of up to 33 satellites. This was scaled back to twelve, ten and then finally extended to twelve again, with the series serving as an interim between the end of Block IIR and the introduction of the next-generation Block III spacecraft.
Block IIF spacecraft are the lightest Block II satellites – at 1,630 kilograms (3,590 lb) – which is achieved because of the more powerful rockets used to launch them.
Evolution of GPS satellites so far. link Graphic sourced from: Lockheed Martin and Boeing Co.
The Atlas V and Delta IV Evolved Expendable Launch Vehicles (EELVs) are both capable of placing the satellites directly into their operational Medium Earth Orbits, whereas earlier spacecraft launched by the Delta II incorporated solid-fuelled apogee motors to inject themselves after initial deployment into a transfer orbit. Block IIF satellites have a design life of twelve years.
The first Block IIF, GPS IIF-1 or USA-213, was launched atop a Delta IV Medium+(4,2) rocket in May 2010. Launches have been split evenly between the Delta and the Atlas V, with Delta deploying the first, second, third, fifth, sixth and ninth satellites and Atlas carrying the fourth, seventh, eighth, tenth, eleventh and twelfth.
Each mission is named after a star – typically a bright or recognisable one which would be important to navigation. GPS IIF-1 was given the name Polaris, IIF-2 was named Sirius, with the subsequent names being Arcturus, Vega, Canopus, Rigel, Capella, Spica, Deneb, Antares and Betelgeuse as the twelfth. GPS IIF-11 is named after Altair, the brightest star in the constellation of Aquila ‘the Eagle’ and the twelfth-brightest star in the night sky.
The Atlas V 401 Launch
Departing from SLC-41, AV-060 ignited its engine 2.7 seconds before countdown reached zero. The first stage, or Common Core Booster (CCB), is powered by a single RD-180 engine – a two-chamber derivative of the RD-170 engine which was developed for the Soviet Union’s Zenit rocket.
Russian company NPO Energomash developed the engine, which burns RP-1 propellant oxidized by liquid oxygen. The CCB can be augmented by up to five solid rocket motors, however none are required for Friday’s mission.
Once the thrust generated by the RD-180 exceeded the weight of the Atlas vehicle and her payload – at 1.1 seconds after the zero mark in the countdown – the rocket lifted off and began its ascent towards orbit.
A series of pitch and yaw maneuvers began 17.3 seconds after liftoff to establish the rocket on an azimuth of 45.8 degrees, taking it northwest over the Atlantic Ocean as it leaves Cape Canaveral.
The vehicle passed through Mach 1, the speed of sound, at 78.5 seconds elapsed time. About 11.8 seconds later it encountered the area of maximum dynamic pressure, or Max-Q, when the vehicle was under its greatest aerodynamic load.
Cutoff of the first stage engine took place four minutes and 3.9 seconds after launch, followed by separation of the spent stage. The Centaur second stage ignited its lone RL10C-1 engine ten seconds later, with separation of the payload fairing from the nose of the rocket a further eight seconds after ignition.
Powered by liquid hydrogen and liquid oxygen, the Centaur’s first burn lasted for 12 minutes and 44.1 seconds.
This burn was followed by a coast phase lasting a few tenths of a second short of three hours. Restarting at the end of the coast for an 86.8-second burn, the Centaur circularized its orbit ahead of spacecraft separation four minutes and forty-six seconds after the conclusion of the burn, at three hours, 23 minutes and 16.1 seconds mission elapsed time.
Following spacecraft separation, the Centaur will likely restart again for a disposal burn to remove itself from the operational GPS orbit.
Saturday’s launch was the eleventh of 2015 for United Launch Alliance.
The Atlas V 401 rocket
Saturday’s launch of United Launch Alliance’s Atlas V was flying in the 401 configuration.
The Atlas V, tail number AV-060, consists of a Common Core Booster (CCB) first stage, with a single-engine Centaur (SEC) upper stage and a four-meter payload fairing fitted atop the Centaur. Although the Atlas V can fly with up to five Aerojet AJ-60A solid rocket motors boosting the first stage. AV-060 will use none.
Atlas V 401 split in its major parts. This is a generic non mission specific graphic configuration
The Atlas V is an expendable medium lift launch system and member of the Atlas rocket family. The rocket is one of the most reliable in the world, having more than 60 launches with no complete failures.
The Atlas V 401 rocket, tail no. AV-060 is standing 58.22 meters - 191 feet tall on SLC-41.
The rocket has two stages. The first is a Common Core Booster (CCB), which is powered by an RD-180 engine with two bells and burns kerosene (RP-1) and liquid oxygen (LOX). This is accompanied by up to five strap-on solid rocket boosters. The second stage is the Centaur upper stage, which is powered by one or two RL10 engines and burns liquid hydrogen (LH2) and liquid oxygen (LOX).
Atlas V rocket is filled with 344 472 liter - 91 000 gallons of RP-1, liquid oxygen and liquid hydrogen. Question is now how much goes to fill each stage and the four tanks. Together they can contain 344,47 m3 RP-1, cryogenic oxygen and cryogenic hydrogen.
The Common Core Booster holds 184 728 liter - 48 800 gallon liquid oxygen chilled to below -182,96 0C Celsius or -297,33 0F Fahrenheit and can fit in a 184,73 m3 oxygen tank.
The Common Core Booster holds 94 635 liter - 25 000 gallon RP-1 highly refined kerosine at room temperature that can fit in a 94,64 m3 fuel tank.
The Centaur upper stage holds about 15 709 liter - 4 150 gallons of liquid oxygen chilled to below -182,96 0C Celsius or -297,33 0F Fahrenheit that can fit in a 15,71 m3 fuel tank.
The Centaur upper stage holds about 48 075 liter - 12 700 gallons of liquid hydrogen chilled to -252,8 0C Celsius or -423 0F Fahrenheit that can fit in a 48,07 m3 hydrogen tank.
The 350 gallon of extra tank capacity found in the LOX tank could be used by Helium gas, Nitrogen gas and Hydrazine pressure vessels. That could be seven 50 gallon tanks.
Still to find is data on Helium gas, Nitrogen gas, pressures levels used and number of tanks - Carbon Overwrapped Pressure Vessels - COPV to store it. And there are tanks to store Hydrazine N2H4 propellant used to maneuver during launch and in orbit.
HAZ GAS operations are completed when the hydrazine is loaded. The RCS thrusters on the Centaur stage are using hydrazine as a monopropellant during orbit insertion.
The reaction control system (RCS) includes the ullage pressure thrust from the tanks and consists of twenty hydrazine monopropellant engines located around the stage in two 2-thruster pods and four 4-thruster pods.
For propellant, 150 kg (340 lb) of Hydrazine is stored in a pair of bladder tanks and fed to the RCS engines with pressurized helium gas, which is also used to accomplish some of the Centaur RL-10C-1 engine start up functions.
In the 401 configuration, the Atlas V is capable of carrying a structural maximum of 9,050 kg to Low Earth Orbit - LEO, 8,200 kg to the International Space Station - ISS and 4,950 kg to Geostationary Transfer Orbit - GTO.
The Common Core Booster contains a total of 284,089 kilograms - 626,309 pounds of RP-1 kerosene and liquid oxygen, weighs 306,271.7 kilograms - 675,213.5 pounds fully fueled, and is 35.63 meters - 116,9 feet tall and 3.81 meters - 12,5 feet wide.
Its RD-180 main engine produces 3,826.9 kilonewtons - 860,321.35 pounds of thrust at sea level while the thrust level increases to 933,406.73 pounds in space.
The Centaur V1 upper stage contains 20,830 kilograms - 45,922.3 pounds of liquid hydrogen and liquid oxygen, weighs 23,073 kilograms - 50,867.3 pounds fully fueled, and is 12.68 meters - 41,6 feet tall & 3.05 meters - 10 feet wide.
Its RL-10C-1 engine is optimized for vacuum usage with a big nozzle - engine bell, so it only produces 101.8 kilonewtons - 22,885.55 pounds in space.
Atlas V 401 weighs an estimated 333,464.7 kilograms - 735,163.8 pounds, including the GPS IIF-12 spacecraft; and is 58.22 meters - 191 feet tall and 4.2 meters - 13,8 feet wide.
The GPS IIF-12 spacecraft weigh 1,632.0 kilograms - 3,598 pounds on their own, that’s with the fairings weight excluded.
The Atlas V 401 LPF fairings weigh 2,487.0 kilograms - 5,482.9 pounds. The weight of a 3 foot fairing extension is estimated to be a small part of the LPF fairing. 100 kg at most.
Doing the math: 306272 kg + 23073 kg + 1632 kg GPS IIF-12 + 2487 kg = 333464 kg.
The Atlas V 401 rocket has a three number configuration code.
The first number represents the fairing diameter size in 4 or 5 meters, so in this instance there is a 4 meter fairing. This launch will use the 12.2 meter long (40 ft) LPF.
The standard four-meter fairing, named the Long Payload Fairing (LPF), measures 12.2 meter (40 feet) in length and was first introduced as a larger fairing for the Atlas I rocket that was used as a launch vehicle in 1990.
One or two 90-centimeter (3-foot) cylindrical segments can be added to the fairing to form an Extended Payload Fairing (EPF) 13.1 meters (43 feet) or Extra-Extended Payload Fairing (XEPF) 14.0 meters (46 feet) respectively for payloads that require the additional space.
The second number denotes the number of solid rocket boosters (SRBs), which attach to the base of the rocket. The number of SRBs for a 5 meter fairing can range from 0 – 5. In this case there will be no SRB’s attached to the center core.
The third number shows the number of engines on the Centaur Upper Stage, which is 1 in this configuration. So this means that this rocket will have a 4 meter fairing, no solid rocket boosters, and 1 engine bell on the Centaur Upper Stage.
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