Screenshot from NASA/ULA Webcast of the GOES-R launch. Sometimes We watch far to much TV
Mission Rundown: ULA - Atlas V 541 - GOES-R
Written: December 27, 2022
What’s the Weather like up there?
ULA’s Atlas V rocket successfully deployed a next-generation weather satellite for the US National Oceanic and Atmospheric Administration on Saturday. The United Launch Alliance (ULA) rocket launched from SLC-41 at Cape Canaveral at the end of a one hour-long window at 18:42 local time (23:42 UTC).
The GOES-R satellite, which rode aboard Saturday’s launch, begins a new fifth generation of geostationary weather satellite for the United States. It is the first of four satellites in its class which are expected to launch over the next eight year period.
GOES-R is part of the Geostationary Operational Environmental Satellite (GOES) program, operated by the National Oceanic and Atmospheric Administration (NOAA).
Once operational, the GOES-R/GOES-16 satellite will produce 3.5 terabytes of data per day, and like all NOAA satellites, the data will be available to the public at no cost.
The GOES-R Payload
GOES consists of two operational satellites in geosynchronous orbit over the United States, providing images and data for weather forecasting across the western hemisphere. One satellite is located at a longitude of 75 degrees West – a station designated GOES-EAST – covering the Eastern United States, the Central and West Atlantic, the Gulf of Mexico and the Caribbean.
The other satellite, designated GOES-WEST, is positioned at 137 degrees West and covers the western States – Alaska and Hawaii – as well as the Eastern and Central Pacific.
At present, the GOES-EAST slot is occupied by GOES 13, while GOES-WEST coverage is provided by GOES 15. These satellites launched in May 2006 and March 2010 as GOES-N and GOES-P respectively. The GOES 14 satellite, formerly GOES-O, has served as an on-orbit spare since its launch in 2009 and has occasionally been called into service to cover outages as GOES 13 begins to show its age.
In addition to weather forecasting, the GOES satellites are used to study space weather phenomena and do research into the Earth’s magnetosphere and radiation environment.
GOES-R is the first of four GOES-R-class satellites that form the fifth generation of the GOES constellation. Constructed by Lockheed Martin and based on the A2100A satellite bus, each satellite has a dry mass of 2,857 kilograms (6,299 lb) which increases to 5,192 kilograms (11,466 lb) when fully-fuelled at launch. The spacecraft measure 6.1 by 5.6 by 3.9 meters (20 x 18 x 13 feet) and have fifteen-year design lives; expected to consist of ten years of operational use and up to five years of storage as an on-orbit spare.
Screenshot of GOES-R main satellite body - payload and satellite bus - points at Earth. Solar arrays with the other part of the payload instruments point at the Sun. The man is there for scale only
GOES-R carries six scientific payloads and a data relay payload. Its nadir-pointing – Earth-facing – instruments are mounted on the side of the satellite which will be pointed towards Earth in orbit. Solar-pointing instruments are located on the arm which holds the satellite’s solar array; to provide power to the spacecraft this arm must track the sun, allowing its instruments to make near-constant observations. Further sensors will allow the satellite to study its surrounding environment.
GOES-R’s data will support short-term weather forecasts and severe storm warnings, maritime forecasts, seasonal predictions, drought outlooks and predictions about space weather. Additionally, GOES-R products will improve hurricane tracking and intensity forecasts, and increase thunderstorm and tornado warning lead time.
The Atlas V 541 Launch
The launch of GOES-R took a little over three and a half hours from liftoff to spacecraft separation, with the satellite expected to be deployed into a geosynchronous transfer orbit with a perigee of 8099 kilometers (5032 miles, 4373 nautical miles), an apogee of 35,286 kilometers (21,926 miles, 19,053 nautical miles) and 10.6 degrees inclination to the equator. The launch took place from Space Launch Complex 41 (SLC-41) at the Cape Canaveral Air Force Station.
Atlas vehicles are assembled atop a mobile launch platform in the nearby Vertical Integration Building and rolled to the launch pad shortly ahead of launch. AV-069 was moved to the pad Friday morning.
The Atlas is a two-stage vehicle, consisting of a Common Core Booster (CCB) first stage and a Centaur upper stage. The CCB is powered by a single RD-180 engine, manufactured by NPO Energomash of Russia, which burns RP-1 propellant oxidized by liquid oxygen.
Igniting 2.7 seconds ahead of the planned liftoff, the RD-180 is the rocket’s principal source of thrust during the early stages of flight as Atlas climbs through Earth’s atmosphere. At liftoff, four Aerojet Rocketdyne AJ-60A solid rocket motors (SRMs) will ignite to provide additional thrust.
After 1st stage ignition, it took a few seconds for the RD-180 to reach launch thrust. Liftoff was at about 1.1 seconds after the zero mark in the countdown, when the force generated by the main engine and solid rocket motors exceeds the weight of the loaded vehicle.
AV-069 began her ascent away from Cape Canaveral, beginning a series of pitch and yaw maneuvers 5.2 seconds after launch. The rocket flew along an azimuth of 100.7 degrees, taking it East and slightly South over the Atlantic Ocean.
Thirty-five and a half seconds after liftoff, Atlas’ velocity reached Mach 1, the speed of sound. The rocket experienced maximum dynamic pressure – or Max-Q – 10.7 seconds later as it continued to climb. The SRMs burned out around 85 to 90 seconds into flight and separated in pairs; the first pair detaching at 110.4 seconds after liftoff and the second pair a second and a half later.
At three minutes and 29.9 seconds after launch, the payload fairing separated from around GOES-R at the nose of the rocket. By this stage, Atlas was at an altitude in excess of 100 kilometers (62 miles, 54 nautical miles), above the denser regions of the atmosphere which would damage the spacecraft if it were unprotected.
Because the five-meter fairing encapsulates not just the satellite but also the Centaur upper stage, it must be jettisoned before the first stage can separate.
First stage flight ended with Booster Engine Cutoff, or BECO, four minutes and 21.8 seconds after liftoff. The spent stage separated six seconds later.
Following staging, the Centaur’s single RL10C-1 engine began a pre-start sequence ahead of its ignition ten seconds later.
Powered by the combustion of liquid hydrogen propellant, oxidized by liquid oxygen, the Centaur made three burns during Saturday’s mission. From separation, the first burn lasted seven minutes and 37.8 seconds.
Following a nine-minute, 43-second coast phase, the Centaur restarted for a five-minute, 38-second burn that raised its orbital apogee towards geosynchronous altitude.
Following the burn, Centaur coasted towards its apogee, with its third burn eighteen-tenths of a second short of three hours later. The third and final burn lasted 93.3 seconds, raising the orbit’s perigee and reducing its inclination; decreasing the amount of propellant GOES-R will need to burn to reach its final geostationary station.
Spacecraft separation occurred 69 seconds after the end of the third burn, at three hours, 31 minutes and 54.9 seconds mission elapsed time.
Following separation GOES-R will use its LEROS-1C apogee motor to perform a series of orbit-raising maneuvers. Upon arrival in geostationary orbit, the satellite will undergo around a year of test and checkout operations.
It is currently expected to replace GOES 13 in the GOES-EAST slot late next year, with GOES 13 becoming an additional on-orbit spare. GOES-R is designed for up to ten years of operational life plus five years of on-orbit storage; it is currently scheduled to be replaced by GOES-T in late 2025.
The Atlas V 541 rocket
GOES-R was launched by United Launch Alliance (ULA), using an Atlas V rocket. The vehicle, with the tail number AV-069, flew in the 541 configuration, with a five-meter (16.4-foot) payload fairing, four AJ-60A solid rocket motors augmenting a Common Core Booster first stage, and a single-engine Centaur upper stage.
Saturday’s launch was the 67th flight of an Atlas V, and the 4th for the Atlas V 541.
Atlas V 541 can lift better than 6.2 metric tons (tonnes) to GEO-1500 m/s delta v orbit. GOES-R weighs 2.8 tonnes dry and 5.2 tons wet - fueled.
If the propellant mass fraction is similar to previous GOES, that translates to an almost 4.9 tonne liftoff mass, which an Atlas 521 should theoretically be able to lift.
Combining the four AJ-60A boosters and the RD-180 engine, this Atlas V 541 rocket will produce a sea-level thrust of 2,216,369 pounds.
Centaur running slightly oxidizer rich. In general, propellant utilization (PU) will need to burn off "excess" LO2, as the ratio of the tank load is greater than the nominal mixture ratio. How long it stays at the upper stop also depends on the flight profile (burns/coasts).
Centaur is continuing its barbecue roll maneuver to even out its thermal conditions and is firing two of four ullage rockets to ensure that the LOX and LH2 propellants remain stable.
Atlas V 541 split in its major parts. Some known facts have been found in various ULA tweets
