Screenshot from ULA Webcast of the Landsat 9 launch - It's too foggy and wet. Turn up the heat
Mission Rundown: ULA - Atlas V 401 - Landsat 9
Written: November 25, 2022
Keeping a keen eye on Earth
United Launch Alliance has launched NASA’s most powerful Earth-imaging satellite, Landsat 9, on an Atlas V rocket. Liftoff occurred at 11:12 AM PDT (18:12 UTC) on Monday, September 27, from Space Launch Complex-3 East (SLC-3E) at Vandenberg Space Force Base in California.
Atlas V placed the satellite into a near-polar, sun-synchronous orbit at an altitude of 705 km and a 98.2-degree inclination. Sun-synchronous orbits are often used by Earth-imaging satellites to ensure that the spacecraft will always be at the same position relative to the sun when visiting the same location on Earth. This allows scientists to accurately compare two images at different times and track changes over time.
Atlas V will stand 194 feet tall (59.1 meters) and weigh 749,479 pounds (339,958 kg) at liftoff. Atlas V is ULA’s workhorse rocket, with a total of 87 launches prior to Landsat 9. The variant in use for this mission, the Atlas V 401, was previously launched 38 times.
Using a three-digit configuration number, the first digit denotes the diameter of the payload fairing, the second indicates the number of solid rocket motors (SRMs), and the third represents the number of RL-10 engines on the Centaur upper stage.
Atlas used the longest-available 4.2-meter fairing known as the Extra Extended Payload Fairing (XEPF), and a single RL-10 engine on the Centaur upper stage.
This launch was scheduled for December 2020, but due to shortages of liquid oxygen and liquid nitrogen due to the COVID-19 pandemic, it was delayed to September 2021.
The launch countdown began with the loading of liquid oxygen onboard Atlas V. The rocket was already fueled with RP-1 kerosene two days before during the completed WDR.
At T – 2 seconds, the RD-180 engine ignited, and the rocket lifted off. At T + 1 minute and 27 seconds, Atlas V reached maximum aerodynamic pressure, max. q, where the rocket experienced the largest forces exerted by the Earth’s atmosphere.
At T+ 4 minutes and 8 seconds, the RD-180 engine shut down, the Centaur upper stage separated from the booster, and the RL-10 engine ignited. It burned for over 12 minutes before the first Main Engine Cutoff (MECO-1) at T+ 16 minutes. After reaching its main polar orbit T+ 1 hour 4 minutes, Landsat 9 was separated from the payload adapter.
Next mission objective is the deployment of the 4 CubeSats. For that, the Centaur’s main engine undergoes two more burns to reduce its orbit. The CubeSat deployment begins at T+ 2 hours 14 minutes. Once the deployments are complete, Centaur initiates a fourth and final burn to deorbit itself, completing Atlas V’s mission.
ELaNa 37 with 18 CubeSats missed its ride due to Covid restrictions, and two years spent on preparing the ESPA rings with its mountings was almost wasted, but ULA engineer Elizabeth Sorrell has the knowhow until the next launch opportunity. Link
Landsat 9 compass course, azimuth is 185.70 degrees retrograde so it will follow the Sun fixed above while the Earth rotates below its flight path. Shadows will always have the same angle.
The Landsat 9 Payload
Landsat 9 is the latest satellite in the NASA and U.S. Geological Survey (USGS) Landsat program, started in 1972 as an Earth observation satellite program. Of eight satellites previously launched, seven successfully reached orbit, and two satellites: Landsat 8 for eight years and Landsat 7 for twenty two years are still currently in operation.
Landsat 9 is a near-identical twin of the Landsat 8 satellite. Both satellites are based on the Northrop Grumman LEOStar-3 satellite. LEOStar-3 is Northrop Grumman’s newest low Earth orbit satellite bus offering and is the same satellite bus that will be used for the Joint Polar Satellite System (JPSS).
The first instrument is the Operational Land Imager (OLI-2), built by Ball Aerospace. OLI-2 will take measurements in the visible, near-infrared, and shortwave infrared portions of the electromagnetic spectrum. The spatial resolution of the images will be 15 meters for the panchromatic band and 30 meters for the multispectral bands. OLI-2 has a 15-degree field of view covering 185 kilometers across the ground.
The second instrument used on Landsat 9 is Thermal Infrared Sensor 2 (TIRS-2). TIRS-2 will measure land surface temperature in two thermal infrared bands. Just like OLI-2, TIRS-2 will have the same 15-degree field of view covering 185 kilometers.
Both instruments for Landsat 9 were completed and delivered to Northrop Grumman in Arizona in late 2019 and were integrated with the satellite in January 2020. This allowed the satellite to begin final testing for launch and operations. Landsat 9 completed electromagnetic and radiation testing in the fall of 2020, and in April 2021, the satellite completed 42 days of thermal vacuum testing.
Landsat 9 being encapsulated by its fairings. Note the two ESPA rings below the satellite. NASA
The top of the two ESPA rings contain avionics or at least the satellite release mechanism needed to deploy Landsat 9 in its correct planned near polar orbit. The bottom of the two ESPA rings contain four release mechanisms to deploy the ELaNa 34 CubeSats.
There are four CubeSats on this mission sponsored by the Defence Innovation Unit, Air Force Research Laboratory, Missile Defence Agency, and NASA. The NASA CubeSats include the Colorado Ultraviolet Transit Experiment (CUTE) from the University of Colorado at Boulder and the Cusp Plasma Imaging Detector (CuPID) from Boston University.
CUTE will measure how near-ultraviolet light from a host star changes when an exoplanet passes in front of it and through a planet’s atmosphere. CuPID will measure X-rays emitted when solar wind plasma collides with neutral atoms in Earth’s atmosphere.
Cesium Sat 1 and 2 are built by Cesium Space in Austin Texas. CesiumAstro attempted to test communications payloads on two cubesats launched on September 27 on a United Launch Alliance Atlas 5 rocket alongside the NASA-U.S. Geological Survey Landsat 9 mission. Unfortunately, both cubesats experienced what Sabripour thinks were power failures that precluded demonstrations the company planned.
The Atlas V 401 rocket
The Atlas V core in use for this mission is AV-092. It was delivered to Vandenberg on an Antonov An-124 cargo aircraft on June 28 and underwent preparations to go vertical at Mobile Service Tower (MST). Just under a month later, on July 13, the Atlas V first stage was lifted vertically by the MST crane onto the Fixed Launch Platform (FLP), in a milestone known as Launch Vehicle on Stand (LVOS).
The next day, the Atlas V interstage was installed on top of the first stage followed by the thinner Centaur upper stage installation on July 15. The lower portion of the payload fairing, the boattail, was then installed on top of the Centaur, completing the majority of the Atlas rocket assembly.
On September 3, Atlas V underwent a Wet Dress Rehearsal (WDR). A WDR is one of the final major tests of all the systems on the Atlas V, which includes fueling the rocket as if it is about to launch. 25000 gallons of RP-1 to be exact.
Completing its Pre-Ship review and Flight Operations Review, Landsat 9 was ‘delivered’ to VSFB in early July. Wasn’t it already ‘there’? From ULA to NASA control?
The fairing halves that encapsulate the satellite went vertical for encapsulation in July and, on August 10, Landsat 9 was approved by NASA to proceed with its September launch.
After receiving this approval, the satellite was stacked on top of the EFS and safely encapsulated in its 4.2-meter payload fairing. On September 15, the encapsulated payload was transported from the Integrated Processing Facility (IPF) to SLC-3E and was later integrated with the Atlas V.
Centaur hydrazine load complete. This notice means that the RCS thrusters on the Centaur stage are using hydrazine as a monopropellant during orbit insertion.
The reaction control system (RCS) also provides ullage 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 main engine functions.
September 25, the ULA, NASA, and Space Force teams underwent a Launch Readiness Review (LRR) and gave the approval to continue preparations for the launch on Monday. The LRR, led by NASA Launch Manager Tim Dunn, assessed the readiness of rocket, payload, and mission assets, and heard technical overviews of the countdown and the flight. The teams polled and gave a unanimous “ready” status for launch.
Space is incredibly cold. All heat vanishes from every part of the Centaur, especially the propellant. Liquid hydrogen and oxygen both can freeze solid. Pipes can plug up and be useless in a startup sequence and fuel pumps don’t like huge chunks of ice going through them. That is the main problem during long duration missions.
Usually small burns of the thrusters will heat the pipes just long enough to prevent them from freezing shut, the propellant is wasted on such pointless thrust maneuvers. Doing a ‘rotisserie’ maneuver by performing a slow roll to ‘bake’ the spacecraft evenly in the Sun is a more commonly practiced maneuver.
To date, Atlas V missions haven't been required to do no more than three Centaur burns. The stage has the capacity to do more, and the flight design of the Landsat 9 and EFS mission takes advantage of that capability.
A fourth and final burn by the Centaur's RL10C-1 cryogenic main engine executes a deorbit maneuver nearly three hours after liftoff to dispose of the stage in a safe manner that does not contribute to space debris or cause an uncontrolled re-entry.
A larger battery pack with electric heaters to prevent the freezing of propellant lines in the Hydrazine ACS thrusters, and blockage of the main engines propellant pipes.
It has long been my belief that solar cell arrays, a small science payload and a passive mission should accompany the spent second stages so they can keep a quiet eye on things in space since they already are left there in graveyard orbits.
The Centaur stage is capable of up to twelve restarts, but is limited by propellant, orbital lifetime, and mission requirements. Combined with the insulation of the propellant tanks, this allows Centaur to perform the multi-hour coasts and multiple engine burns required on complex orbital insertions.
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