The test team conducted a pre-test briefing in the Test Control Center at the B test complex at NASA’s Stennis Space Center near Bay St. Louis, Mississippi, and gave a “go” to proceed with testing and to fill the propellant tanks.
Over the next several hours, the teams will monitor the systems and load more than 700,000 gallons of cryogenic, or supercooled, liquid oxygen and liquid hydrogen that will be fed to the four RS-25 engines during the hot fire test later today.
The hot fire will last up to 8 minutes and is scheduled to take place during a two-hour window that begins at 3 p.m. EDT. Live coverage will begin 30 minutes before the test on NASA Television and the agency’s website.
Learn more about Green Run, and check back at this blog for updates on the SLS core stage hot fire test.
During NASA’s Green Run hot fire test, the team will be especially interested in several key operations when testing the Space Launch System (SLS) rocket core stage under conditions it may experience during a variety of deep space missions.
Green Run, an end-to-end system test of the core stage with Artemis I flight hardware, will help validate the core stage design. One of the main questions Green Run will answer is: How does the integrated core stage perform during a series of dynamic operations it may experience during launch and ascent to deep space? The test is not only for environments and operations that the rocket’s core stage will encounter on Artemis I, but also for those it will undergo during future missions.
This video explains more about the operations occurring during the Green Run hot fire.
Hot fire day begins with filling the liquid oxygen and liquid hydrogen tanks with more than 700,000 gallons of propellant. After the supercold propellant is loaded and the core stage systems are conditioned to cryogenic temperatures as low as minus 423 degtrees Fahrenheit, the test conductor will poll the team. When everything is ready, they will proceed with the terminal countdown that includes the final 10 minutes before the hot fire. During the terminal countdown, the team will initiate the autonomous launch sequence that simulates the countdown for the Artemis I launch. Then, the test transitions from ground control to on-board software control of the core stage so that the test is fully automated starting at T-30 seconds.
The core stage RS-25 engine ignition starts at approximately six seconds before T-0, beginning with Engine 1, followed by Engines 3, 4, and 2, each ignited in sequence a few hundredths of a second apart. Recording data on how the stage performs at T-0 and as the engines ramp up to 109 percent power is one critical test operation. Another is when the engines are throttled down to 95 percent, just as they are throttled down in flight at Max-Q, or maximum dynamic pressure when aerodynamic forces put the greatest stress on the rocket.
The team will also test the margins of the core stage thrust vector control system that gimbals, or moves, each engine in a specific pattern. Each engine has its own thrust vector control system that is essential for moving the engine to control the rocket’s flight. Depending on the trajectory flown, the thrust vector control system can gimbal the engines to direct thrust and thus the rocket’s path. The first gimbaling occurs a little over a minute into the test.
An important part of the hot fire occurs when this system begins rapidly moving the engines in specific patterns that are more extreme than those planned for Artemis missions. This occurs around 2 minutes and 10 seconds into the test. This test is called the frequency response test because it measures the stage’s frequency as the thrust vector control system gimbals the engine. The test ensures the thrust vector control system’s response is demonstrated under a variety of flight-like conditions. This is a very dynamic portion of the core stage hot fire test and understanding the thrust vector control system and the core stage’s response across a range of frequencies is important to understand the stage’s performance during flight.
To ensure SLS can safely send humans to space, NASA will use data from the Green Run test campaign, along with modeling and analysis, to show the core stage design can fly not only on Artemis I, but also for many deep space missions.
Engineers have initiated power up of the flight computes and avionics for the Artemis I core stage. This begins the countdown for the hot fire test with the core stage of NASA’s Space Launch System (SLS) rocket scheduled for Thursday, March 18.
Before the test, the management team in the Test Control Center at the B test complex will provide approval to proceed into the test. One of the first actions on hot fire day will be to load the stage’s huge tanks with more than 700,000 gallons of propellant. Six barges filled with liquid hydrogen and oxygen will supply the propellant to the B-2 test stand at NASA’s Stennis Space Center near Bay St. Louis, Mississippi, where the Green Run tests are taking place. The engines use cryogenic, or supercooled, liquid hydrogen as fuel and liquid oxygen as oxidizer to create combustion.
To fill each of the six barges, three for liquid oxygen and three for liquid hydrogen, it required 18 to 20 tanker trucks worth of propellant. The barges are towed by tug from a fuel depot at Stennis to the B-2 stand.
In this video, SLS Stages Manager Julie Bassler, describes avionics and flight software testing conducted in the Systems Integration Laboratory at NASA’s Marshall Space Flight Center in Huntsville, Alabama, to support Green Run. The computers and avionics are the “brains” of the rocket, and they control the core stage systems during the test, just like they will be required to control the rocket during the Artemis I flight.
Learn more about Green Run, and check back at this blog for updates on the SLS core stage hot fire test.
NASA is targeting Thursday, March 18 for the second hot fire of the Space Launch System (SLS) rocket’s core stage at NASA’s Stennis Space Center near Bay St. Louis, Mississippi.
After performing tests to demonstrate that a recently repaired liquid oxygen pre-valve was working, the team has continued to prepare the core stage, its four RS-25 engines, and the B-2 test stand for the second hot fire at Stennis. Later this week, the team will power up the core stage again and do a final check of all its systems. Then, on March 16, two days before the test, they will power up the stage, starting the clock for the second hot fire.
This hot fire is the last test before the Artemis I core stage is shipped to the agency’s Kennedy Space Center for assembly and integration with the rest of the rocket’s major elements and the Orion spacecraft. Exploration Ground Systems teams at Kennedy have stacked all parts of the solid rocket boosters for Artemis I in the Vehicle Assembly Building and are finishing up booster assembly. After the core stage arrives, it will be lifted and placed between the two boosters and attached at the core stage engine and intertank sections. Other parts of the rocket and the Orion spacecraft are also at Kennedy and are being prepared for final assembly and integration.
NASA’s SLS rocket is the most powerful rocket in the world, built to send both astronauts aboard Orion and supplies on missions to the Moon and beyond. The Green Run is a comprehensive test of the SLS core stage, a complex new rocket stage that not only includes four RS-25 engines and enormous propellant tanks that hold more than 700,000 gallons of super cold propellant, but also flight computers and avionics that control the first eight minutes of flight. The Green Run test series will help validate that the SLS core stage is ready for its first flight on Artemis I and subsequent missions.
Engineers have successfully repaired a liquid oxygen valve on the Space Launch System rocket’s core stage with subsequent checks confirming the valve to be operating properly. The team plans to power up the core stage for remaining functional checks later this week before moving forward with final preparations for a hot fire test in mid-March at NASA’s Stennis Space Center near Bay St. Louis, Mississippi. NASA anticipates setting a target date for the hot fire next week.
Last week during checkouts for the second hot fire test, data indicated the valve (a type of valve called a pre-valve) was not working properly. The valve is part of the core stage’s main propulsion system and is opened at the beginning of the test and closed if necessary to stop the flow of liquid oxygen from the core stage propellant tank to the respective RS-25 engine during the hot fire.
While the valve was repaired over the weekend, the team continued to prepare the core stage, its four RS-25 engines, and the B-2 test stand for the second hot fire at Stennis. This hot fire test will be the last test before the Artemis I core stage is shipped to the agency’s Kennedy Space Center for assembly and integration with the rest of the rocket’s major elements and the Orion spacecraft.
The Space Launch System (SLS) rocket’s interim cryogenic propulsion stage (ICPS) moved into the Multi-Payload Processing Facility February 18, 2021, at NASA’s Kennedy Space Center in Florida alongside one of its flight partners for the Artemis I mission, the Orion spacecraft. Both pieces of hardware will undergo fueling and servicing in the facility ahead of launch by teams from NASA’s Exploration Ground Systems and their primary contractor, Jacobs Technology. The rocket stage and Orion will remain close during their journey to space.
Built by United Launch Alliance and Boeing, the ICPS will be positioned above the core stage and will provide the power needed to give Orion the big push it needs to break out of Earth orbit on a precise trajectory toward the Moon during Artemis I.
This is the first time since the shuttle program that two pieces of flight hardware have been processed inside this facility at the same time. Once final checkouts are complete, the ICPS and Orion will part ways on the ground and be reunited in the Vehicle Assembly Building for integration onto the SLS rocket.
Artemis I will be an integrated flight test of the SLS rocket and Orion spacecraft ahead of the crewed flights to the Moon. Under the Artemis program, NASA will land the first woman and the next man on the lunar surface and establish a sustainable presence at the Moon to prepare for human missions to Mars.
NASA and Space Launch System (SLS) core stage prime contractor Boeing are thoroughly examining a liquid oxygen valve inside the stage’s engine section in order to identify repairs needed before a second hot fire with the Artemis I stage.
During preparations for the second hot fire, data indicated the valve was not opening correctly. Technicians installed platforms that allow engineers to access the valve inside the core stage engine section while the stage remains in the B-2 stand at NASA’s Stennis Space Center near Bay St. Louis, Mississippi. After completion of troubleshooting, which will continue over the weekend, NASA will be in a better position to identify a potential date for the second hot fire test.
This valve, called a pre-valve, must be fully operational during hot fire testing. The valve is part of the core stage main propulsion system, and it helps deliver liquid oxygen propellant flowing from the liquid oxygen tank to an RS-25 engine. For the first hot fire on Jan. 16, all four liquid oxygen pre-valves performed as expected as did all four liquid hydrogen pre-valves.
The Green Run is a comprehensive series of tests for the SLS core stage before it launches the Artemis missions to the Moon, and the hot fire is the final and most intensive test. The Green Run tests have provided invaluable information on how the new rocket stage operates before it is used to launch the Artemis I mission.
NASA’s Artemis IOrion spacecraft is being outfitted with additional artwork as technicians began installing the logo for ESA (European Space Agency). ESA provided the European-built service module, which provides power and propulsion for the Orion spacecraft, and will also provide water and air for astronauts on future missions.
Artemis I extends NASA and ESA’s strong international partnership beyond low-Earth orbit to lunar exploration with Orion on Artemis missions. The ESA logo joins the historic NASA “meatball” insignia on the Artemis I spacecraft adapter jettison fairing panels that protect the service module during launch.
Orion is currently stationed at NASA’s Kennedy Space Center in the Multi-Payload Processing Facility, where it will undergo fueling and servicing by NASA’s Exploration Ground Systems and Jacobs Technology teams in preparation for the upcoming flight test with the Space Launch System rocket under the agency’s Artemis program.
The twin boosters will power the first flight of the agency’s new deep space rocket on its first Artemis Program mission. Artemis I will be an uncrewed flight to test the SLS rocket and Orion spacecraft as an integrated system ahead of crewed flights.
NASA plans to conduct a second Green Run hot fire test as early as the fourth week in February with the Space Launch System (SLS) rocket’s core stage that will launch the Artemis I mission to the Moon. The Green Run is a comprehensive assessment of the rocket’s core stage prior to launching Artemis missions.
While the first hot fire test marked a major milestone for the program with the firing of all four RS-25 engines together for the first time for about a minute, it ended earlier than planned. After evaluating data from the first hot fire and the prior seven Green Run tests, NASA and core stage lead contractor Boeing determined that a second, longer hot fire test should be conducted and would pose minimal risk to the Artemis I core stage while providing valuable data to help certify the core stage for flight.
Inspections showed the core stage hardware, including its engines, and the B-2 test stand are in excellent condition after the first hot fire test, and no major repairs are needed to prepare for a second hot fire test at NASA’s Stennis Space Center in Bay St. Louis, Mississippi.
All SLS rockets use the same core stage design, so a second Green Run hot fire will reduce risk for not only Artemis I, but also for all future SLS missions. The Green Run series of tests is designed to certify the core stage design and verify that the new stage is ready for flight. The hot fire test is the final Green Run test and will provide valuable data that minimizes risk for American deep space exploration missions for years to come.
The Green Run team scrutinized data from the first hot fire test and determined that a second hot fire lasting approximately at least four minutes would provide significant data to help verify the core stage is ready for flight. A second hot fire test is planned for about eight minutes to simulate the amount of time it will take to send the rocket to space following launch. The Green Run wet dress rehearsal and first hot fire test completed several operations:
transitioning to the automated launch sequence operated by the core stage flight computer and Green Run software,
completing the terminal countdown sequence that is like the launch countdown
pressuring the tanks and delivering propellant to the engines and demonstrating performance of the core stage’s main propulsion system,
firing the engines at 109 percent power level, and
operating the thrust vector control system that steers the engines.
Conducting a second hot fire test will allow the team to repeat operations from the first hot fire test and obtain data on how the core stage and the engines perform over a longer period that simulates more activities during the rocket’s launch and ascent. To prepare for the second hot fire test, the team is continuing to analyze data from the first test, drying and refurbishing the engines, and making minor thermal protection system repairs. They are also updating conservative control logic parameters that resulted in the flight computer ending the first hot fire test earlier than planned. The team has already repaired the faulty electrical harness which resulted in a notification of a Major Component Failure on Engine 4. This instrumentation issue did not affect the engine’s performance and did not contribute to ending the first test early.
After the second hot fire test, it will take about a month to refurbish the core stage and its engines. Then, the Pegasus barge will transport the core stage to NASA’s Kennedy Space Center in Florida where it will be assembled with the other parts of the SLS rocket and the Orion spacecraft being prepared for the Artemis I launch later this year.