Green Run Update: Tanking Complete for Rocket Hot Fire Test

Engineers have completed tanking for the hot fire test of NASA’s Space Launch System (SLS) rocket core stage at the agency’s Stennis Space Center, and the countdown is proceeding normally.

The liquid hydrogen tank holds 537,000 gallons of liquid hydrogen, cooled to minus 423 degrees Fahrenheit. The liquid oxygen tank holds 196,000 gallons of liquid oxygen, cooled to minus 297 degrees Fahrenheit. After tanking is complete, the team will continue chilling down the liquid oxygen propellant to condition it before the hot fire. While they are conditioning the liquid oxygen, they replenish the liquid hydrogen as it boils off due to temperature fluctuations as the propellant is loaded. The tanks can be loaded up to 22 times for testing and launches.

core stage liquid hydrogen tank
This image shows the core stage liquid hydrogen tank at NASA’s Michoud Assembly Facility in New Orleans where it and the rest of the core stage where built and assembled. The flight core stage for the Artemis I mission is being tested today. Boeing, the prime contractor for the core stage, has already manufactured liquid hydrogen tanks for the Artemis II and Artemis III lunar missions.

This part of the test timeline is also important as it pertains to simulating launch. During a launch, many activities will be happening on the pad at this time, such as loading the crew. The hot fire test provides an opportunity to demonstrate that the core stage can remain in a stable configuration and be replenished as needed before engine firing to launch the rocket.

Learn more about Green Run, and check back at this blog for updates on the SLS core stage hot fire test.

Green Run Update: Test Teams Gives “Go” to Proceed with Tanking 

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. 

SLS core stage
This infographic provides information on the core stage including its two large propellant tanks.

Learn more about Green Run, and check back at this blog for updates on the SLS core stage hot fire test. 

Green Run Update: Hot Fire Exposes Core Stage to Spaceflight Stresses

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.

For updates on Green Run progress, check back at this blog. NASA TV coverage will begin about 30 minutes before the test. For more information about SLS Green Run, visit https://www.nasa.gov/artemisprogram/greenrun

Green Run Update: Power Up Started for Hot Fire Test

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.

Green Run Update: NASA Targets March 18 for SLS 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.

Test Like you Fly Infographic
This infographic explains the objectives of the Space Launch System rocket’s core stage Green Run test series.

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.

Check back at this blog for an update on core stage power up for the second Green Run hot fire. For more information about SLS Green Run, visit https://www.nasa.gov/artemisprogram/greenrun

Mammoth Artemis I Rocket Boosters Stacked on Mobile Launcher

The Space Launch System boosters are stacked on the mobile launcher inside the Vehicle Assembly Building.
The Space Launch System twin solid rocket boosters are fully assembled and stacked on the mobile launcher inside the Vehicle Assembly Building at NASA’s Kennedy Space Center in Florida on March 3, 2021. Photo credit: NASA/Isaac Watson

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Stacking is complete for the twin Space Launch System (SLS) solid rocket boosters for NASA’s Artemis I mission. Over several weeks, workers used one of five massive cranes to place 10 booster segments and nose assemblies on the mobile launcher inside the Vehicle Assembly Building (VAB) at NASA’s Kennedy Space Center in Florida. Engineers with Exploration Ground Systems placed the first segment on Nov. 21, 2020, and continued the process until the final nose assembly was placed on March 2.

Prior to the arrival of the core stage, the team will finish installing electrical instrumentation and pyrotechnics, then test the systems on the boosters. When the SLS core stage arrives at Kennedy, technicians will transport it to the VAB and then stack it on the mobile launcher between the two boosters.

The SLS will be the most powerful rocket in the world, producing up to 8.8 million pounds of thrust during its Artemis I launch.

“Seeing the Space Launch System solid rocket boosters stacked completely on the Mobile Launcher for the first time makes me proud of the entire team especially  the Exploration Ground Systems crew at Kennedy who are assembling them and also the teams at Marshall and Northrop Grumman who designed, tested and built them,” said Bruce Tiller, the SLS boosters manager at NASA’s Marshall Space Flight Center. “This team has created the tallest, most powerful boosters ever built for flight, boosters that will help launch the Artemis I mission to the Moon.”

Artemis I will be an uncrewed test of the Orion spacecraft and SLS rocket as an integrated system ahead of crewed flights to the Moon. Under the Artemis program, NASA aims to land the first woman and the next man on the Moon  and establish sustainable lunar exploration.

Green Run Update: Engineers Repair Valve for Mid-March Hot Fire Test

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.

Propellant barges docked near the B-2 Test Stand 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.

Please check back at this blog for an update on the date NASA is targeting for the second Green Run hot fire. For more information about SLS Green Run, visit https://www.nasa.gov/artemisprogram/greenrun

Artemis I Boosters Reach New Heights

Space Launch System boosters for the Artemis I mission are stacked in the Vehicle Assembly Building.
In High Bay 3 of the Vehicle Assembly Building at NASA’s Kennedy Space Center in Florida, the left-hand and right-hand forward segments are secured on top of the center forward segments on the mobile launcher (ML) for the Space Launch System (SLS) on Feb. 24, 2021. Photo credit: NASA/Glenn Benson

NASA’s Space Launch System (SLS) solid rocket boosters have grown taller with the addition of the fifth and final pair of motor segments in preparation for the launch of Artemis I later this year. At NASA’s Kennedy Space Center in Florida, engineers with Exploration Ground Systems lowered the final solid rocket booster into place on the mobile launcher on Feb. 23. Up next, the nose assemblies will be placed atop the segments to complete the boosters. The twin boosters will power the first flight of the agency’s new deep space rocket during the launch of Artemis I. This mission is an uncrewed flight to test the SLS rocket and Orion spacecraft as an integrated system, preparing the way for Artemis II and other crewed flights to the Moon.

SLS Rocket Stage and Orion Share Space at Kennedy ahead of Artemis I

The ICPS is inside the Multi-Payload Process Facility at Kennedy Space Center on Feb. 18, 2021.
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 for the Artemis I mission. Photo credit: NASA/Glenn Benson

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.

The ICPS is moved into the Multi-Payload Process Facility on Feb. 18, 2021 at Kennedy Space Center.
The interim cryogenic propulsion stage is in view inside the Multi-Payload Processing Facility on Feb. 18, 2021, at Kennedy Space Center. Photo credit: NASA/Glenn Benson

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.

View additional photos here.