Work Continues to Return Artemis I Moon Rocket Back to Launch Pad for Next Test

Teams at NASA’s Kennedy Space Center in Florida continue to work on the main tasks needed to prepare the Space Launch System (SLS) rocket and Orion spacecraft to return to launch pad 39B for the next wet dress rehearsal attempt.

After re-tightening the flange bolts on the tail service mast umbilical lines to address a hydrogen leak identified during the previous wet dress rehearsal, engineers determined the seals on the bolts are no longer relaxing, and the system should remain tightly sealed during propellant loading. As a precaution, teams also moved the location of a heavy cantilevered filter on the tail service mast umbilical, which filters out any contaminants in the gaseous helium – a purge gas – that travels through the drain assist purge line. Engineers did not identify any leaks at its previous location, but relocating the filter will ensure it does not contribute to future leaks. Engineers conducted additional leak checks and have not detected any leaks at ambient air temperature.

Additionally, after replacing the helium check valve on the interim cryogenic propulsion stage (ICPS), engineers found a damaged rubber O-ring seal in the flight side of the quick disconnect – the area that separates the ICPS from the mobile launcher during launch. The O-ring came loose and entered the valve, preventing the valve from sealing correctly. Teams removed the flight and ground side of the quick disconnect system and replaced support hardware that was downstream of the check valve. Work is underway to determine the root cause to prevent any recurrences. Next, teams will re-pressurize the system and test the replaced hardware on the upper stage.

The supplier for gaseous nitrogen completed upgrades to its facility to meet the requirements for the next wet dress rehearsal attempt. Engineers will test the system next week to ensure it’s ready to support tanking operations. During wet dress rehearsal and launch, teams pump gaseous nitrogen into dry structures to protect avionics during propellant loading.

Teams also completed additional work needed, such as inspecting the Orion spacecraft for water damage that may have occurred during a heavy thunderstorm at the spaceport during the initial wet dress rehearsal attempt. Teams determined there was no damage to the systems inside the capsule and continue with inspections and wrapping up other work before retracting the platforms inside the Vehicle Assembly Building (VAB) to prepare to roll SLS and Orion back to the launch pad. NASA will announce dates for rolling out to the pad and the next wet dress rehearsal attempt once work inside the VAB and testing of the nitrogen system are nearing completion.

Artemis I Rocket, Spacecraft Prepare for Return to Launch Pad to Finish Test

Since returning to the Vehicle Assembly Building (VAB), ground systems teams have worked to prepare the Artemis I Space Launch System (SLS) rocket and Orion spacecraft to roll back to Launch Pad 39B in late May to complete the wet dress rehearsal test in the early to mid-June timeframe.

Inside the VAB at NASA’s Kennedy Space Center, engineers replaced a faulty helium check valve on the interim cryogenic propulsion stage that was identified after the second wet dress rehearsal attempt. Engineers have inspected the valve and found a small piece of rubber that prevented the valve from sealing correctly. Teams are looking at possible sources of the debris, but did not see any issues with the valve itself, and plan to test the newly installed valve later this week to confirm it is operating as expected.

Engineers also performed tests to address a hydrogen leak on one of two tail service mast umbilicals between the mobile launcher and the rocket. These umbilicals provide liquid oxygen and liquid hydrogen propellants, as well as electrical connections, from the mobile launcher to the rocket’s core stage during the launch countdown. Teams conducted leak checks on all the joints and tightened several flange bolts, or fasteners that act as a washer to increase the compression strength, that can loosen over time and were the most likely source of the leak. Teams re-tightened the flange bolts on the liquid hydrogen, liquid oxygen, and core stage intertank umbilicals. Engineers have not detected leaks in subsequent testing at ambient air temperature, and will continue to monitor for leaks when loading the super cold propellants at the launch pad.

The supplier that provides gaseous nitrogen for operations during tanking is upgrading its facility to meet the requirements for the next wet dress rehearsal attempt and the Artemis I launch. Teams are on track to complete the work early next week, followed by testing to ensure the system is ready for tanking. During the test, teams pump gaseous nitrogen into dry structures to protect avionics during propellant loading.

Once all major work is completed, teams will retract the working platforms and prepare the integrated SLS rocket and the Orion spacecraft for the second journey to the launch pad. NASA will announce dates for roll to the pad and the next wet dress rehearsal attempt once work is nearing completion inside the VAB.

Artemis I Wet Dress Rehearsal Update 

NASA is planning to proceed with a modified wet dress rehearsal, primarily focused on tanking the core stage, and minimal propellant operations on the interim cryogenic propulsion stage (ICPS) with the ground systems at Kennedy. Due to the changes in loading procedures required for the modified test, wet dress rehearsal testing is slated to resume with call to stations on Tuesday, April 12 and tanking on Thursday, April 14. Wet dress rehearsal is an opportunity to refine the countdown procedures and validate critical models and software interfaces. The modified test will enable engineers to achieve the test objectives critical to launch success.  

Engineers have identified a helium check valve that is not functioning as expected, requiring these changes to ensure safety of the flight hardware. Helium is used for several different operations, including purging the engine, or clearing the lines, prior to loading propellants during tanking, as well as draining propellant. A check valve is a type of valve that allows liquid or gas to flow in a particular direction and prevents backflow. The helium check valve is about three inches long and prevents the helium from flowing back out of the rocket. 

Following the modified test, the Space Launch System rocket and Orion spacecraft will return to the Vehicle Assembly Building (VAB) where engineers will evaluate the valve and replace if needed. Teams are confident in the ability to replace the valve once back in the VAB.   

NASA will host a teleconference to discuss details on Monday, April 11. Check back at this blog for an update on the countdown timeline prior to the modified wet dress rehearsal testing for the Artemis I mission. NASA is streaming live video of the rocket and spacecraft on the Kennedy Newsroom YouTube channel 

Artemis I WDR Update: Go to Proceed for Tanking – Countdown Resumes

The countdown for the wet dress rehearsal has resumed at 10:52 a.m. EDT and clocks have picked back up at T-6 hours, 40 minutes on the clock (L-7 hours, 10 minutes). A new planned T-0 of 6:02 p.m. has been established.

An earlier issue with an outage with the vendor of gaseous nitrogen required for tanking preparations has been resolved. Overnight, teams also resolved the issue with the malfunction of the fans used to provide positive pressure to enclosed areas in the mobile launcher and keep out hazardous gases, and they have a plan for operating the fans to prevent issues from reoccurring. The team was able to successfully bring up and run the primary fan through the night to provide confidence, and has configured the secondary fan to run at 80% capacity to support tanking operations.

At approximately 10 a.m. EDT, the launch director gave the “go” to begin tanking the rocket. Cryogenic loading operations are scheduled to begin with chilling down the liquid oxygen lines for the core stage. Once propellant loading operations begin, liquid oxygen (LOX) and liquid hydrogen (LH2) will flow into the rocket’s core stage and interim cryogenic propulsion stage tanks and be topped off and replenished as some of the cryogenic propellant boils off. The team will also conduct leak checks to ensure propellant loading is proceeding as expected.

NASA is streaming live video of the rocket and spacecraft at the launch pad on the Kennedy Newsroom YouTube channel. Venting may be visible during tanking operations. NASA is also sharing live updates on the Exploration Ground Systems Twitter account.

The next blog update will be provided when core stage propellant loading is underway.

Mission Management Team ‘Go’ to Proceed with Artemis I Wet Dress Rehearsal  

At approximately 7:40 a.m. EDT, the mission management team chair gave the “go” to proceed with tanking the rocket for the Artemis I wet dress rehearsal test. Later in the countdown the Launch Director will give the “go” to begin the tanking process. Meteorologists with Space Launch Delta 45 said there were no weather constraints for the test.  

Teams are continuing to hold the clock to resolve an outage with the vendor of gaseous nitrogen required for tanking preparations. Nitrogen is used to prepare for, and during tanking operations, to provide a non-flammable environment inside of the SLS. When the issue is resolved, the countdown clock will pick back up with T-6 hours, 40 minutes on the clock (L-7 hours, 20 minutes) remaining in the countdown, beginning with chilling down the liquid oxygen lines for the core stage. 

Once propellant loading operations begin, liquid oxygen (LOX) and liquid hydrogen (LH2) will flow into the into the rocket’s core stage and interim cryogenic propulsion stage tanks and be topped off and replenished as some of cryogenic propellant boils off. The team will also conduct leak checks to ensure propellant loading is proceeding as expected.  

NASA is streaming live video of the rocket and spacecraft at the launch pad on the Kennedy Newsroom YouTube channel. Venting may be visible during tanking operations. NASA is also sharing live updates on the Exploration Ground Systems Twitter account 

Artemis I Wet Dress Rehearsal Preparations Underway   

Engineers and technicians are continuing to prepare for the Artemis I wet dress rehearsal test which is slated to begin on April 1 and conclude on April 3.    

 The wet dress rehearsal will begin at 5 p.m. EDT on April 1 with “call to stations,” when members of the launch control team at Kennedy Space Center in Florida will arrive to the firing rooms in the Launch Control Center and start the approximately two-day test launch countdown.  The team will target a two-hour test window that opens at 2:40 p.m. April 3. 

 The countdown for the wet dress rehearsal will follow a similar timeline as the team will use on the day of launch. Below are the approximate times for countdown milestones during the wet dress rehearsal test. All times below are Eastern. 

During the test, the timing for some events on account of several planned operational demonstrations tied to specific capabilities and test objectives may differ from the day of launch countdown. These demonstrations include tests on the cryogenic systems and an approximately three-minute hold inside the terminal count, which would not normally occur on launch day. If needed, the test team also may hold as necessary to verify conditions before resuming the countdown, or use the test window or extend beyond it, if consumables and resources allow them to complete test objectives. 

The following activities will occur for the Space Launch System (SLS) rocket, the Orion spacecraft, and supporting ground systems: 

Prior to Call to Stations 

  • The Orion crew module hatch is closed (will occur at ~L-37.5 hours for launch) 
  • The crew access arm is retracted (will occur at ~L-30 hours for launch) 
  • Leak checks are completed on the Orion spacecraft and the launch abort system is closed (will occur at ~L-29 hours, 30 minutes for launch) 

5 p.m., April 1 – L-45 hours and counting  

  • The launch team arrives on their stations and the countdown begins (L-45, 40 minutes hours)  
  • Fill the water tank for the sound suppression system (L-45 hours)  
  • The Orion spacecraft powered up start (L-41 hours)  
    • May be powered earlier during the test 
  • The SLS core stage is powered up (L-35 hours, 20 minutes)  
  • Final preparations of the four RS-25 engines complete (L-30 hours, 30 minutes)  
    • Engines will not fire during this test 
  • Side flame deflectors are moved into place (L-21 hours)   

1:40 a.m., April 3 – L-13 hours and counting  

  • The SLS interim cryogenic propulsion stage (ICPS) is powered up (L-12 hours, 50 minutes)  
  • All non-essential personnel leave Launch Complex 39B (L-12 hours)    

6 a.m. – L-8 hours, 40 minutes and counting 

  • Built in countdown hold begins and lasts approximately 1.5 hours (L-8 hours, 40 minutes)  
  • The launch director and mission management team chair conduct a weather and tanking briefing (L-8 hours, 20 minutes)   
  • The launch director and mission management team chair decide if they are “go” or “no-go” to begin tanking the rocket (L-7 hours, 50 minutes)   

6:40 a.m. – L-8 hours and counting 

  • 7:20 a.m.: Core stage LOX chilldown start (L-7 hours, 20 minutes)  
  • 8:15 a.m.: Core stage LOX slow fill start (L-6 hours, 25 minutes)  
  • 8:30 a.m.: Core stage LOX fast fill start (L-6 hours, 10 minutes) 
  • 8:35 a.m.: Core stage LH2 chilldown start (L-6 hours, 5 minutes)  
  • 8:40 a.m.: Core stage LH2 slow fill start (L-6 hours)  
  • 9:00 a.m.: Core stage LH2 fast fill start (L-5 hours, 40 minutes)  

 10:10 a.m. – L-4 hours, 30 minutes and counting  

  • 10:10 a.m.: Core stage LH2 topping start (L-4 hours, 30 minutes)  
  • 10:15 a.m.: ICPS LH2 chilldown (L-4 hours, 25 minutes)  
  • 10:15 a.m.: Core stage LH2 replenish start (L-4 hours 25 minutes)  
  • 10:20 a.m.: Orion communications system activation start (RF to Mission control) (L-4 hours, 20 minutes)  
  • 10:40 a.m.: ICPS LH2 fast fill (L-4 hours) 

11:10 a.m. – L-3 hours, 30 minutes and counting  

  • 11:15 a.m.: Core stage LOX topping start (L-3 hours, 25 minutes)  
  • 11:20 a.m.: Core stage LOX replenish start (L-3 hours, 20 minutes)  
  • 11:20 a.m.: ICPS LOX chilldown start (L-3 hours, 20 minutes)  
  • 11:25 a.m.: ICPS LH2 validation and leak test start (L-3 hours, 15 minutes)  
  • 11:40 a.m.: ICPS LH2 tanks load topping start (L-3 hours)  
  • 11:40 a.m.: ICPS/SLS telemetry data verified with mission control and SLS Engineering Support Center (L-3 hours)  
  • 12 p.m.: ICPS LH2 replenish start (L-2 hours, 40 minutes)  
  • 12 p.m.: ICPS LOX validation and leak test (L-2 hours, 40 minutes)  
  • 12:20 p.m.: ICPS LOX topping start (L-2 hours, 20 minutes)  
  • 12:30 p.m.: ICPS LOX replenish start (L-2 hours, 10 minutes)  
  • 12:40 p.m.: WDR-specific core stage LOX/LH2 stop flow and recover test (L-2 hours through L-55 minutes) 

 2 p.m. – L-40 minutes and holding  

  • 2 p.m.: Final NASA Test Director briefing is held  
  • 2 p.m.: Built in 30-minute countdown hold begins  
  • 2:25 p.m.: The launch director polls the team to ensure they are “go” for terminal count for test purposes

 2:30 p.m. – T-10 minutes and counting (WDR Run 1) 

  • 2:34 p.m.  
    • Orion ascent pyros are armed (T-6 minutes)  
    • Orion set to internal power (T-6 minutes)  
    • Core Stage LH2 terminate replenish (T-5 minutes, 57 seconds)  
  • 2:36 p.m.  
    • Core Stage auxiliary power unit starts (T-4 minutes) 
    • Core stage LOX terminate replenish (T-4 minutes)   
    • ICPS LOX terminate replenish (T-3 minutes, 30 seconds)  
  • 2:38 p.m. 
    • ICPS switches to internal battery power (T-1 minute, 56 seconds)  
    • Core stage switches to internal power (T-1 minute, 30 seconds)  
    • ICPS enters terminal countdown mode (T-1 minute, 20 seconds)  
  • 2:39 p.m. 
    • ICPS LH2 terminate replenish (T-50 seconds)  
    • Ground launch sequencer sends “cut-off” command (T-33 seconds)  

Perform Critical Safing and Planned Recycle back to T-10 minutes and holding (takes approximately one hour) 

 T-10 minutes and counting  (WDR Run 2) 

  • Orion ascent pyrotechnics are armed (T-6 minutes)  
  • Orion set to internal power (T-6 minutes)  
  • Core Stage LH2 terminate replenish (T-5 minutes, 57 seconds)  
  • Core Stage auxiliary power unit starts (T-4 minutes) 
  • Core stage LOX terminate replenish (T-4 minutes)   
  • ICPS LOX terminate replenish (T-3 minutes, 30 seconds)  
  • ICPS switches to internal battery power (T-1 minute, 56 seconds)  
  • Core stage switches to internal power (T-1 minute, 30 seconds)  
  • ICPS enters terminal countdown mode (T-1 minute, 20 seconds)  
  • ICPS LH2 terminate replenish (T-50 seconds)  
  • Ground launch sequencer sends “Go for automated launch sequencer” command (T-33 seconds)  
  • Core stage flight computer to automated launching sequencer (T-30 seconds)  
  • Ground launch sequencer manual cut-off at T-9.34 seconds 

Proceed with Critical Safing Operations  

Proceed with Core Stage and ICPS Cryogenic Fuel Drain Operations 

NASA ‘Go’ for Artemis I Wet Dress Rehearsal

In a pre-test review on March 28, NASA gave the “go” to proceed with the Artemis I wet dress rehearsal scheduled for April 1-3. The approximately two-day test will run the Artemis I launch team through operations to load propellant into the rocket’s tanks, conduct a full launch countdown, demonstrate the ability to recycle the countdown clock, and also drain the tanks to give them an opportunity to practice the timelines and procedures they will use for launch.

During the rehearsal, controllers will count down to T-1 minutes and 30 seconds and pause to demonstrate the ability to hold for up to 3 minutes, then resume until 33 seconds before when launch would occur, then pause the countdown. Then they will recycle back to ten minutes before launch and conduct a second terminal countdown to approximately 9.3 seconds before launch, then end the countdown. Sometimes called a “scrub,” launch controllers may decide not to proceed with launch if a technical or weather issue arises during or prior to the countdown. At the end of the test, the team will drain the propellant to demonstrate the procedures that would be used during a launch scrub. After draining the tanks, the team will review the test data before setting an official target launch date.

NASA will provide a live video stream of the rocket and spacecraft at the launch pad beginning at Noon EDT on April 1 on the Kennedy Newsroom YouTube channel. In addition to updates on this blog, NASA also will provide operational updates on the Exploration Ground Systems Twitter account.

NASA Continues Artemis I Preparations at Pad Wet Dress Rehearsal Test

Following arrival of the Space Launch System rocket and Orion spacecraft for Artemis I at Launch Pad 39B at NASA’s Kennedy Space Center in Florida on March 18, teams have connected numerous ground support equipment elements to the rocket and spacecraft, including electrical, fuel environmental control system ducts, and cryogenic propellant lines. Teams successfully powered up all elements of the integrated system at the pad for the first time on March 21 in preparation for the wet dress rehearsal test planned for April 1-3.

Engineering testing is underway to ensure systems continue to operate as planned with the rocket and spacecraft now configured at the pad. Additionally, technicians will don self-contained atmospheric protective ensemble suits, or SCAPE suits, to practice operations in the event of an emergency at the pad during fueling and launch. After checkouts at the pad are complete next week, the team will start system walkdowns ahead of the test.

The approximately two-day wet dress rehearsal test will demonstrate the team’s ability to load cryogenic, or super-cold, propellants into the rocket, conduct a launch countdown, and practice safely removing propellants at the launch pad. After wet dress rehearsal, engineers will roll the rocket and spacecraft back to the Vehicle Assembly Building for final checkouts before launch.

Artemis I Integrated Testing Update

NASA’s Space Launch System (SLS) rocket and Orion spacecraft are undergoing integrated testing inside the Vehicle Assembly Building at NASA’s Kennedy Space Center in Florida to ensure they are “go” for launch of the Artemis I mission early next year.

After stacking the Orion atop the SLS rocket, the engineers completed several tests to ensure the rocket and spacecraft are ready to roll to the launch pad ahead of the Artemis I wet dress rehearsal. These tests included ensuring Orion, the core stage, and boosters can communicate with the ground systems and verification testing to make sure all the pieces of the rocket and spacecraft can power up and connect to the consoles in the Launch control Center.

During a recent core stage power test, engineers identified an issue with one of the RS-25 engine flight controllers. The flight controller works as the “brain” for each RS-25 engine, communicating with the SLS rocket to provide precision control of the engine as well as internal health diagnostics. Each controller is equipped with two channels so that there is a back-up, should an issue arise with one of the channels during launch or ascent. In the recent testing, channel B of the controller on engine four failed to power up consistently.

The controller had powered up and communicated successfully with the rocket’s computers during preliminary integrated testing, in addition to performing a full duration hot fire during Green Run testing with all four RS-25 engines earlier this year at NASA’s Stennis Space Center near Bay St. Louis, Mississippi. NASA and lead contractor for the RS-25 engines, Aerojet Rocketdyne, also test all RS-25 engines and flight controllers for Artemis missions at Stennis prior to integration with the rocket.

After performing a series of inspections and troubleshooting, engineers determined the best course of action is to replace the engine controller, returning the rocket to full functionality and redundancy while continuing to investigate and identify a root cause. NASA is developing a plan and updated schedule to replace the engine controller while continuing integrated testing and reviewing launch opportunities in March and April.

Verification testing of the Interim Cryogenic Propulsions Stage is ongoing along with closeouts of the boosters, and parallel work continues with core stage engineering testing. Communication end-to-end testing is underway, and countdown sequence testing will begin as early as next week to demonstrate all SLS and Orion communication systems with the ground infrastructure and launch control center. Integrated testing will culminate with the wet dress rehearsal at historic Launch Complex 39B. NASA will set a target launch date after a successful wet dress rehearsal test.

SLS will be the most powerful rocket in the world and is the only rocket that can send Orion, astronauts, and supplies to the Moon in a single mission. With the Artemis missions, NASA will land the first woman and the first person of color on the Moon and establish long-term exploration in preparation for missions to Mars. SLS and Orion, along with the commercial human landing system and the Gateway that will orbit the Moon, are NASA’s backbone for deep space exploration.

 

NASA has named three students the winners of the Artemis Moon Pod Essay Contest for their creative visions of a pioneering journey to the Moon. Nearly 14,000 students entered the contest, each competing for the grand prize: a trip to NASA’s Kennedy Space Center in Florida, where they will witness the first launch of the Artemis era.

NASA invited students to envision themselves leading a crew, or “pod,” on a mission to the Moon’s South Pole, and capture these ideas in their essays. NASA and Future Engineers, an online platform for student challenges, launched the contest in September 2020 for K-12 students nationwide. The contest’s goal is to encourage the Artemis Generation – kids growing up during the era of NASA’s return to the Moon – to think ahead about the human and technological needs of a lunar expedition. What types of tools or technologies would they bring to the Moon? Who would they include in their “pod” of crewmembers? What would they leave behind for future lunar crews to use?

Grand-prize winning essays in the three, grade-level-based categories are:

  • Kindergarten through fourth grade category: Austin Pritts of Wolcott, Indiana.
  • Fifth through eighth grade category: Taia Saurer of Laguna Beach, California.
  • Ninth through 12th grade category: Amanda Gutierrez of Lincoln, Nebraska.

>>Read more