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 WDR Update: Core Stage Liquid Oxygen Propellant Loading Halted, Expected to Resume 

Liquid oxygen loading into the core stage was automatically halted near the beginning of slow fill operations when temperature readings on the propellant showed it was warmer than intended. The rocket is in a safe configuration while teams troubleshoot and determine a path forward.  

Engineers believe they understand the issue and are working a solution that will allow operations to continue. Teams saw a similar issue during the wet dress rehearsal attempt on April 4, but at a slightly different point in propellant loading operations. 

The slow fill process involves slowly filling the core stage with propellant to thermally condition the tank until temperature and pressure are stable before beginning fast fill operations, which is when you fill the tank at a quicker pump speed. 

Follow along with the countdown on the Exploration Ground Systems Twitter and watch a live stream of the test on the Kennedy Newsroom YouTube channel. 

Artemis I Update: Core Stage Liquid Oxygen Chilldown Underway 

The launch control team has begun chill down operations and resumed the countdown clock ahead of flowing super cold liquid oxygen (LOX) into the core stage tank.  The new T-0 time for today’s test is 3:57 p.m. EDT for the first of the two terminal count runs for the wet dress rehearsal.  

The process for the chill down, or cooling, uses the propellant lines to load the Space Launch System rocket’s core stage liquid oxygen in preparation for tanking. The liquid oxygen tank holds 196,000 gallons of liquid oxygen, cooled to minus 297 degrees Fahrenheit. Venting from the super-cold propellant may be visible during this time.  

Liquid oxygen will soon flow into the rocket. Teams will fill the tank slowly at first and then will begin filling it more quickly. As the super cold liquid oxygen fills the core stage tank, some venting may be visible.  

The next blog update will be provided when core stage liquid hydrogen loading begins. 

Follow along with the countdown on the Exploration Ground Systems Twitter and watch a live stream of the test on the Kennedy Newsroom YouTube channel. 

 

Artemis I Update: Launch Director Gives “Go” for Propellant Loading, Countdown Set to Resume 

At approximately 8:05 a.m. EDT, the launch director gave the “go” to start tanking operations.  The countdown will resume at 8:47 a.m. EDT at T-6 hours, 40 minutes.  

Tanking begins with chilling down the liquid oxygen lines for the core stage. In sequential fashion, liquid oxygen (LOX) and liquid hydrogen (LH2) will flow into the into the rocket’s core stage tank and be topped off and replenished as some of cryogenic propellant boils off.  The team also will conduct leak checks to ensure propellant loading is proceeding as expected.  Only minimal cryogenic operations are being conducted on the interim cryogenic propulsion stage because of an issue with a helium check valve found several days ago which cannot be fixed at the launch pad. Teams will chill down the lines used to load propellant into the upper stage but not flow any actual propellant to the stage. 

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 Update: Teams Extending Current Hold, Gaseous Nitrogen Supply Reestablished 

Teams have extended the current hold in the countdown beyond the planned 1.5 hours. Supply has been reestablished of gaseous nitrogen used to purge oxygen from the rocket prior to tanking operations to ensure a safe environment for propellant loading, but teams need additional time to switch supply from air back to the gaseous nitrogen and to discuss confidence in the supply. When the countdown resumes, it will pick up at T-6 hours, 40 minutes. 

Artemis I Update: Mission Management Team “Go” to Proceed with Tanking Pending Resolution of Gaseous Nitrogen Supply Issue 

The mission management team chair has given a “go” to proceed  with tanking the rocket for the Artemis I  wet dress rehearsal test, pending resolution of an issue with an outage at an off-site vendor of gaseous nitrogen used inside the rocket before propellant loading. While a similar issue with a supplier of gaseous nitrogen was experienced during a previous test attempt April 4, teams expect the supply to be reestablished shortly.  Following resolution of the issue, the launch director will give the “go” to officially begin the tanking process. Meteorologists with Space Launch Delta 45 said there were no weather constraints for the test. 

 Tanking begins with chilling down the liquid oxygen lines for the core stage. In sequential fashion, liquid oxygen (LOX) and liquid hydrogen (LH2) will flow into the into the rocket’s core stage tank and be topped off and replenished as some of cryogenic propellant boils off. The team also will conduct leak checks to ensure propellant loading is proceeding as expected.  Only minimal cryogenic operations are being conducted on the interim cryogenic propulsion stage because of an issue with a helium check valve found several days ago which cannot be fixed at the launch pad. Teams will chill down the lines used to load propellant into the upper stage but not flow any actual propellant to the stage. 

 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 Update: Rocket’s Upper Stage and Boosters Powered Up, Countdown On Track

The Space Launch System rocket’s interim cryogenic propulsion stage (ICPS) and boosters were powered up overnight. Teams are in the process of clearing all non-essential personnel from the launch pad area in preparation for propellant loading operations.  

At 6 a.m. EDT, or L-8 hours, 40 minutes, the launch team is expected to reach a planned 1 hour, 30-minute built-in hold. During this time the mission management team will review the status of operations, receive a weather briefing, and make a “go” or “no-go” decision to proceed with tanking operations. 

Tanking milestones include filling the rocket’s core stage with several hundred thousand gallons of liquid oxygen and liquid hydrogen. This will occur over a series of different propellant loading milestones to fill, top off, and replenish the tank. Because of an issue found several days ago with a helium check valve on the rocket which cannot be fixed at the launch pad, cryogenic propellant will not be loaded into the rocket’s upper stage.  

NASA is streaming live video of the rocket and spacecraft at the launch pad on the Kennedy Newsroom YouTube channel. NASA is also sharing updates on the Exploration Ground Systems Twitter account.   

The next blog update will be provided after the “go” or “no-go” decision to proceed with tanking operations.  

Artemis I Update: Countdown is Underway for Wet Dress Rehearsal

At approximately 5 p.m. EDT, or L-45 hours, 40 minutes before the initial targeted test T-0, the launch team arrived at their stations inside the Launch Control Center at NASA’s Kennedy Space Center in Florida. The countdown is now underway for the wet dress rehearsal test for NASA’s Artemis I mission.

Prior to “call to stations” the team completed several activities including closing the Orion crew module hatch and conducting leak checks. Technicians then closed the hatch on the launch abort system and conducted final activities in the White Room, the access point between Orion and the Mobile Launcher. The crew access arm, where the White Room is located, was retracted away from the spacecraft and rocket. On March 31, Orion was powered-up and will remain on throughout the duration of the test.

Teams are now filling the sound suppression system with water at the launch pad, which is used to dampen and absorb acoustic energy during liftoff. Even though the Space Launch System engines will not fire during this test, teams are practicing carrying out operations as they would on launch day.

Overnight, teams will charge the SLS core stage batteries and configure ground systems to power up the stage, and purge and remove ducts for the RS-25 engines. The next operational update will be posted the morning of April 2.

Watch a live video stream of the rocket and spacecraft at the launch pad now 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 from Jeremy Parsons, deputy manager for Exploration Ground Systems.

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