At approximately 9:15 a.m. EDT, NASA’s Space Launch System (SLS) rocket and Orion spacecraft for the Artemis I mission were secured inside the Vehicle Assembly Building at the agency’s Kennedy Space Center after a four-mile journey from Launch Pad 39B that began at 11:21 p.m. Monday, Sept. 26 ahead of the arrival of Hurricane Ian.
After the storm has passed, teams will conduct inspections to determine impacts at the center and establish a forward plan for the next launch attempt, including replacing the core stage flight termination system batteries and retesting the system to ensure it can terminate the flight if necessary for public safety in the event of an emergency during launch.
At 11:21 p.m. ET Monday, NASA’s Artemis I Moon rocket left launch pad 39B atop the crawler-transporter and began its 4-mile trek to the Vehicle Assembly Building (VAB) at NASA’s Kennedy Space Center in Florida.
Managers decided to roll back based on the latest weather predictions associated with Hurricane Ian not showing improving expected conditions for the Kennedy area. The decision allows time for employees to address the needs of their families and protect the integrated rocket and spacecraft system.
Fast fill continues for the Space Launch System (SLS) rocket’s core stage liquid hydrogen (LH2) tank at a reduced pressure as teams monitor the area where the hydrogen leak was detected. Fast fill is complete for the core stage liquid oxygen (LOX) tank and engineers have completed the engine bleed test, which flows supercold LH2 to the four RS-25 engines, bringing their temperature down to the conditions required for launch.
Teams have resumed the flow of liquid hydrogen into the core stage after warming up the quick disconnect, or interface where the fuel feed line connects to the rocket, to reseat the connection as part of their troubleshooting plan to fast fill the propellant.
Fast fill is underway for the Space Launch System (SLS) rocket’s core stage liquid oxygen (LOX) tank. Next, teams will transition from slow fill to fast fill for the liquid hydrogen (LH2) tank and initiate, or “kick start,” the engine bleed, which will begin flowing supercold LH2 to start cooling the four RS-25 engines down to the temperature conditions required for launch.
Following the Artemis I pre-launch briefing, meteorologists with the U.S. Space Force Space Launch Delta 45 predict a 60% chance of favorable weather conditions at the beginning of the two-hour launch window that opens at 2:17 p.m. EDT Sept 3, increasing to an 80% chance of favorable weather conditions toward the later part of the window. The primary weather concern for the two-hour launch window remains scattered rain showers. The weather guidelines for NASA’s Artemis I flight test identify conditions to launch the agency’s Space Launch System (SLS) and Orion spacecraft.
Teams will continue working their way through the countdown conducting planned health checks on SLS and Orion systems. The mission management team will meet early in the morning, Saturday, Sept. 3 and give the final determination for a “go” or “no-go” decision to begin tanking operations.
The uncrewed flight test will test SLS and Orion as an integrated system, demonstrating the performance of the rocket and testing the spacecraft’s capabilities as it journeys about 40,000 miles beyond the Moon over the course of about six weeks.
The first in an increasingly complex series of missions, Artemis I will pave the way for long-term lunar exploration, providing the foundation for extending human presence to the Moon and beyond.
Artemis Launch Director Charlie Blackwell-Thompson has given the “go” to officially begin loading propellants into the Space Launch System rocket. The launch weather officer now reports there are no indication of lightning within five nautical miles of Launch Pad 39B. Tanking begins with chilldown of the core stage liquid oxygen transfer line.
The Artemis I Mission Management Team has given the “go” to proceed toward tanking operations.
Weather conditions remain 80% favorable at the beginning of the two-hour launch window which opens at 8:33 a.m. EDT Aug. 29, with chances for rain showers increasing toward the later part of the window.
Artemis I launch director Charlie Blackwell-Thompson is scheduled to give the “go” to officially begin propellant loading operations just before midnight.
During tanking operations, teams will fuel the Space Launch System (SLS) rocket with liquid oxygen (LOX) and liquid hydrogen (LH2), beginning with the rocket’s core stage and then the interim cryogenic propulsion stage.
Tanking begins with chilling down the LOX lines for the core stage. The process for the chill down, or cooling, uses the propellant lines to load the rocket’s core stage LOX in preparation for tanking. The LOX tank holds 196,000 gallons of liquid oxygen, cooled to minus 297 degrees Fahrenheit. In sequential fashion, LOX and LH2 will flow into the rocket’s core stage tank and be topped off and replenished as some of the cryogenic propellant boils off.
The 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 the tank is filled at a quicker pump speed. As the super cold liquid oxygen fills the core stage tank, some venting may be visible. The team also will conduct leak checks to ensure propellant loading is proceeding as expected.
At midnight, NASA TV coverage begins with commentary of tanking operations to load propellant into the SLS rocket. Full coverage begins at 6:30 a.m. in English and at 7:30, coverage in Spanish begins.
Below are the countdown milestones as planned for tanking:
Core Stage LO2 transfer line chilldown (L-8H15M – L-8H)
Core stage LO2 main propulsion system (MPS) chilldown (L-8H – L-7H20M)
Core stage LO2 slow fill (L-7H20M – L-7H5M)
Core Stage LO2 fast fill (L-7H5M – L-4H15M)
Core Stage LH2 chilldown (L-7H15M – L-7H5M)
Core Stage LH2 slow fill start (L-7H5M – L-6H15M)
Core Stage LH2 fast fill (L-6H15M – L-5H5M)
Core Stage LH2 topping (L-5H5M – L-5H)
L-5 hours and counting
Core Stage LH2 replenish (L-5H – Launch)
ICPS LH2 ground support equipment (GSE) and tank chilldown (L-4H45M – L-4H30M)
ICPS LH2 fast fill start (L-4H30M – L-3H30M)
Orion communications system activated (RF to Mission Control) (L-4H20M – L-3H45M)
Core stage LO2 topping (L-4H15M– L-3H55M)
Core Stage LO2 replenish (L-3H55M – Launch)
ICPS L02 MPS chilldown (L-3H55M– L-3H45M)
ICPS L02 fast fill (L-3H45M– L-2H55M)
ICPS LH2 validation and leak test (L-3H30M – L-3H15M)
ICPS LH2 tank topping start (L-3H15M – L-2H55M)
L-3 hours and counting
ICPS/Space Launch System (SLS) telemetry data verified with Mission Control and SLS Engineering Support Center (L-2H55M – L-2H45M)
ICPS LO2 validation and leak test (L-2H55M – L-2H30M)
The Space Launch System rocket’s interim cryogenic propulsion stage (ICPS) has been powered up, the NASA test director has given the “go” for booster power up, and all non-essential personnel have left the launch pad area in preparation for propellant loading operations.
At 10:53 p.m. EDT, or L-9 hours, 40 minutes, the launch team is expected to reach a planned two 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 and replenish the tanks.
At midnight, NASA TV coverage begins with commentary of tanking operations to load propellant into the SLS rocket. Full coverage begins at 6:30 a.m.
Around 7:30 a.m. EDT the Space Launch System rocket and Orion spacecraft for the Artemis I mission arrived atop Launch Complex 39B at NASA’s Kennedy Space Center in Florida after a nearly 10-hour journey from the Vehicle Assembly Building.
In the coming days, engineers and technicians will configure systems at the pad for launch, which is currently targeted for no earlier than Aug. 29 at 8:33 a.m. (two hour launch window). Teams have worked to refine operations and procedures and have incorporated lessons learned from the wet dress rehearsal test campaign and have updated the launch timeline accordingly.