The Space Launch System (SLS) rocket and Orion spacecraft for the Artemis I mission are rolling to Launch Complex 39B at the Kennedy Space Center in Florida for the very first time. At about 5:45 p.m. ET, with the integrated SLS and Orion system atop it, the crawler-transporter began the approximately 4-mile, journey from the Vehicle Assembly Building (VAB) to the launch pad. Once outside the VAB high-bay doors, the Moon rocket will make a planned pause allowing the team to reposition the Crew Access Arm before continuing to the launch pad. The crawler-transporter will move slowly during the trek to the pad with a top cruising speed of .82 mph. The journey is expected to take between six and 12 hours.
After they arrive at the pad, engineers will prepare the integrated rocket and Orion spacecraft for a critical wet dress rehearsal test that includes loading all the propellants.
The rocket and spacecraft for NASA’s Artemis I mission have fully left Kennedy Space Center’s Vehicle Assembly Building (VAB) for the first time on the way to Launch Complex 39B for a wet dress rehearsal test.
The team is in a planned pause outside the building to retract the Crew Access Arm (CAA). The arm interfaces with the Orion spacecraft stacked atop the Space Launch System (SLS) rocket to provide access to the Orion crew module during operations in the VAB and at the launch pad. On crewed Artemis missions beginning with Artemis II, the access arm also will provide entry and exit for astronauts and payloads that will fly aboard. Several days before the rollout began, the arm was moved closer to the rocket to fit through the VAB door. Engineers are extending it to lock it in its travel position.
Once the CAA retraction is complete, the team will continue the four-mile trek to Launch Complex 39B.
Artemis is the first step in the next era of human exploration. Together with commercial and international partners, NASA will establish a sustainable presence on the Moon to prepare for missions to Mars.
Engineers will conduct the final test, known as the wet dress rehearsal, of the Space Launch System (SLS) rocket, Orion spacecraft, and Exploration Ground Systems before the Artemis I launch at LaunchPad 39B at NASA’s Kennedy Space Center in Florida. The rehearsal 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 approximately two-day test, teams will start by activating the facilities needed for launch and formally beginning the countdown sequence. Team will staff the Launch Control Center at Kennedy and connect with staff in the Mission Control Center at NASA’s Johnson Space Center in Houston, the Space Force Eastern Range, and the SLS Engineering Support Center at the agency’s Marshall Space Flight Center in Huntsville, Alabama. Launch controllers will power on different rocket and spacecraft systems, along with ground support equipment.
Teams will then load more than 700,000 gallons of cryogenic, or super cold, propellants including liquid hydrogen and liquid oxygen into the rocket at the launch pad on the mobile launcher according to the detailed timeline they will use on the actual launch day. They will practice every phase of the countdown, including weather briefings, pre-planned holds in the countdown, conditioning and replenishing the propellants as needed, and validation checks.
During the wet dress rehearsal, once launch controllers reach the point just before the rocket’s RS-25 engines will ignite on launch day, they will recycle back to the T-10 minute point, and then resume the countdown once more after a hold. The team will then deliberately halt the countdown at about 10 seconds before the simulated liftoff to demonstrate stopping a launch and draining the propellants from the rocket. Sometimes called a “scrub,” launch controllers may decide not to proceed with the launch if a technical or weather issue arises during or prior to the countdown, so demonstrating the ability to remove propellants will ensure teams are prepared for various launch day scenarios.
Several days after the wet dress rehearsal, the integrated rocket and spacecraft will be rolled back to the Vehicle Assembly Building (VAB). In the VAB, technicians will extend platforms to reestablish access to several parts of the rocket and spacecraft. They will remove sensors specifically used for monitoring during the wet dress rehearsal, charge Orion and other system batteries, stow late-load cargo into Orion, and run final checkouts on several elements, among other tasks. Orion and SLS will roll to the launchpad for a final time about a week before launch.
NASA will review data from the rehearsal before setting a specific target launch date for the Artemis I launch. The first in a series of increasingly complex missions, Artemis I will provide a foundation for human deep space exploration and demonstrate our commitment and capability to extend human existence to the Moon and beyond prior to the first flight with crew on Artemis II.
Source: NASA