How extreme is the speed of a 322 feet rocket? At Kennedy Space Center, it is approximately 11 mph that snail pace is part of the point.
The Space Launch System and Orion crew capsule constructed by NASA traveled the distance between the Vehicle Assembly Building and Launch Pad 39B on a crawler-transporter, which was a common hardware of the Apollo and the shuttle program, but redesigned to support heavier loads. The combined stack is about 11 million pounds and the actual speed gives the technicians time to inspect loads, clearances and ground connections as the vehicle passes through the assembly phase to enter the launch phase.
To the Artemis II crew, Commander Reid Wiseman, Pilot Victor Glover, Mission Specialist Christina Koch, and Canadian Space Agency astronaut Jeremy Hansen, the rollout process is one of the most observable ones leading to a mission that will do something NASA has not tried to do since 1972: send people around the Moon and back. The designed flight is an out-and-back flight of a free-return flight taking a round trip of approximately 10 days on a free return orbit, missing the moon, but circling around the back end of the moon and then utilizing the lunar gravity to curve the Orion back to the earth. The mission will not go to the lunar orbit and will not seek to send the rocket and the spacecraft to land, however it will be aimed at confirming the entire end-to-end system: the rocket, the spacecraft, ground teams and recovery.
“What a great day to be here,” Wiseman said during the rollout. “It is awe-inspiring.”
The second SLS launch has the burden of Artemis I lessons including the test that uncrewed the 2022 test that landed Orion around the Moon and returned it to Earth. The mission revealed some unforeseen friction in the heat shield of Orion, where scalding protective material burned away in a manner engineers had not anticipated. The reaction has been a combination of experimentation, inspection and operational modifications that now determine the final preparations of Artemis II-at least as the program changes to not demonstrating that a vehicle can fly, but that it can fly with people on board.
NASA work is now more procedural than cinematic, connecting electrical and environmental control wires, attaching propellant and pneumatic hoses, and bringing the entire vehicle to life in its launch shape. One of the most important milestones is the wet dress rehearsal, fueling and countdown this involves loading over 700,000 gallons of cryogenic propellants as well as testing the team through terminal-count holds, resumes and recycle. It is during that “tanking” rehearsal that the most stringent tolerances of the launch system tend to emerge, be it in the handling of hydrogen, the functionality of ground hardware, and it is during that rehearsal that closeout crew rehearses how to get astronauts into Orion and put the hatch together.
Timing of launch, on the other hand, is not an easy issue of when the rocket is ready. The cycle involved in mission planning is the rotation of the Earth and the monthly movement of the Moon, which results in clusters of days that can be safely launched with intervening periods between them, and the path has to ensure that Orion does not spend too much time in the dark to ensure that its solar arrays can continue to operate and the temperature stays below dangerous limits. The free-return design of the mission places an extra requirement on making the right geometry to achieve a trans-lunar injection and to reach Earth with the right entry corridor.
The most evaluated engineering change can be found at entry in the Artemis II. The plan of NASA (moving forward) is based on retaining the current heat shield of Orion, but a modified return profile to minimize the conditions suspected of the material loss during the Artemis I flight. Other NASA press releases also related further examination of the structure underlying Orion, such as of so-called “damage tolerance” work which was expected to restrict the consequences in the event of the loss to the outer layer of larger parts of the outer layer than had been previously planned.
Once the rollout has happened, the next public facing point of the program is not about spectacle as much as discipline pass the fueling demonstration, pass the flight ready check and only then schedule a date. NASA authorities have stressed the order, among other aspects Jared Isaacman remarks that there was no intention to communicate a real launch date until the propellant test is run.
The trip that the crawler undertakes is terminated at the pad. The more difficult adventure–that a system to go to the moon will be crew-ready–is still going on in checklists, valves, data checks, the silent urgency that the next step is going to make the next.