WASHINGTON — An ongoing review of data from the Artemis 1 mission has shown no problems that would delay the crewed Artemis 2 mission, scheduled for launch late next year.
In a March 7 briefing, NASA leaders said analysis of data from the Space Launch System, Orion spacecraft and ground systems had found only minor issues that can be addressed ahead of Artemis 2.
The biggest problem, and one not previously disclosed, was with the heat shield on the Orion crew capsule. Howard Hu, Orion program manager at NASA, said the material on the heat shield had ablated differently than what engineers expected from ground tests and computer models.
“We had more release of the charred material during reentry than we expected,” he said. Engineers have just begun a detailed analysis of the heat shield to determine why it behaved differently than expected.
However, he said the difference in performance was not a safety concern. “We have a significant amount of margin left over” in terms of pristine or “virgin” Avcoat, the ablative material used on the heat shield. “I don’t think we hit any limits. From a margin perspective, it definitely took more of the Avcoat than we anticipated.”
Hu said work continues on a problem with the power system on Orion’s service module called a latching power limiter, which opened without command two dozen times during Artemis 1. The controller closed the limiters without any negative impact on the spacecraft’s power system.
The European Space Agency and Airbus, the main contractor for the service module, are planning a test at the end of the month to better understand what caused the uncontrolled events, such as electromagnetic interference. If those tests don’t find a root cause, he said, controllers on the ground or astronauts inside Orion can continue to close the restrictors manually on future missions. A software update may also fix the problem.
Ground systems engineers are repairing damage to the mobile launcher from the SLS launch. “There are a few things that took more damage than we expected,” said Shawn Quinn, who succeeded Mike Bolger as head of the Exploration Ground Systems program after the Artemis 1 mission.
This damage includes pneumatic lines corroded by debris from the solid rocket boosters; he said a problem with a gaseous nitrogen system delayed the supply of water to wash away the residue. The elevators in the mobile launcher tower were also knocked out of service, but one is now back in service.
Some post-splashdown work on 11 December, notably the removal of avionics units from the Artemis 1 Orion capsule to be refurbished and reinstalled on Artemis 2 Orion, took place ahead of schedule. It is unlikely to change the planned launch of Artemis 2, which is currently set for late November 2024.
“I don’t think it helps us move it in,” Jim Free, NASA associate administrator for exploration systems development, said of the Artemis 2 schedule. “We’ll certainly look for ways to build margin in our schedule. That’s how we look at it.”
That schedule calls for sending the SLS core stage from the Michoud Assembly Facility in New Orleans to the Kennedy Space Center in June or July, said John Honeycutt, NASA SLS program manager, a date “well in advance” of when it will be needed. Other SLS components are either at KSC or ready to be shipped as needed.
Hu said he expects to pair the Orion crew module with the service module in late June. In the first quarter of 2024, workers will begin stacking the combined SLS/Orion vehicle, Quinn said, to support a late 2024 launch.
Free said NASA still expects to have the next mission, Artemis 3, launched about a year after Artemis 2, but noted that it will depend on the progress of other elements, namely SpaceX’s Starship lunar lander and new spacesuits under development by Axiom Space. “Our plan has always been 12 months, but there is significant development that needs to happen,” he said. “That’s just the nature of trying to land people on the moon.”