WASHINGTON — An ongoing review of data from the Artemis 1 mission has turned up no issues that would delay the crewed Artemis 2 mission scheduled for launch late next year.
In a March 7 briefing, NASA managers said that 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 issue, and one not previously disclosed, was with the heat shield on the Orion crew capsule. Howard Hu, Orion program manager at NASA, said that material on the heat shield had ablated differently than what engineers expected from ground tests and computer models.
“We had more liberation of the charred material during reentry than we had expected,” he said. Engineers are just beginning 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 issue. “We have a significant amount of margin left over” in the form of untouched or “virgin” Avcoat, the ablative material used on the heat shield. “I don’t believe we reached any limits. From a margin perspective, certainly it took more of the Avcoat off than we had expected.”
Hu said work is continuing on an issue with the power system on Orion’s service module called a latching current limiter, which opened without being commanded two dozen times during the Artemis 1. Controller closed the limiters without any adverse impact on the spacecraft’s power system.
The European Space Agency and Airbus, the prime contractor for the service module, are planning a test at the end of the month to better understand what caused the uncommanded 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 manually close the limiters on future missions. A software update could also address the problem.
Ground systems engineers are fixing damage to the mobile launcher from the SLS launch. “There are a few things that did receive more damage than we expected,” said Shawn Quinn, who succeeded Mike Bolger as manager of the Exploration Ground Systems program after the Artemis 1 mission.
That damage includes pneumatic lines corroded by residue from the solid rocket boosters; he said a problem with a gaseous nitrogen system delayed the supply of water meant to wash that residue away. The elevators in the mobile launcher tower were also knocked out of commission, but one is now back in service.
Some work after the Dec. 11 splashdown, notably the removal of avionics units from the Artemis 1 Orion capsule to be refurbished and reinstalled on the Artemis 2 Orion, took place ahead of schedule. That is unlikely to change the planned launch of Artemis 2, 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 will certainly look for ways we can build margin in our schedule. That’s how we look at it.”
That schedule anticipates shipping 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’s needed. Other SLS components are either at KSC or ready to be shipped when needed.
Hu said that he anticipates mating the Orion crew module with the service module in late June. By the first quarter of 2024 workers will start 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, launch about a year after Artemis 2, but noted 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 are significant developments that have to occur,” he said. “That’s just the nature of trying to land people on the moon.”