WASHINGTON — NASA has approved plans to move on to the critical next step of the Artemis 1 mission, a maneuver of the uncrewed Orion spacecraft as it flies close to the moon Nov. 21.
NASA announced in late Nov. 19 that the Artemis 1 mission management team had approved the Powered Outflight (OPF) maneuver, a burn-out by Orion’s main engine as the spacecraft passes about 130 kilometers in the air. above the lunar surface. The maneuver will send Orion into a distant retrograde orbit around the moon.
The burn, expected to last two and a half minutes, is scheduled for 7:44 a.m. Eastern Time on Nov. 21. The maneuver will take place while the spacecraft is behind the moon, during a 34-minute blackout period between 7:25 a.m. and 7:59 a.m. Eastern Time, when the spacecraft is not in communication with Earth. .
“This is absolutely a critical burn. This is the one Orion needs to achieve,” said Jim Geffre, Orion vehicle integration manager at NASA’s Johnson Space Center, during a briefing on Tuesday. November 18. Combustion can be done by the main engine or multiple auxiliary thrusters if there is a problem with the main engine.“We designate it as critical, which is why we have configured the software to ensure that burning occurs.”
A second maneuver, scheduled for November 25, will insert Orion into the distant retrograde orbit, ranging up to 432,000 kilometers from Earth. It will remain in this orbit for six days before performing two more maneuvers to exit orbit and fly close to the moon again, returning to Earth.
During the briefing, agency officials said Orion has been performing well since its Nov. 16 launch during the test flight. “Overall, the mission, in just three days, is proceeding and exceeding expectations,” Mike Sarafin, Artemis 1 mission manager, said during the November 18 briefing.
The mission was not without problems, however. He said they looked at 13 anomalies, most of which he said were “relatively benign” and learned about system performance. A problem, with the spacecraft’s star trackers, necessitated the convening of an anomaly resolution team which concluded its work at the Nov. 18 briefing.
Sarafin said the problem with star trackers was “dazzling” imagers by plumes from thrusters. “The thrusters were picked up by the star tracker because it was pushing above the star tracker’s field of view, by design,” he said. “The light was hitting the plume and it was picking it up,” confusing the software.
“The star tracker itself works perfectly,” Geffre said, noting that the problem stemmed from a combination of factors that couldn’t be fully simulated in the field. He said he expects to see the issue “periodically” throughout the mission, but the team is now ready to handle it.
The issue never violated flight rules, said flight director Jeff Radigan. “It was really a case of us seeing something that we didn’t understand,” he said. “At all times, they provided us with measures that could allow the mission to continue.”
Sarafin said the agency was also evaluating the performance of the Space Launch System rocket that launched Orion. “All indications were that the system was working perfectly,” he said, noting that the core stage and boosters placed Orion and its upper stage ICPS very close to its intended altitude, and that the ICPS burn that sent Orion on the moon “was exactly where we expected it to be.
The launch also caused damage to ground systems, such as the mobile launch platform, creating pad-level hazards that delayed photographers taking remote cameras for two days. This included nitrogen and helium gas leaks, as well as elevator blast doors that were blown out, knocking out the mobile launcher’s elevator, according to Sarafin.
“We anticipated a certain amount of damage, and they are seeing a certain amount of damage,” he said. “The mobile launcher itself worked well. We just have to work our way through some of the damage assessments.
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