Orion swings by the moon on its way back to Earth

NASA’s Orion spacecraft flew by the moon for a second and final time Dec. 5, performing a maneuver that sets up the spacecraft for a splashdown in the Pacific Ocean in six days. The Orion’s European Service Module fired its main engine for 3 minutes and 27 seconds starting at 11:43 a.m. Eastern. The maneuver, called the Return Powered Flyby, took place during a close approach to the moon that brought Orion within 130 kilometers of the lunar surface. NASA officials said at a later briefing that the maneuver, the largest and last major engine burn of the Artemis 1 mission, went as expected, putting the spacecraft on a trajectory that returns it to Earth for a Dec. 11 splashdown. That maneuver “is essentially our deorbit burn,” said Judd Frieling, flight director at NASA’s Johnson Space Center, at the briefing. “This sets us up for the landing trajectory that going to occur on Dec. 11.” With the flyby complete, NASA is moving ahead with preparations for splashdown. Mike Sarafin, NASA Artemis 1 mission manager, said the mission management team gave its approval to deploy recovery forces on Dec. 7. That includes a U.S. Navy ship, the USS Portland, that will host the recovery forces and bring the Orion spacecraft onboard to return to the port of San Diego, California. Melissa Jones, landing and recovery director for the mission at NASA, said the recovery team completed a three-day rehearsal for the recovery last week. “We are ready and honored, as an integrated team, to bring Orion home on the last leg of her journey,” she said. Orion, which launched nearly three weeks ago, continues to perform well with only minor problems. That includes continuing issues with latching current limiters in the spacecraft’s power distribution system. Four of those devices had switched off during a test, affecting power to six reaction control thrusters. Controllers were able to restore power to those thrusters.

A view of the Orion spacecraft, moon and Earth during the Dec. 5 return powered flyby of the moon by Orion. Credit: NASA

“What it appears is that they were commanded open, but there were no commands sent,” Debbie Korth, NASA Orion deputy program manager, said of the current limiters at the briefing. “We’re not exactly sure of the root cause yet.”

She said engineers are doing some testing of the power system in a ground-based lab, and will likely propose some tests to do later this week on the spacecraft ahead of the end of the mission. “We discard the service module, so we have a pretty limited window if there’s anything we want to do before that happens.”

She and other agency officials at the briefing downplayed the significance of it, noting there are redundant systems onboard. Had it taken place on a crewed mission, Frieling said, the astronauts would have been informed on their displays, but would not have noticed any other effects.

There was also a communications outage lasting four and a half hours on Dec. 3 that was caused by a hardware problem with a Deep Space Network (DSN) center in Goldstone, California. The outage would have been longer, Sarafin said, but the mission was able to negotiate with other missions using the DSN to get time on the network.

Praise from former agency leaders

The success of the mission to date won praise from two previous top NASA officials who see it as evidence that the overall Artemis effort is now on track after years of development delays.

“I feel really good about it,” former NASA Administrator Jim Bridenstine said at a SpaceNews event Dec. 5. “I think one of the biggest achievements is that there’s a lot of hardware here that has been under development for a long time. The Artemis program just gave all that hardware a mission, which is what we needed in order to get to where we are today.”

“I think it truly is a great thing to see this mission being so successful, as Jim said. A long time to get here, for sure,” said former NASA Deputy Administrator Lori Garver at the same event.

Bridenstine, who gave the Artemis program its name while in office during the Trump administration, credited the Biden administration for retaining it. “NASA has a long history of programs getting cancelled, and billions of dollars being wasted,” he said. “And in this case, they kept continuity of purpose and moved forward and I’m just very grateful for that.”

Garver, deputy administrator during the Obama administration, noted the program brought together hardware started in various administrations. “I think the timing was right and it was good to do,” she said. However, she expressed skepticism that the technical approach, including use of the Space Launch System, was the right one for the long term.

“I do not believe that the country can or should probably spend the amount of money we are on launch infrastructure over the longer term. I think that when we have private launch capabilities that rival this we should transition, and that will make me feel a lot better about the future and the future success of Artemis,” she said.

She said she had argued against SLS and Orion while at NASA, but lost that argument. “I was clear when I was at NASA that, once that decision had been made, our job was to make it the very best vehicle we could have.”

“You did not lose the argument,” Bridenstine said. “You got the argument started. It is still going forward and it’s transitioning how we do space.”