Science and Exploration

Orion Enters The Moon’s Sphere of Influence

By Keith Cowing
Press Release
November 21, 2022
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Orion Enters The Moon’s Sphere of Influence
@AirbusSpace – #Artemis I – the Moon and the Earth (and @NASA_Orion) in one shot Taken during the Moon flyby of the Orion spacecraft 🛰️ powered by the @esa service module at more than 300,000 km from Earth and only a few hundred km above the Moon. Larger image

Five days into the 25.5-day Artemis I mission, Orion continues on its trajectory toward the Moon. Flight controllers in the White Flight Control Room at NASA’s Johnson Space Center in Houston captured additional imagery of the Moon using the optical navigation camera.

Gathering imagery of the Earth and the Moon at different phases and distances will provide an enhanced body of data to certify its effectiveness as a location determination aid for future missions under changing lighting conditions.

Orion completed its third outbound trajectory correction burn at 6:12 a.m. CST, firing the auxiliary thruster engines for a duration of 6 seconds at a rate of 3.39 feet per second to accelerate Orion and adjust the spacecraft’s path while en route to the Moon. The amount of speed change determines which of Orion’s service module engines – reaction control, auxiliary, or orbital maneuvering system – to use for a particular maneuver.

The spacecraft entered into the lunar sphere of influence at 1:09 p.m. CST, making the Moon, instead of Earth, the main gravitational force acting on the spacecraft. Overnight, Orion will conduct the fourth outbound trajectory correction burn in advance of the outbound powered flyby burn. Flight controllers will conduct the outbound powered flyby burn by firing the orbital maneuvering system engine for 2 minutes and 30 seconds to accelerate the spacecraft, harness the force from the Moon’s gravity, and direct it toward a distant retrograde orbit beyond the Moon.

The outbound powered flyby burn is the first of a pair of maneuvers required to enter a distant retrograde orbit around the Moon. NASA will cover the maneuver live starting at 7:15 a.m. EST on the agency’s website, NASA Television, and the NASA app. The outbound powered flyby will begin at 7:44 a.m., with Orion’s closest approach to the Moon targeted for 7:57 a.m., when it will pass about 80 miles above the lunar surface. Engineers expect to lose communication with the spacecraft as is passes behind the Moon for approximately 34 minutes starting at 7:26 a.m. The Goldstone ground station, part of NASA’s Deep Space Network, will acquire the spacecraft once it emerges from behind the Moon.

Mission managers currently have two active anomaly resolution teams. Anomaly resolution teams are a standard part of managing the mission by pulling together a team of technical experts to focus on a specific issue by examining data to understand the implications in a particular system. Activating a separate team for this work enables engineers and flight controllers to continue focusing on commanding and monitoring the spacecraft and assessing the progress of the flight test.

One team is currently looking at the star tracker system to understand a number of faults in the random access memory, which have been successfully recovered with power cycles. A second team is analyzing a few instances in which one of eight units located in the service module that provides solar array power to the crew module, called a power conditioning and distribution unit umbilical latching current limiter, opened without a command. The umbilical was successfully commanded closed each time and there was no loss of power flowing to avionics on the spacecraft. Both systems are currently functioning as required, and there are no mission impacts related to these efforts. Analyzing the data for these systems and understanding their behavior during an active flight test while the hardware is in the deep space environment will improve mission operations on Artemis I and future missions.

At 1:25 p.m. CST on Nov. 20, Orion had traveled 232,683 miles from Earth and was 39,501 miles from the Moon, cruising at 371 miles per hour. See which antennas are communicating with Orion in real-time on Deep Space Network Now and track Orion via the Artemis Real-Time Orbit Website, or AROW. 

Learn more about the Orion spacecraft in the Orion reference guide.

SpaceRef co-founder, Explorers Club Fellow, ex-NASA, Away Teams, Journalist, Space & Astrobiology, Lapsed climber.