On Saturday, Nov. 19, the Mission Management Team polled “go” for Orion’s outbound powered flyby past the Moon. NASA will cover the flyby live on NASA TV, the agency’s website, and the NASA app starting at 7:15 a.m. EST Monday, Nov. 21. The burn is planned for 7:44 a.m. Orion will lose communication with Earth as it passes behind the Moon from 7:25 a.m. through 7:59 a.m., making its closest approach of approximately 80 miles from the surface at 7:57 a.m.
During flight day four, flight controllers moved each solar array to a different position to test the strength of the WiFi signal with the arrays in different configurations. The Integrated Communications Officer, or INCO, tested the WiFi transfer rate between the camera on the tip of the solar array panels and the camera controller. The goal was to determine the best position to most efficiently transfer imagery files. Teams learned that having multiple cameras on at once can impact the WiFi data rate, and therefore, future solar array wing file transfer activities will be accomplished from one solar array wing at a time to optimize transfer time.
The Emergency, Environmental, and Consumables Manager, or EECOM, tested Orion’s radiator system. Two radiator loops on the spacecraft’s European Service Module help expel excess heat generated by different systems throughout the flight. Flight controllers are testing sensors that maintain the coolant flow in the radiator loops, switching between different modes of operation and monitoring performance. During speed mode, the coolant pumps operate at a constant rate. This is the primary mode used during Artemis I. Flow control mode adjusts the pump speed as needed to maintain a constant flow through the system. The flight test objective is to monitor system performance and the accuracy of flow sensors to characterize the stability of this mode of operation. Each loop is monitored in flow control mode for 72 hours to provide sufficient data for use on future missions.
As part of planned testing throughout the mission, the guidance, navigation, and control officer, also known as GNC, performed the first of several tests of the star trackers that support Orion’s navigation system. Star trackers are a navigation tool that measure the positions of stars to help the spacecraft determine its orientation. In previous flight days, engineers evaluated initial data to understand star tracker readings correlated to thruster firings.
Engineers hope to characterize the alignment between the star trackers that are part of the guidance, navigation and control system and the Orion inertial measurements units, by exposing different areas of the spacecraft to the Sun and activating the star trackers in different thermal states.
Just after 5:30 p.m. on Nov. 19, Orion had traveled 222,823 miles from Earth and was 79,011 miles from the Moon, cruising at 812 miles per hour. You can track Orion via the Artemis Real-Time Orbit Website, or AROW.
Overnight, engineers in mission control will uplink large data files to Orion to better understand how much time it takes for the spacecraft to receive sizeable files. On flight day five, Orion will undergo its third planned outbound trajectory correction burn to maneuver the spacecraft and stay on course to the Moon.