JAXA 3-Way Doppler Support to Artemis I Mission

This paper presents a collaborative effort between NASA and JAXA to make 3-way Doppler data from JAXA tracking stations available to the Artemis 1 navigation team to improve orbit determination. The paper describes the system configuration and concept of operation of this capability. Testing effort at the three JAXA’s ground stations – the Uchinoura’s 20-m and 34-m antennas and Usuda’s 64-m antenna – are discussed. Both aspects of system testing are highlighted, first on the use of Artemis 1 recorded signal to ensure compatibility between ground and flight systems, and second on the tracking with the Lunar Reconnaissance Orbiter, as a substitute for Artemis before launch, to validate other key operational functions such as ephemeris processing, spacecraft tracking capability, data delivery, and interactions among multiple operational teams in different organizations. Results from actual support to Artemis 1’s Orion spacecraft in November-December 2022 are also presented.