Explore the Orbit Determination Strategy of the JWST

The James Webb Space Telescope (JWST) was launched from Kourou Spaceport on December 25, 2021, at 12:20 UTC on an Ariane 5 launch vehicle. The launch vehicle inserted JWST into a 30-day transfer trajectory to the Sun-Earth-Moon (SEM) Lagrange point L2 region. JWST executed three mid-course correction maneuvers (MCCs) to insert the spacecraft into a quasi-halo orbit about SEM L2; JWST will maintain its trajectory about L2 for at least 5.5 years, with a goal of at least 10.5 years. This paper summarizes the flight dynamics support for JWST, including the prelaunch nominal trajectory design, the launch window analysis, contingency planning for trajectory-related anomalies, mission operations support for the first 6 months, and a comparison of the planned and achieved actual JWST trajectory results. The orbit determination strategy, both planned and executed, will be summarized, and the method of addressing the anomalies as they occurred will be included.

Introduction

The James Webb Space Telescope (JWST) is a deep space infrared observatory investigating the history of the universe. JWST was launched December 25, 2021, at 12:20 UTC from Kourou Spaceport, French Guiana on an Ariane 5 with a cryogenic upper stage, the ESC-A+, into a transfer trajectory to the Sun Earth-Moon (SEM) L2 region. After injection, JWST performed midcourse corrections (MCCs) using a bi-propellant propulsion system to finalize injection into a quasi-halo orbit about the SEM L2 region one month after launch; station-keeping orbit maintenance began approximately 21 days later.

This paper will give a brief overview of the JWST mission and the transfer trajectory, followed by a discussion about prelaunch support, focusing on the trajectory-related aspects of the mission. There will be a brief summary of the support provided by the personnel, the Flight Dynamics Team (FDT) and facilities, primarily the Flight Dynamics Facility (FDF) at NASA Goddard Space Flight Center (GSFC). The launch events and MCCs as flown will be compared to prelaunch nominal predictions and the impacts will be discussed, followed by conclusions.

 

 

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