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How did the JWST plan for alternative scenarios?
The NASA James Webb Space Telescope (JWST) mission successfully launched on Dec 25, 2021, at 12:20 Coordinated Universal Time (UTC). During the 30-day transfer to the second Sun-Earth-Moon (SEM) libration point (L2), JWST executed three mid-course correction (MCC) maneuvers to insert into a quasihalo orbit about L2. This paper covers the design and modeling for these three maneuvers with a focus on the timeline around the execution of each MCC maneuver. It will summarize the actual on-board events as well as the contingency preparation done for maneuver planning, monitoring, and final post-burn reconstruction of all three MCC maneuvers.
Introduction
The NASA James Webb Space Telescope (JWST) launched on December 25, 2021, at 12:20 UTC and was inserted into the second Sun-Earth-Moon (SEM)libration point (L2) operational orbit using three MidCourse Correction (MCC) maneuvers. The JWST MCC maneuvers are unique to other libration orbiters, due to attitude restrictions from thermal requirements and orbit determination challenges in the stowed and deployed sunshield configurations. This paper covers the application of MCC maneuver planning (MP), using both orbit determination (OD) knowledge and MCC burn monitoringand reconstruction. Finally, the paper reviews the long-term impact on propellant use and future JWST flight dynamics operations.
This is a part of a series of papers on JWST flight dynamics operations, with this paper focused on MCC real-time support. The overall JWST flight dynamics support is detailed in Reference 7. The finalized MCC design as a result of launch and impacts is seen in Reference 4, while the sunshield deployment orbit determination is more deeply detailed in Reference 9. Older papers have explored the impact of JWST MCC maneuver design from the initial launch insertion orbit effects, 11 resultant long-term libration orbit characterization,1 Monte Carlo testing of nominal MCC burn designs, 5 and MCC contingencies and designs. 6 Finally, Reference 10studies orbit determination ground stations contact schedule variations and their impact on maneuver design.
Figure 1 shows the JWST configuration post-sunshield deployment. It contrasts the stowed configuration shown in Figure 2. Together, these two images demonstrate the different spacecraft models that were used during the MCC maneuvers.
Figure 1. JWST Hardware Overview
JWST is a NASA flagship observatory that will observe astronomical phenomena in the near- to midinfrared spectrum in the exploration of dark matter, first light from galaxies, exoplanets, and other astronomy research topics. A pre-launch image of the JWST observatory prior to rocket payload integration and with a stowed mirror can be seen in Figure 2. The launch window was designed for maximum opportunities throughout the calendar year, with monthly limitations due to the Moon and the use of a fixed launch trajectory profile. Further analysis on the on-orbit launch profile performance and launch window can be seen in Reference 11.
Figure 2. JWST Pre-Deployment Stowed Configuration3
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