NASA’s Lucy Mission Continues Work on Solar Array Deployment Fix

Lucy Solar Array Deployment

Lucy will explore the Jupiter Trojan asteroids – thought to be “fossils of planet formation.” Credit: NASA’s Goddard Space Flight Center

NASA’s Lucy mission launched on October 16, 2021, aboard a United Launch Alliance Atlas V rocket. Initially, everything seemed fine — Lucy was on its daring mission to explore Jupiter’s Trojan asteroids.

However, they soon hit a snag. Although both solar arrays deployed, one didn’t quite open all the way and latch in the fully deployed position. While the solar arrays are producing plenty of power, NASA is concerned that a main engine burn in the present configuration could damage the array. Therefore, the team decided to move forward with a plan to fix the problem.

NASA’s Lucy mission team is in the midst of that multi-stage effort to further deploy the spacecraft’s unlatched solar array. On May 9, the team commanded the spacecraft to operate the array’s deployment motor using both the primary and backup motor windings simultaneously to generate more torque, i.e. a harder pull. The motor operated as expected, further reeling in the lanyard that pulled the solar array open. After running the motor for a series of short intervals to avoid overheating, the team paused to analyze the results. Data from the spacecraft showed that the deployment was proceeding similarly to engineering ground tests, allowing the team to move forward with the second stage of the attempt. Analysis of the data also suggested that there was still additional lanyard to be retracted. The team sent the same commands again on May 12. Although this series of commands did not latch the solar array fully open, it did advance the deployment enough to increase the tension that stabilizes the arrays as was hoped.

Lucy Spacecraft Near Large Asteroid

Illustration of the Lucy spacecraft near a large asteroid with Jupiter visible in the distant background. Credit: Southwest Research Institute

On May 26, the spacecraft was again commanded to deploy the solar array. As in the first two attempts, both motor windings were operated simultaneously for short periods of time to avoid overheating. Afterward, the team again analyzed the data from the event, which again showed that the array was continuing to open. The team repeated the deployment command sequence a fourth time on June 2. While the array still did not latch, the data indicates that it continued to further deploy and stiffen throughout the attempt.

The team has several more opportunities to repeat these deployment commands. While there is no guarantee that additional attempts will latch the array, there is strong evidence that the process is putting the array under more tension, further stabilizing it. Even if the array does not ultimately latch, the additional stiffening may be enough to fly the mission as planned.

The spacecraft completed a trajectory correction maneuver on June 7. This was the first in a series of maneuvers the spacecraft will take in preparation for the mission’s first Earth gravity assist scheduled for October 16, 2022.

Launched on October 16, 2021, Lucy is the first space mission that will explore the Trojan asteroids. These are a population of small bodies that are left over from the formation of the solar system. They lead or follow Jupiter in their orbit around the Sun, and may tell us about the origins of organic materials on Earth. Lucy will fly by and carry out remote sensing on six different Trojan asteroids and will study surface geology, surface color, and composition, asteroid interiors/bulk properties, and will look at the satellites and rings of the Trojans. Credit: NASA’s Goddard Space Flight Center

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